Diesel hot water systems

[whatcharterboat]

Continued from "More design ideas / questions"

Dontpanic42 said

I am really enjoying this exchange and am learning a lot. I have been interested in retro fitting my camper with a diesel hot water system and cooker. I really want to lose the propane syetem. Here in the lower 48 and particularly the Republic of TEXAS, they act as you are out of your mind for suggesting such a thing. Can you point me towards some websites, vendors, or reference materials so that I can learn more about the systems and availability.

Bruce, Sorry for sounding dumb but what does the “lower 48” mean?

I’ll just throw you some info on diesel heating systems now and maybe this will help. Also I must emphasize that any installation that differs from the manufacturers recommendations should be checked with them before going ahead blindly. And that this post will refer only to Webasto’s products that we have used and may not specifically apply to others or other brands.


I really want to lose the propane syetem ……….they act as you are out of your mind for suggesting such a thing

LOL. Same here and our propane (LPG) systems in Australia are nowhere near as advanced as in the States. Not the stoves and hot water systems but the propane storage itself . In Aus we don’t have tanks > just bottles. So storage is more limited. LPG is still the norm here for camping but we stopped installing it in our motorhomes about 3 years ago and haven’t looked back.. We also use alcohol yacht stoves/ovens as an alternative to the diesel cooktops depending on the clients’ preference but I’ll concentrate on the hot water systems for now.

Terms I’ll use:
diesel furnace : heats coolant and normally has a pump attached or built in
calorifier : a storage tank with 1 or 2 coolant / heat exchange circuits passing through it
dual top: one unit that combines a furnace , watertank and fan and does NOT heat coolant
space heater: a radiator/fan combo similar to a normal under dash unit.

A typical “diesel furnace” based hotwater system comprises of a furnace that draws diesel prefererably straight from the vehicles fuel tank. (BTW best practice is to install a separate pick up in the main tank as opposed to a “T” into the main fuel line.). However there is nothing wrong from running a separate tank for the furnace supply if you need to set it up this way to allow for removal of the camper or if we are talking about a camper trailer/caravan.

Typically the furnace heats coolant in a circuit, which can run through a calorifier and the trucks cooling system. As an example in an FG this circuit can simply be “T”ed in parallel with the factory cabin heater. Also a space heater can easily be plumbed in parallel with the calorifier (BTW if you do this put an isolation “Gate” valve in series with the space heater so that it can be shut off in summer OR so the coolant can be fine tuned to flow more or less through the heater or calorifier).

So what we now have is an engine, furnace and a calorifier/space heater in a circuit. When the engine runs the coolant heats the calorifier and the furnace remains off. When the furnace runs it heats the calorifier AND the engine so you have your pre heat for cold climates/sub zero starting. The tricky bit is isolating the engine from the circuit, so that when you don’t need the engine pre heat you aren’t losing coolant heat through the engine block when you are camped up but still retain the engine coolant heating when you are traveling.

2 or more ways to do this. Firstly you can isolate the truck with manual valves but this is a bit off a hassle to do all the time or alternatively you can use solenoid valves. More than a couple of hundred bucks each here and you need 2 of them. (BTW make sure you get the “normally closed” or “normally open” bit right so that the valves are energized only when the ignition is “on” and not drawing power when your camped up. So when you are driving the engine is IN the circuit and when you are camped the engine is OUT of the circuit.

If engine pre heat is not a priority, another option is to use a dual circuit calorifier. This gives you an engine coolant heating through one circuit of the calorifier and the furnace runs through the other circuit. The down side here, although minor, is that you have to have a separate coolant header tank for this circuit. With the first option, of course, the engines’ radiator is in effect the header tank and point of fill.

The calorifiers come in a big range sizes from 10 litres up and we have even used a straight heat exchanger (about the size of a brick) with no storage tank at all and this was still successful.

While this next option may not be the most efficient, it is probably the one we do most of and particularly suits short stays and fairly constant travel rather than periods camped up. That is to simply have a calorifier “T”ed in parallel with the engine. If you pull up in the afternoon clients tell me that they still have hot water for a shower the next morning and if it’s necessary you can run the engine for 20 minutes to give you enough heat for a shower. Sure that’s a lot of fuel just for a shower but do the math. You’re charging batteries at the same time and saving the cash outlay of the furnace. Not the way I’d go but simple all the same. I’d prefer to camp up for long periods.

Actually I spoke to the guys at Watts2c (See thread “Simple electrical system for expedition vehicles) regarding development of a new water-cooled DC Genset and the possibility of plumbing a calorifier into its’ coolant circuit. This would be another way to possibly eliminate the furnace say if the genset was to run for ½ an hour a day.

The last common option is to run a Dual Top. We haven’t used one yet but I’m sure they have a place. They don’t run coolant at all and heat the water directly. Also they have 2 hot air outlets that can be ducted into the vehicle for space heating. So a bit of co-generation going on there. Very compact and have a tank built in.

Some other points to make here are that the calorifiers all have an electrical heating element built in so that if you pull into a vanpark or a mates’ place you can run off electricity for awhile and the other point for now is that if you are going to run a calorifier especially plumbed into the engine then fit a thermastically controlled temperature kit to it as a safeguard. These are an adjustable valve that goes on the hotwater outlet of the calorifier and mixes with coldwater to give set output temperature..Very simple to set up but well worth it. If the engine has provided the heat the temps can get very hot and vary so its’ not as simple as dialing down the thermostat on the furnace.

If you could follow all that you’ve done well cause I went to sleep about 3 paragraphs ago. Open for questions but like I said I’m sure there are guys a lot smarter than me around here but this stuff works really well in our climate here and I know all the clients are happy not having to worry about gas.

Hope this helps Bruce. Guess Texas climate would be similar to here too.
Regards John.

[DontPanic42]

John,
Thanks for the info. I appreciate you taking the time to put it together.
"Lower 48" refers to all the States in the US south of Alaska and Canada. Guess I picked it up from friends and relatives in Eastern Canada.
I must admit it took me a bit to catch on to what "Oz" is.
Thanks again. Don't be surprised if I ask some very basic questions in the near future.
Bruce

[FusoFG]

John,

Nice summary of diesel options.

I have an Espar furnace, an Indel single heat exchanger circuit calorifier and 2 space heaters connected to the engine as you suggested.

Some additional points:

I use a "Ball" valve instead of a "gate" valve to isolate the engine from the furnace. You can tell whether the valve is open or closed just by looking and you won't break something by trying to turn the handle the wrong way thinking the valve is jammed.

I think you only need a valve in one of the coolant lines between the engine and furnace to stop the coolant flow. Think cab heater control.

A calorifier with 2 heat exchanger circuits not only needs a coolant header tank in the furnace circuit, it also might need 12v pumps to move coolant in the circuit that's not "hot".

I insulate any long coolant hoses between the engine, furnace and space heaters that are exposed to outside temperatures to save diesel when heating the camper in cold weather.

I use both the espar timer and a battery operated room thermostat to control the furnace.

I use the timer when I want engine preheat at a certain time of day or if I want to run the furnace for 15 - 20 minutes to heat shower water after sitting for a day or so.

I use the thermostat to keep the camper comfortable when camped incold weather. It's programmable to a cooler setting at night and a warmer setting in the morning.

The space heater fans can be controlled by the furnace control (that's how I did mine) or they can be controlled by an "aquastat" that doesn't turn the fans on until the coolant reaches a certain temperature. Prevents the space heater from blowing cold air waiting for the furnace to get hot.

You are absolutely right about the requirement for a mechanical thermostat valve on the calorifier. When heating water with the engine it can reach over 212 F (100C). Even the diesel furnaces can reach 180F. This may cause severe burns.

Calorifiers for use on boats are designed to be heated by engine coolant and often come with a thermostatic mixing valve from the factory (at least in the US).

Maybe it should be a separate thread, but if you're going to use a diesel furnace to avoid propane (lpg) you also need to change the propane cooktop.

You mentioned marine alcohol cooktop / oven. People like alcohol on a boat because the fire can be extinquished with water.

But alcohol requires carrying another fuel and an alcohol flame is almost invisible so a fire can start unoticed pretty easily. I had a friend that burnt his boat to the waterline because a fire spread from his cooktop before he saw the flames.

I think a diesel cooktop is the way to go.

There are 2 types - an open flame burner similar to a alcohol or propane cooktop and the sealed burner typed manufactured by Wallas and sold by either Wallas or Webasto.

The open flame type has a distinct diesel smell and requires alcohol to preheat the burner.

The sealed version doesn't smell and has an outside exhaust to reduce condensation from water vapor created by combustion.

The newest version has a switch to allow high altitude operation, a complaint lodged against older versions.

I've never had any trouble with my older version unless battery voltage was too low for the built in glow plug or the camper was parked so wind blew in the exhaust pipe. The newest model can exhaust through the floor which would eliminate the wind problem.

Tom

[Mickldo]

My first introduction to Webasto products was when I worked on this GU Patrol camper. It had diesel stove fitted. In the top photo you can see the back of the stove on the top shelf and the separate diesel tank/bottle on the bottom shelf. You can also see the exhaust pipe/stainless skin fitting at the bottom left.

http://inlinethumb27.webshots.com/16538/2051108640103919311S600x600Q85.jpg (http://good-times.webshots.com/photo/2051108640103919311lApOQf)

http://inlinethumb17.webshots.com/36688/2380867860103919311S600x600Q85.jpg (http://good-times.webshots.com/photo/2380867860103919311IKDzry)

[Mickldo]

If when setting up the hot water system and for a calorifier you want a bigger one or you need a more compact one there heaps of others available on the market.

Isotherm - BLA (http://www.bla.com.au/index.php?fn=keywordAction&id=2263&elt=pg&dId=1&eId=10&sId=224202a16a9e13a4f7fec57ec78b5d9f)

Woodies - Marine Direct (http://www.marinedirect.com.au/catalogue/category1158/p173889)

[whatcharterboat]

"Lower 48" refers to all the States

Bruce. Of course. But now I do feel dumb.

Tom, Glad you replied cause it will clear a few things up.


I use a "Ball" valve instead of a "gate" valve to isolate the engine from the furnace.

I should have said that we do too. Of course in any "on/off" or isolation only type situation a ball valve is the correct type for all the reasons that you stated. In the situation I refered to (in space heater circuit parallel to the calorifier ) where you may need some adjustment (albeit a little crude), IMO a gate valve is more suitable.


I think you only need a valve in one of the coolant lines between the engine and furnace to stop the coolant flow. Think cab heater control.

I could never picture this happening. Remember I live in the sub-tropics so I am the last person to claim to be an expert in "engine pre-heat" but when we have been doing a typical system it has been with a “normally closed” solenoid valve before the one of the “T”s in the engine heater line and a “normally open” solenoid valve between the 2 lines heading to the “T”s in the heater line. I’m sure a diagram would explain this better. Let me know if it’s not clear as mud. So anyway this gives you flow from the engine heater line through the “normally closed “ valve, through the furnace and calorifier and back to the other engine heater hose when the engine is running and the solenoid valves are energized.

When you are camped up the first valve closes the circuit from the engine heater (eliminating coolant flow through the motor but still maintaining coolant level through the other engine heater line). Then the second valve opens and allows a bypass loop so the furnace can pump in closed circuit. As this is wired, it doesn’t allow for pre heat but could easily be reconfigured (electrically) that way if required.

Tom. Do you want a diagram? Very keen to learn from your experience on this one.


A calorifier with 2 heat exchanger circuits not only needs a coolant header tank in the furnace circuit, it also might need 12v pumps to move coolant in the circuit that's not "hot".


Webasto furnaces have a pump either built in or attached to the out side case. They are also "freeflowing" . Not the correct terminology but let's just say that the engine heater coolant can easily pass through the Webasto pump when the pump is "off".


I insulate any long coolant hoses between the engine, furnace and space heaters that are exposed to outside temperatures to save diesel when heating the camper in cold weather.

Absolutely, but the G O is to have the hose runs as short as possible. We use the same hose insulation as we use on the air con pipes. A good tip to make it easy to slide over your heater hoses is to use plenty of talcum powder.


I use the timer when I want engine preheat at a certain time of day or if I want to run the furnace for 15 - 20 minutes to heat shower water after sitting for a day or so.

I use the thermostat to keep the camper comfortable when camped incold weather. It's programmable to a cooler setting at night and a warmer setting in the morning.

The space heater fans can be controlled by the furnace control (that's how I did mine) or they can be controlled by an "aquastat" that doesn't turn the fans on until the coolant reaches a certain temperature. Prevents the space heater from blowing cold air waiting for the furnace to get hot.


This sounds great. The furnace heat adjustment on the Webastos is excellent but we haven't really played with the space heaters that much.The space heaters we use are really small and only run 1 or 2 computer fans. After reading this I will look at thermostat control for these on the next one for sure.


Maybe it should be a separate thread, but if you're going to use a diesel furnace to avoid propane (lpg) you also need to change the propane cooktop.

You mentioned marine alcohol cooktop / oven. People like alcohol on a boat because the fire can be extinquished with water.

But alcohol requires carrying another fuel and an alcohol flame is almost invisible so a fire can start unoticed pretty easily. I had a friend that burnt his boat to the waterline because a fire spread from his cooktop before he saw the flames.


Yes it requires another fuel but they are still excellent > easy to use and install , self contained (no wiring or plumbing), have an oven (Webasto don't at this point) and relatively safe and virtually nothing to go wrong (so I'm told anyway).

Can relate to the boat story. My brother said he helped put out an alcohol fire on a neighboring boat and while they saved it, they used 3 extinguishers to do it. Imagine if they only had 2. So while I think of alcohol (metho) as dangerous fuel, the newer generation of metho stoves are much safer than the older units. They no longer use a tank but rather use flat cans full of material similar to a fuel cell in a modern race car. Therefore they are non-splillable and the fill opening must be about 2 & 1/2" diameter.

We aren't really biased either way. Diesel or metho. The diesel works out at more money but as you say > only one fuel that can be sucked straight from the main tank. So I suppose less hassle (if it all goes to plan).


There are 2 types - an open flame burner similar to a alcohol or propane cooktop and the sealed burner typed manufactured by Wallas and sold by either Wallas or Webasto.

The open flame type has a distinct diesel smell and requires alcohol to preheat the burner.

The open flame type doesn't sound that great. Never seen one in a motorhome before.


The newest model can exhaust through the floor which would eliminate the wind problem.


The Webasto cooktop have an exhaust for the diesel fumes that runs out through the floor and a larger one that forms a shroud around it and blows air from underneath the cooktop and out around the smaller pipe which also cools the smaller pipe as it passes through the cupboard and then the floor. Webasto also provide extremely detailed installation instructions regarding the running of the exhausts.


The newest version has a switch to allow high altitude operation, a complaint lodged against older versions.


Tom. Any idea how a metho stove would rate against this diesel unit at altitude. Oz is basically flat (and hot) so I can't comment on this either but at what altitude is a diesel or alcohol stove affected? What happens? Performance drops away or just won't work at all??

Last thing. Took a pic for you today. If you end up with a Webasto product, they come with a complete fuel pick up/ filter / supply line kit. They advise that this is better than "t"ing into the main truck fuel line. Most of our campers get a custom fuel tank and we add seperate pick ups for these type of devices. However most Mitsubishi and Isuzu trucks use "Tokyo Radiator" fuel tanks as standard, which have a spare /inspection plate so it's easy to just drill through this plate to fit the Webasto pick up. Just be careful that the down pipe doesn't conflict with the swing of the fuel gauge sender.

Thanks for the reply Tom.

http://farm4.static.flickr.com/3187/2918598384_ef7ce237de.jpg
http://farm4.static.flickr.com/3255/2918596678_103a90f2d2.jpg

[Bogo]

FYI: for those stuck with gas (petrol) powered engines you can get a petrol fired boilers from Espar. They have two in their lineup. Sadly they don't make an air output furnace like the diesel ones they have.

Hydronic 4
http://www.espar.com/html/products/hydronic4.html

Hydronic 5
http://www.espar.com/html/products/hydronic5.html

[spressomon]

Since everyone here seems to know alot about hydronic heaters and because I'm basically lazy :sombrero: can one of the Espar water heaters be utilized in trailer application for on-demand water heating? How long does it typically take (I know this is a function of water temp...but just a general guide question) take to get hot water (100 degrees F) from the time the Espar is fired up to the heated water?

Can the Espar water heater be utilized in a stand-alone type application such as a little trailer?

Thanks in advance,
Dan

[Bogo]

The Espar Hydronic series of boilers specifically state they are for heating coolant water only, not fresh potable water. There is nothing to stop you from running that cooleant water through a water to water heat exchanger. Just remember to plumb your water to water heat exchanger so it is easy to fully drain the fresh water side when the camper is stored during freezing weather. You'd need a coolant expansion and reservoir tank in the coolant loop. Might as well add air heating heat exchangers too.

[Bogo]

Just thought of this. A small car engine radiator and overflow tank could be used as the expansion tank and water to air heat exchanger. You'd need a fan but that is easy. Often small car ones are electric.

The gas fired Espar units are max 4300W and 5000W output so their instant water heating capacity is limited. Diesel fired boilers are available with much higher outputs. They should be able to heat water on demand for a shower head like used on the sun shower bags. I'd plumb in a temperature limiter valve after the heat exchanger in the fresh water side and set it for the desired shower temperature.

I'm planning on using a gas fired unit in my micro RV for heating and may go with a small calorifier for hot water. IsoTemp has a slim line 5 gallon unit that looks tempting.

[Bogo]

Another thought I had in my notes: The tank for a heater could be a jerry can. I have heard of people doing this and have ran across caps for jerry cans that have fuel pickups and fill volume senders already installed in them. I figured I'd just make my own cap/pickup unit when the time came.

[Bogo]

I'm in the process of designing the Micro RV which is to be built on a '94 Toyota 4x4 mini truck pickup (Hilux). Space is at a real premium so I decided to go and get the sizes of the Hydronic 5 unit and it's accessory parts.

Things I noticed while at the Espar site:

The documentation they have online is very good.
I saw mention of an Airtonic 4 for petrol.
They have a high altitude compensation device, it is for all models, big to small and gas or diesel. They only say it optimizes emissions and just changes the fuel flow of the fuel pump.
They say protect the Hydronic units from excessive splashing. I take this to mean it can't get dunked in a stream crossing.:eek: I see the solution being to install it in a diving bell :D and make sure the exhaust and air intakes are water proof and run to above the expected high water line. Hoses can go through the sides via bulkhead fittings while the exhaust and air intake are routed through the open bottom. A side will need to be gasketted and removable for installation and servicing.

[Seawali]

John,

Nice summary of diesel options.

I have an Espar furnace, an Indel single heat exchanger circuit calorifier and 2 space heaters connected to the engine as you suggested.

Some additional points:

I use a "Ball" valve instead of a "gate" valve to isolate the engine from the furnace. You can tell whether the valve is open or closed just by looking and you won't break something by trying to turn the handle the wrong way thinking the valve is jammed.

I think you only need a valve in one of the coolant lines between the engine and furnace to stop the coolant flow. Think cab heater control.

A calorifier with 2 heat exchanger circuits not only needs a coolant header tank in the furnace circuit, it also might need 12v pumps to move coolant in the circuit that's not "hot".

I insulate any long coolant hoses between the engine, furnace and space heaters that are exposed to outside temperatures to save diesel when heating the camper in cold weather.

I use both the espar timer and a battery operated room thermostat to control the furnace.

I use the timer when I want engine preheat at a certain time of day or if I want to run the furnace for 15 - 20 minutes to heat shower water after sitting for a day or so.

I use the thermostat to keep the camper comfortable when camped incold weather. It's programmable to a cooler setting at night and a warmer setting in the morning.

The space heater fans can be controlled by the furnace control (that's how I did mine) or they can be controlled by an "aquastat" that doesn't turn the fans on until the coolant reaches a certain temperature. Prevents the space heater from blowing cold air waiting for the furnace to get hot.

You are absolutely right about the requirement for a mechanical thermostat valve on the calorifier. When heating water with the engine it can reach over 212 F (100C). Even the diesel furnaces can reach 180F. This may cause severe burns.

Calorifiers for use on boats are designed to be heated by engine coolant and often come with a thermostatic mixing valve from the factory (at least in the US).


Tom

Good Day!
Adam from Poland. I am new over here. Good to see you.
Interesting in exp camp. Would like to ... you know what :smiley_drive:

Tom may you tell who made that system you talking about. Is it Webasto?

all the best,
Adam

[Seawali]

Holy smoke....

"Espar furnace, an Indel single "

[jesusgatos]

You guys might want to look into some of the diesel / multi-fuel heaters (http://www.steelsoldiers.com/deuce-modification-hot-rodding/40882-multi-fuel-heater-application.html) from military vehicles. I just bought two of these brand-new water/cooant heaters (http://cgi.ebay.com/ebaymotors/Southwind-Coolant-Heater-Diesel-Fired-15K-BTU-Military_W0QQcmdZViewItemQQhashZitem1c0e5ca4a6QQit emZ120500036774QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5 fAccessories#ht_500wt_1182) for $100ea.

[ersatzknarf]

<snip>
The last common option is to run a Dual Top. We haven’t used one yet but I’m sure they have a place. They don’t run coolant at all and heat the water directly. Also they have 2 hot air outlets that can be ducted into the vehicle for space heating. So a bit of co-generation going on there. Very compact and have a tank built in.

Some other points to make here are that the calorifiers all have an electrical heating element built in so that if you pull into a vanpark or a mates’ place you can run off electricity for awhile and the other point for now is that if you are going to run a calorifier especially plumbed into the engine then fit a thermastically controlled temperature kit to it as a safeguard. These are an adjustable valve that goes on the hotwater outlet of the calorifier and mixes with coldwater to give set output temperature..Very simple to set up but well worth it. If the engine has provided the heat the temps can get very hot and vary so its’ not as simple as dialing down the thermostat on the furnace.

<snip>
Regards John.

Hello John !

Since this thread came back to life, I wanted to ask if you folks had installed a Webasto Dual Top, yet ?

I am still going back and forth between that and the Isotherm calorifier (which I just read can have dual heating circuits to be able to use not only engine coolant heat but a separate hydronic heater, if I read it correctly).

Of course, it will likely come down to which set-up I can fit in the space available.

Thanks !



Cheers,
Frank

[whatcharterboat]

Hello John !

Since this thread came back to life, I wanted to ask if you folks had installed a Webasto Dual Top, yet ?

I am still going back and forth between that and the Isotherm calorifier (which I just read can have dual heating circuits to be able to use not only engine coolant heat but a separate hydronic heater, if I read it correctly).

Of course, it will likely come down to which set-up I can fit in the space available.

Thanks !



Cheers,
Frank

Hey Frank. Always a pleasure.

As a matter of fact, we are just in the final few days of one of those large MAN dream rigs which has our first Dual Top. We haven't fired it up yet but it's all in place bar the fuel tank pick up. Everything went together really well but I'm not sure if we'll do it again. Perfect for a sealed road 2wd whale type motorhome. Perfect. But if you're putting together an outback tourer where extreme dust is a concern and space is at a premium I think the more conventional Webasto furnace/calorifier/space heater(s) combination is more adaptable and can certainly be designed to do so much more. So in our situation we can put in a space heater and plumb the coolant lines to it rather than ducting 90mm or 75mm pipe work throught cupboards etc. We were also concerned with deep water fording so we mounted the Dual Top in a cupboard inside the vehicle rather than under it. It was still a neat install but for an expedition camper I think it's useful if you can utilize the engine heat for initial hotwater heating. So as an example, if you pull up for an overnight stay your furnace may not even need to turn on so your fuel consumption will therefore be optimized.

Please don't take this the wrong way. The Dual Top is an excellent bit of kit(as with any of their products) but it just doesn't suit our trucks like the old system. For a first time home builder, a Dual Top would be a very good choice but carefully plan ( and do it early) for the necessary ductwork, location,etc.

Seeing as how the thread has been re ignited, I'll follow up with some pics soon.

Seawali. Got your PM re: this thread too. Will reply soon. Thanks for you patience.

[whatcharterboat]

I am still going back and forth between that and the Isotherm calorifier (which I just read can have dual heating circuits to be able to use not only engine coolant heat but a separate hydronic heater, if I read it correctly).

We don't use the dual circuit type. If you do, it means you need a separate header tank. Through some tricky valving, we get away with a single circuit tank and you can preheat the motor with the furnace if you need to. Haha, as I sit here sweating away in a heatwave. Price wise, the extra you pay for the dual circuit tank is about the same as 2 solenoid valves but a proper header tank maybe another couple of hundred bucks. Just a thought. Do the math. I looked at dual circuit tanks years ago and thought maybe>>> just never went down that road. Plenty to think about heh?

We even built a Round The World truck at work some time back that had no calorifier. Instead it just had a tiny heat exchanger that made instant hotwater from a larger Webasto furnace (with selectable engine preheat and a space heater). It worked fine too.

[whatcharterboat]

I am still going back and forth between that and the Isotherm calorifier (which I just read can have dual heating circuits to be able to use not only engine coolant heat but a separate hydronic heater, if I read it correctly).

Hey Frank, while I think of it >>> a little tip with the Isotherm units that you may not realize is that they should be mounted with the bolt holes at the bottom. For anyone who doesn't have a clue what we're talking about >>> Isotherm calorifiers look like a "stretched D"- shaped tank and should be mounted with the flat section to the bottom. Now you could in fact mount them with any orientation you desire as the mounts are certainly strong enough to hang upside down, say from under the floor but the reason I say this is that the insulation is actually much thicker at the top than the bottom. So for it's for efficiency sake that I make this comment as I have seen them mounted incorrectly in the past when guys have just said "She'llberightmate" and you certainly wouldn't know about the insulation thickness just by looking at them. Something to remember when it's time.

Again >> a very good product. Good backup electrical elements in them too.

Oh and make sure you fit a thermostatically controlled valve to the hot water outlet to be on the safe side.

John.

[jesusgatos]

Another thought I had in my notes: The tank for a heater could be a jerry can. I have heard of people doing this and have ran across caps for jerry cans that have fuel pickups and fill volume senders already installed in them. I figured I'd just make my own cap/pickup unit when the time came.
Like this (http://www.steelsoldiers.com/auxillary-equipment/42097-fuel-burning-heater-wick-you.html#post502404)?

[ersatzknarf]

Hey Frank. Always a pleasure.

As a matter of fact, we are just in the final few days of one of those large MAN dream rigs which has our first Dual Top. We haven't fired it up yet but it's all in place bar the fuel tank pick up. Everything went together really well but I'm not sure if we'll do it again. Perfect for a sealed road 2wd whale type motorhome. Perfect. But if you're putting together an outback tourer where extreme dust is a concern and space is at a premium I think the more conventional Webasto furnace/calorifier/space heater(s) combination is more adaptable and can certainly be designed to do so much more. So in our situation we can put in a space heater and plumb the coolant lines to it rather than ducting 90mm or 75mm pipe work throught cupboards etc. We were also concerned with deep water fording so we mounted the Dual Top in a cupboard inside the vehicle rather than under it. It was still a neat install but for an expedition camper I think it's useful if you can utilize the engine heat for initial hotwater heating. So as an example, if you pull up for an overnight stay your furnace may not even need to turn on so your fuel consumption will therefore be optimized.

Please don't take this the wrong way. The Dual Top is an excellent bit of kit(as with any of their products) but it just doesn't suit our trucks like the old system. For a first time home builder, a Dual Top would be a very good choice but carefully plan ( and do it early) for the necessary ductwork, location,etc.

Seeing as how the thread has been re ignited, I'll follow up with some pics soon.

Seawali. Got your PM re: this thread too. Will reply soon. Thanks for you patience.

Hi John,
Thanks.
Same here - always a pleasure :)

Glad to hear that you've done an installation of a Dual Top, but can understand well that it might not be the best choice for an overlander, compared to installation in a more "traditional" RV...
If we were to go with one, it would almost certainly need to be under the car and although Webasto say it is designed for it, I can't imagine they were thinking about deep water fording. I also had the same concerns about routing the furnace ductwork and how to fit that along with everything else.

So, the alternative for us looks to be the Webasto Thermo Top "C" that can do either engine heating or cab heating (through the car's heater vents) and I think we can fit one of those square Isotherm calorifier units up in front of a rear tire between the outer and inner wheel arch bodywork, but if that won't work, I think we can find space for one of the standard, round ones.

Regardless, I am anxious to see photos ;)


Cheers,
Frank

[ersatzknarf]

We don't use the dual circuit type. If you do, it means you need a separate header tank. Through some tricky valving, we get away with a single circuit tank and you can preheat the motor with the furnace if you need to. Haha, as I sit here sweating away in a heatwave. Price wise, the extra you pay for the dual circuit tank is about the same as 2 solenoid valves but a proper header tank maybe another couple of hundred bucks. Just a thought. Do the math. I looked at dual circuit tanks years ago and thought maybe>>> just never went down that road. Plenty to think about heh?

We even built a Round The World truck at work some time back that had no calorifier. Instead it just had a tiny heat exchanger that made instant hotwater from a larger Webasto furnace (with selectable engine preheat and a space heater). It worked fine too.

Hi again John,

Ah, hah ! That's right about the extra plumbing required. I was reading the posting by "jammyauto" about his Sportsmobile and recall reading that a dual circuit Isotherm was being used with one circuit plumbed to the engine and the other to an Espar hydronic unit.

"Haha, as I sit here sweating away in a heatwave." LOL ! Yes, I forgot our seasons are opposite ! Trade ya' ! ;)

Since we are building on a much smaller scale, I think we'll be fine with the more simple approach.

I keep getting carried away with all the neat bits that can be fitted and have to rein myself in and regain focus of the design, but that is actually part of the enjoyment...

The idea of "instant hot water" from the heat exchanger sure sounds nice. I think if we just keep it simple, the Webasto Thermo Top "C" (Caravan) and the Isotherm should do us fine. That way, we'll have engine preheat/calorifier heating and cab heating. We'll have a back-up catalytic heater as well, since we'll have a small outside tank for an outside-use gas cooker.


Cheers,
Frank

[ersatzknarf]

Hey Frank, while I think of it >>> a little tip with the Isotherm units that you may not realize is that they should be mounted with the bolt holes at the bottom. For anyone who doesn't have a clue what we're talking about >>> Isotherm calorifiers look like a "stretched D"- shaped tank and should be mounted with the flat section to the bottom. Now you could in fact mount them with any orientation you desire as the mounts are certainly strong enough to hang upside down, say from under the floor but the reason I say this is that the insulation is actually much thicker at the top than the bottom. So for it's for efficiency sake that I make this comment as I have seen them mounted incorrectly in the past when guys have just said "She'llberightmate" and you certainly wouldn't know about the insulation thickness just by looking at them. Something to remember when it's time.

Again >> a very good product. Good backup electrical elements in them too.

Oh and make sure you fit a thermostatically controlled valve to the hot water outlet to be on the safe side.

John.

Hey again John,
Thanks for that tip on the orientation of the "round" Isotherm - I did not know that at all, but it makes perfect sense.

Yes, I recall reading about the thermostatically controlled valve (that is an option ?) being a very good idea to avoid scalding ! 8^O

Thanks for that reminder. I need to make doubly sure to do that.

(I think I might have seen one on an Isotherm and it's really just a valve marked "hot" with an arrow pointing the way ?)

Cheers,
Frank

[egn]

We also use an Isotemp water storage together with a Webasto diesel furnace. It works fine for us, we have warm water about 2 days. To heat it faster we use the model with the two heat exchangers. The temperature controlled valve doesn't work that good together with the temperature controlled shower. So we opened it fully all the time.

[ersatzknarf]

Thanks for the reply on that, Emil.
In the photo, there is a valve at the bottom of the tank. That is the "thermostatically controlled valve," isn't it ? There looks to be another control near there (a blue/grey box with a control lever). Is that related to the water temperature control ?


Cheers,
Frank

[dzzz]

Great thread well worth reviving.

The isotherm does come with a mixing valve. I ordered the Basic 40 Double Coil (http://www.indelmarineusa.com/)which is an 11 gallon unit.
The isoterms I looked at also have a 750w heater, which may have some use. The double coil increases cost a bit, but separates the systems. I will need a little expansion tank and probably a pump. My truck already has an cab/engine webasto, but I'll add a second unit for cabin heat. My only concern with webasto is that the units are too high powered for heating small spaces. I prefer the smaller Espar units, but I'm not going to run two brands.

In the first part of this thread there was a discussion on propane. I would not use propane on a boat (a sealed bowl). But I am using it for cooking in a camper. I don't like diesel cooktops.

[charlieaarons]

The 5kw Webasto is not too high powered for a camper. The 9kw for the engine/cab is 9kw in order to heat things up in 1hr. The camper takes at least several hrs, as much as 8hrs, in order to get thoroughly warm from -15 F. Even with R13 insulation. Not just the air but the solid objects like the camper batteries, which are hidden away under a sub-floor.

Charlie

[ersatzknarf]

Great thread well worth reviving.

The isotherm does come with a mixing valve. I ordered the Basic 40 Double Coil (http://www.indelmarineusa.com/)which is an 11 gallon unit.
The isoterms I looked at also have a 750w heater, which may have some use. The double coil increases cost a bit, but separates the systems. I will need a little expansion tank and probably a pump. My truck already has an cab/engine webasto, but I'll add a second unit for cabin heat. My only concern with webasto is that the units are too high powered for heating small spaces. I prefer the smaller Espar units, but I'm not going to run two brands.

In the first part of this thread there was a discussion on propane. I would not use propane on a boat (a sealed bowl). But I am using it for cooking in a camper. I don't like diesel cooktops.

Agreed ! This is a great thread !

Glad to hear that the mixing valve comes with the Isotherm. I was wondering about that.

11 gal. would be wonderful to have but I think tough for us to fit.

With the cab/engine Webasto, how well does it work for heating the "cab" area do you feel ? Our arrangement is open from the cab all the way back...

For the space we have, I am thinking that we can hide the "Slim Square" (4.2 gal.) in the back, because it can also be stood on its side, which will allow us to tuck it into the empty space between the inner and outer bodywork.

Cheers,
Frank

[dzzz]

.............

With the cab/engine Webasto, how well does it work for heating the "cab" area do you feel ? Our arrangement is open from the cab all the way back...

............

From my limited experience with a separate cab/chassis, it works very well. But I'm unclear what configuration we're talking about. On the one end there's Charlie's completely seperate two boiler system. On the other is FusoFG with a single boiler and one system with the ability to turn off flow to the engine.
I'm installing a hybrid, where the two systems can exchange heat through the water heater (calcifier).

[ersatzknarf]

From my limited experience with a separate cab/chassis, it works very well. But I'm unclear what configuration we're talking about. On the one end there's Charlie's completely seperate two boiler system. On the other is FusoFG with a single boiler and one system with the ability to turn off flow to the engine.
I'm installing a hybrid, where the two systems can exchange heat through the water heater (calcifier).

Oops ! You're right, I think we got a little confused there. I was referring to the Webasto Thermo Top "C" and when I read "cab/engine webasto," I thought it was the same thing... The plan is to use that for engine and cab, etc. heat with the side benefit that it will heat the Isotherm and if I understood Charlie's post correctly, the "C" should handle our needs. Since we'll be using an outside-mounted propane tank for an outside-use camp stove, we're looking at a small catalytic heater for back-up.


Cheers,
Frank

[egn]

In the photo, there is a valve at the bottom of the tank. That is the "thermostatically controlled valve," isn't it ?


Yes, this is this thermostatically controlled valve mentioned above. It mixes hot water from tank with cold water.



There looks to be another control near there (a blue/grey box with a control lever). Is that related to the water temperature control ?


This is a electrically controlled 3-way valve to switch between summer and winter operation. In summer the hot water from the Webasto flows only through the Isotemp. In winter it flows after the tank also through the heating pipes and convector. This valve has been replaced later by a manual 3-way valve, because this was easier to handle.

I have attached two schematic drawings to give you an idea. Sorry for being in German language. Please feel free to ask any questions.

[egn]

The 5kw Webasto is not too high powered for a camper. The 9kw for the engine/cab is 9kw in order to heat things up in 1hr. The camper takes at least several hrs, as much as 8hrs, in order to get thoroughly warm from -15 F. Even with R13 insulation. Not just the air but the solid objects like the camper batteries, which are hidden away under a sub-floor.


For faster heating I have installed 3 water/forced air heat exchangers with 3 kW power each. They are a bit noisy, but it is getting warm within a few minutes when the Webasto 90ST (9,1 kW) has reached its operating temperature. After that the normal convector keep the temperature. In spring and autuum running this together with water heating is enough to get a very comfortable temperature in the bath room.

[dzzz]

................................. we're looking at a small catalytic heater for back-up.


..........

That's exactly what I'm doing as far as back-up heat.

My concern with a large size furnace is that both Espar and Web. clog up if not run regularly on high power. But considering Charlies post I'm not going to worry about installing a 5kw unit.

Question about heating cabinets and storage areas: Is just running supply and return lines through these spaces enough to add heat? Should I run a line through the house battery space? These lines would only be active when heating the camper. Hot water heating in summer would not run through these lines.

Anyone able to do water to air heat without fans? I can't find the surface area to do that.

[ersatzknarf]

Yes, this is this thermostatically controlled valve mentioned above. It mixes hot water from tank with cold water.


Great ! :) Thank you for confirming that.



This is a electrically controlled 3-way valve to switch between summer and winter operation. In summer the hot water from the Webasto flows only through the Isotemp. In winter it flows after the tank also through the heating pipes and convector. This valve has been replaced later by a manual 3-way valve, because this was easier to handle.


That is a great idea ! It makes sense to change to a more simple, manual valve, but still a very interesting solution.



Cheers,
Frank

[jesusgatos]

I've laid 1/2" PEX tubing into the floor of my M109 motorhome conversion. Planning on running engine coolant through a separate, closed-loop system and will have a few different ways of generating/regulating heat. This stuff is all new to me, and I'm only figuring it out as I go...

[charlieaarons]

That's exactly what I'm doing as far as back-up heat.

My concern with a large size furnace is that both Espar and Web. clog up if not run regularly on high power. But considering Charlies post I'm not going to worry about installing a 5kw unit.

Question about heating cabinets and storage areas: Is just running supply and return lines through these spaces enough to add heat? Should I run a line through the house battery space? These lines would only be active when heating the camper. Hot water heating in summer would not run through these lines.

Anyone able to do water to air heat without fans? I can't find the surface area to do that.

I have no fans. There are flexible steel braided hose coils under the mattress, a radiator under the step to the dinette area and a large tube type radiator AKA towel drier in the bathroom. This is so effective that when running the heat in very cold weather when not driving I always leave the bathroom door open.
http://www.unicat.net/en/pics/TC49compact-2.html
The camper has R13 insulation with virtually no cold paths except the windows. Even though there are no fans the batteries, hidden way away under a subfloor (with a large thermal mass) get up to +15C. after the heat is on for 36 hrs at outside temp of -25C. with thermostats set at +21C.
The lack of fans is why it takes a while for the camper to get warm in cold weather. But it stays warm; the estimated heat loss (including windows) at -25C. is 1.2kw, less than 25% of the Webasto's capacity.

Charlie

[egn]

I have put the images into a PDF. I hope it helps.

[charlieaarons]

Very good, Emil. I wish I could preheat my generator with one of my Webastos. I do think I have a solution (not ideal): a 200W magnetic oilpan heater that I can attach to the engine block of the generator and preheat for 2-3 hrs. Of course, after drawing 50A-hr = 6% of battery capacity in 3 hrs I will need to run the generator for 10-15 min just to restore the batteries.

Charlie

[skysix]

Yes it requires another fuel but they are still excellent > easy to use and install , self contained (no wiring or plumbing), have an oven (Webasto don't at this point) and relatively safe and virtually nothing to go wrong (so I'm told anyway).

Wallas has a diesel oven with a stove to which a blower lid can be added
http://www.wallas.fi/default.asp?id=ne5dxgegchu
http://www.wallas.fi/contentlibrary/images/products/big/87D.jpg

http://www.wallas.fi/default.asp?id=v5s0u7xwkzz
http://www.wallas.fi/contentlibrary/images/products/big/85DP_270.jpg

[4x4 explorer]

EGN/Emil,
Thanks for the "Schema". I have purchased the same Isotherm exchanger/heater and a Webasto diesel heater. I was in the process of installing so this thread is very helpful. I have yet to buy a recirculating pump for the hydronic system. Any recommendations? Also, on engine coolant heat source, I had thought about a separate loop with its own heat exchanger and then to the Isotherm, to isolate if there was a failure rather than direct line from engine to Isotherm. Any thoughts on which is best way to go. I have a Unimog 1300. Where is the best place to tap into the engine coolant system, "T" the heater line or is there a better alternative?
On the EGN/Emil schema, if some of the German words could be translated for this ignorant American who is ashamed to only speak english, it would be very helpful. Ausgleichsgefab
Fuhrerhaus
Alde Warmetauscher
Schalter Bad
Heizgeblase Bad
Heizgeblase Wohnraum
Schalter Panel
Kreislauf Kabine
Alde Elektropatrone
Universalempfanger
Sitzgruppe rechts
Kuche
Schlafzimmer li
Wasser Luft
Thanks for sharing, Roger

[dzzz]

Espar has some installation videos (http://www.espar.com/html/service/download/technical.html), which generally apply to Webasto.

Webasto doesn't make much effort on education.

[egn]

Sorry for the late answer.


EGN/Emil,
I have yet to buy a recirculating pump for the hydronic system. Any recommendations?


The Webasto has a build in pump. May be you get an auxiliary pump at Espar.



Also, on engine coolant heat source, I had thought about a separate loop with its own heat exchanger and then to the Isotherm, to isolate if there was a failure rather than direct line from engine to Isotherm. Any thoughts on which is best way to go.


This is a good idea. Most installations I know separate both loops with a heat exchanger. I shouldn't be to hard to get such a head exchanger. I got mine from a manufacturer of heating systems for RVs.



I have a Unimog 1300. Where is the best place to tap into the engine coolant system, "T" the heater line or is there a better alternative?


Sorry I dont know this. My truck has no water coolant at all. :sombrero:



On the EGN/Emil schema, if some of the German words could be translated for this ignorant American who is ashamed to only speak english, it would be very helpful.


Don't worry regarding speaking only one language. A lot more people speak english than german.

Ausgleichsgefab - water reservoir, equalising tank
Fuhrerhaus - drivers cab
Alde Warmetauscher - heat exchanger from Alde company
Schalter Bad - switch in bath room
Heizgeblase Bad - water/forced air head exchanger (Webasto 3 kW) bath room
Heizgeblase Wohnraum - water/forced air head exchanger living room
Schalter Panel - switch at control panel
Kreislauf Kabine - loop at cabin
Alde Elektropatrone - electric heater 1/2 kW from Alde company
Universalempfanger - RF receiver to thermostatic controller
Sitzgruppe rechts - bench right side
Kuche - kitchen
Schlafzimmer li - sleeping room left side
Wasser Luft - water air

You are welcome.

Emil

[4x4 explorer]

Emil, Thanks for all the information and the translation. Roger

[charlieaarons]

The next time I turn it on (to keep my batteries charged up in the winter) I'll measure the temp with an IR thermometer and let you know.

Charlie

[egn]

For floor heating you should use a temperature controlled valve in the return flow. Therefore for direct routing of the flow from the furnace the piping must be a bit different.

Example:
furnace -> distribution manifold with valves for each loop -> furnace
manifold -> water heater -> manifold
manifold -> conventional radiators in series -> manifold
manifold -> conventional radiators in series -> manifold
manifold -> floor heating loop 1 -> temperature valve -> manifold
manifold -> floor heating loop n -> temperature valve -> manifold

The important point is that it is never allowed to block the flow through the furnace, otherwise the pump will be destroyed in short time. The pump needs very free flow all the time, so the piping thickness should be selected accordingly.

So the valve for the water heater must be always fully opened. The flow through the other loops must be regulated accordingly so that each of the loops get the right share of the flow when the temperature controlled valves are open. It is not easy to get a balanced system.

The temperature valves in the return pipe from the floor heating limit the floor temperature to a comfortable value. Here it is important to have sufficient thermal mass in the floor heating, otherwise you will still get to hot feet at the beginning of the loop. For more info on that you should contact a specialist for floor heating.

The direct system has the disadvantage for me that the furnace has to be used to control the overall temperature, at least for simple systems without thermostatic valves at each radiator. This means that the water heater may not get enough heat.

I have used a separate loop with heat exchanger, because I use the system from Alde for heating RVs. Here no direct flow from non-Alde heaters is allowed. The temperature of the cabin is also very easy to control by just switching the very silent pump on and off. And the Webasto can run on full power to heat the water.

[devdally]

thanks for all the helpful info!

[alaskaboy]

Gentlemen,

Could someone help me out with the controls on the Wabasto hydronic heaters. It seems they are timer driven. I could not find a thermostat on the corporate web site, although, is listed as a heater option with the Espar heaters.

Charlie, your 5 kw is the thermotop correct? How is yours set up for control?

mnb

[charlieaarons]

The 9kw for the cab and engine has a 7 day timer
The 5kw has an on-off switch. with thermostat controls at each of 3 radiators.

Charlie

[FusoFG]

I have a espar 5kw that I added a thermostat to.

Using the wiring diagram, I located the wire (yellow, I think) from the timer to the furnace that made it run.

I placed a single pole double throw switch in that line that I can use to connect either the timer to the furnace control line or a battery operated thermostat I purchased from Home Depot.

That way I can use either the timer or the thermostat to control the furnace.

The thermostat should be battery operated instead of using voltage from the furnace so it can supply 12 volts to the furnace control lead.

And I set the "swing" on the thermostat to it's maximum of three degrees so the furnace runs longer and less frequently instead of shorter and more frequently.

[egn]

I use a thermostat in the separate heating loop, which is connected to the webasto loop by a heat exchanger (see drawing at previous page).

So the webasto is free running just with it's internal thermostat. But AFAIK it has a control input which can be used to turn it on and off by a thermostat.

This setup has the advantage that the warm water heater always gets the full heat of the webasto, even when there is no heat for space heating required.

[dzzz]

I use a thermostat in the separate heating loop, which is connected to the webasto loop by a heat exchanger (see drawing at previous page).

So the webasto is free running just with it's internal thermostat. But AFAIK it has a control input which can be used to turn it on and off by a thermostat.

This setup has the advantage that the warm water heater always gets the full heat of the webasto, even when there is no heat for space heating required.

That's the setup I'm leaning towards, as it allows the (espar in my case) to better regulate the variable burner. If the unit is turned on and off by air temp it can't directly know the heat deficit.

The water heater always in the loop stores BTU's to allow for a quick warm-up ("quick" being a relative term in Alaska)