Propex HS2000 installation discussion - ducting

#1
Hi All,
I have been using a portable Propex HS2000 to heat two RTTs for about a year now. This is my first winter with it. This spring and summer, I've simply run the supplied hot-air duct into the tent (through a zippered opening) and let the heater draw return air from the outside... and it has been good enough.

Winter is different. When the unit fires up and shuts down, it operates the fan for a few minutes before and after supplying heat for safety. Since I do not have a return-air running between the heater and tent, it is pumping -25º air into the tent while cycling. That's bad. I should have thought of this and didn't.

I need to come up with a solution for both return and supply air for the Propex and the units arrive with a shrimpy little bit of 60 mm hose. There are a lot of options for 60 mm duct on the Interwebs, but not a lot of specs from Propex nor ideas in general.

I'm wondering:
  • What max temperature rating do I need to plan for (when the hot air leaves the Propex)?
  • Does anyone know if a cost-effective option exists for an industrial-like 60 mm high-temp hose with integral insulation?
  • Is anyone aware of some sort of boot or fitting that I could permanently install in the soft part of an RTT to attach the hose to (to avoid running hoses through zippered doors)? Twist-lock or rubber friction type fittings would be awesome.
  • Please keep in mind that my hoses will be outside. The heater is protected in an enclosure and I would like to have some sort of ducting that can get wet and isn't required to be dried (like the hose that ships with it).

Input would be awesome. I can't be the first guy to check into this stuff. Thanks.
 
#3
I plan on installing actual floor vents in my CVT Denali Extended Summit RTT. On side with return and one output. Just connect the hoses to the bottom of the tents floor when needed.

Does the heater keep the RTT comfortable in weather -25? That's pretty impressive if it does without using a return air duct to recirculate heated air.
 
#4
I plan on installing actual floor vents in my CVT Denali Extended Summit RTT. On side with return and one output. Just connect the hoses to the bottom of the tents floor when needed.

Does the heater keep the RTT comfortable in weather -25? That’s pretty impressive if it does without using a return air duct to recirculate heated air.
Well, that was a typo. I meant 25ºF :). It keeps it nice and warm, but only when it's burning gas. The minutes before and after pretty much undo the heating effect. I think that having a return would dramatically reduce the cycling frequency.

I have considered installing the Propex in the Jeep and permanently running the vents up through the fiberglass roof, then through the fiberglass floor of the RTT, but cutting 2.5 inch holes in the RTT worries me. I'm a big guy, and the holes will certainly weaken the structure of the tent. These holes would need to be cut through the mattress too. Good chance of smothering either the supply or return with a blanket and popping the limit switches. Not to mention dropping pocket knives and stuff down the ducts. Maybe a removable pipe with an elbow could be inserted in the holes when the RTT is in use (to raise the duct above the people and stuff). When closing the tent, take them out and leave them in the tent? This would allow you to direct the air flow for the supply as well. Hmmmmm.

Could wind up going that route but it would take a big bite out of the resale value for both the RTT and the JK.
 
#5
Floor vents are an interesting idea... i was looking at installing a Propex in my horizon (replacing the jerry can holders with a single box and the propex in it).. you almost would need a snorkel for the vents but if placed at the edge of the tent i should clear the tent frame when folding and the mattress sould just smush in around it or just need a small cut to make it work i bet.
Fit should be pretty easy to test, duck tape a couple of 12oz cans to the floor where you want the vents. and i be structurally it wouldn't matter since its on the edge of the frame away from the "load" so to speak.

-for longer hoses something like this may work (with a hose clamp or an adapter) I.D is 2.5" https://ducting.com/collections/automotive-hose/products/neo-300
also all webastco and espar heaters use 60mm ducting - so west marine is a source for it and the outlets as well
 
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#7
Honestly sounds like you need warmer sleeping bags and or a camper.
I have several of each. This is my "quick and dirty" camping rig for Friday night trips after work. I'm not a big fan of pulling either trailer on snow or ice.

This duct looks like it shrinks up in size, and might hold up again some rain. But my god...the price!
 
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#9
Well, that was a typo. I meant 25ºF :). It keeps it nice and warm, but only when it's burning gas. The minutes before and after pretty much undo the heating effect. I think that having a return would dramatically reduce the cycling frequency.

I have considered installing the Propex in the Jeep and permanently running the vents up through the fiberglass roof, then through the fiberglass floor of the RTT, but cutting 2.5 inch holes in the RTT worries me. I'm a big guy, and the holes will certainly weaken the structure of the tent. These holes would need to be cut through the mattress too. Good chance of smothering either the supply or return with a blanket and popping the limit switches. Not to mention dropping pocket knives and stuff down the ducts. Maybe a removable pipe with an elbow could be inserted in the holes when the RTT is in use (to raise the duct above the people and stuff). When closing the tent, take them out and leave them in the tent? This would allow you to direct the air flow for the supply as well. Hmmmmm.

Could wind up going that route but it would take a big bite out of the resale value for both the RTT and the JK.
I understand the concerns with the floor vents my idea was to cut and re-sow the mattress so it had a couple inches of room around the vents. Also, my tent is mounted on a trailer so I got a HUGE tent, the CVT Denalli. It's about 2x larger than the one I had on my Jeep. My wife, kid and I can sleep in it and get no where near the edges, it's 12" wider than a king (87x96"). Your idea with elbows is good, I just plan on using a straight piece of pipe that is a little taller than the matress then mounting one of those 4" directional vent covers on it to keep stuff out and direct the air towards the center of the tent.

For me resale isn't an issue because the tent and the trailer will be sold as a package and who wouldn't want a heated tent?! No way I'd cut a hole in the roof of my Jeep.
 
#12
LOL, yup. The idea has given me pause. It would be wicked cool to pop up the tent, plug in the propane, and turn on the thermostat though.
What if you installed a pair of kayak access ports? They are easy to install, Black, available in any number of sizes, cheap and water tight.
 
#13
What if you installed a pair of kayak access ports? They are easy to install, Black, available in any number of sizes, cheap and water tight.
Thank you sir. I had no idea these existed. I wouldn't mind putting holes in the side of the JK top. They are cheap and have multiple sizes. come in black too!

I could permanently mount the Propex inside and pick ports large enough to allow for supple, return, and the propane hose to run through at camp. Maybe built some plates to mount inside the ports to allow friction-fit couplers for the hoses. Meaning that the supply and return in the Jeep are permanently installed. At camp you could just remove the Kayak port and plug in another insulated extension to the tent.

My thought is that having the Propex running inside the Jeep will keep the internal temp above freezing at night. Could store water in there and keep the NL Power Pack above freezing too.

I have a feeling I'm going to do this or something similar this spring.
 

Martyn

Supporting Sponsor, Overland Certified OC0018
#14
I have measured the hot air from the heater at 104'F. That will perish most flexible hose unless it's lined with reflective inner hose. Temperature ratings on ducting is rated for 10 minutes you see the damage when you exceed that point.