Heat Exchange/Hot Water Idea

[corprin]

I popped the radiator on my '99 Cherokee on the last overland trip, and am in the process of stuffing in a new unit. When pulling the whole thing, I started thinking....

The XJ has a nasty issue with lacking trans cooling from the cooler built into the cold end radiator tank, so its common to add an external stacked plate unit. When I opened up my new radiator today, I found the internal trans cooler was either tube/fin or bar/plate unit... all with NPT fittings. I am headed to the JY to pick up an extternal unit, but I was thinking of omitting the factory cooler, and pluming water through it as a heat exchanger.

Has this been tried, and do you all think its a feasible idea to use the internal unit as a heat exchanger?

[Scoutn79]

I think it is a perfectly viable idea...in theory. I have often wondered this myself but since I run a manual I don't have an exchanger.
You would have to control the temp by how fast the water goes through the exchanger and thus would control the amount of water out of a shower head. I have no idea how fast the cold water will heat to a desirable temp and then how much water you'll get out of the head but it would be a very simple test to just do a couple hookups use a small pump bucket for water and a valve of some sort and see if there is a good balance between a good temp and GPM...Let us know what you come up with.
Darrell

[Doctor W]

It would work better if the heat exchanger (auto trans cooler) was in the HOT end tank of the radiator. The size of the heat exchanger is about the same as those hot shower heat exchangers you can add to the hoses of the heater circuit, so it should work..... as stated above a bit of trial and error experimentation is called for.

[corprin]

I know it would be better in the hot end, but sadly it's not

The plan is to put a 12-15gal tank behind the driver's seat. Two lines will be plumed into the tank, one hot and one cold, with a pump on the cold line. Between the heat exchanger and the pump will be a tee fitting leading to a kitchen sink sprayer with an on/off valve stopping flow to the exchanger. Somewhere in the cold line, or possibly the lower end of the tank, a thermostatic switch to turn on/off the pump at a given temp. When on the road, cycle the water through the tank heating it to my desired temp so I have hot water when needed. When hot water is needed, toggle the pump on, close off the heat exchanger, and use the sprayer as a shower. I know the heat exchanger is not ideal, but it's already there!

I got the trans cooler installed over the weekend, pulled from a 90s suburban... $7 with brackets!

[dwh]

The way I rig trans coolers (per the recommendations of an engineer at B&M) is to run the hot fluid across the temp gauge, then through a large trans cooler to bring the temp down, then through the coil in the radiator to bring the temp back up to 180. (Then through a remote 1 qt. filter and then back into the trans.)

The engineer said that too hot will burn the fluid, but too cold will cause any condensation in the fluid to not evaporate and I'd eventually end up with water mixed with my trans fluid.

Rigged like that, the engine and trans temp gauges normally stay locked together at 180 all day once it's warmed up.


EDIT: Woops. Hit post too soon...

So anyway, I wouldn't use the coil in the radiator for hot water. Also, the tranny cooler in the pic above looks too small. I'd get a bigger one for the trans, and use that little one for the power steering. (I've done that, and the power steering cooler is always hotter than either the radiator or the trans cooler...unbelievable amount of heat there.)