Where to tap coolant for a shower heat exchanger?

[ftillier]

Does the cooling system have enough heat capacity that you could get a hot shower out of it with the engine off? Wondering if you can hook it in parallel with an electric circulator and get adequate results, allowing you to get your shower without leaving the engine running.

I suspect the 'minimum flow rate' is what you need to drive in order to achieve the advertised energy transfer of the heat exchanger.

 

[avslash]

The problem is that I can't just tap it. I have to insert this in series with it.

Looking over this diagram, that section of the upper hose, or at the section that Tees off toward the thermostat, might be a good place. Provided this thing doesn't restrict flow to any appreciable degree.
View attachment 21782

Thats why I was thinking rear wheel well heater hoses. You could cut the existing supply line, and plumb your exchanger inline on a less critical coolant path.

Can you post a picture of the exchanger with something for scale? I'm wondering how large of a unit we are talking about.

 

[greiswig]

Here it is. Looks like I have some cleaning to do, too.

I have a Tactical 4x4 front bumper on the way, and I was wondering if there will be some room behind that for this guy. But in any case, it isn't that big. But the ports are huge! Like I said, 1" pipe thread.

 

[ftillier]

If you don't have a winch, I'd think it should be able to fit between the frame rails in front of the radiator possibly, though running the hoses might be a pain. I have a similar heat exchanger in my house for the heated floor - if it's good enough to heat a concrete slab, I'm sure it'll overkill for a camp shower.

 

[Stuart Barnes]

Thats why I was thinking rear wheel well heater hoses. You could cut the existing supply line, and plumb your exchanger inline on a less critical coolant path.

Can you post a picture of the exchanger with something for scale? I'm wondering how large of a unit we are talking about.

I’d be looking at this option.

 

[avslash]

I have a TR front bumper. If you don't use their relocated washer fluid tank, their might be room on the driver's side. Passenger side has bracket for the front air block that would probably be in the way, but maybe enough room to wedge it in their.

That would make it easy to cut a couple holes in the front bumper to mount your input/output water fittings.

 

[greiswig]

Thats why I was thinking rear wheel well heater hoses. You could cut the existing supply line, and plumb your exchanger inline on a less critical coolant path.

This might work fine. And I got to thinking this might help simplify another problem.

I assume that the heat exchanger is really efficient: it lists at 200,000 BTU/H, and I found online the formula of "System Delivered BTU = 500 x GPM x System Water Temperature Change", so if I want a 50 degree rise in temp, that's still only asking for 25,000 BTU at a gallon a minute of flow. If I'm understanding the math right, and if the source of the hot water side has sufficient flow to actually get there.

Anyway, if I assume that a hot engine will actually make shower water TOO warm, then I still need a bypass of sorts. If I tap the rear heater, I gather that means I will only be able to use this if I turn on the rear heater. I'm wondering if that little drawback also means I can actually use the rear heater temp control to find the sweet spot to get a lower temperature from the shower.

 

[avslash]

HaHa. I thought of that when going to sleep last night.

You could probably easily end up with 200 degree shower water, which would probably make for a short shower.

 

[greiswig]

HaHa. I thought of that when going to sleep last night.

You could probably easily end up with 200 degree shower water, which would probably make for a short shower.

Yeah, the other way to deal with it, as I mentioned before, is to just have a bypass valve.

 

[ftillier]

A mixing valve would give you more consistency if your hot water tank overshoots your ideal shower temperature. Are you thinking of heating the water, and then running the shower, or doing it in one go, without the intermediate storage step?