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Liquid to Liquid heat exchanger for hot water?

Posted: Wed Dec 14, 2016 1:38 pm
by Furi
I'm looking to use a liquid-liquid heat exchanger in-line with the cars coolant line to be able to heat water for showers, etc. Plan is to pump water through the HE. There seems to be two types; plate based as well as tube-in-shell HE. Although plate based seems more efficient and is cheaper, the tube-in-shell seems to have a better flow through and handle vibration better. Most of the products available for offroad vehicles seem to be tube-in-shell but I've also read many people use the plate based with no issues.

I was mainly worried that using the plate based HE would effect the coolant flow and the engines cooling process. Anyone has a setup? Thoughts and experience? Thanks in advance.

Liquid to Liquid heat exchanger for hot water?

Posted: Tue Dec 20, 2016 3:16 pm
by lazycoyote
Everything you mentioned seems correct. Remember with the higher risk of fluid to fluid contact in the plate exchanger, you risk adding poisonous glycol to your potable water. Domestic systems must always have edible glycol or pure water as the heating medium.

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Liquid to Liquid heat exchanger for hot water?

Posted: Thu Dec 22, 2016 3:54 pm
by poochike
I use the tube in shell, i believe it was called a marine heat exchanger for cooling oil. Work pretty well, but in hindsight I would have purchased a larger one. I just cycle the water through a few times and it works a charm. That way i can shut of the engine while I shower, no exhaust fumes. It's plumber into the rear heater on my L400 and believe you can do it in the same place on the L300. I use a pump and manual manifold to switch between fresh water and shower water. That way my drinking water doesn't pass through the heat exchanger and I only need the one pump. I have seen guys make their own tube in shell heat exchangers with good results. The one I bought was only $30 off ebay so couldn't pass up the deal.

Good luck!

Liquid to Liquid heat exchanger for hot water?

Posted: Thu Dec 22, 2016 6:59 pm
by Furi
Thanks both.
poochike wrote:I use the tube in shell, i believe it was called a marine heat exchanger for cooling oil. Work pretty well, but in hindsight I would have purchased a larger one. I just cycle the water through a few times and it works a charm. That way i can shut of the engine while I shower, no exhaust fumes. It's plumber into the rear heater on my L400 and believe you can do it in the same place on the L300. I use a pump and manual manifold to switch between fresh water and shower water. That way my drinking water doesn't pass through the heat exchanger and I only need the one pump. I have seen guys make their own tube in shell heat exchangers with good results. The one I bought was only $30 off ebay so couldn't pass up the deal.

Good luck!
Did you mean something like this?

http://www.ebay.com/itm/MarineSurplus-M ... vv&vxp=mtr

Found a few companies in Australia that makes HX specifically for this purpose but the cheapest I could find is ~$250 delivered. so the marine HX might be a better alternative if its not too small. How big is your HX? Was there a bigger one available?

Liquid to Liquid heat exchanger for hot water?

Posted: Wed Dec 28, 2016 3:47 pm
by poochike
That looks like the exact one I bought. The ones for $250 I think are better, but if you don't mind cycling the water a couple times before showers than you can't beat the $79 price tag. 8

Liquid to Liquid heat exchanger for hot water?

Posted: Thu Dec 29, 2016 12:57 pm
by Furi
Found it for $59 shipped so even better. I don't mind the xtra few minutes; whats the rush when on the road!? :) And at this price could get another one and install in serial to speed things up if necessary. Thanks for the pointer.

Guessing you didn't notice any issues with coolant flow? Which outlets did you connect the coolant and which fresh water?

Liquid to Liquid heat exchanger for hot water?

Posted: Wed Jan 04, 2017 8:59 pm
by poochike
Good price! I've also thought about buying another one, but I'll wait until I road test the current set up a bit more. No coolant flow issues at all. I plumbed mine into the rear heater. There's an inflow/outflow that's easy to access. I Was able to use the stock hoses so if something happens it's easy to put back to original and bypass the heat exchanger. There is an access hole into the van just behind the driver's seat so that's where I ran my fresh water inflow/outflow for the shower. My water pump is inside the van which I use for the shower and fresh water. I'll try and get some pics for you and post them up here. hope the install goes well for you.l

Liquid to Liquid heat exchanger for hot water?

Posted: Wed Jan 04, 2017 9:01 pm
by poochike
Just realized I didn't answer your question.

Coolant goes to the larger straight through and fresh water goes to the smaller top connections.

Liquid to Liquid heat exchanger for hot water?

Posted: Thu Jan 05, 2017 1:29 pm
by Furi
Great into; thanks a bunch. Look forward to the pictures.
Do you have two different water source for fresh water and shower?

I'm taking the rear AC/Heater out so will be using the same coolant lines.

Link to the $59 HX for future reference...

https://marinesurplus.com/products/mari ... ion-cooler

Liquid to Liquid heat exchanger for hot water?

Posted: Thu Jan 05, 2017 3:17 pm
by poochike
No worrie!

I have the lines set up so I can shower from my fresh water tank or pick up from a bucket, river, Lake etc. All runs through the same pump. Was a bit of a head scratcher to figure out how to set up the manifolds, but worked it out. I have a 50L tank inside the van for fresh water.

Liquid to Liquid heat exchanger for hot water?

Posted: Fri Feb 10, 2017 12:19 pm
by speleokip
Bunged the Australian Glind brand in mine with a 12v pump so I can pull water from creeks etc. I have two quick connects at the back for water in and shower out. Works a treat and the way it is set up i can use the pump to fill my fresh tank from a water source as well.

A shower on board has the additional benefit of making number 2 so much happier.

Liquid to Liquid heat exchanger for hot water?

Posted: Thu Mar 09, 2017 11:20 am
by poochike
Furi wrote:Great into; thanks a bunch. Look forward to the pictures.
Do you have two different water source for fresh water and shower?

I'm taking the rear AC/Heater out so will be using the same coolant lines.

Link to the $59 HX for future reference...

https://marinesurplus.com/products/mari ... ion-cooler
How'd the install go?

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Liquid to Liquid heat exchanger for hot water?

Posted: Fri Mar 10, 2017 7:46 am
by Furi
poochike wrote: How'd the install go?

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Few dependencies which I haven't been able to complete yet. i.e. removing rear heater/ac unit, etc. which I need to go to a shop for. But hitting the road in early June so a hard deadline :)

Liquid to Liquid heat exchanger for hot water?

Posted: Sat Nov 11, 2017 5:28 pm
by Furi
poochike wrote:
Furi wrote:Great into; thanks a bunch. Look forward to the pictures.
Do you have two different water source for fresh water and shower?

I'm taking the rear AC/Heater out so will be using the same coolant lines.

Link to the $59 HX for future reference...

https://marinesurplus.com/products/mari ... ion-cooler
How'd the install go?

Sent from my SM-G920W8 using Tapatalk
Rear heater is finally out and the heat exchanger is ready to go in.
My next stop is an auto shop for a reducer to join the cars coolant line with the in/out of the heat exchanger as they are separate sizes. Do you remember what you used?

Liquid to Liquid heat exchanger for hot water?

Posted: Sat Nov 11, 2017 9:43 pm
by poochike
Furi wrote:
poochike wrote:
Furi wrote:Great into; thanks a bunch. Look forward to the pictures.
Do you have two different water source for fresh water and shower?

I'm taking the rear AC/Heater out so will be using the same coolant lines.

Link to the $59 HX for future reference...

https://marinesurplus.com/products/mari ... ion-cooler
How'd the install go?

Sent from my SM-G920W8 using Tapatalk
Rear heater is finally out and the heat exchanger is ready to go in.
My next stop is an auto shop for a reducer to join the cars coolant line with the in/out of the heat exchanger as they are separate sizes. Do you remember what you used?
Good stuff. I don't remember what I used for couplings, but I do remember not being able to find metric so the fit was a bit less than perfect. Also, I kept my rear heater in so my set up is a bit different. I didn't cut the stock hoses just in case I need to switch it back because of a leak or something. What I do want to add is a drain for the fresh water side for winterizing. If it freezes it could burst and cause problems. Right now I just use my compressor to blow out the system.

Good luck

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