liquid to liquid heat exchanger for on board warm/hot water

I saw another thread from @ProForce about having pressurized onboard water,

https://www.tacomaworld.com/threads...or-the-2005-current-toyota-tacoma-obw.453005/



I've seen a few storage tanks that are black and should generally heat from being in the sun. My idea is likely more trouble than it's worth but wanted to share it. Maybe someone will expand on the idea and make it more feasible.



Basically use the exchanger, to transfer heat from the coolant system to the clean water storage. The same pump in the first picture could be used with a solenoid diverter valve and perhaps a FET to run it at a lower duty cycle for longer periods of time. Scaling would also be an issue on the fresh water size. I'm not sure how to get around this other than just descale it every now and then. The worst part about this idea is likely running the water lines.

• FET -- https://en.wikipedia.org/wiki/Field-effect_transistor
• Motor Driver Circuit using a FETs -- https://www.mouser.com/applications/industrial-motor-control-mosfets/

 

Hey I stumbled across this post looking for something else... but wanted to say, I did this exact thing in my truck and it is great. It took a couple of years of intermittent effort. I cannot possibly recommend it as a good use of your time. But having hot water on demand is super nice. You can read about it here, here, and here.

 

Wow, your hot water setup is really nice work, and I’m not trying to poop on it, but I bought one of these and made the job a lot easier. I was kind of proud of it until I saw what you did - man that is a beautiful set up, but I can imagine the amount of work you put into it. Plus for those of us that don’t have the welding equipment, it would be rather expensive to start a project like that.

Hot water on demand Campworld Low Pressure 1.58GPM/6L LPG Portable Propane Gas Hot Water Heater:

Campworld Low Pressure Startup,Overheating Protection,1.58GPM/6L LPG Portable Propane Gas Hot Water Heater,Digital Display With Shower Head.Lightweight for RV,Outdoor Camping

https://www.amazon.com/dp/B08GFDZJB1/ref=cm_sw_r_cp_api_glt_fabc_9BGEVD645JY2KV6R735M

 

I just heat water on a camp stove and then use one of these:http://www.hotjugz.com/

 

Old idea. Although the ones I saw years ago used a manual valve for isolation and a bimetallic valve for temp control.

 

That's an interesting idea, think I might just go cheap and buy a garden sprayer and wrap it in reflectix or something though.

 

Lol nice to see the conversation jump into gear. There's no right or wrong way to go about this, I just wanted to highlight my approach as one of the many ways to do this, and one making use of a heat exchanger to harvest engine heat per OP's OP.

The downside is that it's a ton of work, probably a few hundred hours counting learning how to weld and running 220V to my garage! The upside is it's a tuly on demand system, no setup required, just pull the sprayer out of the bedside and you have water like your kitchen sink sprayer. If the engine is warm, then you get tempered hot water, perfect for showering and doing dishes. It has 13 gallons capacity with zero lost bed space, but was a huge endeavor to install.

I wouldn't trade my setup for the world, but if I had to do it again, I'd probably just go with a propane heater!

This was one of those projects where you do it to prove you can, not because it makes the most sense!

An old one but a good one... I included such valves as well.

 

If you had already known how to weld I’d have thought you were a steam fitter. We use liquid to liquid exchangers quite a bit for heat recovery and cooling.

 

I have installed gas lines for pyrophoric neurotoxins in R&D settings, but I know damn well not to mess with the steam lines! Some things are best left to the pros.

 

I tried a garden sprayer in the past but found that it is Hot Jugz' low flow shower head that allows one to shower with 2 gallons of water. It also has a pressure release valve.

 

Never messed with that stuff. But have done high purity stainless stuff and chemical lines.

The old guy that taught me said to just think first and take your time. It isn’t a race. Funny thing about that type of knowledge. I passed it on to those I taught.

 

I've messed with steam lines just a little bit, low pressure, low volume, I don't think I want to be anywhere even close to PYROPHORIC NEUROTOXINS!?

 

What ever you do, don’t let that guy get disgruntled at your workplace!

Yeah, that welding workmanship is impressive!

 

What I worked on was just quarter inch stainless tubing ... but using an orbital welder on stainless tubing is nothing like learning to mig weld! It's a fully automatic machine, you just cut the tube to length, clean it, and stick both ends in this machine. It does everything else magically. I probably wasted half the material we bought because I'm so bad at eyeballing, er, uh, "measuring" lengths, especially accounting for the bends... but the welds were always perfect!

Mig welding is much harder to pick up, but a hell of a lot more useful for working on a truck!

 

Makes me wonder, how many even know how to gas weld anymore. When I learned there was a logical progression.
Solder, braze, gas weld then arc. Sometimes after that mig & tig came along.

Though as long as we’re talking burning metal, my hats off to the guy that invented the plasma cutter.

 

Hey guys — thinking of doing this on my 2nd gen soon! Where does everyone tap in the heat exchanger?

My brief look under the hood seemed to reveal coolant lines running through the firewall on passenger side, but not sure which is source and which is return. Also appears they’re steel so not sure how to tap in without breaking something is the little plastic dealie on there a quick release of some sort..?

Thanks for any advice!

 

I think you're looking at the AC lines.

Check out the description I linked in post 2 above, it shows where I installed and tapped into mine.

 

Thanks, but I don’t really see anything about it other than you used 5/8” hose and heat shielding. There is a picture but it’s very unclear to me where these actually tap in to the existing cooling system...

Am I missing something?

 

I recommend tapping in to one of the hoses for the heater core, and connecting the heat exchanger in series with it. The heater core is in the dash, with two connections at the firewall behind the engine, slightly to the drivers side. These are the 5/8" hoses, and each connects basically to the rear of the engine. They're somewhat difficult to access, but you can see them coming from the firewall inboard of the brake booster. I don't think it matters which side you tap, so long as you do it correctly. Water will flow through the heater core and the heat exchanger, in one or the other order. You can install a 4-port diverter valve to turn off flow to the heat exchanger, without blocking flow to the heater core. If you used a regular 2-port shutoff valve it would block coolant to the heater core as well.

 

Thanks for this, by the way! Finally got this project finished yesterday, after far too many trips to the hardware store.

My setup is not as elaborate as yours, @mk5 — I plumb fresh water from a tank on the camper or a stream — but works great in testing! Looking forward to “trail testing” in Moab tomorrow...