Heat exhanger choice for onboard hot showers

[overlander]

so I'm committed to an onboard hot water system for expo travel and family good carma. My 110 has a TDI and I have recently installed a Webasto coolant heater, which is fantastic at keeping the coolant hot without running the engine. I had originally worried about having the shower setup in the back with hot diesel exhaust flowing, but now that's no longer an issue in the campsite. I've chosen the quick disconnect RV shower spigot that AT offers, to control hot/cold water as part of my design.

That being said, I need the right exchanger. I see the Helton style copper based cylindrical exchangers out there, and I see the plate style exchangers. So are they on par with each other, or are there tradeoffs to be considered. Mounting position is not a concern, but I see many more choices here in the US for the plate style exchangers, and more competitive pricing, than for the cyclindrical style. If there is no performance difference, I would lean toward the plate style on price, but defer to those out there with more experience on these. :coffeedrink:

 

[ersatzknarf]

Planning a similar concept, also, using a Webasto coolant/cabin heater.

I would talk to AT about a water heater, too : http://www.expeditionportal.com/forum/showpost.php?p=646090&postcount=133

By the way, I like their quick-disconnect shower, but I wonder about making the hose a little longer...

 

[mhiscox]

The Isotherm Slimline in the EarthRoamer Jeep works well, but it's got a four gallon tank--mine's cylindrical; they also make rectangular--which takes up quite a bit of space. Also not cheap, around $700. Still, it's pretty much a no-compromise solution that would leave you with plenty of hot water between coolant heatings.

 

[Gokracer1]

I would shoot Kurt with Cruiser Outfitters (crusieroutfit) a PM or check out his site, he sells the Helton Hot Water systems...

http://cruiseroutfitters.com/helton.html

 

[JackW]

I'd use the flat plate style like I did - much more compact, lots of internal surface area and more efficient. I bought mine off Ebay for around $100.

look in this thread for more info:

http://expeditionportal.com/forum/showthread.php?t=28275&page=2

 

[womacje]

When using the heat exchangers, plate or tube, do you have to bleed off the hot water that is coming out of the exchanger when the water flow is stopped? Is this just a precaution you give everyone, when using it? I'm not too worried about myself, mostly the ladies that would be joining me.

Thanks for the great info, Jack your setup looks really affordable! Kurt, wealth of knowledge, thanks.

 

[chasespeed]

Depends on how complex you want to make.... IF you wanted to not bother with bleeding it, you COULD get a mixing valve, and set that at a desired temp, BUT, you would need cold and hotwater flow for it to work.... So, if you had a separate pump for each side, you would have to wire them to come on simutaneously when you activate the h/w pump. But, the other thing that would become an issue, is temp/pressure relationship. If its always tied in with the cooling system, the temp in the heat exchanger can hit 200*, or more if doing heavy wheeling/towing, etc. water boils at 212, @ SEA LEVEL. If you can put pressure in the system, it will raise the boiling point just like your cooling system.

So.... how complex of a system do you want, in a niche, where, we things as simple, and reliable as possible?

Chase

 

[womacje]

So, if i'm understanding this correctly: the water, when stopped, that is in the exchanger will continue to heat until the flow is started again. To use your example of 200degrees, even with a mixing valve, i could have a burst of 200 degree water, mixed with the ambient water source, that could scald someone or at least make the water fluctuate drastically when the flow starts again. If i'm looking to conserve as much water as possible and avoid big fluctuations in water temp, how would I do that. Oh yeah, while keeping it as simple as possible.

thanks,

 

[cruiseroutfit]

Jeremy, yes the heat exchanger will continue to heat stagnant water and while it can be very noticable it is easily mitigaged with your shower practices through several options.

1. Preheat the water
2. Anti-scald device
3. Regulating mixing valve

I preheat, its fast and then you take a nice leisure shower without having to even have the engine running. For example we had ~8 people shower on the Carbon Nuetral Expedition off of 10 gallons of water, all preheated by placing the showerhead in the same container as the pickup water. Once its up to shower temp, turn off the engine and shower away.

 

[rusty_tlc]

.....

I preheat, its fast and then you take a nice leisure shower without having to even have the engine running. For example we had ~8 people shower on the Carbon Nuetral Expedition off of 10 gallons of water, all preheated by placing the showerhead in the same container as the pickup water. Once its up to shower temp, turn off the engine and shower away.

That's how we used the Zodi. (They have a proclivity to melt down if you let them burn with no water flow.) It works pretty well except unless the first shower is very warm the last is kind of tepid.

 

[overlander]

Thanks for input all. I ordered a red Helton hot water exchanger from Kurt, and also ordered a 2GPM pressurized ShurFlo pump to start off my project. next will be mixer, which I will likely go with the AT one (I really like that) but I really need to sort out exactly where I'm going to setup my shower tent in vicinity of my vehicle. I have a Eezi-Awn T-Top and awning, so my camping setting is pretty fixed, and I have a dedicated tent for the PETT.

I just need to figure out if I'm going to dual purpose the PETT tent, or do showering in the lower room of the T-Top. decisions on where to put the Scepter source water cans and mount the mixer controls are keeping me up at night.

I have until end of next month to get it all sorted out, installed and validated before the Mid Atlantic Rover rally at end of September.

Has anyone else gone through these thought processes? I'm particularly concerned about mounting mixer in rear of vehicle, since if I should have to run the vehicle, the exhaust is right there, and with the T-top up, that's like taking a shower in the garage with the door closed and the car running.

this could be my most complex install yet?

 

[adventureduo]

We run a Helton from Kurt. Works great man.. let us know how your install goes.

 

[womacje]

We run a Helton from Kurt. Works great man.. let us know how your install goes.

Dave,

Do you have an install thread that shows your components and routing? I currently have a freshwater tank and 2gpm pump setup. I'd like to figure out how to maintain only one pump for hot and cold, incorporating the AT mixer.

Jeremy

Ps. Congrats on the Trasharoo's, they seem to be hauling butt out of your warehouse!

 

[overlander]

Dave,

Do you have an install thread that shows your components and routing? I currently have a freshwater tank and 2gpm pump setup. I'd like to figure out how to maintain only one pump for hot and cold, incorporating the AT mixer.

Jeremy

Ps. Congrats on the Trasharoo's, they seem to be hauling butt out of your warehouse!

The one pump for mixer should be easy; that's my plan. i'm running source to filter to pump. from pump it T's into hot and cold line. hot line goes through exchanger to mixer. cold line goes direct to mixer. boom done. that also gives me option to circulate the water in source until source is shower warm, then turn off vehicle and run shower straight off cold (which is now shower warm) without having to go through exchanger at all. it's the ultimate in flexible design I think.

 

[womacje]

Heres a terrible schematic of what i'm thinking, any forseen issues from those of you who have done it?

Thanks for all the help on this. I think the heat exchanger might the the best way to go after talking it out with the pros (you guys)

Jeremy