Bus RV domestic hot water

[frank-id]

Has anyone made a hot water source using engine heat?  This is a type of heat exchanger.  Many years ago, I wrapped  the tank of my propane heater with about 18 turns of soft copper.  The original heater sheet metal was modified and replaced.  I got lots of free hot water from the engine coolant, driving down the hiway.  I'm thinking of fabricating a ss tank of about 5 gallons.  Any one else done this magic?  Just thinking.
          Frank

[Jeremy]

Unless I am missing something, what you are describing is a very common system for boats and motorhomes - the tank thing with the heating coils you fabricated is called a calorifier in the UK - they may be called something else in the States. I have bought a 70 litre Surecal calorifier for my bus, which is a twin coil tank so it can run both the heating and hot water, with the heat being supplied by either the engine or the Webasto, or an electric immersion heater in the tank - although in fact since I also want to be able to quickly heat a small amount of water electrically (for showers etc), I also have a much smaller 7 litre electric water heater as well.

The calorifier is very heavily insulated, and I am assured that when you arrive somewhere the tankful of 'free' hot water (heated by the engine on the journey) will last for a couple of days at least depending on usage and the amount of 'topping up' you do with occasional running of the Webasto or immersion heater. I think my immersion heater is a 3kw (at 240v) job, so whenever I am running the generator to charge the batteries I will have enough spare generator capacity to run the immersion heater as well - in other words more 'free heat'.

For anyone interested, Surecal's website is here:

http://www.surejust.co.uk/index2.html

Jeremy

[Runcutter]

Frank, my 4107 has such a creature, factory made.  Runs on 110 volts, but also has a coolant loop - so heat from the bus diesel, or from the generator will provide heat.  After running all day, it's nice to have free hot water the next morning.  Although it was already installed when we bought the coach, I've done a little research - I'd never seen one before.  I'm sure other folks have more information, and will provide links, but I believe it's a marine-type water heater.  I know this isn't quite what you're mentioning, but I like the dual ability to use the engine heat, _or_ standard water heater electric elements.

Arthur

[Paso One]

Hi Frank
I have one rigged up down stream from my webasto. It is actually a side arm to my water heater.
Driving down the highway engine coolant circulates thru the heat exchanger and heats the water in my electric water heater by default.  If I use the webasto one loop  circulates thru the heat exchanger if I close the valve to heat exchanger it will just heat the engine.  I have a temp gauge at top of heat exchanger level with the top of the water heater reads 180 engine tempeture. Water heater should also be close to that. ( If water truly finds it own level)    I have never check the tempeture using just the webasto.

Jeremy  nice link  I would have used one of those in a heart beat. I didn't know they existed. What ball park price are they.

[NJT 5573]

Frank. Free is good, but don't spend alot to get it. I just returned from a 17 day family outing with 4 other family members. We all showered each day, 5X17=85 showers. I have the Suburban 10 gal propane heater. The hot water is on a dedicated 5 gal bottle of propane. I just filled the bottle, it was not mt, it took 2.5 gal to fill it. ($6.00)

[boogiethecat]

HI Frank,
I've been doing it for years.  I nab those little industrial "shell & tube" heat exchangers fom surplus stores, then I find the old temperature-compensating mixing valves that used to be common in darkrooms to keep water temperature at a set temperature no matter how hot the inlet water was or how fast the water is flowing.   Stick the heat exchanger in the coolant loop and take perfect temperature showers forever as long as the engine is idling.  That was the sole hot water source in my first bus.
   I also put one in my pickup for the same thing.. I go camping a lot and you have no idea how many friends I make when I announce that there are infinite hot showers...hook it to the camp's hose bib, start the car and make people happy!!!

[Jerry32]

I had a 1976 Revcon motor home that had factory installed unit for engine heated hot water. Jerry

[TomC]

Personally did not want to run another coolant line, or pay for a heat exchanger equipped water heater.  I have two Home Depot bought 10 gal electric water heaters that feed one into the next with the second one powered through the inverter.  I just keep the inverter and water heater on while driving and have 10 gals of hot water available anytime of the day.  Then when stopped, I heat the other water heater with either the power pole or when the gen is running.  Simple, have had no problems with this system since installed in 1995.  Good Luck, TomC