[cbfb]

I could fit a 15L Isotemp heat exchanger (https://www.rvworldstore.co.nz/isotemp- ... er-slim-15) in my engine bay.

Does anyone own one of these already and can please tell me:
1. How long it takes to heat the cylinder from cold (using engine not 240 AC)
2. How long will the water stay warm enough to wash up or take a shower?

I am intending to find some way to insulate it to keep water warm for a while.

The van is my daily driver and the reason for wanting the heater is to wash up while camping (just overnight trips no long stays) and the odd shower after being in the sea.

Running off AC is not an option as I won't be installing a grunty enough inverter.

Just trying to weigh up if it's worth the expense/effort or should I just boil a saucepan to wash up.

[Karmann57]

We have an Isotemp square model mounted under the sink in our LT35, so has a run of about 2 metres for the engine coolant hoses.
They heat from cold very quickly after about 20 minutes driving and stay warm for about 12 hours.
The unit is packed with polystyrene foam insulation so should not require additional insulation. You don't say what vehicle you have but I would be surprised if you have room to install in the engine bay. You will of course need a fresh water tank, pump and grey tank to complete the instal, so are better to instal the Isotemp close to where it will be used. The longer coolant run from the engine will not be a problem.

[Nut17]

We fitted an Atwood 3 way water heater in our bus back in 2000. This had a crude heat exchanger (a piece of aluminium tube welded to the underside of the tank that hot coolant from the engine passed through) It did surprise me how efficient it was and as the tank was reasonably well insulated, an hour on the road provided a good supply of hot water. The Isotemp unit you are looking at looks very well made and with a more efficient coil type heat exchanger would heat more quickly than that Atwood. The speed that your engine temperature rises and the normal operating temperature will also have some influence. Late model engines tend to reach operating temperature more quickly and run at higher temperatures than the lazy old Mazda 3500 SL cast iron engine in my bus.
Karmann57 has replied while I was typing this and has confirmed the efficiency of the Isotemp unit.

[cbfb]

Thanks all.

Karmann57 it's going in a Ford Transit, there's room in the engine bay for the 15L model. Thanks for the info, couldn't find anywhere that gave warm-up time and stay-warm time!

If I stick with the 15L model it'll go in the engine bay so I can keep the coolant hose short and close to the radiator. A failed coolant hose would be a much bigger problem than a failed water hose (I'll route these along the chassis, insulated).

Now you got me thinking about relocating it though, there's very little difference in price for much bigger units so will see what I can squeeze in.

Am doing a conversion of a minibus from scratch so there's plenty of options still, just at the design phase.

[Karmann57]

The coolant hoses are normal automotive heater hoses and are tee'd into the existing heater hose lines. They run under the van floor and up into the sink cupboard. Risk of the heater hose bursting is minimal if you use standard heater hose from Repco/Supercheap. Installing inside the vehicle will make your fresh water plumbing and pump, shower, taps much shorter so less heat loss there.