Water heater

[adpsimpson]

Thinking of fitting a hot water source to the Surf. I reckon the way to go is a small tank (say 10 or 20 litres) with a water pump to a heat exchanger mounted in the engine bay, running off the engine coolant water (similar to how people do it it heat WVO).

It'd need a small insulated tank (probably mounted at the rear, in spare wheel space - planning to put an extended range tank in there anyway), water pump, heat exchanger, a routing valve to bypass the heat exchanger (turn the system off) once the water's hot, and a valve and switches to allow the hot water to be pumped to roof level for use (shower, tap etc). It'd also need a temp monitor with a display inside, and either a manual or automatic switch to stop the system at a certain temp.

So... Any thoughts? What sort of heat exchanger would be best? I'd rather keep it near the engine to prevent too much modification of the cooling system. Is it even possible to suck too much heat out of the system too quickly? Also anyone know of a decent temp gauge that would work? Had a quick look on ebay but not sure if any of them are that good. Any ideas what sort of valves to use? Finally would it be easy to put the insulated hot tank below the vehicle? How could I insulate it but keep it fully water/mud/stone proof?

[POPEYE]

if this is any help i made this to heat the veg but it'd heat water as well, it's just 15 &22mm tube and fittings, file the stops out the 22's so the 15 will pass through and solder away, the coolant passes through the 22mm and heate the oil/water passing through the 15mm, you could make as many turns as you like, the longer it takes the stuff to pass through the quicker it'll warm up, the size of the storage tank would be the biggest prob i think, it'd need to be quite large to be of any use for showers etc and a heat exchanger of my type would take ages to warm it, electric would be quicker if you can sourse owt in 12v or maybe a invertor?
if your fitting a second tank at the back there aint gonna be a whole lot of room left so in the back may be best, as for a temp gauge any one would do although most start at 40 deg and it'd need to a dam sight warmer than that for me to shower in it caravan water pump would do for circulation and by use of valves it'd do the lifting and shower i guess,

[adpsimpson]

Thanks Ian, looks ideal (and cheaper than buying one), will probably go that route. I'd seen that pic before in your dual tank thread but thought it was simply submerged in your WVO tank, didn't realise it was an exchanger. Caravan type pumps look ideal too.

Electric would be quicker, but I like the idea of using waste heat. Besides we'll be covering long distances once we get going, so should be able to run it for a few hours.

Any ideas on where to find valves for directing water flow? I think I'd need two, both two way valves, one to allow the engine coolant to bypass the heat exchanger, one to change from pumping water to the heat exchanger to be heated, towards a useful outlet (tap or similar). Can't find anything on ebay, but don't really know what search terms to look for.

[POPEYE]

I did a single pipe set that looked like this pic, that was the one inside the tank, you could use both coolant and electric, combine the two,
Valves!! not sure if the "pollok" type 3 or 6 port valves would do, the bores are pretty small (made for fuel as opposed to water) or maybe a couple of central heating 3 port motor valves which are 22m bore, driveing them would be the issue as their step motors at 220-240v, the motor and gear does come off tho leaveing a small "flat tag" you can turn with an adjusable, or again maybe an invertor would let you use the motors, the electrical know alls might be able to give you some advice there, there's also the cable opperated valves like the one on the bulkhead for the heater shut off,
scrappers??

[wishbone]

Don't know if you've seen this site yet ?

A bit pricey but may have some ideas on placement etc..

Rob.

[adpsimpson]

Ian, the cable actuated valve looks like a workable option. Not sure wiring 240V round the truck would be my favourite plan, although we'll probably want an inverter in there one day anyway.

Wishbone, hadn't seen that site - looks exactly the sort of thing I'm looking for. Thanks!

Edit - realised they assume your engine will be running, continually heating water, instead of heating a tank during the day. Misses the point a bit...

[POPEYE]

As you say a bit pricey, you could knock up summat for less than that i'm sure, it's sourceing all the bit's, pumps gonna be the most expensive i guess, unless you can find a car with an electric one at the brakers, rest of it's just plumbing, i'd just make up a decent exchanger and hand opperated valves to keep it simple, anyway depending on the river/pond (muddy ditch) you drawing water from, i would'nt fancy showering in it, might be stuff liveing in there

[wishbone]

How funny,

I was just browsing the expeditionportal forums and found this thread about fitting water tanks too.

Rob.

[POPEYE]

Ian, the cable actuated valve looks like a workable option. Not sure wiring 240V round the truck would be my favourite plan, although we'll probably want an inverter in there one day anyway.

Wishbone, hadn't seen that site - looks exactly the sort of thing I'm looking for. Thanks!

Edit - realised they assume your engine will be running, continually heating water, instead of heating a tank during the day. Misses the point a bit...

We used to fit cable opp valves in the heaters on the buses, may still have a couple, you got the water shut off part (like the surfs one) a cable and a rotery geared nob on the dash, quite simple, guessing the nob bit would suit you better than the surfs heater sliders, if ya want i'll have a look see wot i got,

[POPEYE]

How funny,

I was just browsing the expeditionportal forums and found this thread about fitting water tanks too.

Rob.

I can see a lot of £ signs on them custom tanks, stick one of them 1000lt carboids in the back or tow a bowser

[adpsimpson]

This is why I post here

Thanks guys. Thinking of doing this at the same time as a simple range-extending tank, in the next few weeks. Will post more as I do it.

Reckon actually the coolant bypass won't be necessary, just leave it running through the heat exchanger continually. Presumably if I don't do anything silly the pressure drop won't matter too much (Ian, what do you reckon? Seeing as you've put a second radiator and a heat exchanger in, has that caused any problems?). So that leaves a pump in the tank (off ebay for £10-20), and for that price it's probably cheaper just to fit a second pump for using the water. That would go to a flexible pipe with a tap on the end, curled up in one of the rear lockers, long enough to reach roof level. Can be refilled through the same flexible pipe too.

So to heat water as you drive, once engine is up to temp, turn on pump 1 (push cold water from the tank, through the heat exchanger and back to tank). To use it, open the tap and turn on pump 2. Pump 1 fed off a source that dies when engine's not running, pump 2 off a permanent 12V feed. Nice and simple.

[wishbone]

Just re-read the 1st post and now see what you want to do..

1 large water can. pump to the heat exchanger and return to top of can. Fit a thermostat that switches off pump at set temp. Saves messing with bypass valves etc.

Use a seperate tap and pump to go to shower head.

That's what I'd try.

Good luck with the project.

Rob.

[adpsimpson]

We used to fit cable opp valves in the heaters on the buses, may still have a couple, you got the water shut off part (like the surfs one) a cable and a rotery geared nob on the dash, quite simple, guessing the nob bit would suit you better than the surfs heater sliders, if ya want i'll have a look see wot i got,

Posting at the same time as you here... That would be cool. Do you think it would be sensible to have a way of bypassing the heat exchanger? Or just stop sending cold water to the exchanger but leave coolant running through it?

[adpsimpson]

Just re-read the 1st post and now see what you want to do..

1 large water can. pump to the heat exchanger and return to top of can. Fit a thermostat that switches off pump at set temp. Saves messing with bypass valves etc.

Use a seperate tap and pump to go to shower head.

That's what I'd try.

Good luck with the project.

Rob.

Yup, that's what I'm thinking now (posts crossing over...)

Will post pics when I get round to starting it in a few weeks.

[POPEYE]

Thermostat switch from these guys will do the temp controll for your water pump, remember these are normally "made" so will allow current through till it gets up to temp, used em on my fans/pump in an arse about face way (switching the other way round via a standard relay and a 5 pin crossover relay) tho the water pump's still on constant, not got round to doing the relays on that yet, no probs with leaveing it on, as the take off's on the heater side of the engines stat the engine still heats up as normal and when the stat opens you get the hot water going to the rear, i'll see if i can find the valves cables etc,
http://cpc.farnell.com/jsp/search/br...at+switch&Ntx=