Thread: FBH for Camping Shower Hot Water - anyone considered it?

I use a 2m length of 1/2" copper tuber, coiled into about 4 coils with two tails sticking out. Sits perfect on top of one of cheap cast propane gas burners. Garden hose from that to small 12v bilge pump in 20 liter bucket. Circulate it round and round (takes 5/10 minutes till water is at good temp. Then divert water to shower (again am just using standard hose 2way tap. Presto very happy wife. It needs car for power Is simple elegant and cost about $100. PS if you want to speed it up I put kettle on top. Has worked for years

I think not,these things warm the coolant so the heaters etc are ready to go when you want an early start on a cold morning.
Hence my thoughts that they have their own fuel pump.The main pump would flatten the battery,at least it would be cosy waiting for AA
Andrew

I have a FBH in the Kamper. It's one of the Webasto thermotop units. The hot water (for the kitchen and shower) works via a heat exchanger, which is driven by the Webasto by means of a glycol filled header tank and closed loop recirculating system. The FBH is used to heat the glycol system (50/50 green) which circulates through the heat exchanger, plus in my case, the glycol circuit also loops (in series) to a 2nd heat/air exchanger in the tent, driven by a two speed fan, for heating.

I think the FBH works more like a furnace, not like an on demand instantaneous HWS. The glycol is used as a heat bank, and once to temp the FBH cycles off (stops burning diesel) but keeps recircing the glycol. Once the glycol temp drops too low the furnace re-ignites. Mines takes maybe 15A for a few minutes to establish proper ignition, then runs on straight diesel (2.5hrs with tent heater and hot water running at MAX used less than 1/2 cup of diesel ... Really does run on the smell of an oily rag! )

Takes around 3-4 minutes to get 50deg hot water, and tent heat output is maybe 1.5-2kw.

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Kev,

Thanks for this. Very interesting.
Any chance of some photo's?
Thanks,

Andrew ... the fuel supply comes from a stand alone fuel tank in the kamper (about 3L or so) but no reason it couldn't be plumbed into the vehicles tank ... doesn't have it's own pump. Kamper has a small inline solenoid/pulse type 12v fuel pump to deliver fuel to the FBH with a return/spill line for excess fuel to dump back to the tank.

Phil, I'll take some shots and post them up when I get home tonight.

Originally Posted by Celtoid

Does the engine need to be running? .... whilst quiet is the D4 ... not that quiet.


And unless you have a DPF ... they stink if you're down wind ... (which probably means bad stuff to breath, regardless of the DPF or otherwise).

No, the engine doesn't need to be running.(in my proposed setup anyhow) Well it does when it leaves the factory because the canbus looks for a certain ambient temp, engine running signal, etc etc before it allows the fbh to fire up. When fitted without the canbus wiring I am proposing to simply fit a switch to energise the signal input to tell it to start up. It will "cycle" using its inbuilt sensing circuitry and that will be what I am going to use to heat up and maintain my hot water supply. The dpf does come with a small muffler on the exhaust pipe to keep it quieter but when in the great outdoors I'm not too concerned about a little noise. Cheers

Originally Posted by LandyAndy

I think not,these things warm the coolant so the heaters etc are ready to go when you want an early start on a cold morning.
Hence my thoughts that they have their own fuel pump.The main pump would flatten the battery,at least it would be cosy waiting for AA
Andrew

Doh, that's right ... they warm everything up before start up.


Silly question .... LOL!!!

Pic's as requested ... and a bit of explanation as to how it all works ... might help in designing an alternative system matti !


The business side of the kamper ... Diesel tank RHS, Glycol header tank LHS and box below glycol tank houses the Webasto, water pump, heat exchanger and changeover valves (water inlet pressure reducing valve & flick mixer/garden hose click-on connection of showers is on the front of the box)




Here's the fuel tank & supply lines via the inline filter and solenoid/pulse style fuel supply pump ...




This gives you an idea on the size of the diesel tank (the can is just for comparison!) ... I filled this to the brim when we picked up the Kamper Dec' last year and that's all the fuel we've used for hot water in the kitchen & showers for 11 nights camping and a 2.5Hr test run of the tent heater 2 weeks ago. Very economical on fuel useage !!




The glycol header tank (50/50 mix) used for the heater exchanger for the hot water supply and the heat exchanger in the tent for air heating.




Left hand side of the box where it's all housed ... The Webasto is tucked in at the rear ...




Here's the tent heater. It's approx' the size of a tower PC power supply (a tad higher than the guitar case seen in shot). Has a 2 speed fan (like a PC cooling fan). Heat output is comparable to a portable household fan heater on high.




This is the hot water heat exchanger ... Not much bigger than a can. Spec' says it has a 0.15L water holding capacity. It's wrapped in styrene foam and the red gaffa is used to keep it all together ... not very big at all.




Here's a closeup of the "box". Heated glycol from the Webasto enters the heat exchanger via the LHS rubber hose, then exits via the RHS rubber hose, which then continues on to the heater in the tent (approx' 2.5m run), then returns to the header tank, then back to the Webasto inlet. It's circulated by a small pump built into the Webasto. The red pipework is the hot water delivery which drops through the floor and travels across the kamper to the kitchen, and also delivers hot water to the shower mixer tap. Can be driven by the pump in the box with water supply from the rear water tank ... Rear tank can be isolated and mains water can be used via the pressure limiter inlet (white device on the RHS of the photo) to supply the hot water ... OR a suction line can be attached to the pressure limiter inlet so the 12v pump can be used to draw water from an external source (bucket, creek, river, etc) for endless hot showers! The silver hose at the bottom left is the Webasto air intake line with a muffler fitted (black plastic item).




Front of the services box - Water inlet (via the 65psi pressure limiter) and the mixer & outlet for the shower.




Then there's an exhaust for the Webasto. Leaves through the floor of the "box" and is routed out the side. The extension (covered in an insulating sleeve) is shown fitted IF you need to clear the canvas side skirt. The exhaust is (obviously) very hot, BUT there's very little if any smoke or particulate matter emitted ... a tad on startup, and virtually no bad smells of burning diesel ... the unit burns such a minute amount of diesel that there's next to nothing out the exhaust.




The control panel & master switches, mounted in the front kitchen side area. Water pump doesn't get turned on if your only running the heater, only if you want hot (or cold) water. The Webasto is started/stopped from the control unit. You can start it, then set a run time (up to 60min), then it shuts down after the time has elapsed. It can also be set to startup at one of 3x preselected times ... ie:set it to turn on at 7am for 30min so the tent is all nice and toasty when you get out of bed ... luxury! There's also a modification that can be done at the control panel to wire in a switch which effectively over-rides the timer circuit to make the FBH run continuously.

You can't just turn the Webasto off at the master switch when you've finished using it. It MUST be turned off from the control panel, at which point it does a "burn-off" cycle to keep the combustion chamber clean (a bit like a DPF burn off cycle I guess). Failing to do the burn-off causes the Webasto to progressivley soot up and run with excess amounts of smoke.




... and finally, the spec' sheet from the owners manual. My unit is the Thermo Top E - D (4.2kw output). The fuel consumption figures shown must be the max/extreme useage figures as mine doesn't burn anywhere near what's stated. All depends on the duty cycle.




There's another page giving spec's for the circ' pump but I forgot to photograph it. I think is was around 2A for the circ' pump.

It works brilliantly! The glycol tank gets way too hot to touch once running temperature is reached ... and takes ages to cool down, so you can still draw off some hot water after the system has been shut down.

I don't know how matti will go trying to run straight water thru the Webasto as their designed to heat coolant and work with a heat exchanger ... 4.2kw/5.2kw is gonna create lots of steam if it's not designed just right!! ... if he can do it there'd be merit in designing it into a small stand alone box with a water pump, inlet, outlet, exhaust and a 12v supply in, to make it a portable diesel fired hot water system !


Cheers !