Hydronic vs. Non-Hydronic Heating. (Air & Water)
- Thread starter waveslider
- Start date
thebigblue
Adventurer
I know, my reply to Coachgeo was based on that he mentioned compatibility of hoses in the water heater and cabin heater side of things...
Hi
As far as I've been told, if you plumb into a vehicle cooling system and then extend that a considerable amount all round a camper, the engine will struggle to create the same pressure it would as standard, and so "perhaps" not cool as efficiently. Lower pressure gives lower boiling point.
So yes, a heat exchanger allowing heat but no fluid to be shared from engine circuit to camper is what is recommended by I think Eberspacher at least.
You're also not supposed to mix copper and ally componants due to corrosion issues.
YMMV
As far as I've been told, if you plumb into a vehicle cooling system and then extend that a considerable amount all round a camper, the engine will struggle to create the same pressure it would as standard, and so "perhaps" not cool as efficiently. Lower pressure gives lower boiling point.
So yes, a heat exchanger allowing heat but no fluid to be shared from engine circuit to camper is what is recommended by I think Eberspacher at least.
You're also not supposed to mix copper and ally componants due to corrosion issues.
YMMV
javajoe79
Fabricator
If you share coolant throughout the engine and camper system you would plumb it like you would the heater core on a car. Appropriate rubber hose or hard lines.
I don't see how adding an espar on to an engine system would create any issues with pressure. The pressure is controlled by the cap.
I don't see how adding an espar on to an engine system would create any issues with pressure. The pressure is controlled by the cap.
Coachgeo
Explorer
good points about mixing metal types causing issues. Also could see the engine water pump having to work harder to move the coolant thru the camper area as well. Keep in mind as well.... some engine heaters are said to NOT be run when the engine is running unless they are a separate circuit. Mine is NOS military it is does say to NOT operate when engine is running. I was planing to run two selectable separate circuits myself. Selectable in such a way it could be .... (A) just engine/cab, (B)just habitat, or (C) all the above. but when in (A) or (C) Id not have engine running.
Joe917
Explorer
Use appropriate materials, not hard.
Why would you run the coolant heater and engine at the same time?
The way the coolant circuit and camper circuit are plumbed(if done correctly), the engine pump works no harder to move coolant. The coolant will flow where there is the least resistance.
Why would you run the coolant heater and engine at the same time?
The way the coolant circuit and camper circuit are plumbed(if done correctly), the engine pump works no harder to move coolant. The coolant will flow where there is the least resistance.
The only reasons I could imagine you may change the attainable pressure in the engine coolant circuit is normally that circuit might have perhaps a few feet of rubber piping, but changing that to tens of feet round a camper might be too much? Plus the camper will need a header tank, plus a lot more joints that may seep a little at times.
I know on the few occasions I opened the valves to join the camper/Eberspacher circuit for heat share a lot of air entered the camper circuit. Because those pipes were kind of flat on the camper floor the few little high spots were a pig to get at to move that air. So engine preheat never really got used, or was needed on that engine. With the valves closed both circuits worked fine.
There might also be a can of worms if lots of people connected their own design of camper circuit into a still warrantied engine.
For me, if engine preheat was a real requirement I think I would try and do a factory install for the engine only and seperate from the camper.
Otherwise, normally 20 minutes of camper heater burn is not so much of a big deal to get a hot shower that using residual engine heat becomes such a fabulously important factor to me. I'd rather leave the engine as the factory intended
I know on the few occasions I opened the valves to join the camper/Eberspacher circuit for heat share a lot of air entered the camper circuit. Because those pipes were kind of flat on the camper floor the few little high spots were a pig to get at to move that air. So engine preheat never really got used, or was needed on that engine. With the valves closed both circuits worked fine.
There might also be a can of worms if lots of people connected their own design of camper circuit into a still warrantied engine.
For me, if engine preheat was a real requirement I think I would try and do a factory install for the engine only and seperate from the camper.
Otherwise, normally 20 minutes of camper heater burn is not so much of a big deal to get a hot shower that using residual engine heat becomes such a fabulously important factor to me. I'd rather leave the engine as the factory intended
Joe917
Explorer
My Webasto was a factory install in 1994 (I have the paper work).
The system is tied directly to the engine coolant loop.
Hot coolant expands, that is the reason for a header tank to relieve pressure not make it, so extra rubber hose would help that in theory.
Our system is all PEX.
We do not have a header tank in the camper, but the top of the highest radiator always holds a little air so this acts as a header tank.
To me not using the waste engine heat for your hot water is like putting solar on the roof and always charging with the alternator.
These heaters are connected to thousands of trucks, I would be surprised if there was any warranty issue.
The system is tied directly to the engine coolant loop.
Hot coolant expands, that is the reason for a header tank to relieve pressure not make it, so extra rubber hose would help that in theory.
Our system is all PEX.
We do not have a header tank in the camper, but the top of the highest radiator always holds a little air so this acts as a header tank.
To me not using the waste engine heat for your hot water is like putting solar on the roof and always charging with the alternator.
These heaters are connected to thousands of trucks, I would be surprised if there was any warranty issue.
waveslider
Outdoorsman
Does anyone have experience with the Dual Top models? If the hydronic has the benefit of engine pre-heat in cold temps and the advantage of driving (or idling) providing for "instant" hot water. It feels like the Dual Top model is a "set it and forget it" type system that takes longer to get to temp but stays there easily and with minimal energy consumption (fuel and/or electric power) EDIT: And an inherently simpler design that doesn't tie into the vehicle coolant circuit.
Regarding the engine preheat - has anyone experimented with the idea of simply plugging in the block heater for an hour or so before starting to warm it up? Obviously that is a serious power draw but with a large expedition vehicle the electric capacity might well be able to accommodate it - just thought it's an interesting concept.
Regarding the engine preheat - has anyone experimented with the idea of simply plugging in the block heater for an hour or so before starting to warm it up? Obviously that is a serious power draw but with a large expedition vehicle the electric capacity might well be able to accommodate it - just thought it's an interesting concept.
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I wasn't suggesting an issue with factory fit as engine pre heat or cabin heat if OE.
I've been told Eberspacher suggests a heat exchanger to isolate the engine coolant circuit from the camper one, with the engine struggling to pressurise as a possible consequence if you don't put a heat exchanger in.
Tee-ing off using Eberspacher parts to a D5WS may have been following Eberspacher guidelines for that engine on my old camper, but then running that around the one off camper build is something else.
I'm sure there are thousands of self install coolant heaters in use without any apparent problem, but may not be performing to quite what the manufacturer specifies?
I don't know for sure the reasons behind Eberspachers heat exchanger idea, warranty might be the most obvious these days and "pressure" a smokescreen, but would be following those suggestions if I was fitting one now.
If a hydronic heater is plumbed in to let residual engine heat run round the camper's calorifier for instance, does that go through the engine radiator too? Is there a valve to close once parked so burning the Eber for camper heat doesn't heat that rad too?
Jason
Hi.
I wasn't suggesting an issue with factory fit as engine pre heat or cabin heat if OE.
I've been told Eberspacher suggests a heat exchanger to isolate the engine coolant circuit from the camper one, with the engine struggling to pressurise as a possible consequence if you don't put a heat exchanger in.
Tee-ing off using Eberspacher parts to a D5WS may have been following Eberspacher guidelines for that engine on my old camper, but then running that around the one off camper build is something else.
I'm sure there are thousands of self install coolant heaters in use without any apparent problem, but may not be performing to quite what the manufacturer specifies?
I don't know for sure the reasons behind Eberspachers heat exchanger idea, warranty might be the most obvious these days and "pressure" a smokescreen, but would be following those suggestions if I was fitting one now.
If a hydronic heater is plumbed in to let residual engine heat run round the camper's calorifier for instance, does that go through the engine radiator too? Is there a valve to close once parked so burning the Eber for camper heat doesn't heat that rad too?
Jason
Coachgeo
Explorer
Plug into what? Nearby bush?
Assume you mean your own campers battery system. I've not done the math .. but yea sounds like too much draw and wear on the system. Now if you have a genny...... hmmmm..... good point. Course getting genny started in cold weather is another issue too.
waveslider
Outdoorsman
I suspect most draw around 1100wats or what would that be? 10 amps? Obviously, that a serious draw. But wouldn't an induction cooktop be in the same neighborhood?
Joe917
Explorer
The way our system runs:
We have a shut off valve between the engine side and the Webasto living space side, the valve is only on one side of the loop.
engine on, Webasto off, valve open: engine heat heats calorifier and cabin(radiators controlled by individual valves(in summer you can heat domestic water only)
engine off, Webasto on,valve open: engine preheat, calirofier heat, cabin heat
engine off, Webasto on, valve closed, engine is out of loop, Webasto heating calorifier and cabin only. Cabin temperature controlled by a thermostat.
In summer the valve is just left open. In winter, closed when parked, open for preheat and driving.
This set up is also used on boats.
javajoe79
Fabricator
Another thing worth mentioning is the need for another pump to circulate coolant if you have the two systems separated by a heat exchanger. Not sure that hose expansion is as big of an issue as you think it is considering installs have been done like this for years without issue. I've never seen a heat exchanger recommended by the manufacturer anyway. Do you have a link to that info?