Diesel hot water systems

[egn]

In the photo, there is a valve at the bottom of the tank. That is the "thermostatically controlled valve," isn't it ?

Yes, this is this thermostatically controlled valve mentioned above. It mixes hot water from tank with cold water.

There looks to be another control near there (a blue/grey box with a control lever). Is that related to the water temperature control ?

This is a electrically controlled 3-way valve to switch between summer and winter operation. In summer the hot water from the Webasto flows only through the Isotemp. In winter it flows after the tank also through the heating pipes and convector. This valve has been replaced later by a manual 3-way valve, because this was easier to handle.

I have attached two schematic drawings to give you an idea. Sorry for being in German language. Please feel free to ask any questions.

 

[egn]

The 5kw Webasto is not too high powered for a camper. The 9kw for the engine/cab is 9kw in order to heat things up in 1hr. The camper takes at least several hrs, as much as 8hrs, in order to get thoroughly warm from -15 F. Even with R13 insulation. Not just the air but the solid objects like the camper batteries, which are hidden away under a sub-floor.

For faster heating I have installed 3 water/forced air heat exchangers with 3 kW power each. They are a bit noisy, but it is getting warm within a few minutes when the Webasto 90ST (9,1 kW) has reached its operating temperature. After that the normal convector keep the temperature. In spring and autuum running this together with water heating is enough to get a very comfortable temperature in the bath room.

 

[dzzz]

................................. we're looking at a small catalytic heater for back-up.


..........

That's exactly what I'm doing as far as back-up heat.

My concern with a large size furnace is that both Espar and Web. clog up if not run regularly on high power. But considering Charlies post I'm not going to worry about installing a 5kw unit.

Question about heating cabinets and storage areas: Is just running supply and return lines through these spaces enough to add heat? Should I run a line through the house battery space? These lines would only be active when heating the camper. Hot water heating in summer would not run through these lines.

Anyone able to do water to air heat without fans? I can't find the surface area to do that.

 

[ersatzknarf]

Yes, this is this thermostatically controlled valve mentioned above. It mixes hot water from tank with cold water.

Great ! Thank you for confirming that.

This is a electrically controlled 3-way valve to switch between summer and winter operation. In summer the hot water from the Webasto flows only through the Isotemp. In winter it flows after the tank also through the heating pipes and convector. This valve has been replaced later by a manual 3-way valve, because this was easier to handle.

That is a great idea ! It makes sense to change to a more simple, manual valve, but still a very interesting solution.



Cheers,
Frank

 

[jesusgatos]

I've laid 1/2" PEX tubing into the floor of my M109 motorhome conversion. Planning on running engine coolant through a separate, closed-loop system and will have a few different ways of generating/regulating heat. This stuff is all new to me, and I'm only figuring it out as I go...

 

[charlieaarons]

That's exactly what I'm doing as far as back-up heat.

My concern with a large size furnace is that both Espar and Web. clog up if not run regularly on high power. But considering Charlies post I'm not going to worry about installing a 5kw unit.

Question about heating cabinets and storage areas: Is just running supply and return lines through these spaces enough to add heat? Should I run a line through the house battery space? These lines would only be active when heating the camper. Hot water heating in summer would not run through these lines.

Anyone able to do water to air heat without fans? I can't find the surface area to do that.

I have no fans. There are flexible steel braided hose coils under the mattress, a radiator under the step to the dinette area and a large tube type radiator AKA towel drier in the bathroom. This is so effective that when running the heat in very cold weather when not driving I always leave the bathroom door open.
http://www.unicat.net/en/pics/TC49compact-2.html
The camper has R13 insulation with virtually no cold paths except the windows. Even though there are no fans the batteries, hidden way away under a subfloor (with a large thermal mass) get up to +15C. after the heat is on for 36 hrs at outside temp of -25C. with thermostats set at +21C.
The lack of fans is why it takes a while for the camper to get warm in cold weather. But it stays warm; the estimated heat loss (including windows) at -25C. is 1.2kw, less than 25% of the Webasto's capacity.

Charlie

 

[egn]

I have put the images into a PDF. I hope it helps.

 

[charlieaarons]

Very good, Emil. I wish I could preheat my generator with one of my Webastos. I do think I have a solution (not ideal): a 200W magnetic oilpan heater that I can attach to the engine block of the generator and preheat for 2-3 hrs. Of course, after drawing 50A-hr = 6% of battery capacity in 3 hrs I will need to run the generator for 10-15 min just to restore the batteries.

Charlie

 

[skysix]

Yes it requires another fuel but they are still excellent > easy to use and install , self contained (no wiring or plumbing), have an oven (Webasto don't at this point) and relatively safe and virtually nothing to go wrong (so I'm told anyway).

Wallas has a diesel oven with a stove to which a blower lid can be added
http://www.wallas.fi/default.asp?id=ne5dxgegchu

http://www.wallas.fi/default.asp?id=v5s0u7xwkzz

 

[4x4 explorer]

EGN/Emil,
Thanks for the "Schema". I have purchased the same Isotherm exchanger/heater and a Webasto diesel heater. I was in the process of installing so this thread is very helpful. I have yet to buy a recirculating pump for the hydronic system. Any recommendations? Also, on engine coolant heat source, I had thought about a separate loop with its own heat exchanger and then to the Isotherm, to isolate if there was a failure rather than direct line from engine to Isotherm. Any thoughts on which is best way to go. I have a Unimog 1300. Where is the best place to tap into the engine coolant system, "T" the heater line or is there a better alternative?
On the EGN/Emil schema, if some of the German words could be translated for this ignorant American who is ashamed to only speak english, it would be very helpful. Ausgleichsgefab
Fuhrerhaus
Alde Warmetauscher
Schalter Bad
Heizgeblase Bad
Heizgeblase Wohnraum
Schalter Panel
Kreislauf Kabine
Alde Elektropatrone
Universalempfanger
Sitzgruppe rechts
Kuche
Schlafzimmer li
Wasser Luft
Thanks for sharing, Roger

 

[dzzz]

Espar has some installation videos, which generally apply to Webasto.

Webasto doesn't make much effort on education.

 

[egn]

Sorry for the late answer.

EGN/Emil,
I have yet to buy a recirculating pump for the hydronic system. Any recommendations?

The Webasto has a build in pump. May be you get an auxiliary pump at Espar.

Also, on engine coolant heat source, I had thought about a separate loop with its own heat exchanger and then to the Isotherm, to isolate if there was a failure rather than direct line from engine to Isotherm. Any thoughts on which is best way to go.

This is a good idea. Most installations I know separate both loops with a heat exchanger. I shouldn't be to hard to get such a head exchanger. I got mine from a manufacturer of heating systems for RVs.

I have a Unimog 1300. Where is the best place to tap into the engine coolant system, "T" the heater line or is there a better alternative?

Sorry I dont know this. My truck has no water coolant at all. :sombrero:

On the EGN/Emil schema, if some of the German words could be translated for this ignorant American who is ashamed to only speak english, it would be very helpful.

Don't worry regarding speaking only one language. A lot more people speak english than german.

Ausgleichsgefab - water reservoir, equalising tank
Fuhrerhaus - drivers cab
Alde Warmetauscher - heat exchanger from Alde company
Schalter Bad - switch in bath room
Heizgeblase Bad - water/forced air head exchanger (Webasto 3 kW) bath room
Heizgeblase Wohnraum - water/forced air head exchanger living room
Schalter Panel - switch at control panel
Kreislauf Kabine - loop at cabin
Alde Elektropatrone - electric heater 1/2 kW from Alde company
Universalempfanger - RF receiver to thermostatic controller
Sitzgruppe rechts - bench right side
Kuche - kitchen
Schlafzimmer li - sleeping room left side
Wasser Luft - water air

You are welcome.

Emil

 

[4x4 explorer]

Emil, Thanks for all the information and the translation. Roger

 

[charlieaarons]

The next time I turn it on (to keep my batteries charged up in the winter) I'll measure the temp with an IR thermometer and let you know.

Charlie

 

[egn]

For floor heating you should use a temperature controlled valve in the return flow. Therefore for direct routing of the flow from the furnace the piping must be a bit different.

Example:
furnace -> distribution manifold with valves for each loop -> furnace
manifold -> water heater -> manifold
manifold -> conventional radiators in series -> manifold
manifold -> conventional radiators in series -> manifold
manifold -> floor heating loop 1 -> temperature valve -> manifold
manifold -> floor heating loop n -> temperature valve -> manifold

The important point is that it is never allowed to block the flow through the furnace, otherwise the pump will be destroyed in short time. The pump needs very free flow all the time, so the piping thickness should be selected accordingly.

So the valve for the water heater must be always fully opened. The flow through the other loops must be regulated accordingly so that each of the loops get the right share of the flow when the temperature controlled valves are open. It is not easy to get a balanced system.

The temperature valves in the return pipe from the floor heating limit the floor temperature to a comfortable value. Here it is important to have sufficient thermal mass in the floor heating, otherwise you will still get to hot feet at the beginning of the loop. For more info on that you should contact a specialist for floor heating.

The direct system has the disadvantage for me that the furnace has to be used to control the overall temperature, at least for simple systems without thermostatic valves at each radiator. This means that the water heater may not get enough heat.

I have used a separate loop with heat exchanger, because I use the system from Alde for heating RVs. Here no direct flow from non-Alde heaters is allowed. The temperature of the cabin is also very easy to control by just switching the very silent pump on and off. And the Webasto can run on full power to heat the water.