Dedicated Heating / Hydronics / Diesel heating thread

Alloy

Well-known member
I missed the plan view of the system....

Separating the the loop for the bathroom is easy to do then you can choose to run them as 1 zone or separately

Closing up the spacing at the door will direct more heat there.

Consider running the return where there water lines are inside a cabinet that may freeze up. I've had lines inside a cabinet and laying against the outside wall freeze.

Is that a towel warmer in the bathroom?

Better if radiators are on 3 sides of the bed.
 

Iain_U1250

Explorer
I see that a lot of the northern hemisphere trucks have major heating system, including underfloor heating, multiple radiators and also small windows. I did a some calculation on heat loss based on the insulation we have and figured out I needed about 5kW @ -30C. I doubt we will be spending much time at temperatures like that, and a lot of the other systems on the truck are not suitable for that especially the fuel supply, batteries etc which will need heating pads etc.

I wonder how hot you want it inside the truck, is everyone targeting over 25C so you don't have to wear a jersey ( or anything) inside?
 

Geo.Lander

Active member
I see that a lot of the northern hemisphere trucks have major heating system, including underfloor heating, multiple radiators and also small windows. I did a some calculation on heat loss based on the insulation we have and figured out I needed about 5kW @ -30C. I doubt we will be spending much time at temperatures like that, and a lot of the other systems on the truck are not suitable for that especially the fuel supply, batteries etc which will need heating pads etc.

I wonder how hot you want it inside the truck, is everyone targeting over 25C so you don't have to wear a jersey ( or anything) inside?
25C sounds about right, Id rather have good margin even though we are not really "cold" people in general when it comes to heating etc. We originally wanted a small wood stove in the truck but it breaks up the design too much to consider it at this stage.

I wont be using heated batteries or those silicon heat pads for various reasons, I will however have a small 230V garage heater connected to the AC2 output on the inverter to keep the batteries charging and water from freezing when parked up at the house.

Im thinking a heated towel rack and underfloor heating might be enough for our smallish box, that diagram is for a 7m box! to be honest I dont like the extra pumping complexities of hooking into the engine cooling, especially the need for controlling the values on the box manifold loops for switching off heating vs hot water, etc. Of course I suppose I will need another value from furnace to engine somewhere close to the engine loop so im not having to keep the engine loop warm when i just want to heat the box.. so many questions :LOL: lucky I have time, more delays from our box and subframe builder 😥
 

Geo.Lander

Active member
especially the fuel supply, batteries etc which will need heating pads etc.
It is amazing how many German trucks and central EU trucks build in heated tank and fuel delivery systems to keep their fuel from freezing. During our winter ski trips we are often stuck for hours at a time before mountain passed waiting for "kolonnekjøring" (basically as it sounds, driving in a column with the lead driver being snow plow).
Our record is about 9 hours waiting for a window to pass. Anyway, weather permitting I Always try and chat with the truckers as they put on their snow chains, it boils down to this, they do not have tank heating systems or heated fuel filters etc.. for the most part. The advice they gave me was to keep the tank as full as possible, and Ive never had an issue with my V8 and V6 land rover engines starting all over Norway as most of my driving is in winter.. I do not know the exact science of freezing fuel etc (i know there is a good thread on this forum).
I think most of the EU style builders overbuild for one sole purpose, that of cash money, that is just an opinion. There is a guy on the MB expedition FB page installing 3 or 4 Diesel furnaces for "redundancy".. within the same loops..
 

Peter_n_Margaret

Adventurer
When touring, the engine connection to the calorifier is the most valuable part of the system from our perspective.
It means there is always 30L of very hot water available (and it is available for a couple of days) to wash the dishes or to have a shower without ever running the Webasto. It is just there. Turn the tap on and hot water comes out. :) You don't have to think about it.
It also allows drying the cloths in the bathroom while driving and pre heating the house while driving (either/or or both) without running the Webasto.
It is only while parked up in the cold that we would need to run the Webasto.
Cheers,
Peter
OKA196 motorhome
 

Geo.Lander

Active member
When touring, the engine connection to the calorifier is the most valuable part of the system from our perspective.
It means there is always 30L of very hot water available (and it is available for a couple of days) to wash the dishes or to have a shower without ever running the Webasto. It is just there. Turn the tap on and hot water comes out. :) You don't have to think about it.
It also allows drying the cloths in the bathroom while driving and pre heating the house while driving (either/or or both) without running the Webasto.
It is only while parked up in the cold that we would need to run the Webasto.
Cheers,
Peter
OKA196 motorhome
Thanks @Peter_Austin !

It seems like no brainer to hook into the engine heat but in my mind this is simply saving fuel right? I could run a Truma combi for example to keep the water and cabin hot while driving and accept double spend on energy whilst reducing complexity... Those units are pretty efficient.. decisions decisions. I think I first need to make a detailed hydronic plan and compare costs, install time and space savings, etc..
 

Alloy

Well-known member
Thanks @Peter_Austin !

It seems like no brainer to hook into the engine heat but in my mind this is simply saving fuel right? I could run a Truma combi for example to keep the water and cabin hot while driving and accept double spend on energy whilst reducing complexity... Those units are pretty efficient.. decisions decisions. I think I first need to make a detailed hydronic plan and compare costs, install time and space savings, etc..
It's good to test run everything but why run a pcs of equipment and increase the service levels for when there's no need to....and it provides redundancy.
 

VerMonsterRV

Gotta Be Nuts
Our system is pretty close to @Neil 's system. We use a Termo Top C (has easily kept up with 0 degree f temps) with a separate loop in the habitat. In that loop are 2 heat exchangers with multi-speed fans, a 6 gallon marine water heater and a water to water heat exchanger. Oh, I also have a small 12v DC circulation pump as the pump on the Webasto looked a bit small. I also replaced the 110v water heater element with a 12v for when we have plenty of solar. I tapped into the engine coolant for the other side of the water to water heat exchanger and in that loop is a 12v pump. Pre-heating the engine is great and I highly recommend it for colder temps. Starts way easier and emits way less smoke, plus I would think it is easier on the engine.

So, about scavenging the engine heat for habitat heating and water heating. We are not there yet, the plumbing is there but I need to work out a control system for it. Why do I want this? Well if you are traveling in below freezing temperatures being able to walk into a heated cabin with hot water after a day of driving sounds great, plus I really don't want to drive with our furnace running. Not really about saving the fuel, though that is a nice side benefit.
 

Geo.Lander

Active member
Our system is pretty close to @Neil 's system. We use a Termo Top C (has easily kept up with 0 degree f temps) with a separate loop in the habitat. In that loop are 2 heat exchangers with multi-speed fans, a 6 gallon marine water heater and a water to water heat exchanger. Oh, I also have a small 12v DC circulation pump as the pump on the Webasto looked a bit small. I also replaced the 110v water heater element with a 12v for when we have plenty of solar. I tapped into the engine coolant for the other side of the water to water heat exchanger and in that loop is a 12v pump. Pre-heating the engine is great and I highly recommend it for colder temps. Starts way easier and emits way less smoke, plus I would think it is easier on the engine.

So, about scavenging the engine heat for habitat heating and water heating. We are not there yet, the plumbing is there but I need to work out a control system for it. Why do I want this? Well if you are traveling in below freezing temperatures being able to walk into a heated cabin with hot water after a day of driving sounds great, plus I really don't want to drive with our furnace running. Not really about saving the fuel, though that is a nice side benefit.
So your heat exchanger is heating your water from the engine coolant directly (sorry for the dumb questions)?
My initial thoughts is that I could just use the furnace directly on the engine coolant and run that loop through the calorifier boiler and underfloor heating with no heat exchanger (with valves to isolate both loops to only box loop and the inverse).

One more bonus for the Truma Combi approach would be full climate control when coupled with their air-con units, the 6D is designed to be used while on the road as well but no denying there is something more attractive about tapping into the engine heat.. 🤔 I am not wondering if the extra expense and time is worth the effort..
 

Joe917

Explorer
Having a diesel heater for the engine and a Truma combi in the back is more complicated and more expensive.IMG_20210321_153723_BURST001_COVER.jpg
This is our setup. 28 years of operation does everything you want. Engineered and installed by Webasto Italy.
The habitat loop is tied into the engine coolant with the Webasto tied in across the loop.
The electric valve has long since failed and been replaced by a simple ball valve.
There are 3 passive radiators in the rear habitat. Each one on its own loop with a manual valve. There is also a 20 liter calorifier hwt.
The Webasto is controlled by a Heatmiser T-stat.

Operation is simple.
With the engine valve open, engine can be pre heated by running Webasto .
With the engine valve open , driving, Webasto off, hwt is heated, habitat is heated if radiator valves are open(winter) or not if closed(summer).
With the engine valve closed, parked, the hwt and radiators can be heated by the Webasto, controlled by the T-stat and individual radiator valves.

The system requires no extra pumps, the engine coolant pump and the Webasto pump work very well.
By closing only one side of the loop between the engine and habitat you stop heat flow through the engine block when parked but still allow the system to expand into the engine coolant expansion tank.

This has served us well for many years in temperatures well below-20C. I lived in the truck through the Canadian winter 2 years ago,very toasty!
 
4 thoughts:
1) I hope “Truma Combi” doesn’t mean LPG? I can give you MULTIPLE reasons why LPG heating is a very bad decision for a diesel camper planning to go to many places. Get a diesel heater - Espar, Webasto or Planar.
2) altitude compensation with diesel heaters: Unicat sent me an inexpensive kit (for free!). Just some tubing, T fittings and a little needle valve with knurled knob. It’s a “short circuit” around the fuel pump. Open 1 turn for every 1000m above 2000m ASL. Haven’t tried it yet but properly adjusted it “should” work.
3) 4.8m camper length, 7 windows, 5kw Webasto Thermo Top C in -30C (in my front yard): nice and warm, at least +25C. It does take all day to get there from cold soaked. At least 6-8 hours. I also have 2 x 700w Hornet aircraft heaters set at +5C to avoid any possibility of winter frost damage (run off grid via plug-in of course). At coldest recent temperatures of around -26C the 2 heaters were NOT running continuously - only 1.4kw. So 5kw might even work at ridiculous temperatures like -50 or -60C.
4) keeping fuel warm: once engine starts, fuel recirculates back to the tank and eventually the tank gets pretty warm. I have a 110v 120-150w heater pad I can run off outside 110v outlet I installed near tank; just plug cord in and turn on invertor. Obviously batteries only good for 5-7kwh. Only used it once, at home, to thaw #2 fuel in winter. Installed it for Tibet trip (didn’t go, wife got sick), maybe useful for Bolivia?
Don’t get LPG!!!
 

Geo.Lander

Active member
Having a diesel heater for the engine and a Truma combi in the back is more complicated and more expensive.View attachment 686383
This is our setup. 28 years of operation does everything you want. Engineered and installed by Webasto Italy.
The habitat loop is tied into the engine coolant with the Webasto tied in across the loop.
The electric valve has long since failed and been replaced by a simple ball valve.
There are 3 passive radiators in the rear habitat. Each one on its own loop with a manual valve. There is also a 20 liter calorifier hwt.
The Webasto is controlled by a Heatmiser T-stat.

Operation is simple.
With the engine valve open, engine can be pre heated by running Webasto .
With the engine valve open , driving, Webasto off, hwt is heated, habitat is heated if radiator valves are open(winter) or not if closed(summer).
With the engine valve closed, parked, the hwt and radiators can be heated by the Webasto, controlled by the T-stat and individual radiator valves.

The system requires no extra pumps, the engine coolant pump and the Webasto pump work very well.
By closing only one side of the loop between the engine and habitat you stop heat flow through the engine block when parked but still allow the system to expand into the engine coolant expansion tank.

This has served us well for many years in temperatures well below-20C. I lived in the truck through the Canadian winter 2 years ago,very toasty!
Thanks so much @Joe917 !
This turns my thinking around for sure, I just priced the M10 units and they run almost as much as a full Truma 6D kit (these are diesel only @charlieaarons, no LPG), even with a smaller furnace I need to add the costs for pumping, fixtures and tank (which the Truma of course includes). So Im not sure about double the price but I see your point.

The habitat loop is tied into the engine coolant with the Webasto tied in across the loop.
That is exactly the way I was thinking it would/should work, not a heat exchanger in sight 😆 Im still trying to figure this stuff out, I just wish I found it as fun as planning the electrical system 🤓

The system requires no extra pumps, the engine coolant pump and the Webasto pump work very well.
By closing only one side of the loop between the engine and habitat you stop heat flow through the engine block when parked but still allow the system to expand into the engine coolant expansion tank.
Pretty genius, no external coolant reservoirs at all and no extra pumps sounds ideal. I still think the coolant might be a little hot for underfloor heating but I need to do some more reading to make sure.
 

Geo.Lander

Active member
4 thoughts:
1) I hope “Truma Combi” doesn’t mean LPG? I can give you MULTIPLE reasons why LPG heating is a very bad decision for a diesel camper planning to go to many places. Get a diesel heater - Espar, Webasto or Planar.
2) altitude compensation with diesel heaters: Unicat sent me an inexpensive kit (for free!). Just some tubing, T fittings and a little needle valve with knurled knob. It’s a “short circuit” around the fuel pump. Open 1 turn for every 1000m above 2000m ASL. Haven’t tried it yet but properly adjusted it “should” work.
3) 4.8m camper length, 7 windows, 5kw Webasto Thermo Top C in -30C (in my front yard): nice and warm, at least +25C. It does take all day to get there from cold soaked. At least 6-8 hours. I also have 2 x 700w Hornet aircraft heaters set at +5C to avoid any possibility of winter frost damage (run off grid via plug-in of course). At coldest recent temperatures of around -26C the 2 heaters were NOT running continuously - only 1.4kw. So 5kw might even work at ridiculous temperatures like -50 or -60C.
4) keeping fuel warm: once engine starts, fuel recirculates back to the tank and eventually the tank gets pretty warm. I have a 110v 120-150w heater pad I can run off outside 110v outlet I installed near tank; just plug cord in and turn on invertor. Obviously batteries only good for 5-7kwh. Only used it once, at home, to thaw #2 fuel in winter. Installed it for Tibet trip (didn’t go, wife got sick), maybe useful for Bolivia?
Don’t get LPG!!!
No LPG @charlieaarons ! Made that decision quite early on :)
2) I think i would rather go with a heater that supported the higher altitudes from factory, not knowing a lot about these sort of setups I want to simply interconnections, valves and pumps as much as possible..
3) I think we have the same size box pretty much although only 5 (large) windows including the skylight
4) yea, I remember that part about the fuel recirculation from another post, I couldn't quite remember the correct terminology thou, thanks for clarifying that

Really appreciate the feedback everyone, there are a lot of online sources about this topic but they just kind-of dive into things and mostly on Vans, not much out there with full on design applications explained clearly for novices. I also get the feeling the "van dudes" do not quite know what they are doing or just bought a kit from some online retailer with the assurance "this is what you need" etc..
 

Neil

Observer
I kept my two systems separate, they kiss each other at a small heat exchanger. It works well .

There were several reasons for doing it this way.
Firstly , I didntvwantvthe engine fluid coolant pumping 25 years of debri through my new heating system , which has smaller pipes .

Secondly , I have a raised radiator in the rear of my cabin, which is slightly higher that the engines expansion tank, which needed to be the highest point .

Like many things in truck building there are are several ways to do things.

If it works for you, its right

Neil
 
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