Dedicated Heating / Hydronics / Diesel heating thread

[charlieaarons]

One thing I have done last winter and last week is cover the 3 vents in the roof with ~50mm foam insulation (from mail-order pastrami shipments for example). Last winter I used duct tape but that left marks on the paint, so now I use Velcro.
Last winter in December I noticed the snow would quickly melt off the vent covers before I did this, when using the aircraft heaters, even though they are controlled at 5C. The ceiling and walls are 0.44W/sq m-deg K (R-13), windows double pane and metallized shades, but the vents are a single thickness of plastic. Up high where heat collects.

 

[Joe917]

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

I hope you are not using 25 year old coolant! The fact is these systems are designed for engine coolant.
We have two radiators higher than the engine expansion tank,28 years of use, it is not an issue.

 

[Geo.Lander]

I hope you are not using 25 year old coolant! The fact is these systems are designed for engine coolant.
We have two radiators higher than the engine expansion tank,28 years of use, it is not an issue.

I suppose the pumps in the furnace and engine themselves would act as one way valves in this case.

I just saw that modern building standards state that when using wood floor the temps should not exceed 27C. That seems really low to me.. When trying to figure out the flow temps I am getting a variety of answers all dependent on insulation used and flow rate, etc, etc. But it seems to be from 35-45C dependant on rate of flow.. So, needless to say either Id need to find a way to reduce and regulate this or simply use radiators instead...

 

[Neil]

I hope you are not using 25 year old coolant! The fact is these systems are designed for engine coolant.

No the engine coolant is relatively new and the coolant in the cabin heating system is even newer

Quite often when you change engine coolant there are bits of debri in it. I didn't want this debri going through my eberspacher .

I also felt that having them separated by the exchanger it gave the ability to have a fault on one side without effecting the other.

As said there are several ways to do things and if it works then its good

Ref the higher radiators. Do you get air that inevitably enters the system on the engine side accumulating in the higher ones. I would have thought it would have done , which is why they mount the engine expansion tank at the highest point above the engine .

Neil

 

[Joe917]

No the engine coolant is relatively new and the coolant in the cabin heating system is even newer

Quite often when you change engine coolant there are bits of debri in it. I didn't want this debri going through my eberspacher .

I also felt that having them separated by the exchanger it gave the ability to have a fault on one side without effecting the other.

As said there are several ways to do things and if it works then its good

Ref the higher radiators. Do you get air that inevitably enters the system on the engine side accumulating in the higher ones. I would have thought it would have done , which is why they mount the engine expansion tank at the highest point above the engine .

Neil

Sure bits of scale get into the coolant over time, these heaters are engine coolant heaters . They are designed for pre heating diesel engines, using them to heat our habitats is a small part of their market. I do understand trying to keep everything pristine.
Our highest radiator in the shower does tend to get some air in it. The top 2 bars stay cool, but it stabilizes like that and does not go lower. A sort of secondary mini expansion tank!
you could easily put shut off valves on both sides of the engine to habitat connection to separate in case of a fault or for servicing, just only close one side so that the system can still expand into the engine expansion tank.

I am not sure what the pump design is if it would act as a one way valve or just free flow but the Webasto is designed to allow hot engine coolant to flow through it freely.

 

[Neil]

I think I was also concerned at the time with the pressures. I knew that I wanted my cabin system to have very low pressure but wasn't sure what sort of pressures the engine water pump would produce on the flow side when the tubing diameter became smaller.

I'm pretty happy with it. My calorifier is quite small , 15 litres . Once the engine is hot it takes about 10 minutes the heat it up, And a similar time to get all the radiators and convectors hot if required.

Neil

 

[VerMonsterRV]

Usually coolant style pumps are "flooded" style (so I don't think they would provide much of a check valve, we use Mag drive pumps). Our primary pump, which is separate from the Thermo Top C pump sits right below the coolant fill/reservoir which needs to be the highest point in your system. I think if you were to take a look at our system, I am guessing you would see it is not all that complex. The habitat has a single coolant loop, it just ties the furnace, heat exchangers, water heater, pump, water to water heat exchanger and reservoir together. The engine pre-heat ties into the head/engine block loops to the circulation pump and water to water heat exchanger. Pretty simple plumbing. Now where it will get tricky is controlling the features which is still on my TODO list. Like if I just want to heat hot water while driving but not cabin heat, or thermostatically controlled cabin heat and hot water while driving, or preheat the engine or just heat the habitat and hot water. Pretty sure I could accomplish this with a rotary switch and relays, or I could get fancy and build an Arduino board with relays and Bluetooth. Then write an app for our phone to control it all. Now that sounds complicated, and well it is but maybe I'll do it and call it a hobby.

 

[Joe917]

I think I was also concerned at the time with the pressures. I knew that I wanted my cabin system to have very low pressure but wasn't sure what sort of pressures the engine water pump would produce on the flow side when the tubing diameter became smaller.

I'm pretty happy with it. My calorifier is quite small , 15 litres . Once the engine is hot it takes about 10 minutes the heat it up, And a similar time to get all the radiators and convectors hot if required.

Neil

A good point on the calorifier, we have a 20 liter (Isotherm Spa). It delivers much more than 20 liters of hot water though. The water in the tank can get up to close to engine coolant temps 80C, far too hot to use. A thermostatic mixing valve drops the hot water to a safe temp and increases the volume of hot water available.

The radiators heat up quite quickly, but as Charlie sys it can take all day to heat a frozen habitat to a comfortable level. If you are living in the vehicle though you would never allow it to freeze. I love our hydronic heating system, a nice even quiet heat.

 

[Victorian]

Engine preheater is indeed very nice. We used ours in the sprinter all the time.
having worked/ outfitted trucks with hydronic heating, I realized I’m not a fan of that system . Granted, it’s nice to have radiant heaters to warm towels and such but it can be extremely complicated with many possible failure points. A hydronic system also needs some time to heat up the living space. Great if you are on a long trip but if you are just going away for the weekend I’m not so sure.
I believe in keeping systems as simple and reliable as possible.
here Is what I would do:
2 diesel furnaces, 1 for regular use and the second for redundancy and added heat when needed. Hot water can be generated with either 12v or 110 v through boilers. In our last camper we didn’t have a boiler… I simply placed a water jug in front of the hot air outlet and during the night that water was nicely warmed up for doing dishes etc.
heated floors: certainly a nice feature but can easily feel very uncomfortable if too hot or if you are not used to it. A proper insulated floor shouldn’t feel cold… I would instead lay some cork flooring or blow the hot air across the floor to make it feel warm. If that is not enough, there are 12v floor heating elements available.
keep it simple!

 

[Joe917]

Engine preheater is indeed very nice. We used ours in the sprinter all the time.
having worked/ outfitted trucks with hydronic heating, I realized I’m not a fan of that system . Granted, it’s nice to have radiant heaters to warm towels and such but it can be extremely complicated with many possible failure points. A hydronic system also needs some time to heat up the living space. Great if you are on a long trip but if you are just going away for the weekend I’m not so sure.
I believe in keeping systems as simple and reliable as possible.
here Is what I would do:
2 diesel furnaces, 1 for regular use and the second for redundancy and added heat when needed. Hot water can be generated with either 12v or 110 v through boilers. In our last camper we didn’t have a boiler… I simply placed a water jug in front of the hot air outlet and during the night that water was nicely warmed up for doing dishes etc.
heated floors: certainly a nice feature but can easily feel very uncomfortable if too hot or if you are not used to it. A proper insulated floor shouldn’t feel cold… I would instead lay some cork flooring or blow the hot air across the floor to make it feel warm. If that is not enough, there are 12v floor heating elements available.
keep it simple!

This is the difference between the weekend warrior and full timer.
Hydronic takes a long time to heat up but once it is up to temperature it is a very even heat. Heating water by blowing hot air on a jug? I think that might be a little too simple, #vanlife perhaps!
There seems to be a constant misconception about how complicated hydronic is and all the failure points. It is just not true! A hydronic system is very simple and correctly installed failure should be minimal. I have seen hydronic systems using press fit PEX fittings, this is asking for trouble in a vehicle subjected to constant vibration. compression rings should be used.

Heated hydronic floors are an issue beyond my experience, but I can see keeping the temps low enough will be problematic.

 

[Alloy]

I suppose the pumps in the furnace and engine themselves would act as one way valves in this case.

I just saw that modern building standards state that when using wood floor the temps should not exceed 27C. That seems really low to me.. When trying to figure out the flow temps I am getting a variety of answers all dependent on insulation used and flow rate, etc, etc. But it seems to be from 35-45C dependant on rate of flow.. So, needless to say either Id need to find a way to reduce and regulate this or simply use radiators instead...

A mixing valve is used to will control the temp. It will mix the cool return water with the water from the boiler.

35-45C is way to hot for infloor. Your walking on it

The better the insulation the worse a hydronic floor system performs as a primary source for heat source.
There are some alum plank systems that improve the performance.

Floor Temperatures Limits:: infloor Heating :: Health Effects of Radiant Floors

Recommended floor temperatures for bare feet and for those wearing shoes

www.healthyheating.com

 

[Alloy]

Sure bits of scale get into the coolant over time, these heaters are engine coolant heaters . They are designed for pre heating diesel engines, using them to heat our habitats is a small part of their market. I do understand trying to keep everything pristine.
Our highest radiator in the shower does tend to get some air in it. The top 2 bars stay cool, but it stabilizes like that and does not go lower. A sort of secondary mini expansion tank!
you could easily put shut off valves on both sides of the engine to habitat connection to separate in case of a fault or for servicing, just only close one side so that the system can still expand into the engine expansion tank.

I am not sure what the pump design is if it would act as a one way valve or just free flow but the Webasto is designed to allow hot engine coolant to flow through it freely.

One of these will vent the air.

https://www.supplyhouse.com/Caleffi-508013A-1-8-Automatic-Hygroscopic-Air-Vent

 

[Alloy]

Engine preheater is indeed very nice. We used ours in the sprinter all the time.
having worked/ outfitted trucks with hydronic heating, I realized I’m not a fan of that system . Granted, it’s nice to have radiant heaters to warm towels and such but it can be extremely complicated with many possible failure points. A hydronic system also needs some time to heat up the living space. Great if you are on a long trip but if you are just going away for the weekend I’m not so sure.
I believe in keeping systems as simple and reliable as possible.
here Is what I would do:
2 diesel furnaces, 1 for regular use and the second for redundancy and added heat when needed. Hot water can be generated with either 12v or 110 v through boilers. In our last camper we didn’t have a boiler… I simply placed a water jug in front of the hot air outlet and during the night that water was nicely warmed up for doing dishes etc.
heated floors: certainly a nice feature but can easily feel very uncomfortable if too hot or if you are not used to it. A proper insulated floor shouldn’t feel cold… I would instead lay some cork flooring or blow the hot air across the floor to make it feel warm. If that is not enough, there are 12v floor heating elements available.
keep it simple!

Forced air is OK until you want to keep the tanks from freezing.

 

[Neil]

Insulation is the key.

I put loads of thought into Raditors behind seat backs, 7 program timers day timers, room thermostats and tank thermostats etc.

The reality is that we have never really used any if it to its full ability.

Because we have good insulation we rarely use the heating. If its needed we simply turn it on for about 20 minutes by which time we are probably sitting in our underwear. It will then stay hot all night.

We don't have duvets or heavy bedding, we simply sleep under a very thin fleece sheet and have never been cold.

I have 2 matrix fan heaters and several finned radiators. If I was fitting it again today I wouldn't bother with the radiators and just go with the matrix fan heaters , they put out more than enough.

The lowest we have been is minus 25 at 5000m and it has all performed fine and the inside tempreture overnight was perfect.

What can mess these heaters about is poor diesel , such as Bolivian, but that's whole different issue

Neil

 

[Geo.Lander]

he habitat has a single coolant loop, it just ties the furnace, heat exchangers, water heater, pump, water to water heat exchanger and reservoir together. The engine pre-heat ties into the head/engine block loops to the circulation pump and water to water heat exchanger. Pretty simple plumbing

Can I ask what all the heat exchangers are for? And water but not glycol / coolant in the loops? I thought the only place that water would be present would be in the water tanks and their respective plumbing..

35-45C is way to hot for infloor. Your walking on it

The were the water flow temps i found for a floor temps not exceeding 27C

Forced air is OK until you want to keep the tanks from freezing.

Right, I am spec'ing a grey tank with a coolant loop.. just in case