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Diesel heater retrofit


webpax

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I've been thinking of adding a diesel heater to my motorhome as backup to the Truma Combi 6 which is LPG only. I intend doing some extensive touring in Nordic countries next winter and do not want to rely on LPG which seems to last only a relatively short while (even with 2x11kg Gaslow).

 

I'll probably go for an Eberspacher or Webasto 4/5kw model and was wondering whether it would be possible to tee the outlet from the diesel heater into the existing Truma ducting to get heat around the van? Has anyone done this?

 

One of the issues I can see is making sure the hot air does not make it's way into the Truma heater, do they have some sort of one way valve to prevent this?

 

Alternatively if this is not possible, I'm wondering if heat from a single duct in the lounge would provide enough warmth throughout the van to stop the tanks from freezing and generally keep the chill off the rest of the motorhome? It's a 7.4m van with a double floor (which contains the tanks).

 

Thanks.

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Is your Hymer built on a Mercedes chassis?

 

If so did it have the optional factory fitted Eberspacher heater fitted?

 

There have been members on the Sprinter Source forum adapt wiring modifications to make them run without the engine having to run.

 

Keith.

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OK, It was worth asking.

 

Unless you have the 'KL1 Sender unit (fuel) for auxiliary heater' as a factory option you will need to drop the fuel tank to fit a pick up tube or 'standpipe'.

 

DO NOT tap into the engine fuel lines as they run at too high a pressure for the Diesel heater and will flood the heater.

 

Also do not drill the carcass of the fuel tank as this will almost certainly lead to splits propagating from the hole, the correct place to fit the standpipe is through the fuel pump flange. The simplest option although costly would be to replace the fuel pump module with one already containing the stand pipe.

 

There is a lot of info on the Sprinter Source forum if you search for it. https://sprinter-source.com/forums/index.php

 

Keith.

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I probably didn't make it clear I will be using a Webasto/Eberspacher dealer to do this so hopefully they will know what they're doing. It was the bit about using existing ducting I was concerned about although I've since read on the Webasto website you can using existing ducting after the first 1m of Webasto ducting.

 

I did read somewhere that the KL1 was standard fit on Sprinters since 2018 but I've not been able to verify this.

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webpax - 2020-05-26 5:28 PM

 

...I'll probably go for an Eberspacher or Webasto 4/5kw model and was wondering whether it would be possible to tee the outlet from the diesel heater into the existing Truma ducting to get heat around the van? Has anyone done this?....

 

Given that your Truma “Combi” heater has four outlets that allow warmed air to be distributed around your motorhome, it’s not easy to see how you could fully integrate an Eberspacher/Webasto air-heater into the Truma system. That’s not to say it couldn’t be done, just that it would be extremely difficult and I doubt that anyone will have attempted it.

 

A 4/5kW Eberspacher/Webasto air-heater should be capable of heating your motorhome reasonably well, but - if you want to heat the underfloor space - you’ll need to lead a duct into that area. In fact, you really need to install a multiple ducts/outlets system if you want to properly exploit the diesel-fuelled heater.

 

Although it would be normal practice for an Eberspacher/Webasto air-heater to take its fuel from a motorhome’s main diesel tank, a separate tank dedicated to air-heater operation could be fitted if there was space to do so.

 

(I’d be a mite wary of assuming that an Eberspacher/Webasto dealer “will know what they’re doing”. That should be the case if you just wanted a straightforward air-heater installation, but if you wanted to link the Combi and the diesel heater’s air trunking together somehow, you’d be wise to check how this would be achieved by the dealer. Essentially, if you don’t know how it should be done, it's likely that the dealer won’t know either.)

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As far as I know, the airducts of a Truma gas stove are not compatible with Webasto heaters.

The air coming out of Webasto is much warmer than the air coming out of Truma.

Someone uses them but I don't think it's a reliable solution.

 

However, I know someone who has replaced the gas Truma with the diesel one (it uses an Eberspaecher burner) without changing airducts.

 

Please note that if used together Truma and diesel heaters can interfere with each other with the result of cooking or being in the cold.

 

As for gas in Scandinavia (at least in Norway) it shouldn't be a problem.

Filling stations should be equipped with the most common fittings. At least they often have Italian ones.

Take a look at http://www.lpgnorge.no/stasjonsoversikt/english/

 

Remember to register the license plate on http://www.autopass.no/en/autopass and to fine check the ferry timetables.

In the winter season they have fewer schedules and some routes are canceled.

 

Max

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mtravel - 2020-05-27 11:04 AM

 

...However, I know someone who has replaced the gas Truma with the diesel one (it uses an Eberspaecher burner) without changing airducts...

 

 

Truaa’s installation instructions for their gas-fuelled and diesel-fuelled “Combi” heaters show that the same air trunking (Truma 65mm diameter - Part Number 40230-00) should be used for both types.

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Thanks for all the input. As has been suggested linking up the Eberspacher/Webasto heating to the Truma ducting seems to be a non-starter. I did speak to an Eberspacher dealer who would be willing to do it but he said the Truma heater ducts would have to be permanently blocked off and that Eberspacher wouldn't warrant the work.

 

I did look at swapping out the Truma LPG unit for the Truma diesel unit as per mtravel's suggestion. The cost is high though at circa £2850 for the unit and £700 for fitting, I suppose I might be able to sell the LPG unit to offset some of the cost. Although the trunking is the same, apparently the flue outlet for the diesel unit is of a different design and size to the LPG one. The installer I contacted was wary that cutting a hole into the side of the van to install the flue outlet by a non-Hymer agent could potentially void my warranty.

 

I think I will go with an Eberspacher unit venting heat into the lounge area (I have a hidden floor level cupboard that should be ideal). I'll then see if some ducting can be run under floor to the back of the van to distribute the heat to the rear.

 

There are pros and cons with a separate diesel tank as per Derek's suggestion. I've seen installations where the tank is inside the van which I really don't like the idea of. If I can tap into the existing tank then it's only one tank to fill. I could carry spare diesel in a jerry can if needed.

 

I'm meeting an Eberspacher dealer next week so will update this thread for future reference when I get back.

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I have not advised you to replace the gas Combi with the diesel one.

I just said I know someone who did it without changing the airducts.

 

Besides, you said that the Webasto or Eberspaecher would be an addon as a backup system.

Which is a wise thought.

 

As for the fuel tank, the most common installation uses that of the vehicle.

The only trick is that the suction pipe must not reach the bottom in order to avoid finding yourself without fuel.

Usually it places at the height where about 15-20% of the fuel remains in the tank.

 

To my knowledge, both heaters can be installed outside under the floor.

 

Max

 

p.s. Well-functioning clones of Truma and Webasto exist on the Chinese market. Not even half the original prices.

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We supplemented the Alde system in our last van with a diesel heater, to reduce LPG consumption prior to our Scandinavia trip and to warm up the van from cold more quickly. I have to say that we ended up using the diesel heater almost all of the time because it was just so quick and convenient (although getting LPG wasn't a problem throughout Norway). A single outlet was more than adequate although it was a single-floor van so only the living space needed heating.

 

I've had 3 different makes of diesel blown air heater over the years; a Volvo Ardic, an Eberspacher Airtronic D4 and a few Chinese '5kW' D4 copies. If I were buying again I'd choose the Chinese copy over the Eber every time. So cheap that you can carry one of every spare part or even a complete spare unit.

 

Although the Eber Airtronic performed faultlessly for many years it had one very annoying feature which could not be circumvented; once the programmed temperature was reached it would shut down. Then 10-15 mins later when heat was again called for it would go through a restart procedure, using its glowplug and consuming valuable battery power. It was a continual game, usually lost, of trying to keep it going on as low fan speed as possible yet not letting it shut down. The other heaters just kept going at minimum heat which is exactly what was required.

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Made-in-China-air heaters were mentioned in these earlier forum threads

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Diesel-Heater-installation/53883/

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Secondary-gas-supply-/53898/

 

Although service-stations selling ‘autogas’ in Nordic countries may be thin on the ground, Finland may be the only one where autogas is unavailable. I would have thought that the ability to carry 42 litres of gas (2 x 11kg) in webpax’s Hymer should be sufficient to not require going to the trouble (and expense) of having an auxiliary diesel-fuelled heater installed.

 

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Steve928 - 2020-05-29 12:52 PM

 

We supplemented the Alde system in our last van with a diesel heater, to reduce LPG consumption prior to our Scandinavia trip and to warm up the van from cold more quickly. I have to say that we ended up using the diesel heater almost all of the time because it was just so quick and convenient (although getting LPG wasn't a problem throughout Norway). A single outlet was more than adequate although it was a single-floor van so only the living space needed heating.

 

I've had 3 different makes of diesel blown air heater over the years; a Volvo Ardic, an Eberspacher Airtronic D4 and a few Chinese '5kW' D4 copies. If I were buying again I'd choose the Chinese copy over the Eber every time. So cheap that you can carry one of every spare part or even a complete spare unit.

 

Although the Eber Airtronic performed faultlessly for many years it had one very annoying feature which could not be circumvented; once the programmed temperature was reached it would shut down. Then 10-15 mins later when heat was again called for it would go through a restart procedure, using its glowplug and consuming valuable battery power. It was a continual game, usually lost, of trying to keep it going on as low fan speed as possible yet not letting it shut down. The other heaters just kept going at minimum heat which is exactly what was required.

 

Thanks Steve928 that's very useful information as your rationale for the diesel heating is the same as ours. Regarding your single outlet which heated the living space I'm curious to know how long your van is and did you find the heat dispersed into the other parts of the van sufficiently (e.g. sleeping area if at the rear) to keep the chill off?

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Derek Uzzell - 2020-05-29 6:46 PM

 

Made-in-China-air heaters were mentioned in these earlier forum threads

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Diesel-Heater-installation/53883/

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Secondary-gas-supply-/53898/

 

Although service-stations selling ‘autogas’ in Nordic countries may be thin on the ground, Finland may be the only one where autogas is unavailable. I would have thought that the ability to carry 42 litres of gas (2 x 11kg) in webpax’s Hymer should be sufficient to not require going to the trouble (and expense) of having an auxiliary diesel-fuelled heater installed.

 

I'm not too keen on the idea of a Chinese heater at the moment for reasons that are probably not hard to guess. I'm happy to pay a significant premium for a German brand and sleep soundly at night while it keeps us warm.

 

Regarding the 42 litres of gas it's surprising how quickly using the heating eats in to this while conversely for fridge and hot water it lasts a long time. We had a weeks skiing trip in February (+2/3 days travel either side) and despite supplementing the heating with a 2kw oil filled radiator (we were on hook up) we consumed about 21 litres of gas. We did barely any cooking as we ate out a lot and the fridge was on electric. We don't like the van particularly hot and the heating was set to come on only below 15c overnight. So for for longer term independence 'off grid' I think an auxiliary diesel fuelled heater will be of great benefit.

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mtravel - 2020-05-29 9:16 AM

 

I have not advised you to replace the gas Combi with the diesel one.

I just said I know someone who did it without changing the airducts.

 

Besides, you said that the Webasto or Eberspaecher would be an addon as a backup system.

Which is a wise thought.

 

As for the fuel tank, the most common installation uses that of the vehicle.

The only trick is that the suction pipe must not reach the bottom in order to avoid finding yourself without fuel.

Usually it places at the height where about 15-20% of the fuel remains in the tank.

 

To my knowledge, both heaters can be installed outside under the floor.

 

Max

 

p.s. Well-functioning clones of Truma and Webasto exist on the Chinese market. Not even half the original prices.

 

Thanks Max, I wasn't suggesting you'd advised I do that but that it was a possible option. The Eberspacher installation using the existing fuel tank is designed to ensure it never depletes the fuel tank below 25%. Outside installation I believe is an option as you suggest, I'd prefer internal install if possible as I have a spare cupboard which is not much use as a cupboard due to inaccessibility so hopefully it can go there.

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Steve928 - 2020-05-29 12:52 PM

Although the Eber Airtronic performed faultlessly for many years it had one very annoying feature which could not be circumvented; once the programmed temperature was reached it would shut down. Then 10-15 mins later when heat was again called for it would go through a restart procedure, using its glowplug and consuming valuable battery power. It was a continual game, usually lost, of trying to keep it going on as low fan speed as possible yet not letting it shut down. The other heaters just kept going at minimum heat which is exactly what was required.

 

That sounds like an annoying 'feature'. I'm considering the M2/D4 which is the latest incarnation of the D4, I hope this particular bug has been ironed out.

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webpax - 2020-05-29 8:52 PM

 

Thanks Steve928 that's very useful information as your rationale for the diesel heating is the same as ours. Regarding your single outlet which heated the living space I'm curious to know how long your van is and did you find the heat dispersed into the other parts of the van sufficiently (e.g. sleeping area if at the rear) to keep the chill off?

 

It was a 7.4m Bailey 740 and the single outlet was in the forward face of the French bed, directed towards the centre of the van (there's no substitute for 50cfm of very hot air up your trouser legs when crawling out of bed in a cold van to make the early morning cuppa..). It would heat the entire van very well and maintain that heat even on lowest heat output. It was the perfect compliment to the Alde which, although much loved, could take 3 hours to bring the van up from low single figures to a comfortable 21 degrees, consuming a kilogram of gas in the process.

 

I would definitely check with your Eberspacher agent about whether the current units can be prevented from shutting down once the set room temperature is reached. When you're trying to conserve battery power it is an extremely annoying feature.

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Derek Uzzell - 2020-05-29 6:46 PM

 

Although service-stations selling ‘autogas’ in Nordic countries may be thin on the ground, Finland may be the only one where autogas is unavailable. I would have thought that the ability to carry 42 litres of gas (2 x 11kg) in webpax’s Hymer should be sufficient to not require going to the trouble (and expense) of having an auxiliary diesel-fuelled heater installed.

 

The life span of gas depends on many factors.

Vehicle dimensions, thermal insulation quality, presence of the metal cabin or not, number of windows, etc.

Last but not least, the heating system (Truma 3000, Truma Combi, etc.).

 

In winter, the consumption for the refrigerator is negligible, if Combi that for hot water however low, it also heats the water.

I have traveled the Alps for years with average temperatures around -10°C with peaks of -25.

My experience is that an 11Kg cylinder combined with a Truma 3000 in a six meter overcabin bed lasts about four days.

With a Truma Combi 6000 in a 7 meter it drops to three.

 

Said that in Norway winter temperatures can be much lower (even -30/-35°C), the possibility of having an auxiliary heating system is highly recommended as a backup of the main system.

Any problem or even a breakdown could have dramatic consequences.

I say this from experience, due to a Combi breakdown I spent a night in Salzburg at -15° and I guarantee you that it is not comfortable.

 

Max

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Steve928 - 2020-05-30 8:18 AM

 

webpax - 2020-05-29 8:52 PM

 

Thanks Steve928 that's very useful information as your rationale for the diesel heating is the same as ours. Regarding your single outlet which heated the living space I'm curious to know how long your van is and did you find the heat dispersed into the other parts of the van sufficiently (e.g. sleeping area if at the rear) to keep the chill off?

 

It was a 7.4m Bailey 740 and the single outlet was in the forward face of the French bed, directed towards the centre of the van (there's no substitute for 50cfm of very hot air up your trouser legs when crawling out of bed in a cold van to make the early morning cuppa..). It would heat the entire van very well and maintain that heat even on lowest heat output. It was the perfect compliment to the Alde which, although much loved, could take 3 hours to bring the van up from low single figures to a comfortable 21 degrees, consuming a kilogram of gas in the process.

 

I would definitely check with your Eberspacher agent about whether the current units can be prevented from shutting down once the set room temperature is reached. When you're trying to conserve battery power it is an extremely annoying feature.

 

Thanks Steve928 that's very useful, our van is also 7.4m. It's sounds like your heater was ideally placed in the middle of the van. I'm not sure I'll have that option as I think ours will need to go in the lounge, hopefully some ducting can be run under the floor to the back of the van to distribute the heat a bit.

 

I will definitely discuss the problem you highlight with the Eberspacher agent. I'm hoping to put in a Lithium battery at some stage so hopefully this will mitigate the problem if it still exists.

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mtravel - 2020-05-30 9:30 AM

 

Derek Uzzell - 2020-05-29 6:46 PM

 

Although service-stations selling ‘autogas’ in Nordic countries may be thin on the ground, Finland may be the only one where autogas is unavailable. I would have thought that the ability to carry 42 litres of gas (2 x 11kg) in webpax’s Hymer should be sufficient to not require going to the trouble (and expense) of having an auxiliary diesel-fuelled heater installed.

 

The life span of gas depends on many factors.

Vehicle dimensions, thermal insulation quality, presence of the metal cabin or not, number of windows, etc.

Last but not least, the heating system (Truma 3000, Truma Combi, etc.).

 

In winter, the consumption for the refrigerator is negligible, if Combi that for hot water however low, it also heats the water.

I have traveled the Alps for years with average temperatures around -10°C with peaks of -25.

My experience is that an 11Kg cylinder combined with a Truma 3000 in a six meter overcabin bed lasts about four days.

With a Truma Combi 6000 in a 7 meter it drops to three.

 

Said that in Norway winter temperatures can be much lower (even -30/-35°C), the possibility of having an auxiliary heating system is highly recommended as a backup of the main system.

Any problem or even a breakdown could have dramatic consequences.

I say this from experience, due to a Combi breakdown I spent a night in Salzburg at -15° and I guarantee you that it is not comfortable.

 

Max

That's useful information thanks Max, it supports my view that a diesel backup heater is necessary for long periods camping off grid.

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Regarding the on/off problem of the Eberspaecher, I am not an expert on this brand but I have had a Webasto Dual Top (combined heater/boiler) for thirteen years.

It modulates, that is, once it reaches the set temperature it does not turn off and then on again but continues to heat with less power.

Being less energy consuming.

I believe the Air Top and Air Top Evo models also do it, look at https://www.webasto.com/fileadmin/webasto_files/documents/international/rv/data-sheet/DS_RV_Air_Top_2012_ENG.pdf

 

I don't know if Eber has the same behaviour.

 

Max

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Diesel heaters have a thermostat which turn off the heater if above their set temperature. Whit a delay time. But they cut out

 

If the thermostat is placed on a cold wall like my VW T6 you have to adjust the setting..

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