Diesel Heater Questions (1 Viewer)

Oct 9, 2019
350
566
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65,077
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Hymer S650 Starline
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Pretty much getting my MH set up for when my wife and I retire next June. Am planning some projects for the Autumn one of which is to get a diesel heater for the MH. Have done some research and looked at a few youtube videos and it seems that the Chinese heaters are cheap and effective and easy to fit so am going to order one from ebay. A couple of basic questions though. Firstly my old 1997 Hymer is 7 metres so would a 2 or 5 kw be best?
Secondly I think I'll be ok fitting it but for connecting it to the electrics a couple of sites that I've been on are saying that it should be connected directly to the battery. I would have thought it should be connected through the elektroblock, so any advice on that would be gratefully recieved.
Cheers Martin
 
Jul 6, 2009
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The main thing to ensure is that there is no danger of the power supply to the heater being turned of say through the habitation switch. It is important that when these heaters are turned off they are able to go through the correct shutdown cycle. Where the fuel is stopped but the heater continues to run the combustion and air flow fans until below a set temperature. Otherwise damage to the heater may be caused. If it were me I would connect direct to the batteries.
 
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jopparocks
Oct 9, 2019
350
566
Joppa
Funster No
65,077
MH
Hymer S650 Starline
Exp
Newbie
The main thing to ensure is that there is no danger of the power supply to the heater being turned of say through the habitation switch. It is important that when these heaters are turned off they are able to go through the correct shutdown cycle. Where the fuel is stopped but the heater continues to run the combustion and air flow fans until below a set temperature. Otherwise damage to the heater may be caused. If it were me I would connect direct to the batteries.
Thanks Bessie for the clear answer.

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Jan 17, 2014
1,109
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Wellington, Telford, Shropshire
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Van Conversion
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Since 1977
I can only comment on Eberspacher heaters which in various formats I have used in my campers for well over 20 years.
Bessy765 is perfectly correct in warning that this type of heater should always have power to shut down in an orderly manner.
I have fitted my recent campers with Eberspacher D2 Airtronic type which with appropriate controllers using the external thermostat can work exactly like a domestic central heating, switch it on and set the required temperature and let it do its job. In colder weather we switch ours on before leaving home and switch it off on our return, simple as that.
These versions also have the option of running as an ambient air circulator i.e. just the blower running, no burner.
The Eberspacher wiring loom is supplied with a single 12v +ve connection to connect to an uninterutable supply then splitting into two via a supplied fuse holder, one fuse for the unit and one for the control circuit. Long looms are available for use where the heater is distant fron the controller location which if using the external thermostat operation needs to be sited thoughtfully.
Note that in all the kits I have had the main loom between the heater and the controller is missing the wire that enables the external thermostat operation. It's a bit of a faff inserting an extra wire for this but well worth doing.

Rod
 
Nov 4, 2011
5,676
38,819
Uk
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18,763
MH
A class
Exp
2001
I fitted one to my 2001 Hymer B584, fitted in a box above the spare wheel under the van, I did run a supply straight from the battery and put feed the fuel from the main diesel tank.
 

Two on Tour

LIFE MEMBER
Sep 16, 2016
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Manic has fitted a Chinese diesel heater to their classic Hymer so can maybe give you a few pointers.

One thing you will certainly need to do is replace the supplied power cables with either 4mm2 or 6mm2 depending on the length of your cable run to your battery or shunt if you have one fitted.


Edit : manic has arrive while I was typing. :giggle:

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Aug 18, 2014
22,570
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Lorca,Murcia,Spain
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16 years since restarting
Firstly my old 1997 Hymer is 7 metres so would a 2 or 5 kw be best?
in all honesty & speaking as someone who has 2 of them i think the 2kw is 5kw & the 5kw is 2kw. I.e the same .
Only when you go to 8kw does the physical size increase.
I bought a 2kw one some 4 years ago, might be 5. No differnt to the 5 kw one I bought this year. Apart from 20 quid dearer.
I've been on are saying that it should be connected directly to the battery
Yes they should via a 15A fuse or fuse board. When I built mine I put in a couple of fuse boards, , with red telltale lights if one blows , to wire all the accessories through.That is how I would do it.
Also see if you can get one with the harder nylon small diameter pipe as some of the newer ones come with a larger diameter 'green' coloured softer tube that many complain expands when the diesel pump pulses.
 
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OP
jopparocks
Oct 9, 2019
350
566
Joppa
Funster No
65,077
MH
Hymer S650 Starline
Exp
Newbie
in all honesty & speaking as someone who has 2 of them i think the 2kw is 5kw & the 5kw is 2kw. I.e the same .
Only when you go to 8kw does the physical size increase.
I bought a 2kw one some 4 years ago, might be 5. No differnt to the 5 kw one I bought this year. Apart from 20 quid dearer.

Yes they should via a 15A fuse or fuse board. When I built mine I put in a couple of fuse boards, , with red telltale lights if one blows , to wire all the accessories through.That is how I would do it.
Also see if you can get one with the harder nylon small diameter pipe as some of the newer ones come with a larger diameter 'green' coloured softer tube that many complain expands when the diesel pump pulses.
Thanks Gus
 
Oct 2, 2008
4,307
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Salopia
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4,247
MH
Duro 6x6 Overlander
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since 1968
The chinese ones are very variable in quality , I would not rely on just one , they are cheap enough to fit two for redundancy .
They are also better run hard than on low settings (less problems with coking up ) . So two 2kw (not a very accurate rating) is more effective in addressing the above .

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jopparocks
Oct 9, 2019
350
566
Joppa
Funster No
65,077
MH
Hymer S650 Starline
Exp
Newbie
There have been changes to who can use red diesel but it looks like we can still use it for heating our vans:
"At Budget 2020 the government announced that it was removing entitlement to use red diesel from most sectors, except for agriculture (as well as horticulture, forestry and fish farming), rail and non-commercial heating, from 1 April 2022."
Just looked at farmers weekly red diesel prices in uk and the price has almost doubled from 59.2 last year to 108.5 this week.
I'll need to work it out whether its still cheaper than lpg for heating the van.
 
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OP
jopparocks
Oct 9, 2019
350
566
Joppa
Funster No
65,077
MH
Hymer S650 Starline
Exp
Newbie
There have been changes to who can use red diesel but it looks like we can still use it for heating our vans:
"At Budget 2020 the government announced that it was removing entitlement to use red diesel from most sectors, except for agriculture (as well as horticulture, forestry and fish farming), rail and non-commercial heating, from 1 April 2022."
Just looked at farmers weekly red diesel prices in uk and the price has almost doubled from 59.2 last year to 108.5 this week.
I'll need to work it out whether its still cheaper than lpg for heating the van.
Quote for who can use red diesel came from the following
 

Jaws

LIFE MEMBER
Sep 26, 2008
23,762
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Thetford Norfolk
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since 2006 ( I think ! )
I have fitted maybe 6 or 7 of them.. Always straight to the leisure batteries but via a heavy duty switch
Why a switch ?
Although current draw is miniscule on standby it IS still a draw, and if the van stands up for a few weeks it soon adds up
Also, on the most common type of controller , the display is back lit by a single LED. While LED's have an average life of 10,000 hours, the ones used in the displays are pretty awful and do not last well at all***

Diesel feed
For me, I always try to fit the supplied tank rather than go to the main tank
Diesel is expensive ( and only going more so ! )
By using the separate supplied tank I can use cheaper options such as heating oil

Mounting the pump
They use a thing called a dose or dosing pump
The make a very low 'thunk' noise all the time the heater is running.. It drives me nuts !
I mount them off a composite exhaust strap, thereby isolating the pump completely from the body of the van
It is very effective and silences them virtually completely

Size
I put an 8kW unit in our van which is 30ft long.. BIG mistake !!!
We can only have it on for maybe 30 minutes even at its lowest setting.. any longer and its strip to under crackers and start melting !!!!
OK, I will admit its great on a cold evening when you get in a chilly van as it warms the place nicely in 10 minutes, but if I did it over I would go smaller
There IS a difference in output twixt the 2 and 5kW units, having put two side by side and checked them with my portable temp sensor
It is not more than double as the ratings would suggest, but at least 80% different

All the units I have fitted have all been cheapo chinese ones from Fleabay
In 6 years of using and fitting them I have had two issues
Had one heater plug fail ( but I think that the unit was very old ) and recently had a pump pack up on the one I have fitted in the workshop

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Apr 6, 2019
3,453
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Eye, Peterborough, UK
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59,702
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RV
Exp
FourWinds Windsport 6.8L V10
Maxspeedingrods have been supplying Chinese models for many years now so I consider more reliable than any old Joe on fleabay
 
Dec 2, 2019
3,511
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South Lincolnshire
Funster No
67,140
MH
Rapido 7065+
Exp
Broken most bits now
Fitted the 5 kW £90 Chinese one off the main tank last year and it kept us warm enough through last winter running at low speed. No problems once I'd sorted out the exhaust condensate draining. A bit whiffy on warm up but fine once running.

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OP
OP
jopparocks
Oct 9, 2019
350
566
Joppa
Funster No
65,077
MH
Hymer S650 Starline
Exp
Newbie
I have fitted maybe 6 or 7 of them.. Always straight to the leisure batteries but via a heavy duty switch
Why a switch ?
Although current draw is miniscule on standby it IS still a draw, and if the van stands up for a few weeks it soon adds up
Also, on the most common type of controller , the display is back lit by a single LED. While LED's have an average life of 10,000 hours, the ones used in the displays are pretty awful and do not last well at all***

Diesel feed
For me, I always try to fit the supplied tank rather than go to the main tank
Diesel is expensive ( and only going more so ! )
By using the separate supplied tank I can use cheaper options such as heating oil

Mounting the pump
They use a thing called a dose or dosing pump
The make a very low 'thunk' noise all the time the heater is running.. It drives me nuts !
I mount them off a composite exhaust strap, thereby isolating the pump completely from the body of the van
It is very effective and silences them virtually completely

Size
I put an 8kW unit in our van which is 30ft long.. BIG mistake !!!
We can only have it on for maybe 30 minutes even at its lowest setting.. any longer and its strip to under crackers and start melting !!!!
OK, I will admit its great on a cold evening when you get in a chilly van as it warms the place nicely in 10 minutes, but if I did it over I would go smaller
There IS a difference in output twixt the 2 and 5kW units, having put two side by side and checked them with my portable temp sensor
It is not more than double as the ratings would suggest, but at least 80% different

All the units I have fitted have all been cheapo chinese ones from Fleabay
In 6 years of using and fitting them I have had two issues
Had one heater plug fail ( but I think that the unit was very old ) and recently had a pump pack up on the one I have fitted in the workshop
Great reply - thanks Jaws. So to recap from all replies so far I would take the wires that come with the heater and replace them with heavier duty wires and not only put a fuse in line but also a heavy duty switch. Also it has been suggested to replace the green fuel line with hard plastic 4mm.
Even for my limited abilities I think I can now fit a diesel heater to my van (y)
 
Dec 2, 2019
3,511
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South Lincolnshire
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67,140
MH
Rapido 7065+
Exp
Broken most bits now
Great reply - thanks Jaws. So to recap from all replies so far I would take the wires that come with the heater and replace them with heavier duty wires and not only put a fuse in line but also a heavy duty switch. Also it has been suggested to replace the green fuel line with hard plastic 4mm.
Even for my limited abilities I think I can now fit a diesel heater to my van (y)
The supplied 10 gauge wire on our Chinese heater is good for 30amps although fused at 15amp and has never shown any signs of struggling to run the fan.
 

Two on Tour

LIFE MEMBER
Sep 16, 2016
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Near the junction of the A14 and A1, Cambs
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The supplied 10 gauge wire on our Chinese heater is good for 30amps although fused at 15amp and has never shown any signs of struggling to run the fan.

Was yours really supplied with 6mm2 cable? , never seen one yet that's been supplied with anything more than 2.5mm2 that's come through my hands.
10 awg = 6mm2
14 awg = 2.5mm2

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Jaws

LIFE MEMBER
Sep 26, 2008
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Thetford Norfolk
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C class, Chieftain
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since 2006 ( I think ! )
To be honest I have never felt the need to replace the wire, but then I have up to now always had installations with very VERY short cable runs
When starting up they all seem to draw 8A near as dammit
I have never had the ( albeit short ) wires get even slightly warm to the touch
 
Last edited:
OP
OP
jopparocks
Oct 9, 2019
350
566
Joppa
Funster No
65,077
MH
Hymer S650 Starline
Exp
Newbie
Have ordered a heater off ebay. Just now been out to the van and had a look at where I could put it. There's a good place under the side seating as there is space next to the water tank - its near the batteries and would be very easy to connect to the heating ducts but there is no room for the fuel tank in there. There's definitely room between the passenger seat back rest and the couch but don't think its a good idea for it to be out in the open and anyway swmbo would not like it sitting just behind her. I don't think I would either!
I suppose I could put the fuel tank in one of the back lockers and run the fuel pipe under the van to the heater from there but was wondering if having such a long length of pipe would be ok.
The other option is to put both the heater and tank together in the rear locker and but not sure then how I would get the heat to the van. Would mean a long run of wire to the batteries though.
 
Jan 17, 2014
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Wellington, Telford, Shropshire
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Van Conversion
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Since 1977
Have ordered a heater off ebay. Just now been out to the van and had a look at where I could put it. There's a good place under the side seating as there is space next to the water tank - its near the batteries and would be very easy to connect to the heating ducts but there is no room for the fuel tank in there. There's definitely room between the passenger seat back rest and the couch but don't think its a good idea for it to be out in the open and anyway swmbo would not like it sitting just behind her. I don't think I would either!
I suppose I could put the fuel tank in one of the back lockers and run the fuel pipe under the van to the heater from there but was wondering if having such a long length of pipe would be ok.
The other option is to put both the heater and tank together in the rear locker and but not sure then how I would get the heat to the van. Would mean a long run of wire to the batteries though.
Assuming that your vehicle is diesel why have a separate smelly diesel tank inside. You will find that the fuel consumption of a diesel heater is negligible and not worth sourcing a cheaper type than your normal van fuel.

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jopparocks
Oct 9, 2019
350
566
Joppa
Funster No
65,077
MH
Hymer S650 Starline
Exp
Newbie
Assuming that your vehicle is diesel why have a separate smelly diesel tank inside. You will find that the fuel consumption of a diesel heater is negligible and not worth sourcing a cheaper type than your normal van fuel.
Good point and the fuel tank is right underneath where I want to put it. But maybe one step beyond my technical capabilites.
 
Aug 18, 2014
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Lorca,Murcia,Spain
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Transit PVC
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16 years since restarting
I suppose I could put the fuel tank in one of the back lockers and run the fuel pipe under the van to the heater from there but was wondering if having such a long length of pipe would be ok.
This wouldn't be a problem but I would ensure that the tank is higher than the heater if possible & that the pump is as close to the heater as possible. That way the fuel will gravity feed to the pump & once primed the pump is only pumping a short distance.
That would be preferable to long cable runs.
 
Mar 30, 2019
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You need to consider where your going to run the exhaust pipe, not easy if the diesel tank is directly below the heater. Also the pumps push far better than they pull.

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Dec 2, 2019
3,511
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Jus
Was yours really supplied with 6mm2 cable? , never seen one yet that's been supplied with anything more than 2.5mm2 that's come through my hands.
10 awg = 6mm2
14 awg = 2.5mm2
Just going off the OD of around 3.5mm although could be 12awg looking back over the photos when fitting

Screenshot_20220906-212439~2.png
 
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jopparocks
Oct 9, 2019
350
566
Joppa
Funster No
65,077
MH
Hymer S650 Starline
Exp
Newbie
You need to consider where your going to run the exhaust pipe, not easy if the diesel tank is directly below the heater. Also the pumps push far better than they pull.
Have gone out and had a look and its not directly below but a bit forward but not much. I can see the wooden floor of the habitation area and there's good access if I need to drill holes.
I coming to think that that the place to put it then is in the rear locker and connect the duct somehow to one of the gas heating ducts at the rear as well.
 
Apr 6, 2019
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Eye, Peterborough, UK
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There is a silent version of the fuel pump if you want..... But around £100. 😂

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Mar 30, 2019
2,689
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Cardiff, UK
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Since 2016
Have gone out and had a look and its not directly below but a bit forward but not much. I can see the wooden floor of the habitation area and there's good access if I need to drill holes.
I coming to think that that the place to put it then is in the rear locker and connect the duct somehow to one of the gas heating ducts at the rear as well.
Ideally you need to drill a big hole (about 110mm from memory) and fit a turret of the correct length to fit through your floor. This will protect your wooden/plastic floor from the heat of the exhaust pipe.
One like this.
Screenshot_20220907-200356.png
 

TheBig1

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Nov 27, 2011
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I would mount it under the floor and feed the air pipe in through a sealed hole in the floor. I don't like C0 producing appliances inside the van if not essential
 
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OP
jopparocks
Oct 9, 2019
350
566
Joppa
Funster No
65,077
MH
Hymer S650 Starline
Exp
Newbie
Ideally you need to drill a big hole (about 110mm from memory) and fit a turret of the correct length to fit through your floor. This will protect your wooden/plastic floor from the heat of the exhaust pipe.
One like this.
View attachment 661070
Have taken your advice and bought one of ebay. Also have bought a smaller fuel tank around a 6 litres in size which can fit underneath the side seat next to the heater. Will fill the larger one that will come with the heater and keep it in the back locker. Although I have a fairly large MH there are surprisingly few places to put this heater and fuel tank together.
What connectors should I use to connect it to the battery, and also I have two batteries - should I connect it to the the positive and negative on one battery or pos on one battery and neg on the other.
Sorry for all the technical questions but I'm new to doing this sort of thing and want to get it right.
Thanks everyone for all the help you're giving me.

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