# Duotherm problem



## johng1974 (Jan 17, 2007)

Hi all, I have been fulltiming for about a month, but last night my heating seemed to pack up 

It just blows cold air

I know the propane bottle is getting low, but the hot water and hob work fine.. is the heating extra sensitive, or have I got a problem?

It's not freezing right now, but could still do with heating for another month or so,...

Would the average plumber know anything about RV's heating?

thanks
John


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## zaskar (Jun 6, 2005)

johng1974 said:


> Would the average plumber know anything about RV's heating?
> 
> thanks
> John


Errr, NO! Absolutely not I'm afraid. You need, either, someone who knows about RV systems, or, there are a few things you can check yourself. It would help if you had a back copy of ARVE magazine. I have a copy of a breakdown and trouble shooting guide fo rthe blower. Which is yours? Suburban or Atwood? One of the commonest faults on either is the Sail switch. It senses when the fan has started and only then will it allow the burner to fire up. Trouble is, it's a bugger for getting bunged up with dust and jamming. Thankfully. I've never had to do either of mine (violently touches wood!!!!!! 8O ) but I believe it's a doddle one you know where to look.


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## johng1974 (Jan 17, 2007)

many thanks Zaskar!

My next question was, what is the sail switch! (I have an exploded diagram of 66012 and 66017 - not sure what models they are, or what I have) - will see later on when i get back....

J


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## zaskar (Jun 6, 2005)

johng1974 said:


> many thanks Zaskar!
> My next question was, what is the sail switch! (I have an exploded diagram of 66012 and 66017 - not sure what models they are, or what I have) - will see later on when i get back....
> J


exactly what it says. Its a switch mounted on the heater casing which prodrudes into the airflow chamber. On the switch is a flat plate (i believe). As the fan starts, the airflow hits the plate and operates the switch. The circuit board now "knows" that there is airflow and will now allow the burner to fire up. If the burner were to fire up without first having airflow, it would VERY quickly burn through its own casing which would not be a good day out! 8O.


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## johng1974 (Jan 17, 2007)

aah..  it finally clicks...

sail = wind


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## 101411 (Oct 15, 2006)

We used to have a chevvy Fleetwood that looked a lot like your RV. Our heating packed up on a regular basis but it was just a build up of soot on the ignition electrodes. Take off the front cover of the heater and check for the 2 electrodes above the burner. If covered with soot give em a blow off and a quick rub with some wire wool.

Worked every time with ours

Good luck

Dazzer


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## johng1974 (Jan 17, 2007)

Opened the front cover & tried the heating again; the small window showed the pilot light lighting, and the main flue lit. 

The heat exchanger got hot & after 3 seconds the glow in the pilot light window went out, and the HE became cold.

Because the burner & the pilot lit, that must suggest that the sail switch and the pilot igniter are both working?

Have turned control to the 'off' position for safety; will that cut the gas supply completely to the unit - because I think can still smell gas.

Any more thoughts, many thanks

John.


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## 101411 (Oct 15, 2006)

Hi John.

Sounds like the thermocouple has packed in. :roll: If the thing fires up and then shuts down almost immediately. 

The thermocouple is the little probe that is heated by the pilot light. Make sure the probe is actually been heated by the pilot light and hasn't moved or been knocked. Its job is to detect if the pilot light has been blown out and then shuts off the gas supply  . If its in place take it off and take it to your local plumber merchant to get a replacement. They are not expensive  and as long as it fits and is been heated by the pilot light it doesn't need to be a direct like for like replacement.

Good luck

Dazzer


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## johng1974 (Jan 17, 2007)

Thanks Dazzer
Will have a look at that and get back asap
Cheers
John


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## johng1974 (Jan 17, 2007)

Sorry I got it wrong - I have no pilot light system, in fact, on this furnace; the light I saw was the furnace light.

It is electronic ignition; have still not got it to work properly yet , and still noticing a smell of gas even though it is switched off.

Tested around unit with a lighter (!) and there was a gas leak somewhere where the remote-off-switch-unit is...

Is there a sensor, does anyone know, that will detect leaking gas and shut down the system ie have I got a gas leak which is stopping the system fromworking?

Thanks all

John


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## 101411 (Oct 15, 2006)

Hi John

Water and washing up liquid with a small paint brush is much better (not to mention safer!!!) that a lighter!!

Brush plenty of the bubbly water on all unions and pipe bends. Once you find the leak(s!!!) nip up the couplings and try again.

Have you cleaned the spark electrodes and if so can you see it sparking when it tries to light??

Its a matter of eliminating possible faults (gas leaks been the most major!!) try the bubbly when the system tries to ignite as well

Dazzer


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## johng1974 (Jan 17, 2007)

Thanks Dazzer

Definately gas leaking from the on off rotary valve. 

Is the valve unit sometthing I can buy? I could still do with knowing if there is a sensor which detects leaking gas and shuts the system.

John


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## 101411 (Oct 15, 2006)

Hi John.

On a vehicle at the age yours is I doubt very much if there is a system to cut the gas in the event of a leak. Its more likely going to be the faulty rotary valve with a broken O ring. The broken O ring is probably blocking the outlet and stopping the gas from flowing.

Id have a word with Linda at Stateside re spare parts as it will probably have to come from USA. You have nothing to lose by taking the valve apart and seeing if its just a broken O ring (the thing is knackered anyway so what have you got to loose)?? Just make sure you can isolate the pipe from the rest of the gas system before taking it to bits!! or the gas will have to stay off till you get a new one!

Good luck and be careful!!

Dazzer


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## johng1974 (Jan 17, 2007)

thanks dazzer

OK have removed the whole heating system and its now in the back of my car! Linda, if you read this, I may badger you for £ of some internal parts of the system when I have investigeted more.
Have cut the 10mm pipe coming in, and installed a £13 gas isolator tap, and have added a stopper to that to, using the correct Gas PTFE. No leaks anywhere, used the washing up liquid method 8) 

Great timing re weather 

running two small oil filled heaters and a small convection heater, hope the site dont notice 

John


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## LC1962 (Oct 6, 2005)

You can badger me by all means John but don't leave it too long....we will be shipping again in about 2 weeks and I'd need to locate the parts.


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## johng1974 (Jan 17, 2007)

Linda , Dazzer , anyone

pics show a (looks like asbestos!) gasket that i now need, and the source of the leak. Have not gone any further as yet. Still not sure what Furncae this is, according to PPL there are about a thousand types...


John


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## johng1974 (Jan 17, 2007)

nothing


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## johng1974 (Jan 17, 2007)

nothing either..

how do i delete these posts ....


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## LC1962 (Oct 6, 2005)

Those links don't work either John


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## LC1962 (Oct 6, 2005)

That last one did albeit a bit small....hang on while I get me specs!


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## johng1974 (Jan 17, 2007)

hmm looks like i need to get a bit of webspace or something.. myspace seems useless...

how does everyone else do this... i sohuld know really


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## LC1962 (Oct 6, 2005)

Hi John

I just save pics in a file on my PC then add by clicking the "add an attachment" button below this gives you an option to "browse" - find the file, click open and hey presto........a bit like this......


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## johng1974 (Jan 17, 2007)

god i am stupid !


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## LC1962 (Oct 6, 2005)

John....a silly question I'm sure but I'll ask anyway..........are there any numbers on it anywhere which would indicate a serial number or part number?


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## johng1974 (Jan 17, 2007)

sorry linda just go and check.. its in back of car

sec


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## johng1974 (Jan 17, 2007)

no nothing,,,

it has a number on the general controler (leaking part) 

P ?/R V28SBR68 but thats all..

the side panel is back at van, but that wouldn't have the numbers I wouldn't have thought..

as dazzer says, an o-ring or similar may have failed inside..

will keep investigating


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## johng1974 (Jan 17, 2007)

ok all.. the inside of a control unit on a generic 27 year old RV furnace...

there is the on / off knob (1), which burnt last week due to the gas leak from I think O ring (2), and there is a cork gasket I need to renew (3)
on top of this there was what looked like an asbestos gasket (earlier pics)

I guess if i can get all of these parts, maybe , just maybe my heating will work again..

One question still unanswered.. why didn't the heating work, despite the leak..?

to refresh - burner lights for 3 seconds then stops.

The sail switch must be ok, or the burner wouldn't light
the electric ignition works, or the burner wouldn't light. ( I took it out and tried it, no probs)

John


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## 88927 (May 10, 2005)

Hi John
The three items bottom right in your last picture would appear to me to be a pressure regulator of some kind. I know the type as we use them for pressure control in a pressure vessel, although they are a little different to the one shown.....
They can suffer from splits in the diaphragm, worn needle valve or weak loading springs. You can usually get repair kits for these and if you can see any identification marks on the body you should be able to source one (or maybe Linda can....).
I am not saying that this is your problem but it definitely sounds like a gas supply fault and this would be a likely candidate.....
Good luck mate

Keith


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## johng1974 (Jan 17, 2007)

thanks Keith..
yes checked the main Diaphragm.. looks fine, have not checked other parts..

seems ok.. I think that the 3 parts you mentioned are the only way the gas is shut off / on really.. or regulated it as you say 

will look at it more..

J


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## 88927 (May 10, 2005)

Was there a coil attached to the top of the casing John? If so then it could well be the on/off valve with inbuilt pressure regulation. Worth having a good look at it because they can sometimes stick and cause problems especially if the spring or the coil have become weak over time. Can you try connecting up the valve with coil attached to an air line and then switching on the unit to see that it opens and stays open? It will be safer than trying it connected to the gas pipe mate :lol: 

Keith


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## johng1974 (Jan 17, 2007)

will have a look Keith in next day or so 

cheers,
J


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