# Truma 3400 query Hymer 544



## 89603 (May 31, 2005)

Any suggestions much appreciated on the following. 
1995 Hymer 544 with Truma C3400 boiler/heater. I have tended to leave this on the water only setting during colder months but I turned it off last week, went away for couple of days and temperature plummeted. 
Tried to fire up and no joy - red light on constant. 5amp fuse in block OK and plenty of gas in tank.
Have tried draining and refilling the boiler and resetting frost protection valve but still refuses to fire. 
Driving me to the edge of insanity!!!


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## mangothemadmonk (Aug 6, 2006)

Are you sure the red frost button is fully and and staying there? If it drops down then the boiler will empty. Get a clothes peg or cut a cork to fit and jam it up for the time being.
Have you bled the air out of the hot water side as an air lock can leave your boiler emptyish so will cause the red light to come on as well.
Johnny F


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## mangothemadmonk (Aug 6, 2006)

Oh just a thought, is there anything blocking the vent pipe for the boiler fumes? 
Can't think of anything else but I am sure there are more reasons.
Hope you get sorted.
Johnny F


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## 89603 (May 31, 2005)

Many thanks for your replies Johnny,

Nothing blocking the vent pipe. Not sure how you go about bleeding the air from the hot water side? On my boiler the frost protection valve has a yellow button which needs to be depressed to reset and boiler dumps when it pops up - at least I think that's the case!


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## Boff (May 10, 2005)

Hi,

this should have nothing to do with the frost safety valve. The valve only drains the boiler if temperature drops below a certain threshold AND the heater is switched off. 

The issue must therefore be something else. Are you maybe using BUTANE gas instead of Propane?

Best Regards,
Gerhard


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## 89603 (May 31, 2005)

Postscript. 
Tried again tonight. Filled the boiler and it fired up first go!. Only differences being the air temp is now much higher then last week plus I used a hairdryer (tip from other enquiries) around the frost valve. Perhaps the valve was not 100% closed previously or maybe freezing temps had made gas supply to boiler sluggish? Working now though and reckon will leave on water only mode whilst it remains cool.

Thanks to those who replied. 
Finally, anyone any experience of the projected lifespan of one of these Trumatic C3400 's ? Have looked at replacement costs because I am paranoid like that, & they are scary to say the least! 
Do other folk get them serviced on a regular basis or as and when they fail?


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## Boff (May 10, 2005)

Hi again,

you are sure it is propane and not butane in your gas bottles? Because, as said, the frost safety valve should have nothing to do with the gas burner. But a failure of gas devices at temperatures around freezing is almost certainly caused by using butane instead of propane.

Regarding the life span: In my current van, as well as it was in all the rental vans I had before, the Trumatic C heating is about the most reliable device there is. The only maintenance mine gets is that about every three years I fill up the boiler with diluted acetic acid (or just take the cheapest of all vinegars from my local superstore) to remove scale.

Best Regards,
Gerhard


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## zoro (May 1, 2005)

HI 
I have the same heater and the manual says the heater will work without any water when you select heating only, so the outside temperature should have made no difference. I have run my heater a couple of times over the cold spell with no problems. Hope this helps and not confuses you

Steve F


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## JockandRita (Jun 1, 2005)

zoro said:


> HI
> I have the same heater and the manual says the heater will work without any water when you select heating only, so the outside temperature should have made no difference. I have run my heater a couple of times over the cold spell with no problems. Hope this helps and not confuses you
> 
> Steve F


sdsplus,

We have the same system albeit with a different dump valve, and it works a treat.

I have to go along with Boff's theory about the possibility of you using Butane as opposed to propane. Or, if it is a bulk gas tank, having a higher butane to propane ratio. Did you last fill up here in the UK, or from a sunnier clime?

My gas solenoid valves stuck once, due to lack of use, which would give the same lack of firing and heating as you were experiencing.

Jock.


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