Vailliant mag 125 water heater in static caravan, will not stay alight

[tda171]

Can anyone suggest how I can clear/check waterway for blockage?
I have a MAG125 water heater that runs the pilot OK and when ho****er is demanded, it fires up for just about 1 minute. The gas then shuts down.

A local guy has said that the problem is almost certainly lack of water pressure inside the heater. However, because of previous pressure problems, I have installed a neg head pump that is providing plenty of pressure to the static (on demand) and this is confirmed by the cold supply. The system has worked well for the last 4 years, but has started playing up now, for the first time, on getting the van up and running this month.

As the caravan is in Cornwall (a very soft water area) I would be surprised if the problem is a result of mineral blockage.....but it could be..??

Anybody got any ideas??

Tim

 

[Mike Jackson]

What's the flow rate out of the tap like?

 

[SimonJohns]

Does the pilot go out?

 

[tda171]

What's the flow rate out of the tap like?

Hi Mike. Thanks for getting back. The flow rate out of the hot tap is fairly low, although it is variable as the temperature control is altered. I have always experienced a lower flow rate than the cold side, simply because I assumed that the time required in the heat exchanger would have an effect on the output? Afraid I havn't measured it, but I can tell you that there is enough pressure to carry the hot supply to a shower the other side of the van (3/4mts)and certainly enjoy an acceptable shower!

Cheers
Tim

 

[tda171]

Hi Simon, thanks for the reply. Yes the pilot does go out. Thgere is effectively a complete shut down of the gas side. However, a standard restart gets the pilot going again straightaway.

Cheers
Tim

 

[SimonJohns]

Get someone in whos good on caravans. This is a very simple fault and can be fixed rather quickly

Besure to check their ID card that they can work on caravans

Btw. Where is the caravan?

 

[mountainman]

Sounds like it's shutting down on the ASD.
As has already been suggested get a Gas Safe engineer to look at it as it could be dangerous and don't attemp to use the appliance in the meantime.

 

[tda171]

Hi Simon

Caravan is in North Cornwall, Padstow area.

Tim

 

[tda171]

Thanks for the advice. Dummy question I guess...but can you tell me what ASD stands for..??

Tim

 

[tda171]

So Simon, do you reckon this is a gas side or water side problem (as a guess) from the info given??

Cheers, Tim

 

[mountainman]

My fault for not explaining.
ASD is Atmospheric Sensing Device.
On water heaters it usually checks for a blocked flue or heat exchanger though it can be activated by downblow.

Definitely not user serviceable or diagnosable and should only be touched by a GSR engineer.

 

[SimonJohns]

Deffo gas

Done loads of these. Shouldn't take the eng that long to do

 

[tda171]

Many thanks for explaining.

If I do a 'clean through' of the waterways, notably some descaling of the heat exchanger that seems a fairly straightforward removal and wash through, is it likelikey or possible that this would cure the ASD problem?

Rest assured I am going nowhere near the gas side, but the problems of getting a gas safe caravan qualified guy out, when I am 200 miles away, and to linkup all the dates is a nightmare !!

Want a freeby week in Cornwall..??

(only joking) Tim

 

[tda171]

Thanks for that! As you can see from the thread, it looks possible that a blocked / furred up heat exchanger might be causing the ASD to shut down, so initially I would like to try and get some descaling done, prior to getting a GS guy out, just to see if that cures the problem first.

Thanks for your time though....much appreciated!!

Cheers

Tim

 

[mountainman]

Sorry again, I've not fully explained myself.
I mean by blocked heat exchanger I mean the flueways not the water pipework.
An ASD is designed to shut the appliance of if there is an escape (spillage) of products of combustion which could put the occupants of the premises at risk.

 

[southcoastboile]

basicaly it needs a service, when was it last done?

 

[tda171]

Got you!! Many thanks for the explanation. Clearly I need to get a GS engeneer to call. I will try and track one down. Thanks for all your help!

Tim

 

[tda171]

.......I fear therein lies the problem!! With only 6 or 8 weeks use a year, it is too easy to overlook the servicing. THAT, isclearly the problem so an engeneer is needed!! Thanks for your time!

Cheers

 

[SimonJohns]

Got you!! Many thanks for the explanation. Clearly I need to get a GS engeneer to call. I will try and track one down. Thanks for all your help!

Tim

If you had no luck with posting on here. Gassafe have a search function on their website to search for someone local with the qualifications you need

 

[tda171]

Thanks Simon!!

Tim