Intermittent fault. Can you solve it? Here are the clues....

[stem]

Here's the equipment:

Glowworm Fuelsaver with fan flue approx 20 years old
Property detached bungalow
Three port valve & pump in the loft.
Cylinder Thermostat, Room Thermostat
Timeswitch Danfoss 102E7

Here's the fault:

The timeswitch is on, thermostat set to 21 degrees, but everything is cold. Switch the timeswitch off and then back on, boiler fires system runs OK for several hours, sometimes longer then all goes off again, until the timeswitch is turned off and on again. (Turning the room stat down and then back up doesn't achieve anything)

The problem is:

The system is installed in a house belonging to an elderly aunt who is unable to perform this albeit simple reset operation, so I have to keep going over and doing it for her (1 hour round trip) The heating system is covered by a BG Homecare Plan. Over the last 3 months, at least 5 engineers have been, not been able to find anything amis and reported that everything is working when they left. All is OK for a few hours then the fault is back.

Other info:

The 3-port valve was replaced in the summer as the original was letting by, so that the rads heated up when the hot water only was on.

The cylinder thermostat was changed a few months ago as even on the lowest setting the DHW was scalding.

My aunt has agreed to have the boiler changed (heat only non condensing) by BG following their recommendation that it should be changed because of it's age and reliability issue. However they can't do this for three weeks. I will be away soon, so won't be able to keep going over for her.

I'm hoping someone may recogonise the parts making up her system and have come across this issue before. Any ideas?

Thanks for any assistance you can offer.

 

[Dan Robinson]

My first guess in the mid position valve.


You won't be getting a non-condensing boiler BTW. You sure you don't mean a combination boiler?

 

[mysteryman]

Sounds like the programmer to me - the valve has been changed.

 

[Dan Robinson]

Possibly....

 

[stem]

You won't be getting a non-condensing boiler BTW. You sure you don't mean a combination boiler?

Yes, sorry meant to type "heat only non-combi"

 

[stem]

Sounds like the programmer to me - the valve has been changed.

The valve was replaced in the summer and it's only since then that the intermittent fault has appeared. BG have taken a new 3-port valve from their quote after they realised a new one was fitted last year. A bit ironic if that turns out to be the faulty item that's prompted everything else to be changed.

 

[Dan Robinson]

Faulty or mis-wired. With BG it cold be either.

 

[Mr Smyth]

The drayron valves BG use are pretty unreliable, so could be.

As likely be a wiring fault from when it was changed.

Is it that the CH only comes on when the HW is calling and that is why it seems intermittent. Try having just Htg only from the clock??

 

[gasbanni]

If your going down the new boiler route........

If shes an oap cant she get it done under the warmfront scheme free ? .......

In any event get a local company with a good reputation to quote it'll be cheaper than bg !

As already stated probably simply a wiring /control fault !!!!

 

[stem]

Try having just Htg only from the clock??

No can do unfortunately. It's a Danfoss 102E7 which only allows the selection of Hot Water or Hot Water & Central Heating. Once it's working it will run for a good few hours. Longer that it takes to heat the hot water cylinder.