Do I need a Heating Engineer ?

unclebulgaria

First thing you need to do is get someone who knows what they're doing!
This guy has charged you so it should be fixed never mind plenty of other things it could be! Its already been said changing things willy nilly isn't working. If he's competent, and not just thinks he is, he should have found the problem by the second visit not just "think" its this and that.
There are lots of things that could be causing your problem and there are also lots of things he should have done to eliminate each part from the problem. Sounds like he was guessing to me!

unclebulgaria

Ruski wrote: »

Run the shower and listen to what the boiler is doing. If it is firing up and then shutting down, firing up etc etc then it's defo the shower valve.

How is that defo the shower valve? That could just be a sign that the plate heat exchanger is blocked with debris and its over heating then cooling then overheating again!

Leodogger

unclebulgaria wrote: »

Ruski wrote: »

Run the shower and listen to what the boiler is doing. If it is firing up and then shutting down, firing up etc etc then it's defo the shower valve.

How is that defo the shower valve? That could just be a sign that the plate heat exchanger is blocked with debris and its over heating then cooling then overheating again!

The heat exchange plate has been replaced.

Leodogger

Ruski wrote: »

Run the shower and listen to what the boiler is doing. If it is firing up and then shutting down, firing up etc etc then it's defo the shower valve.

Do the same with the taps elsewhere in the house - and report the findings - hopefully it won't be doing the same as when the shower is running.

A picture of your shower would help to identify if it is a thermo valve - or if you have any details of make/model etc.

Russ

Just tested the shower as you suggested, turned it on full on hot and left it, the boiler did not shut down but the water was going from red hot to just hand hot and then red hot for 5 seconds or so and then hand hot etc. Tested the taps and the same, no boiler cut out whilst the tap was running.

So according to what you have said it is not the shower value.

Did take pictures with my Smart phone and copied them to my computer but don't know how to insert them into this message unfortunately. The name of the shower is a Grohe but it looks about 8yrs old or more. Don't know the model as it was in when we moved in and we don't have any paperwork for it.

SGM1

Does the boiler have temp display on front? I'd check that when running the shower, it should maintain the temp you set it to within a few degrees. If it fluctuates would indicate a boiler fault.

SGM1

JWhite wrote: »

unclebulgaria wrote: »

The heat exchange plate has been replaced.

Could still be several other things on boiler. If the boiler is shutting down then that would indicate a fault with it not the shower? Would have thought the boiler should get upto temp and maintain it?

Ruski

unclebulgaria wrote: »

Ruski wrote: »

Run the shower and listen to what the boiler is doing. If it is firing up and then shutting down, firing up etc etc then it's defo the shower valve.

How is that defo the shower valve? That could just be a sign that the plate heat exchanger is blocked with debris and its over heating then cooling then overheating again!

Which is why I said do the same with the taps

Russ

Ruski

JWhite wrote: »

Just tested the shower as you suggested, turned it on full on hot and left it, the boiler did not shut down but the water was going from red hot to just hand hot and then red hot for 5 seconds or so and then hand hot etc. Tested the taps and the same, no boiler cut out whilst the tap was running.

So according to what you have said it is not the shower value.

Did take pictures with my Smart phone and copied them to my computer but don't know how to insert them into this message unfortunately. The name of the shower is a Grohe but it looks about 8yrs old or more. Don't know the model as it was in when we moved in and we don't have any paperwork for it.

Excellent! You have proved that the same symptoms happen from different oputlets which means that the source is 'defo' the combi - (unless you have a TMV somewhere but we'll assume you don't)

Just one more q: does the 'flow' of water stay the same or does that fluctuate too when you open a hot tap fully?

As I'm sure you know disgnosing a boiler fault over 'tinternet is nigh on impossible - so I would suggest you opt for a fixed price fix from Vailant or a specialist GSR accredited to them - as others have said above your current one seems to be guessing

HTH

Russ

Leodogger

Tried setting the shower to the highest hotting setting and left it running for two to three minutes and it settled to fluctuating within 3 degrees of the temp setting on the boiler after going up or down a few times of 4 or 5 degrees. Then turned down the shower tap water flow pressure to half and reduced the shower temp to a comfortable heat about a third of the way down and waited for it to settle but for the next 2-3 minutes the boiler fluctuated wildly between 54 and 68 degrees and kept cycling up and down. At one point the temp on the boiler was showing 68 degrees but the water felt cold !

So I am not sure what that proves, does it mean the boiler is not controlling the temperature or the shower temp valve is knackered ?

Leodogger

Ruski wrote: »

Excellent! You have proved that the same symptoms happen from different oputlets which means that the source is 'defo' the combi - (unless you have a TMV somewhere but we'll assume you don't)

Just one more q: does the 'flow' of water stay the same or does that fluctuate too when you open a hot tap fully?

As I'm sure you know disgnosing a boiler fault over 'tinternet is nigh on impossible - so I would suggest you opt for a fixed price fix from Vailant or a specialist GSR accredited to them - as others have said above your current one seems to be guessing

HTH

Russ

My husband said the flow remains the same at the outlets, it is just the temp fluctuating. Are TMV's valves on radiators, if so we do have them on all our radiators but we have had this problem before we had the temp valves fitted to radiators and anyway the problem happens with the heating off so I imagine that isn't a contributing factor.