Boiler Keeps cutting out when on Central Heating. Just changed TRVs

[YoungMarkC]

Hi all,

Please can you help me. I have moved into a house and so far just qualified for wet plumbing NVQ.

I have a Glowworm Compact combi Boiler. It is quite old I reckon as it still has a manual ignition for when it goes out.

I changed the Valves on the rad system and added an anti-lime scale solution as there was no scalemaster fitted. Probably should have put one on in truth.

I put Danfoss TRV's on 4 rads out of a 6 rad system. Left kitchen and Bathroom with normal lock shields.

Then once the heating was being used it kept cutting out and the boiler would keep working but the pilot and burner were out. You could still hear the pump running and circulating the water.

The boiler becomes so hot to touch on the front.

My mate is a Gas Safe engineer and changed the thermocouple but that didn't make any difference. He is unsure what it is and no-one else seems to know either.

It only happened after I changed the TRVs but surely they are not connected to the problem although it does seem strange it happened straight after.

I can also hear that the Rads appear to start getting hot when the hot water is being used. The reason for that is that you can hear the pipes expanding.

The TRV's are reverse flow although normally I think it doesn't matter what side you put them on but with these ones you need to specify which way the flow is an flick a switch.

Does anyone know what the issue is because I haven’t' the foggiest and nor does he.

Any help would be appreciated.

Best wishes,

Mark

 

[WHPES]

Did the boiler get bled to get the air out after changing the valves?

Do you have to reset the overheat stat to get it on again?

 

[GrahamM]

Is all your TRV's & lockshields fully open and no air locks in system?
In my opinion it is still always preferable to have the TRV's on the flow at all times even though they supposed be multi-directional.

 

[YoungMarkC]

Hi there, thanks for this no I didn't bleed any air out of the boiler when I recomissioned it. There are Manual air vents at a higher point on the circuit as the flow and return are taken over a stair / corridor and dropped down into the bathroom so I did bleed air out of those points. Should I try and get air out of the boiler as well?

No I didn't have to reset anything, just re light it again.

Thanks soooo much for your help on this.

 

[YoungMarkC]

Thanks Graham,

I'll keep that in mind re that flop and return. I just put them on the point that were most obvious for everyday use. One of the valves are behind a sofa as an example. I did notice that most of the Valves I put on were on the return instead of the flow but I did it for the above reason knowing that they were reverse flow valves.

There does not appear to be any airlocks as every rad does get hot to the top.

Do you think I would need to change them around again?. We have a small baby so they often need to be changed. Especially in the babies bedroom and so changing the valve to the side that is beind the bed would be tricky in every day use.

Thanks very mucj for your help!

 

[GrahamM]

Make sure auto air vent in boiler is open. Bleed pump and all rads.

 

[YoungMarkC]

Right Oh Graham. Will do. Any idea why the boiler is getting so hot and also why the rads appear to get hot when the hot water is on? Could there be a hole in the diverter valve? Or am I way off. Thanks again. Mark

 

[stevetheplumber]

some older combis have to be vented manually usually on the heat exchanger
you dont have to put the valve on the difficult to reach end just reverse the valve and have the head horizontal
sound like the boiler is overheating some of the old ones have interupters on the thermocouple which knocks the pilot out
its most probably air but you may have flushed some crap into the heat exchanger

 

[arran197]

So are the rads all getting hot? Sounds like the boiler is overheating, possible because of an air lock or if the rads aren't getting hot, the pump. You may need to vent the pump. Old boilers do tend to get quite hot, that's why even room sealed boilers needed ventilation for cooling when they were first introduced. Is the pressure ok? You could also flush the system out and run some cleaner through, before adding some inhibitor.

 

[YoungMarkC]

Hi guys, thanks for that. Yeah the rads are getting hot. Hot to the top, no air there. I have vented the pump, I tried to do the manual AAV in theboiler but nothing came out when I took the cap off, even under pressure which makes me think that perhaps it is blocked with lime scale. I will dose it for a week with X800 and the flush and then put inhibitor through. System is doesed with inhibitor already and limescale reducer but that only happened after I took ownership of the property. There is no service record of it before hand and I don't think it was that well looked after. Thanks for your help guys, I'll give it a lash. :cheesy: