Rads and TRVs

[Macfi]

Hi, problems with radiators banging very loudly (combi boiler) started Friday night. All serviced and checked by B Gas for 5 star contract in August. Two trvs removed and pins released on two rads that were not heating ( by BGas engineer, last month). So called out B Gas, checked boiler, then when the banging started, went round and said its the TRVs. At first said no problem, will fix new ones but now as he cannot prove if they are on the wrong end or not has quoted £200 for the job, as it will be 'improving the system!!' They are Myson Trvs and considering we have had three visits from engineers I would hope one of them might have noticed trvs on the wrong ends? The TRVs are on the opposite ends to the drainage outlet.
Anyway just wanted advice please.

 

[footprints]

Have a careful look at the chrome part of the valve there should be some indication of flow direction, an arrow or triangle pointing out the direction.
Modern Myson TRV's can flow either way as far as I know. If you have a model name or number contact Myson for information.

From cold fire up the heating and simply see which end of the radiator gets hot first, then you know the direction of flow.

As for BG. I would make the point you have here, they missed it so tough luck! (Perhaps a little more politely though )

You may however find the banging is due to sludge or scale in the boiler and that they do exclude from their contract.

 

[Macfi]

Thanks for the reply.
Hubby just returned from week away to find me hopping mad!!!
Proceeded to check all Trvs and tighten (as most were loose), then he bled all the rads, then he balanced the system.
Put on the heating and surprise surprise after an hour, not a whisper!!!!
He found one TRV that is not working so will hopefully sort the pin tomorrow.
Does this mean they are on the right way?
My complaint letter to British Gas is two pages long so far!!!
Just to think if I had been an elderly lady or someone who trusts engineers! And I would be £ 200 worse off. Not once did the engineer check the TRVs for tightening or try bleeding or anything useful!!

 

[ScottishGasMan]

Not once did the engineer check the TRVs for tightening or try bleeding

Probably because neither of those things would cause loud banging.

Just because the noise has stopped at the moment doesnt mean its all ok, once the house is heated up for a while if its the TRV it may start happening again.

To check as said above, most (not all) will have an arrow showing the direction that the water must travel through the valve, from cold feel what side of the radiator valves heat first, thats the water comming in, if its ok thats great, if its the wrong way roung it may well be the issue, you would need to do this on all radiators that have trvs as it just takes one to start the noise.

Also its not something I can imagine any engineer there to service a boiler would check so can hardly have a go at them for that, but they should have been able to say clearly at the time if that was the problem or not and therefor whether its chargeable or not.

If they have been fitted backwards then it wouldnt be covered and you would need to pay to renew them or move them to the right position.

 

[footprints]

Yes just to clarify a stuck pin will not make noise, because the rad is shut off, the noise TRV's make is at the point where they are just opening or just closing. It's the water being squeezed through the valve that makes the noise a bit like a wind musical instrument does.

 

[Agile]

No one has mentioned the auto bypass valve ( ABV ).

Its possible/probable that you don't have one fitted as you should.

If there is a correctly adjusted ABV then you would not normally get any banging noise from the TRVs.

It takes 10 seconds to see if a unidirectional TRV is on the correct end. Its the flow end which gets hotter! Or when first the CH is turned on is the first end to warm up.

Tony