Odd noise from CH when one bedroom TRV is off

[skippy75]

Recently I have noticed a strange noise in the mornings from the CH that I would describe as like someone using a petrol chainsaw in the next garden down as heard through double glazing. Its a low vibration noise thats not very loud but loud enough to be annoying when your trying to sleep.

The room is above the garage that has the boiler in with a radiator at the foot of the bed which is the first rad in the system. I always keep this rad turned off via the TVR and for the last 4 years its been silent. Now it makes this noise sometimes when the heating is on unless I open up the TRV to at least the number 2 setting which boils our feet.

I noticed this morning that the noise stopped when my partner was showering and it stayed quiet for a while after the shower was off but eventually came back.

Its a valiant combi boiler and i have bled the rads today finding no air in the system. I also checked for loose pipes but they are all solid.

Does anyone have any ideas what might be causing this? Its slowly driving me mad and as its an intermittent noise im concerned that the heating engineer wont be able to hear it when he comes.

All I can think is that either the TRV is faulty or the system needs descaling/flushing?

 

[footprints]

Yes it's the valve faulty or fixed on the wrong end.

Opening the vale changes the gap between the valve and seat so stopping the noise which may come back as the room heats up.

The reason it goes off when showering is that combis only do one thing at a time, when hot water is called for the heating goes off so full gas rate is available for hot water, you don't notice this as the rads stay hot for a long time, by the time they started to cool enough to notice the showering has finished.

 

[Agile]

Sounds to me as if you have no auto bypass valve!

Tony

 

[Terry lambert]

It's a combi Tony.

Although I hope he has a by pass rad ( without TRVs on) and that its open

 

[xr4x4]

Yes it's the valve faulty or fixed on the wrong end.

Opening the vale changes the gap between the valve and seat so stopping the noise which may come back as the room heats up.

The reason it goes off when showering is that combis only do one thing at a time, when hot water is called for the heating goes off so full gas rate is available for hot water, you don't notice this as the rads stay hot for a long time, by the time they started to cool enough to notice the showering has finished.

I agree...!

 

[sooey]

Sounds to me as if you have no auto bypass valve!

Tony

+1 He says it's a combi.

 

[Agile]

Makes no difference that its a combi!

They still need an autobypass ( unless its a late Vaillant when the manufacturers say that if its properly set it does not need an auto BPV or a late Viessmann where the same applies ).

But the manufacturers are only deciding that in respect of protecting the boiler. It does not mean that an excessive pump pressure will not cause TRVs to chatter.

Tony

 

[Terry lambert]

I have had cheap valves chatter when close to the boiler.

How many combis in recent times can you list that state you need an auto bypass? I think Intergas, but can't think of another

 

[Agile]

In this case we are not told that this is a very new boiler so the assumption is that its older.

Most makers now include an internal bypass or sometimes a smart pump on their latest boilers which limits the pump pressure as TRVs close.

Intergas pride them selves on the minimum number of moving parts in their boilers so would not want to add an ABV as that would increase their moving parts count!

Tony

 

[skippy75]

Thank you for the replies. This boiler was installed 4-5 years ago and we have had no trouble with noises or anything before so I assume all the proper bits are in the right places. This TRV has been off 90% of that time with no issues until now. We do have a radiator with no thermostatic valve as a bypass and most of the others are open anyway.

As a valve is cheap I will go ahead and fit a new one and see if that cures the issue.

Thanks for the help and suggestions

 

[Agile]

Rather than bothering to replace the TRV there are a couple of easier things you could do.

First change over the head with another in the system.

If that really does not solve it then close the lockshield valve to stop the flow through this rad.

If you want to use the rad sometimes then get a hand knob to fit onto the lockshield and turn it manually.

Tony

 

[skippy75]

Rather than bothering to replace the TRV there are a couple of easier things you could do.

First change over the head with another in the system.

If that really does not solve it then close the lockshield valve to stop the flow through this rad.

If you want to use the rad sometimes then get a hand knob to fit onto the lockshield and turn it manually.

Tony

Thanks, ill try those first.

There are two radiators in that room and it only really needs one. If you had them both up high it would be a sauna