loud vibrating sound central heating

[drives]

Hi all,

I have recently replaced my TRVs on my radiators, but I have a strange problem now which occurs when one of the bedroom radiator TRVs shuts off when the central heating is running. When it does so, I get a loud vibrating noise (rapid almost like a machine gun noise) which is loudest where I have a towel rail in the adjoining shower room. I've attached a video below.

It is a two pipe system. I believe it has only started occurring as I now have TRVs that actually work and shut off this particular bedroom radiator when up to temp, as I cannot see that it is anything to do with the new TRV itself?

Any help much appreciated. If I turn off the towel rail (TRV on frost setting) the noise stops.

Thinking about it, I believe for whatever reason the TRVs on the bedroom radiators (not installed by me; previous owner presumably got someone in to do them) are on the return rather than flow. Is this likely to be the cause of the problem?

https://flic.kr/p/2phf6NL

 

[BlueLoo]

Thoughts:

1) what TRV?
2) Has this trv actually replaced the bypass?
3) is the new TRV bidirectional (Fitted on the right side)

 

[Mike13]

Some TRV's must have the flow in a particular direction, some are not affected by that.
Either change it to the other side or change the type. I know my system was hit by that 4 years ago when it was extended, the original rads became noisy, the plumber just changed the direction of flow at the boiler rather than tinker with lots of rads, but with just one to fix you should swap the trv over.

 

[drives]

Sorry I should have said above- I’ve only changed the TRV head so the valve body has not been replaced. The only reason that I believe the noise has now started is because it now shuts off with the new TRV head i.e. it works whereas the old ones didn't.

It does appear to be bi directional looking at the arrows? That said, a bit coincidental that this is one of only two (I believe) radiators in the house where it is fitted on the return side and when it closes the vibration occurs?

Is it relatively straightforward to swap over? Here's my existing pipework both sides. I assume I can get a right angle lockshield body and valve to do a straight swap on the existing TRV side. Then a straight TRV valve body on the other side, and that would be it? I'll be draining down the system at some point next year anyway to try and replace a radiator downstairs so can do it at same time.

 

[BlueLoo]

Sorry I should have said above- I’ve only changed the TRV head so the valve body has not been replaced. The only reason that I believe the noise has now started is because it now shuts off with the new TRV head i.e. it works whereas the old ones didn't.

It does appear to be bi directional looking at the arrows? That said, a bit coincidental that this is one of only two (I believe) radiators in the house where it is fitted on the return side and when it closes the vibration occurs?

Is it relatively straightforward to swap over? Here's my existing pipework both sides. I assume I can get a right angle lockshield body and valve to do a straight swap on the existing TRV side. Then a straight TRV valve body on the other side, and that would be it? I'll be draining down the system at some point next year anyway to try and replace a radiator downstairs so can do it at same time.

Suggest you get a pencil and paper and trace out the system fully allow you to fault find before you change anything.

 

[drives]

Suggest you get a pencil and paper and trace out the system fully allow you to fault find before you change anything.

It literally happens as that TRV head closes the valve. I’m not following what else it could be or why that wouldn’t be the logical first step but happy to be educated, especially when it comes to plumbing

 

[BlueLoo]

It literally happens as that TRV head closes the valve. I’m not following what else it could be or why that wouldn’t be the logical first step but happy to be educated, especially when it comes to plumbing

If you've no bypass (Bathrooms are often locked open to act as one) your pump will dead head.
But then that will cause other issues so draw it out first

 

[BlueLoo]

I'm not a plumber....

 

[drives]

If you've no bypass (Bathrooms are often locked open to act as one) your pump will dead head.
But then that will cause other issues so draw it out first

Ok thank you. I didn’t know I needed a bypass radiator or what this meant to be honest but just googled it.

Do you think this might be the problem? Would a bypass radiator have a fully opened lock shield on both sides (sorry if this is a stupid question). I have added trvs to the bathrooms and from memory I think at least one had this configuration so I suspect I may have inadvertently done this, albeit the plumbers who replaced two of them didn’t mention this. I did one of them, and perhaps it was that one. Therefore this might be my fault but I got a bit disillusioned with plumbers last year to be honest due to some bad experiences and thus did the last one myself.

Can I just remove a TRV head so it is permanently on? With the TRV switched off (so permanently on) on that bedroom radiator, I don’t get the fault.

 

[drives]

I'm not a plumber....

Posted before I saw this

The heating engineer who installed our unvented cylinder a couple of years back and sealed our central heating system set my flow temp to 55 (even though it’s a heat only boiler so that was the HW cylinder flow temp as well), set cylinder thermostat to 60, and my pump speed right down so I had no heating for weeks until I figured it out, alongside the hot water issues.

Thus I took up DIY plumbing and am trying to learn from this forum- with mixed success it is fair to say but I’ve received some excellent advice on here.

 

[BlueLoo]

Posted before I saw this

The heating engineer who installed our unvented cylinder a couple of years back and sealed our central heating system set my flow temp to 55 (even though it’s a heat only boiler so that was the HW cylinder flow temp as well), set cylinder thermostat to 60, and my pump speed right down so I had no heating for weeks until I figured it out, alongside the hot water issues.

Thus I took up DIY plumbing and am trying to learn from this forum- with mixed success it is fair to say but I’ve received some excellent advice on here.

This site gets its knickers in a twist with DIYs but the professionals should remember that it's likely their negligence and incompetence probably drove us here in the 1st place. There are good uns and bad uns obviously.

I to, have dispaired at the std of work done by professionals. It's depressing so i try to do as much as i can where possible.

At least now my boiler switched live is no longer wired directly to the mains and the pump is pointing in the right direction......


Anyway, have a look around the system. Go read the boiler installation manual. Standard boilers (ie no integrated pump) require a bypass should all of the rad valves and circuits shut down. The typical professional way (ie quick and lazy) is to lock out the bathroom rads but this is inefficient and reduces net boiler output. If the plumber worked to a plan, he may have taken a similar bodge by putting a small bypass (gate vale opened up 1/4 turn) between the HW supply/feed.
The proper way is to have a automatic bypass valve in the system which detects overpressure from dead circuits and opens up to return flow back to the boiler.

These cost £10 instead of the £2 gate valve so are obviously luxury items for the impoverished plumber suffering on his £100/ph call out.

Which is why i said to draw out what you have. Will do you well in the future for maintenance and uogrades.

If you do need a bypass but don't have one fitted, they are easy to fit.

 

[denso13]

Can I just remove a TRV head so it is permanently on?

Yes, could be an easy fix.

 

[ianmcd]

Either remove the sensor head or change the orientation of the valve

 

[BlueLoo]

Yes, could be an easy fix.

And an expensive one as the rad will be on all the time, burning heat and wearing out the boiler.

Gas ain't cheap anymore.

If you do this then at least use the lockshield to throttle the flow as much as is possible before banging returns.

Best solution is to do it right
It's easy enough.

 

[denso13]

And an expensive one as the rad will be on all the time, burning heat and wearing out the boiler.

It just acts like any other bypass.