Central heating pipes 'banging/knocking'

[petercj]

Seriously now ... I once had this problem and it was expansion and contraction of a pipe that was tight on a joist.

But then why would it suddenly start out of the blue?

If no work has been done in and around the house, then maybe a joist has moved slightly for some reason, settlement perhaps, or possibly has become damp and has swollen - it would only take a tiny amount of movement.

If the knocking only occurs when the system is heating up, or cooling down, it's worth checking out. First step being to try and pin-point the area the sound is coming from. Try using a tube or a pipe put to your ear on any suspect areas.

Might also be worth running the heating on very low temperature to see if the knocking doesn't happen then.

 

[callum84]

We did have a carpet laid about a week ago in the Bedroom, but I didnt think that would have caused an issue? Ie there wasnt excessive banging but Maybe it has?

 

[petercj]

We did have a carpet laid about a week ago in the Bedroom, but I didnt think that would have caused an issue? Ie there wasnt excessive banging but Maybe it has?

If they nailed down new carpet grips, they may have tightened up a board, or even caused a slight shift in a joist.

If the pipe was tight before, then just a fraction of a millimeter could make the difference.

The floor can act as a sound board, and it's surprising how much noise can be created by such a simple thing.

 

[glenno1]

Are the grippers touching the pipes

 

[callum84]

Glenno1: No the grippers were gown originally and were re-used.

Can such a thing like the grippers/laminate touching the pipework (as per my previous post) above floor level cause knocking/pinging noises??

 

[glenno1]

What make of valve is it,some budget valves can knock a bit

 

[callum84]

I would have to go home and check what kind of valve.

The noise doesnt seem to be coming from the TRVs or radiator, more in the floor leading up to the rad??

There is sometimes a 'thump' aswell as the rhythmic knocking/pinging, which could resemble the noise of a valve but again seems to be under the floor.

 

[glenno1]

My suggestion would firstly be to turn the valve when the heating is on and see if noise comes and goes

 

[callum84]

Ok i will try that tonight also

 

[petercj]

Have you tried pin-pointing where the noise is coming from by using a pipe or a tube to your ear.

If the grippers were already down, could they have added some nails to firm them up?

If this noise is being caused by expansion/contraction just below a board, you should be able pin-point the spot by using a tube to your ear.

Does closing both radiator valves make any difference?

 

[callum84]

I seem to have pin pointed it to the spare room at the opposite end of the property to where the boiler is.

I tried switching the trvs off and on when the noise was happening but this did little difference, I have however found that when the trv is turned down to the lowest Setting, there seems to almost be a 'static' type noise coming from it?? Then when rad heats up it seems to go??

Also the more rhythmic bangs are when the rad is heating up/cooling down, followed by a louder thud on what seems to be the pipe nearer the hall (next to spare room) almost sounds like a valve type thing closing??

 

[callum84]

To be honest the TRV seems pretty crap, when u turn the damn thing to the lowest setting, it can actually turn further?!?

It seems just now (as the rads cool down) as if the trv is on a lower setting, the banging seems to be a lot less frequent?

 

[petercj]

When I had this kind of noise it was a 15m pipe feeding a radiator valve - they'd brought the pipe up through the floor alongside a joist with a knot in it, then when the rad was connected up, the pipe was hard up against the knot, and it made a hell of a noise. It would start slowly.. bang.......bang ........bang and then speed up bang...bang...bang...bang... then slow down again. This was in a bedroom too! Drove me to drink in the end!

Until I'd freed it up, I couldn't believe something so simple could make such a racket! I removed some of the knot using a small drill, and that was it, job done, all quiet again.

Could the carpet fitters have found a loose or creaky board and nailed it down tight before laying the new carpet?

If someone has laid a pipe under the floor and left a board loose over a pipe that was already tight in a notch, that could explain things.

I never knew why the problem I had started - the house was 20 years old, and it just started up one day.

 

[callum84]

Impossible to say if they have I would have to contact the carpet company and check I think, I don't think the carpenter would admit it even though he had done tho, especially if it has caused an issue.

Just hoping the plumber on Friday can physically do something to help as it is becoming quite depressing really, the thought of having to lift the new carpet and then the floor boards doesn't help either lol!

The more and more input I am getting it seems to be a problem which will need floor finishes lifted rather than anything else but I really hope not.

 

[petercj]

Try the easier possible solutions first.

If you do end up lifting the carpet, you will probably be able to spot any new nails or screws.

Also, look for boards with tongues missing.

 

[callum84]

Thanks petercj, if it did come to lifting the carpet, is it easy enough to see where the issue would be in your opinion?

I guess it would be a case of looking for the pipe work tht is shuddering or coming in contact with the joists/flooring?

Earlier tonight again it was the regular light banging/pinging which reduced as the trv was turned down, then a londer thump, which as I mentioned almost sounded like a valve closing in the hall subfloor, would the typical system have valve type components?

It is probably very evident that I know very little about heating systems unfortunately, but appreciate the time and effort this form has given me.

 

[phpaul]

Thanks petercj, if it did come to lifting the carpet, is it easy enough to see where the issue would be in your opinion?

I guess it would be a case of looking for the pipe work tht is shuddering or coming in contact with the joists/flooring?

Earlier tonight again it was the regular light banging/pinging which reduced as the trv was turned down, then a londer thump, which as I mentioned almost sounded like a valve closing in the hall subfloor, would the typical system have valve type components?

It is probably very evident that I know very little about heating systems unfortunately, but appreciate the time and effort this form has given me.

ok back to basics is a hatch so u can crawl under the sub floor ? if so investigate that way

 

[petercj]

Chances are your plumber will recognise the sounds when he hears them - might be something quite simple, I wouldn't worry about it too much.

 

[glenno1]

Im sure your plumber will do couple of checks and find what it is

 

[callum84]

Thanks guys, I appreciate the positivity!

In terms of a crawl space, it is literally big enough to get into, the subfloor is not deep at all, so although access I available, it is REALLY restricted, and where the hatch is you would have to crawl a good few meters, and there are dwarf walls running opposite direction to the joists every 1500mm or so, so really it's not great for working underneath the floor or even getting a look.

 

[callum84]

Another thought, could low pressure be a cause of noise in the heating pipes??

 

[petercj]

Any luck callum? Did your plumber fathom it?

 

[callum84]

He said its the pipe work rubbing on the floor joists and the only way to fix is to open the floor up I am afraid, he checked the trvs etc and said they are all ok.

It will have to be done as the tick tick tick is driving me crazy at nights even though the wife sleeps right through it all!!

He said the boiler was working fine, he couldn't really explain why the pressure had been fluctuating (from .75 bar wed, to .5 bar thur, then .75 bar this morning) but he has now put the pressure up to about 1.5 bar (when cold)

So I guess the next thing is to open up the floor, I am 99% sure the noise is from the back bedroom but he even said the noise could be traveling along the pipes from anywhere to he honest ( probably what I wasn't wanting to hear!!)

I just hope the noise will be apparent when I am under the floor, think might just lag all the pipes at the same time as they seem to be fairly bare and the cold snap towards the end of this year could be an issue!!

 

[petercj]

If this noise started at the time you had that carpet laid, there must be a very good chance that its under the floor in that room. Most likely explanation being that the carpet fitters found a loose board and nailed it down tight. Chances are that it won't have a tongue on it, which will make it easy to spot.

 

[callum84]

Petercj:

I think it will be quite a time consuming job as I will have to create a hatch (as previous owners must have floored over any hatch that was there) dwang/support the new opening in the floor, then hope the sleeper/dwarf walls have crawl spaces to allow me to access the problem area - if not I will have to form crawl spaces or it would mean forming a load of hatches to access various areas.

The flooring isnt T&G flooring, its actual floor boards fixed to the floor joists, so I think I will have to 'hear' for the problem when under the floor but hopefully it will be pretty apparent.

All in all hopefully get it sorted this weekend.

Boiler pressure seems to be ok, (fluctuating slightly) but the plumber said this is quite normal for a combi, ie mains pressure / temperature can affect it.