Central Heating Experts – why are my pipes banging?!

Bit of background:

We moved into a new house in Feb and when it got really cold, the heating wasn’t really keeping the house warm enough. The radiators were really old and the OH’s dad who is a retired plumber reckons they were a very old design that never radiated particularly well.
However, the heating was as near as damnit, silent. No clunks, bangs, whistles….

Recently we had all the radiators replaced (bar a couple), with new lockshield valves & TRV’s on them too. We also had a new wireless Honeywell heating/hot water controller (Sundial RF Pack 2) and the guy who installed that noticed that the wiring to the motorised valve wasn’t correct, which is why we had only been able to get hot water with the heating on (we’d been using the immersion for hot water over the summer – cheaper elec at night). He re-wired the valve correctly.

Now it’s getting a bit colder & the heating is coming on more regularly, we are getting a steady banging through the pipes. It’s quite well spaced out, about 10-20 secs generally, and seems to occur mainly when the system fires up. This means at the moment we are getting woken up at about 5:30 by this clanging noise and it’s driving us mad.
I bled the radiators which helped, but hasn’t cured it.
I tried opening the TRVs fully on the radiators closest to where the sound seemed to be coming from & this seemed to help for a day or two, but then it started again.
Last night we tried opening all the valves on all the TRVs to max, incase it was some kind of flow restriction issue (clutching at straws) but it was still banging this morning when it started up.
This evening I bled the radiators again and a bit more air came out of the bathroom rad (tallest upstairs radiator). COuld it be that there is air still making it’s way round the system & once this is all out, the banging will stop? The system isn’t really running for long periods at the moment, as it gets up to temp quickly, so I wondered if it just needed to run for an extended period to get the air shoved round to the bathroom rad?
I have also whacked the pump up from 2 to 3 (it’s a grundfos with the 3-speed selector on it) and since then it seems to be banging less, but it does it worse from cold, so I won’t really know if that’s helped until 5:30 tomorrow morning….

Any things we can do/try? Advice? My next plan of attack was to check how open the lockshield valves are and see if there is one that’s almost shut causing some kind of flow problem. I did wonder if this was the reason that the valve had been wired incorrectly – perhaps haivng the hot water/heating running in parallel cured the banging?

I keep meaning to ask my OH’s dad about it, but he is quite busy at the moment and I haven’t had the chance to pop round and quiz him.

try bleeding them again

Have you checked that nobody is trapped in a secret room and is trying to get your attention? I saw this sort of thing in a film once.

we had banging pipes, turned the system pressure down slightly, and voila, no more banging pipes.

Santa claus doing an early reconisance, and is trapped behind the boiler.

Water hammer, can be exacerbated by valves etc. that open or shut too quickly.

“we had banging pipes, turned the system pressure down slightly, and voila, no more banging pipes. “

You have an adjustable pressure regulator! Nice. Or did you just slow down the flow rate under a given pressure head? Slowing the flow down achieved your aim as the issue is related to moving water.

markenduro – Member
try bleeding them again

I bled them last weekend & I re-bled them about an hour ago. As I mentioned above, some more air came out from the bathroom radiator, but not loads.
I wonder if it is quite air that still needs to make it’s way out of the system. I will perhaps give it a daily bleed for a week?

kayak23 – Member
Have you checked that nobody is trapped in a secret room and is trying to get your attention? I saw this sort of thing in a film once.

I’ve checked for secret rooms and trapped people, but can’t see any. I am not sure they would coincidentally be trying to get my attention at the same time the system starts in the morning.
If there are any trapped people, they should just shout “let me out of this bloody secret room”, rather than confuse the issue. But that’s trapped people for you, I guess!?

Coz tha toonz ah massiv!

I’ve checked for secret rooms and trapped people, but can’t see any. I am not sure they would coincidentally be trying to get my attention at the same time the system starts in the morning.
If there are any trapped people, they should just shout “let me out of this bloody secret room”, rather than confuse the issue. But that’s trapped people for you, I guess!?

Posted 1 minute ago # Report-Post

But they may be tied up or gagged and cant shout, and the boiler firing up, makes them hot, so they bang for attention.

anto164 – Member
we had banging pipes, turned the system pressure down slightly, and voila, no more banging pipes.

Is that a sealed system though? I don’t think ours is pressurised.

project – Member
Santa claus doing an early reconisance, and is trapped behind the boiler.

Can’t be. It’s hard up against an outside wall with flue pipe thing passing outside. I’d have noticed his beer gut poking out. And there’s not a sleigh with reindeer accompaniment parked on the roof or the driveway…..

Waderider – Member
Water hammer, can be exacerbated by valves etc. that open or shut to quickly.

Eh? What valves? Motorised or TRV? I opened them all (TRVs)to max last night to see if that made a difference so there shouldn’t have been any valves opening?? I have seen the words ‘water hammer’ mentioned a lot, but not much in the way of explanation or cure.

OH – ONE MORE THING – we checked the TRVs and they are dual flow, so it’s not one of them with flow going the wrong way….

Anto164… we had banging pipes too, which were fixed by turning the pressure up! Central heating is like quantum dynamics; if you think you understand it, you’ve missed something fundamental… 🙂

Drac – Moderator
Coz tha toonz ah massiv!

I said ‘banging’ not bangin’

🙂

project – Member

But they may be tied up or gagged and cant shout, and the boiler firing up, makes them hot, so they bang for attention.

Erm….good point (!?) well made. But to be honest, if they can’t bang out some morse code … — … then they don’t deserve to be released.

It’s still clanging (word changed due to Drac) so I guess turning the pump up hasn’t sorted it. Might go and turn it down now to 1….

phiiiiil – Member
Anto164… we had banging pipes too, which were fixed by turning the pressure up! Central heating is like quantum dynamics; if you think you understand it, you’ve missed something fundamental…

Yep, it does seem to be a bit of hocus pocus. Perhaps that is why plumbers generally spend so much time sucking air through their teeth, shaking their head & looking confused….

If you can’t get your head round water hammer best pay someone maybe?

Easy fixes – reduce water velocity, slow down valve opening/closing, slow down pump starting stopping, ensure pipework is fixed correctly.

Another person with an adjustable pressure regulator!

Stuck flux capacitor on the inlet defribulator assembly, not easy to fix.
A common fault on older systems it appears.

it’ll be the fluffer valve on the fallopian tube thats stuck

Are the new TRVs directional and if so have you fitted them the right way round relative to the flow/return?

Waderider – Member
If you can’t get your head round water hammer best pay someone maybe?

Easy fixes – reduce water velocity, slow down valve opening/closing, slow down pump starting stopping, ensure pipework is fixed correctly.

Another person with an adjustable pressure regulator!

Most explanations I have seen relating to water hammer, say it is generally caused when the system stops, due to a valve closing. How does this relate to the noise generally happening when our system turns on?
As mentioned above, my OH’s dad is a retired plumber and I’ll be asking him to have a look next time I see him, so paying someone isn’t strictly necessary yet.

Your easy fixes:
– reduce water velocity – presumably by turning the pump down? I have done this & it doesn’t seem to be making any difference.
– slow down valve opening/closing. What valve in my heating system does this refer to & how do I slow it down?
– slow down pump starting stopping. Do you mean like soft start? How can I do this with the pump I have?
– ensure pipework is fixed correctly – I am starting to wonder if this is the problem, as it seems to be coming from the same area all the time. Bit of a full-on job though, not something that can be quickly tried as it will mean clearing out the room & getting all the floorboards up.

project – Member
Stuck flux capacitor on the inlet defribulator assembly, not easy to fix.
A common fault on older systems it appears.

Aparently our system was put in just after these were phased out, due to lack of Mr Fusion spares. nice thought though.

RustyNissanPrairie – Member
it’ll be the fluffer valve on the fallopian tube thats stuck

Wrong type of plumbing, but good thinking! The fluffer valve is normally slammed shut, to reduce the risk of banging. And we had the fluffer valve on the rear access panel removed, because it was considered sexist.

tommytowtruck – Member
Are the new TRVs directional and if so have you fitted them the right way round relative to the flow/return?

New TRVs are bi-directional – or so they say. Honeywell VT120E dual flow TRVs.
http://www.honeywelluk.com/products/Radiator-Thermostats/Radplan/VTL120/

EDIT – the installation guide says:
2. Location
The thermostat can be fitted in any orientation with the flow through the body in either direction.

I’ve changed my mind, water hammer is the wrong phrase (thanks wikipedia). I typed in good faith though, I’m a civil engineering student and water hammer causes similar symptoms on the much grander scale of hydroelectric power stations etc.

I’d lift the floor boards myself and fix the loose pipes – certainty level maybe 80%. Pipes need to apply an equal and opposite force as water goes round bends, proportional to the volume of water times velocity. So, reduce flow or fix pipes better. You can’t affect volume as that relates to the diameter and length of pipe. Still 80% certain.

Anyhow, that’s what I would do if it where my house. Apologies if I have been less than helpful.

Now, off to listen to Kate Bushes new album 🙂

ah the unanswerable question.. banging pipes so frustrating so many possibilities..

get the air out of the pipes.. they didnt bang before you let all the water out and when you put new water in they did.. the air is trying to get out.. the air in the water can cause turbulance and thus vibration.. get the air out.. slow the pump down.. turn it off even!!
nothing like hot water to drive air out..

even drain all the water out and refill again.. you never know but it ll just go eventually.. you might even live that long..r

Waderider – Member
I’m a civil engineering student

If you can’t get your head round water hammer best pay someone maybe?

I’ve changed my mind, water hammer is the wrong phrase (thanks wikipedia).

Awesome – the power of Wikipedia.

Thanks, I am aware of the requirement of a pipe system to resist the loads applied to it from the water flowing through it. Perhaps I should dig out my text books from my mech eng degree, but I am not sure that would help greatly (short of stuffing them between the pipes).

Do you have any more info about your simple fixes? Particularly the ‘slowing down’ of pumps starting & stopping/valves opening & closing. I am still not sure how they relate to a domestic heating system. Were they also dug from Wikipedia? 🙄

Yes, I am starting to think that it might be unsecured pipes. I find it strange though as it is the same pump driving the system & the same pipework that was previously silent.
So, unless the old rads were really bunged up restricting the flow (which I don’t think they were), I would expect an approximately equal quantity of flow before & after changing the radiators and other gubbins so why would the pipes start moving now (if that is the cause), when the didn’t previously?

Erm, enjoy Kate Bush!

totalshell – Member
ah the unanswerable question.. banging pipes so frustrating so many possibilities..

get the air out of the pipes.. they didnt bang before you let all the water out and when you put new water in they did.. the air is trying to get out.. the air in the water can cause turbulance and thus vibration.. get the air out.. slow the pump down.. turn it off even!!
nothing like hot water to drive air out..

even drain all the water out and refill again.. you never know but it ll just go eventually.. you might even live that long..r

Yeah, I will try a daily bleed & see if that reduces it/cures it.

I have seen several suggestions online of draining and re-filling the system. Think I will keep that on the list of things to do once I have exhausted all other avenues!
We’ve got bare varnished floors in the room I am currently in (near to the noise) so that will be the best place to investigate loose pipes. Only thing is a skirting bead that will need pulling up/ripping out before the boards can come up….hey ho, this room is quite near the top of the ‘rooms to decorate’ list so it’s no great shakes.

You might even live that long

🙁 don’t say that! 🙂

These are amazing little jobbies if you have air in the system:
http://www.ebay.co.uk/itm/Aladdin-self-bleed-auto-HV30C-chrome-radiator-valve-/180548435237?pt=UK_DIY_Materials_Plumbing_MJ&hash=item2a09867d25#ht_1539wt_905

Also try the sentinel type products, X100/200 did wonders for my system.

I HATE my central heating. The end.

^^ cheers mulacs – I will look into those if the problem persists!

Copper pipes expand when they get hot, and by more than you’d think, especially on a long run. With the regular knocking you describe my first assumption would be that this is what’s happening. Maybe you have a pipe that is hard up against a floorboard or maybe too tight in a notch etc. If this is the case you should be able to locate roughly where this is and maybe lift a few boards to see if it goes away.

Don’t ask on here, go and ask on DIYnot.com. Be sure to give all the details of the system or they’ll massacre you but you’ll get good advice from real plumbers on there.

Assume there is air in the pipes that is causing the banging, and its not reaching the nearest radiator where it would collect and you could bleed it off.

At the other end of the radiator to the TRV’s are the lockshield valves. Radiators close to the boiler will generally have the lockshields nearly closed, as you move to the furthest point the locksheilds will be near fully open. This prevents all the water taking the shortest route through the closest rads and leaving half the house without heating.

Bleed all rads. Close all the lockshield valves, but importantly, leave a note by each one with the number of turns to off. You need to set them back correctly afterwards otherwise you could end up with temperature fluctuations around the house.

Get heating running constantly. Move to closest rad to boiler, fully open both TRV and lockshield for a short period. This will put full flow through the first section of pipework, increasing the chances of purging any air stuck at a high point. Then turn the lockshield valve off and reset TRV. Repeat at each radiator working away from the boiler. Once finishing, turn off heating, reset all the lockshield valves, bleed each rad. If any radiator has more air than normal, then make a note as this could indicate the section of pipework that is susceptible to an airlock.

Reset heating to normal and cross fingers at 5.30am 🙂

Stumpy – this is a common complaint that we receive from the NHBC.

Water hammer is usually associated with the water main, caused by a float valve ‘bouncing’, or taps, showers or washing machines turning off. As modern taps are often ceramic disc they shut off very quickly and this can cause a vibration down the pipework. A washing machine which uses a solonoid valve can cause similar problems.

Noise in a heating system is a far harder problem to sort out though. It can be pipes expanding, moving, knocking on joists as they move, etc. The trouble with noise beneath a floor is that the void can amplify the noise. We have taken up large areas in new houses to insulate the pipework as much as possible and also clip it to stop these noises, but finding the section of pipework that is causing offence is difficult. There are additives that are supposed to help boiler noise, I’ve never tried them as usually another fault stops it first. Oh and if pipes are notched over joists check these are deep enough and the pipes aren’t touching the floorboards.

If it is is one area I would recommend investigating that section of pipework and insulating and clipping it as far as practicable.

Good Luck!

Re-adjust CH to come on when your alarm goes off and simultaneously play music at high volume with the same beat?

The plural of TRV is TRVs.

Maybe you have a pipe that is hard up against a floorboard or maybe too tight in a notch etc.

This is what almost drove my brother insane. Sounds very similar to what you have.
He eventually tore into the ceiling/wall and fixed the pipes properly and the knocking went immediately.

i’m an ex honeywell sales engineer and i’ll offer the following advice: (not read all replies so apologise if treading on toes)

Does your CH system have a wall mounted thermostat?

It should by law have one that provides ‘boiler interlock’ i.e. switches the boiler pump off once room has reached the temperature set. TRV’s do this but when the rad’s reach temp the TRV’s close but the boiler still pumps and causes chatter/hammer, a wall mounted timer/thermostat sends a signal back to boiler to stop pumping.

You should have at least one radiator WITHOUT a TRV, this is called a bypass radiator and allows some flow throw the system if all TRV’s are closed.

The system should have an automatic air bleed valve fitted, this bleeds out the system slowly and over the first few months of install should be slowly set to closed.

Thanks for all the help & suggestions. It was still banging away this morning:

globalti – Member
Don’t ask on here, go and ask on DIYnot.com. Be sure to give all the details of the system or they’ll massacre you but you’ll get good advice from real plumbers on there.

Yeah, I am trying to avoid signing up to yet another forum I am unlikely to use often. Although perhaps in this case, it is not a bad idea.

spooky_b329 – Member

A good idea – I was thinking of trying something like that to increase flow through certain radiators to try & shift the air. I think this’ll be the first thing to try on Sat.

Bear – yeah, I don’t think it is water hammer. Thinking about it, I have heard this before (not in the house) from things like taps going off abruptly.
I think Saturday will be spent pulling the upstairs floorboards to bits to try & find what’s going on. Any ideas for materials to use to stop the pipes moving. I know you can buy specific clips. Is it best to use these? And how about with notches in joists? Could I just pack them out with something like old bits of inner tube to cushion them?
I am wondering if when fitting the new rads, my OH’s dad had has disturbed a pipe slightly that was previously happily seated. Most of the rad sizes didn’t match exactly so he’s had to manipulate some of the existing pipework to get it to fit.

ononeorange – Member
Re-adjust CH to come on when your alarm goes off and simultaneously play music at high volume with the same beat?

This evening, I’ll be re-adjusting the CH to not come on in the morning! I can live without it for a few days….

globalti – Member
The plural of TRV is TRVs.

Eh? That’s not very helpful. If you are referring to spooky b329’s post, he was referring singularly to TRVs not plurally, apart from one occasion. And if you are referring to the apostrophe he used for the plural of TRVs, it is grammatically acceptable to add an apostrophe to an acronym for the sake of clarity.

bedmaker – Member
Maybe you have a pipe that is hard up against a floorboard or maybe too tight in a notch etc.
This is what almost drove my brother insane. Sounds very similar to what you have.
He eventually tore into the ceiling/wall and fixed the pipes properly and the knocking went immediately.

Hmmm, this is what I am thinking along the lines of. If the ‘easy’ things like trying to purge the air out don’t work, then I might as well get stuck in with checking for pipes that are knocking…rather get it over & done with than put up with it for weeks and then do what I should have done at the start.

Thanks everyone.

Thanks for all the help & suggestions. It was still banging away this morning:

globalti – Member
Don’t ask on here, go and ask on DIYnot.com. Be sure to give all the details of the system or they’ll massacre you but you’ll get good advice from real plumbers on there.

Yeah, I am trying to avoid signing up to yet another forum I am unlikely to use often. Although perhaps in this case, it is not a bad idea.

spooky_b329 – Member

A good idea – I was thinking of trying something like that to increase flow through certain radiators to try & shift the air. I think this’ll be the first thing to try on Sat.

Bear – yeah, I don’t think it is water hammer. Thinking about it, I have heard this before (not in the house) from things like taps going off abruptly.
I think Saturday will be spent pulling the upstairs floorboards to bits to try & find what’s going on. Any ideas for materials to use to stop the pipes moving. I know you can buy specific clips. Is it best to use these? And how about with notches in joists? Could I just pack them out with something like old bits of inner tube to cushion them?
I am wondering if when fitting the new rads, my OH’s dad had has disturbed a pipe slightly that was previously happily seated. Most of the rad sizes didn’t match exactly so he’s had to manipulate some of the existing pipework to get it to fit.

ononeorange – Member
Re-adjust CH to come on when your alarm goes off and simultaneously play music at high volume with the same beat?

This evening, I’ll be re-adjusting the CH to not come on in the morning! I can live without it for a few days….

globalti – Member
The plural of TRV is TRVs.

Eh? That’s not very helpful. If you are referring to spooky b329’s post, he was referring singularly to TRVs not plurally, apart from one occasion. And if you are referring to the apostrophe he used for the plural of TRVs, it is grammatically acceptable to add an apostrophe to an acronym for the sake of clarity.

bedmaker – Member
Maybe you have a pipe that is hard up against a floorboard or maybe too tight in a notch etc.
This is what almost drove my brother insane. Sounds very similar to what you have.
He eventually tore into the ceiling/wall and fixed the pipes properly and the knocking went immediately.

Hmmm, this is what I am thinking along the lines of. If the ‘easy’ things like trying to purge the air out don’t work, then I might as well get stuck in with checking for pipes that are knocking…rather get it over & done with than put up with it for weeks and then do what I should have done at the start.

Thanks everyone.

Just to add my 2 pence…..
Don’t use Sentinal…. use Fernox! Luckily for me I happen to work in IT for Fernox so I don’t pay full price! However, enough product pushing, I fitted some new rads at home and had the same issue. Spoke to the tech guys here and they suggested running the F3 cleaner around the system to remove any rubbish from the new rads then putting in the F1 Inhibitor. Told me to make sure all the new pipes were secured and that all the rads were balanced (basically the rad nearest the boiler has the least amount of water getting into it and the furthest the most using the flow restrict valves).
Good luck with the dark art!

HolmwoodDave

Yeah, I think OH’s dad used Fernox.
Did following their advice sort your problem. Was there one thing that seemed to do the trick or was it a combination.

OH’s dad did mention that he didn’t get the chance to fully balance the system.
I think the plan of attack for Saturday is:

– balance system
– try Spooky b329’s air purging procedure
– rip up floor boards, get in a mood, smack my finger with a hammer & wrap every pipe in duckling feathers…..

”Does your CH system have a wall mounted thermostat?

It should by law have one that provides ‘boiler interlock’ i.e. switches the boiler pump off once room has reached the temperature set. TRV’s do this but when the rad’s reach temp the TRV’s close but the boiler still pumps and causes chatter/hammer, a wall mounted timer/thermostat sends a signal back to boiler to stop pumping.

You should have at least one radiator WITHOUT a TRV, this is called a bypass radiator and allows some flow throw the system if all TRV’s are closed.

The system should have an automatic air bleed valve fitted, this bleeds out the system slowly and over the first few months of install should be slowly set to closed.”

sorry to be a pedant.. but..what LAW says your ch has to be fitted with a room stat.. the stat does not tell the boiler to stop pumping it tells it to stop heating water pumps can and are wired seperately regularly

on the other hand would that is a regulation for new boilers that says there should be a boiler interlock with a room stat that should be in a room with rads that arent controlled by TRVees?

no regulation for existing sytems to have an auto vent either or one that is manually operated.. new boilers dont even all have them..

i wish i could offee the Op a constructive simple remedy but i cant and no one else can i m afraid.
i learn every day in this job its one of the best things about it as you ll never know most stuff never mind everything..

Could be one or more TRV’s. Bi-directional valves are not all they are cracked-up to be, They do work better and less noisy if fitted to return connections on rads.
Could be the water actually boiling in the system, I know its called a ‘boiler’ but it should never actually boil. Check boiler thermostat setting, also is boiler stat working? Water from boiler (flow should be around 70-80 Deg C).
Does the system have a By-pass fitted? If the wiring is correct now does the boiler shut off permanently when both H/W and Htg are satisfied, irrespective of timer saying either is on? Or is it still firing now and again when it cools down. When M/V is closed boiler should not fire even if it goes stone cold. Room and Cylinder stats calling for heat should be the only reason boiler will fire, and that would be once the M/V has opened one or circuits.
What temperature is your cylinder stat set at? Does it work? is it fitted nice and tight to the cylinder surface? If its faulty or poorly fitted or incorrectly wired H/W will never be satisfied and boiler will fire all the time (boiler stat permitting).
I know I have gone-on a bit here but it could be any of the above, or even a few I haven’t mentioned.
Hope I have been of some help.