Central Heating Experts – why are my pipes banging?!

Sorry,
Double post.

geordiemick00 – Member
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.

Ooooh, I missed this reply while writing my reply below it. Apologies.
No idea about the legalities of the whole thing, but…..

We have had a Honeywell Sundial RF2 pack 2installed. It’s a heating/hot water controller that comes with a wireless thermostat.
I thought though that some systems have pump overrun fitted specifically to keep the pump running after the boiler has turned off to take heat away from the boiler & stop residual heat causing localised boiling?

Bathroom rad has no TRV

Not sure about an auto bleed valve. I have not seen anything that looks like it might be one….

totalshell – Member
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..

Thanks – I am sure I’ll get it sorted in the end. As mentioned above, my OH’s Dad is a retired plumber so I am sure if/when I get really stuck I can get him to come round and have a look. In the first instance though I’d like to see how far I can get with it before hassling him.

specialknees – Member
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.

Crikey – more suggestions. Thanks.

We have turned all the TRVs to fully open & still get the problem. We also tried closing fully the ones closest to where the sound seems to be coming from, and both things made no difference.
If it was the TRVs, I would expect the problem to go away if they are fully open. Am I right to think this, or not? I thought it was the closing action of the TRV when fitted the ‘wrong way round’ that caused issues?

Boiler thermostat is set to about mid-way from memory. I meant to check that last night & forgot. I will recheck & try and nick a thermocouple from work to measure some temps.

Does the system have a bypass fitted? Erm, sorry I don’t know. What would it look like? A piping path in the airing cupboard? The rad in the bathroom has no TRV, so there should always be a flow path available.

I need to investigate this further, but I am pretty confident that the boiler is coming on and off, as and when it should do depending on requests from the system.
I have definitely heard the boiler fire and turn off and seen the corresponding lights on the controller go on or off. If the room stat gets to temp for example, the light on the controller goes off to indicate that it isn’t demanding radiator heat. But, the radiator symbol is still present to show that the controller is in an timed on-period of heating.
(there are indicators on the display that show that the controller is in an timed ‘on’ period for heat & hot water, as well as a light each for water & heating that illuminate when there is actually a demand for heat).

Cylinder stat is set to 55deg. C or thereabouts. It is strapped to the tank and doesn’t appear to be poorly fitted although I haven’t investigated this thoroughly. The boiler definitely doesn’t fire all the time. It is not trying to continually heat water, so I think that the ‘stat is doing it’s job.

Blimey – lots to check & think about!

Stumpy.
Go back to basics.
Is the noise pipes expanding or is it something else?

If its something else it could be any of the above and you would do best to get the installer back, or be nice to father-in-law.

If its simply pipes expanding you could cure it yourself. It wont be easy, you will need to ID the actual area its comming from but its do-able.

Sorry,
Just looked at my last reply, it looks a bit dismisive. Wasnt intended that way and from what you write, you have a good basic knowledge of Central heating and you could well be on your way to a cure.

Go home tonight and check the suggestions myself and others have made and you may be able to discount a fair few.

Let me know how it goes.

P.S.
Where in UK are you?

No probs….

Yeah, I like back to basics…’easy’ things to do:

– check boiler stat setting & measure output boiler temp.
– look for obvious faults with system; integrity of cylinder stat etc.
– check ‘balance of system’ and adjust if required.
– try ‘purging air’ from radiators as spooky b329 suggested, for the sake of being thorough.
– look for loose pipework.

I appreciate all the help. I will post an update once I have done some stuff. Probably won’t be until after the weekend though.

I live near Peterborough (I must have sinned in another life! 😉 )

Yes, it sorted the noise…… Balance the system first as you need the water to flow evenly throughout the system.

Good luck!

Stumpy

I have found to lag the pipes and wrap a clip over the top to be best, waste pipe clips fit pipe lagging well or fixing band.

And nothing wrong with Sentinel, good product (nothing wring with Fernox either but years ago one of their product affected the balls in Honeywell motorised valves)

What about the speed setting of your circulator pump. Pumps are usually two or three speed and position 2 will be all you need on the three-speed pump.

Spending the money on isulation rather than new radiators would have perhaps been more profitable.

money on new panel rads is never wasted.. they use much less water and benifit from both radiated and convected heat plus you get the trv.. so for 150/200 fitted they are excellent value.. insulating pipes has value but they do provide heat where there are no rads..

I meant insulating the house so you don’t need as much heat.

Two things made my pipes bang; iffy motorised valve or a drained header tank. The ball valve on my header tank sticks in the summer due to no usage and limescale buildup so the tank drains and doesn’t refill. A quick nip up to the loft each autumn to free it up cures the problem. Otherwise the system drags air in rather than water and that air gets trapped in the system and causes the pipes to bang as it is dragged round.

@stumpy01

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.

Dear oh dear. The plural of TRV is TRVs, even in 2011. TRV’s is a possessive: e.g. ‘the top of the TRV’. Or worse, that crime of crimes, a grocers’ apostrophe – used by grocers rather than an individual grocer. Not that I’ll get much support from Stephen Fry on this subject these days if he’s in one of his ‘anything goes, the language is evolving’ moments.

TRV is an abbreviation or ‘initialism’. An acronym is an abbreviation that forms a name e.g. BOB – bag of bolts.

my pipes bang gently just near the wall of my bedroom every time the heating comes on. And all thanks to the excellent installer way back when who drilled a 15mm or 16mm hole through the joists to accommodate a 15mm copper pipe. I’m guessing that as the pipe expands slightly and tries to move a little through the joist it drags and then moves. ‘bang, tap, tap, tap, tap, bang…’. It eventually settles down. Sometimes just before the heating goes off.

Apologies for not reading all the replies: I had a similar noise which was fixed by smoothing the notch where a pipe went through a joist, and padding it with a cloth.

Bear & slowoldgit thanks for the suggestions to seat the pipes.

Edukator, you are assuming I haven’t added copious amounts of insulation to the loft AS WELL as replacing the rads. Which I have. I have also bought thick curtains to reduce heat loss through the windows. I also considered cavity wall insulation but have decided I need to look a bit more into it.

OH’s dad recommended new rads after how ineffective the old ones were last winter. He used to install the ones that were fitted & reckoned that while they were good in their day, modern rads fitted with convectors are much more effective. As totalshell says above.

And I have tried all 3 pump speed settings. It makes no percievable difference.

Souldrummer – thanks. I have seen sticking ball valves mentioned elsewhere too (& motorized valves) so will be adding those to my list of things to check.

Prettygreenparrot – thank’s for contributing too this thread. You’re grammar lesson & interesting tail about a banging pipe has helped me know end.

new idea!
I’ve had problems with Honeywell TVRs; they are supposed to be bi-directional, but aren’t. lift the floor boards near the offending rad and swap over the flow and return at a joint,or put the valve from vertical to horizontal (or vice versa).

How about insulating under the floor and doing the walls on the inside? The only heating system in the room I’m in is from the TV, amp, computer and strip light; the radiator that was in the room is rusting in the shed.

How much is “copious”? You need 40cm in the roof for “passive house” standards.

chickenman – Member
new idea!
I’ve had problems with Honeywell TVRs; they are supposed to be bi-directional, but aren’t. lift the floor boards near the offending rad and swap over the flow and return at a joint,or put the valve from vertical to horizontal (or vice versa).

Oh! When you say ‘they aren’t’ how does this problem manifest itself? If the TRV is fully open – i.e. rotated to number 6 on the knob, does it not just run as an open valve? Would this cause the problem? I thought the problem with running TRVs in the wrong direction is just when they are closing/opening??
I am not saying you are wrong, but I am just trying to understand how this would cause the problem. As mentioned somewhere above, we have run all radiators with TRVs fully open & also with the two radiators near to where the problem is, fully closed and the problem persisted in both cases.

Edukator – Member
How about insulating under the floor and doing the walls on the inside? The only heating system in the room I’m in is from the TV, amp, computer and strip light; the radiator that was in the room is rusting in the shed.

How much is “copious”? You need 40cm in the roof for “passive house” standards.

Edukator, ideally I would like to add more insulation. When we get round to decorating the rooms, we will consider insulation requirements in turn. But, I am not considering ripping up floors or insulating walls on the inside at the moment; particularly the walls if we end up getting cavity wall insulation.
As I said before, I have read pros and cons about cavity wall insulation and would like to find out more for our particular application before going ahead with it.

With regards to loft insulation, we have a shallow pitched roof and at the extremities of the pitch, I have filled the void completely (while still allowing an adequate ventilation gap). Further in, there is the depth of the joist insulated which was there already, plus an extra 250mm that I have added taking it up to about 320-350mm. There is an area of laid boards that we are using for storage. Originally this extended the full length of the roof, but I have substantially shortened this to only the length I envisage we will need for storage. This area has joist depth insulation and the area that I have decided we will no longer use for storage has had the insulation increased to ~320-350mm depth.
Even with all this insulation though, the pipes are still banging so it’s largely academic!

Stumpy.
I like the cut of your Jib, make a list and check each item one by one. A methodical approach always pays-off in the end with things like this.

Insulation is always a good thing but in this instance totally academic. It wont stop the banging noise.

TRV’s They can still shut even on maximum setting. To discount them remove the heads, then test.

Expansion of the pipes is the most likely cause by far (32 Yrs in the business).

Good luck, keep us posted.

i would disagree with the expanding pipes theory, why did’nt it do it before? only the rads and some wiring have been changed. IMO its most probably air, thats what causes the clanging noise. i would check all the high points in the pipework for air release valves. usually hidden in a loft or above the boiler if the pipes rise from the top. there may be an air release valve on the flow going to the cylinder coil. there may be an automatic air release valve in the boiler itself which has been closed.

do the pipes from the rads go down through the floors, or do they drop from above?

supremebean – Member
i would disagree with the expanding pipes theory, why did’nt it do it before? only the rads and some wiring have been changed. IMO its most probably air, thats what causes the clanging noise. i would check all the high points in the pipework for air release valves. usually hidden in a loft or above the boiler if the pipes rise from the top. there may be an air release valve on the flow going to the cylinder coil. there may be an automatic air release valve in the boiler itself which has been closed.

do the pipes from the rads go down through the floors, or do they drop from above?

Sorry, I missed your post.
I am hoping it’s air to be honest, but it does sound like the same pipes that are causing the noise (airlock, perhaps?).
I understand what you mean about it only being the rads & wiring changes, so why would the pipes start clanging when they weren’t before. My thinking was that the old rads were imperial & the piping to them sized, as such. When we replaced them, we got the closest size radiators we could and my OH’s dad had to do a bit of re-piping etc. to get the new ones to fit.
I wonder if in doing so he has disturbed a pipe that was perhaps not held very well and is now freed up.

I will check for an air release valve. There is not one obviously coming out of the boiler.

All of the rad pipes come up through the floor.

This weekend is going to be fun fun fun!!

You mentioned disturbing the pipe while changing something. I believe that’s what happened to me, with a radiator replaced by a towel rail needing wider spaced pipes. It could have been that the fitter bent the pipe where it passed thru the notch. It was obvious where it had been rubbing, once I got the floorboard up.

With the older rads, maybe the flow was slower and the temp. rise and expansion in the pipes more gradual.

– check boiler stat setting & measure output boiler temp.
– check motorised valve
– check ball cock in roof tank
– look for obvious faults with system; integrity of cylinder stat etc.
– check ‘balance of system’ and adjust if required.
– try ‘purging air’ from radiators as spooky b329 suggested, for the sake of being thorough.
– look for loose pipework.

So then….

We turned the heating off on Friday night & just had the hot water left to come on in the morning. Completely silent on Saturday morning.

– Stupidly I forgot to get a thermocouple from work, so we didn’t have any way to check the boiler outlet temp, but it didn’t seem to be getting too hot & boiling…..
– Motorised valve seems to be working OK.
– Ball cock is working in tank, definitely.
– No ‘obvious’ faults, cylinder stat appears to be fitted well & securely. The water from the taps doesn’t get stupidly hot, so presumably it is working OK. Also found what I think is bleed pipe coming from the cylinder (short vertical pipe tee’d off the cylinder with a knurled copper knob on top). No air came out of this.
– Didn’t get round to checking system balance as I had no means to measure temperature.
– Tried Spooky B329’s method of purging air. It seemed to reveal a couple of things. There was a gurgling, surging noise from a couple of radiators upstairs. But not the ones that we think are causing the problem. The boiler cut-out at one point, even though the thermostat set-point hadn’t been achieved in the living room. I think this is due to the flow being restricted, so the system got too hot. The pump carried to run until the system had cooled a bit and then the boiler lit itself again. Upon opening the valves to the radiators that we thing are causing the problem, there was an almost immediate clonking noise, but there was little/no gurgling or other sound to indicate that air was being purged from the system. Indeed, upon letting the whole lot cool down & putting the rad valves back to normal, I re-bled all the rads and absolutely no air came out.

Next stop is to dig up the floor boards, which I am trying to put off! Gonna have to face it at some time…..