Central Heating Pipe Noise

[arun30]

Hi

We live in a town house (three story - Ground, first and second floor).

We were using Warm Air Unit (WAU) for central heating. We recently removed it and installed vaillant combi boiler (vaillant ecotec exclusive green iq 843). This boiler is installed in loft (technically third floor). The radiators / pipes and everything is new (as WAU runs with ducting and blows hot air).

Since the boiler is installed, we hear pipe rumbling noise whenever we turn the heating on.

The boiler engineer said that
1. It was due to air in the system. So he bled the system and tried again, but no luck.
2. He then looked for any leak - but there is no visible leak
3. He then added pipe insulation as he thought the pipes were bruising each other - but no luck
4. He then installed automatic air vent - but no luck
5. He then installed air separator RV2 (SpiroVent RV2)- but no luck
6. He then used Sentinel x200 chemical - but no luck
7. He is now thinking that the boiler is not able to pump enough as its in loft (3rd floor) and this might build up the air on the system. Therefore he now thinks that installing additional water circulation pump between 1st and Ground floor might help the boiler to push the air through return pipe.

Apart from air rumbling noise,
1. When the boiler is running I can hear water discharging on the right most while waste pipe under the boiler (is it called condensate pipe).

2. We have also noticed that the boiler pressure rapidly increases when the heating is switched on. After few days the boiler goes to low pressure and switches off (as it might be discharging the water through outflow pipe).

3. Most importantly; Once we flush out the system, remove all the air, pressure the system again and switch on the heating - Bang! the rumbling noise!!! How can the air enter the system that quickly.

4. I googled and found something about vessel pressurising - but the engineer thinks that its a new boiler and this shouldn't be the case.

This has been a nightmare. We spent lot of money to move away from WAU an installed this boiler. I'm tired of bleeding the radiators for every 2 days.

Any help / thoughts will really be a life saver for us.

Thank you in advance.

 

[ServiceNumpty]

Is it pipework creaking. When you bleed the radiators do you get air or water out of the air vent.

 

[arun30]

Is it pipework creaking. When you bleed the radiators do you get air or water out of the air vent.

Hi

Yes, the pipework which are installed under floor board (between 2nd & 1st floor and 1st floor and G floor) are creaking.

Some of the radiators bleed air for few secs and then the water comes out.

What makes me to wonder is, every time the engineer flushes out the system, pressurise it again and switching the heating on, the noise starts straight away. We really don't know, at what time the air gets into the system. Please also see my other concern where the pressure increases rapidly when the heating is on

 

[ianmcd]

just because a boiler is new does not mean that the expansion vessel is properly charged, how many radiators do you have ?

 

[arun30]

just because a boiler is new does not mean that the expansion vessel is properly charged, how many radiators do you have ?

Hi
Total radiators : 11 ( including 2 towel radiator)

 

[durhamplumber]

We live in a town house (three story - Ground, first and second floor).

Pleased you pointed that out,,,would never have guessed

 

[ianmcd]

Hi
Total radiators : 11 ( including 2 towel radiator)

your boiler has a 10L expansion vessel , set your boiler pressure at 1.5Bar cold then put the heating on and check the pressure again after 20 mins it should not rise by much , it will rise as the water heats, if it goes up near 3 Bar then you have an expansion problem, either the existing one or dependent on your rad sizes you may need an additional external expansion vessel

 

[arun30]

your boiler has a 10L expansion vessel , set your boiler pressure at 1.5Bar cold then put the heating on and check the pressure again after 20 mins it should not rise by much , it will rise as the water heats, if it goes up near 3 Bar then you have an expansion problem, either the existing one or dependent on your rad sizes you may need an additional external expansion vessel

Thanks for your reply.

He has balanced the boiler today, i.e. reduced the thermostat level in second and first floor. And set the ground floor radiators to maximum.He also reduced the pump speed on the boiler.

Since then I can see the boiler holding up the pressure, however the air still rumbling in all the pipes. We are unable to get rid of them. He drains the system and fills it again, but the air is coming along when he pressurise the boiler.

 

[arun30]

just because a boiler is new does not mean that the expansion vessel is properly charged, how many radiators do you have ?

Thats the list of radiators we have.

BTU
Second Floor
Radiator1: 9727
Radiator2: 6532
Radiator3: 7186
First Floor
Radiator1: 5836
Radiator2: 11345
Radiator3: 3404
Ground Floor
Radiator1: 10452
Radiator2: 5350
Radiator3: 6532

 

[oldbutnotdead]

Creaking happens when the (copper) pipes expand as they warm up- if they're not wedged tightly into joist notches/holes then it is barely audible, if there's no clearance at notches/right angle bends etc then it'll be more noticeable (series of quite sharp cracks). As far as I know plastic doesn't creak so sounds as if your installer has gone old school with copper (hurrah).
Air trapped or getting into the system- if your new pipework has some high spots in it then you may have some persistent air pockets which will take ages to clear (if ever). Can be worth bleeding for a long time- ideally take the bleed valve out so there's good water velocity, have a friend at the pressurising loop keeping the system pressure up to whatever it should be and have a bit of hosepipe to jam over the bleed valve hole to stop it getting too messy (run the pump cold if you can, it hurts less when you're trying to get the valve back in!)

 

[arun30]

Creaking happens when the (copper) pipes expand as they warm up- if they're not wedged tightly into joist notches/holes then it is barely audible, if there's no clearance at notches/right angle bends etc then it'll be more noticeable (series of quite sharp cracks). As far as I know plastic doesn't creak so sounds as if your installer has gone old school with copper (hurrah).
Air trapped or getting into the system- if your new pipework has some high spots in it then you may have some persistent air pockets which will take ages to clear (if ever). Can be worth bleeding for a long time- ideally take the bleed valve out so there's good water velocity, have a friend at the pressurising loop keeping the system pressure up to whatever it should be and have a bit of hosepipe to jam over the bleed valve hole to stop it getting too messy (run the pump cold if you can, it hurts less when you're trying to get the valve back in!)

Thanks for your suggestions. I will bleed the radiators for long time as you suggested.

We hear lot of noise when they warm up (as u said) and again when we switch off the boiler. We inspected all the pipes and can confirm that they are not shaking and they are tightly wedged into the joist.

Sorry, am not too technical, but may I ask few questions from your response.

"if there's no clearance at notches/right angle bends" - what does 'no clearance' mean. I can see lot of bends in the pipe work - should I look for something specific with right angle bend.

"As far as I know plastic doesn't creak" - do you mean using plastic clip to secure copper pipes?

"if your new pipework has some high spots" - what does high spots mean.

Thanks again for all your inputs and hoping for a response.

 

[oldbutnotdead]

Thanks for your suggestions. I will bleed the radiators for long time as you suggested.

We hear lot of noise when they warm up (as u said) and again when we switch off the boiler. We inspected all the pipes and can confirm that they are not shaking and they are tightly wedged into the joist.

Sorry, am not too technical, but may I ask few questions from your response.

"if there's no clearance at notches/right angle bends" - what does 'no clearance' mean. I can see lot of bends in the pipe work - should I look for something specific with right angle bend.

That's part of the noise problem then. Copper expands and contracts quite a lot with temperature (about a millimetre per metre when heating from 10 degrees to 60 degrees). If there is room for the pipe to move then the only noise will be a quiet ticking from the actual metal expanding/contracting- in your case since the pipes are wedged into the joists you're getting a buildup of energy as the pipe tries to expand, eventually the expansion force overcomes the friction between copper and timber and you get some loud creaking noises. Solution- open up the notches a bit (one of those electric multitools from Lidl/Aldi is perfect). Where pipes bend through 90 degrees- if the tail of the bend is tight in a notch (or a clip) then it limits movement not just of the bit in the notch but also the long run preceding the bend (eg where there is a long feed between joists then bent up at 90 degrees to meet a radiator. ) Again, makes sure there is a bit of room for the tube to move.

"As far as I know plastic doesn't creak" - do you mean using plastic clip to secure copper pipes?

No I mean plastic barrier pipe as used in many modern heating installations. Placcie does expand and contract quite a lot but because it is flexible you don't get the same sound effects. Plastic pipe clips on copper pipes can cause the creaking (they are very tight so friction as detailed above comes into play)

"if your new pipework has some high spots" - what does high spots mean.

If there are sections of your pipework that run uphill and then downhill (to get over an RSJ for instance) then you have a high spot. You nearly always end up getting air in the pipework somewhere when you fill the system- in a well designed system any uphill legs will lead to a radiator or (I've done this myself) a bleed valve in the pipework itself (because there was no way to get pipes through that bit of the house without having an uphill-downhill section).

Thanks again for all your inputs and hoping for a response.

 

[arun30]

If there are sections of your pipework that run uphill and then downhill (to get over an RSJ for instance) then you have a high spot. You nearly always end up getting air in the pipework somewhere when you fill the system- in a well designed system any uphill legs will lead to a radiator or (I've done this myself) a bleed valve in the pipework itself (because there was no way to get pipes through that bit of the house without having an uphill-downhill section).

Thanks again for your detailed explanation.

Having monitored the pipes for a week now; its definitely the sound of air rushing through (or trapped in bends and not able to flow through). I did an extensive bleeding process. I had my friend in loft and I started from G floor and bled the radiators one by one while he was pressuring the system in order to finish bleeding for all the radiators.

I then slowly pressurised the boiler and switched it on - Hell! its the same noise of air travelling through the pipes.

As you said - yes, the flow pipe comes from boiler in loft, goes to all the radiators in 2nd floor one by one, and then comes to first floor (where the noise is heard all the time), covers the radiators one by one, goes to G floor and then the return pipe goes to loft.

Am really on dead end here. One good thing is (touch wood!); the pressure is now set to 1.0 and it goes to 2.2 when the heating is on, but not reaching 3.0 which is max.

 

[arun30]

The pressure was set to 1.0 after I bled all the radiators. The boiler held the pressure for 2 days, but it now dropped to 0.9.

 

[oldbutnotdead]

Nothing wrong with having the boiler in the loft (as long as there's some way of bleeding the heat exchanger- since it is the highest point in the system air will bubble up into it. Problem may be that if it is designed to be self-bleeding then that feature may not be working for some reason, if it has to be done manually then it would probably need removal of sealed bits of casing which us mortals aren't allowed to do).
If pressure is now only coming up to 2.2 then you've shifted some air for certain.
Give it a week to let air move around the system (hopefully it'll work its way into radiators) then try bleeding again. Sometimes worth bleeding with the lockshield closed/main valve open and then bleeding again with lockshield open/main valve closed (if the system has been balanced, make a note of how many turns it takes to close each lockshield then open it back to that many turns). If you can bleed with a high flow rate you have a better chance of flushing air pockets through the pipework. If you have modern radiators (with the largeish fitting holes at the radiator tops as well as at the bottom) then a handy way to do this is;

• Buy yourself one of these https://www.toolstation.com/rigid-radiator-valve-extension/p86447, one of these https://www.toolstation.com/washing-machine-tap-straight/p76890, one of these https://www.toolstation.com/washing-machine-hose/p71370 and a roll of this https://www.toolstation.com/ptfe-tape/p67236 (other suppliers are available)
• Buy a bucket and an adjustable spanner or medium pipe wrench if you don't already own one
• Fit the washing machine tap to the end of the rad valve extension

Now what to do with them all

1. Starting at the ground floor (probably), select a radiator.
2. Switch BOTH valves OFF (again count how many turns to close the lockshield so you don't stuff up the system balancing)
3. Bleed the radiator til nothing is coming out of the bleed valve (this is just to depressurise the radiator), close the bleed valve.
4. Remove one of the inserts at the top of the radiator (they're usually chrome, one will have the bleed valve in, the other will be blank. If you have a spirit level, remove the one at the highest end of the radiator- it should be the bleed valve one but best to check if you can.
5. Insert your pipe assembly, threaded end first, into the hole, wind it all the way in
6. Switch the washing machine tap OFF
7. Fit the washing machine pipe to the washing machine tap, make sure the other end of the pipe is in the bucket (you might want a brick in the bucket on top of the pipe to stop it flying out when you do the next bit)
8. Fully open the LOCKSHIELD valve ONLY (your new assembly may weep a bit, don't worry if it does. If it starts getting out of control then close lockshield, open washing machine valve, depressurise radiator, remove pipe assembly, wrap 3 or 4 turns of PTFE round the thread then repeat from step 5)
9. Get your friend to open the filling loop, you open the washing machine tap and let about 10 litres run through. Hopefully you'll get some air and some spluttering.
10. Close the washing machine tap
11. Close the lockshield
12. Close the filling loop (when normal pressure achieved)
13. Open the other radiator valve FULLY
14. Get your friend to open the filling loop, you open the washing machine tap and let about 10 litres run through. Hopefully you'll get some air and some spluttering.
15. Close washing machine tap
16. Close the other rad valve
17. Close the filling loop (when normal pressure achieved
18. Open the washing machine valve (depressurise), wait til nothing comes out
19. Remove pipe assembly and any remnants of PTFE tape in the threads in the radiator
20. Replace radiator insert (don't overtighten, make sure the O ring doesn't nip)
21. Open lockshield to recorded number of turns
22. Open main valve
23. Bleed rad (some air will have got in while you were swapping pipework)
24. On to the next radiator

Once you've done this, you'll need to top the system up with inhibitor- if you have a mixing pot in the system then use that, otherwise you'll have to part drain the last radiator (thin bit of flexible pipe through the top entry and down into the innards, syphon) then add probably a litre of inhibitor.

Have fun