Vaillant 637 Ecotec plus - air bubbles in system

[RK_London]

thanks - will test for hydrogen. Still trying to figure out if this issue is connected to banging pipework near other upstairs bath radiator (banging loud in morning when system goes on but some banging when system in pump overrun). No air in this radiator - lowered power of boiler to 15KW to eliminate any sudden expansion issues. Had an external by pass fitted (even though boiler has internal bypass). Even changed radiator but hasn't made any difference.

 

[ianmcd]

First you have to elimiate hydrogen, if definately not hydrogen then close the cap on the automatic air vent inside the boiler, it is drawing air in from there

 

[RK_London]

thanks ianmcd - will look at the cap on automatic air vent as next step if hydrogen test is negative

 

[ianmcd]

thanks ianmcd - will look at the cap on automatic air vent as next step if hydrogen test is negative

It is simply like a car tyre pressure valve cap , fill and bleed the system then close the cap, all ABV are cheap rubbish and leak or draw air, most experienced pros close them once the system is correctly filled

 

[RK_London]

First hydrogen test was negative. Will repeat tomorrow. To access the valve cap I assume I will need to remove boiler cover - will need to get professional help for that.

 

[RK_London]

Update - gas in radiator not hydrogen. After almost 4 weeks of bleeding no more gas in the radiator so I'm assuming gas was air that just took a while to bleed from system.

But problem now is if all air removed from system not sure what is causing loud banging in another upstairs radiator first thing in the morning. I have to close this radiator in the evening because banging so loud at night and in morning can't sleep.

In the morning just after the heating starts ( flow temp only 28C) I turn the valve on radiator barely 1/16 and I hear 7 or 8 loud bangs before it calms down. Thought this was because of trapped air in the pipes but not so sure now. And during the day hear banging in this radiator during pump over-run - had external by pass fitted but still hear noise in upstairs radiator although rest of house seems better.

Maybe issue is valve on radiator - if I open it too much begins to leak but if open 1/4 turn its ok. But in the mornings when the radiator is shut still hear two bangs around the pipes - first one after 15 mins next one after about 30.

None of this happened before I installed new boiler and pipework not touched. Plumber not sure what is going on. I did have water hammer problems in the offending area and the plumber did half fix it by putting in arrestor upstairs although still get problem because he hasn't got round to putting arrestor in downstairs taps. But can't see this having any connection with radiator banging.

So Plumber stumped - he will replace valve on radiator and put in another arrestor downstairs for water hammer. But he is not sure if this will solve banging problem. I suggested a device to remove any bubbles in system but he is not sure if that makes any difference.

Any thoughts from experts on this site welcome.

 

[Harry Bloomfield]

Maybe issue is valve on radiator - if I open it too much begins to leak but if open 1/4 turn its ok. But in the mornings when the radiator is shut still hear two bangs around the pipes - first one after 15 mins next one after about 30.

None of this happened before I installed new boiler and pipework not touched. Plumber not sure what is going on. I did have water hammer problems in the offending area and the plumber did half fix it by putting in arrestor upstairs although still get problem because he hasn't got round to putting arrestor in downstairs taps. But can't see this having any connection with radiator banging.

Maybe - your new boiler is heating up the system much faster than before and the banging is just the pipes expanding much more suddenly than they previously did. A sudden loud bang has replaced the quieter series of expansion creaks and bangs?

 

[sirocosm]

Here are some sources for noises in pipe work that I can think of:
1) Air in the system.
2) Valves. They can cause banging if they close suddenly, or can even vibrate and make other strange noises. I had one TRV that would make sometimes make a load buzzing sound at a specific setting. Normally a TRV should not close too suddenly, but if it sticking it might, and it could be your new system has more flow.
3) Expansion when heating up. This is usually small creaking sounds, but it can get quite loud.

I find it is usually very hard to tell exactly where the noise is coming from.

 

[RK_London]

thank you for your replies.

Harry Bloomfield - I had the same idea as you. But the boiler power setting has been reduced to 15KW from auto on a 37KW boiler to heat up the house more slowly. Usually takes about 30 minutes now to get to target flow of 60C. Problem I have is when the heating switches on the flow temperature is only about 27C and heats up gently so not sure why a 1/16th turn on a closed radiator when the flow temperature is so low should cause such loud banging. And if it is expansion why does the banging happen all day when the system is warmed up? ( banging usuallly around pump over-run). The flow and return temperature difference is only 4-5C when house gets warm.

sirocosm - I have the same 3 items in my list of possibilities

1) Air in system - I have continuously bled system for over 3 weeks and it is now air free ( from radiators anyway).
2) Took off the tops of the TRVs to make sure it wasn't TRV issue - it wasn't.
3) Expansion - normal expansion expected but why so loud when pipework not touched. Boiler power setting only 15KW - previous boiler was a 28KW Vaillant on auto power setting. That's why I was convinced it was air in pipes but I'm not so sure now.

 

[BlueLoo]

Update - gas in radiator not hydrogen. After almost 4 weeks of bleeding no more gas in the radiator so I'm assuming gas was air that just took a while to bleed from system.

But problem now is if all air removed from system not sure what is causing loud banging in another upstairs radiator first thing in the morning. I have to close this radiator in the evening because banging so loud at night and in morning can't sleep.

In the morning just after the heating starts ( flow temp only 28C) I turn the valve on radiator barely 1/16 and I hear 7 or 8 loud bangs before it calms down. Thought this was because of trapped air in the pipes but not so sure now. And during the day hear banging in this radiator during pump over-run - had external by pass fitted but still hear noise in upstairs radiator although rest of house seems better.

Maybe issue is valve on radiator - if I open it too much begins to leak but if open 1/4 turn its ok. But in the mornings when the radiator is shut still hear two bangs around the pipes - first one after 15 mins next one after about 30.

None of this happened before I installed new boiler and pipework not touched. Plumber not sure what is going on. I did have water hammer problems in the offending area and the plumber did half fix it by putting in arrestor upstairs although still get problem because he hasn't got round to putting arrestor in downstairs taps. But can't see this having any connection with radiator banging.

So Plumber stumped - he will replace valve on radiator and put in another arrestor downstairs for water hammer. But he is not sure if this will solve banging problem. I suggested a device to remove any bubbles in system but he is not sure if that makes any difference.

Any thoughts from experts on this site welcome.

TRV valves are buggered?

 

[RK_London]

Noisy radiator is in the bathroom doesn't have a TRV - its a pegler valve.

 

[sirocosm]

Any chance you could post audio? I am not an expert, so I doubt I will be able to tell what it is from hearing it, but someone else might.

 

[RK_London]

I was also thinking about posting audio - will record and try to post on here

 

[RK_London]

Here's a recording of the noise in link below
https://www.dropbox.com/s/abd3p56poxub4s3/Bath Radiator- Turning on in morning.m4a?dl=0

 

[DP]

Thank you again for you replies. I never had this issue with my previous two boilers and I have lived in this house with the same pipework for almost 25 years. There is a possibility the boiler is the issue. I have just got my guarantee through after two years - plumber forgot to register the boiler so kicked up a fuss and finally got it a few months ago and was able to get a Vaillant engineer out but he refused to touch boiler because flue was incorrectly installed.

I agree with you BlueLoo- not sure how boiler can generate air that's why I was asking some expert engineer on here. I don't keep topping up because not much water escapes when I bleed radiator each night. I keep an eye on the pressure and it is always around 1-1.1 KBar when cold.

Corrosion is a possibility. As you said I am starting from scratch to try to figure air and banging problem (in other pipes/radiator) as the plumber not sure what to do and although he is a nice guy his performance hasn't been great. Someone on this site mentioned a device to remove air bubbles in system (Spirovent) but trying to understand how system generates air in first place. Maybe it is just corrosion in which case system needs a proper clean.

Boiler will not be creating air as internal pump has a auto air vent on it*
You have fitted new vertical radiators, turn these off and see if air issue persists
Series 6 and series 4 Vaillant’s are nit the same, your boiler is for sealed system and series 4 is open vented and both these boiler have heat exchanger with high internal resistance
A filter does not need to know how boiler works, a misstep can creates issues like you have found
Internal bypass in the vaillant is quite robust
You are running the boiler at 15Kw- that would amount to a system with 10 radiators ( approximation) and no cylinder unless cylinder is ancient non insulated


*Series 4 vaillant can either work as open vented or be a sealed system. As open vented, if pipe configuration is incorrect, air will be pulled in from the open vent.
Your boiler is a sealed system. To overcome high internal boiler resistance the pump runs at higher power. If you have old radiator valves, it is not unusual for pump to suck in micro air bubbles through the worn valve stems or poor joints.
At neutral point in the system, one Often gets air in the radiator
Some vertical radiators break down the water to create airlock you are experiencing. This is common with bathroom towel rail types.