Central Heating Air Build Up and Cylinder popping noises

[samba1]

Hi Guys,

Been having a real saga and head scratching situation.

I originally had 1 problem, and now 2.

Original issue: Air being built up in rads. Having to bleed every other day if not daily. All upstairs rads getting air, and one downstairs in utility room, same room as boiler and not far from airing cupboard.

No evidence of a leak, used thermal camera and not able to see any leaks. All pipes are copper and are in walls (house built in 1997, so no pipework under floor on ground level) micro bore pipes upstairs, and some downstairs. No wet carpets, or wet walls, Only one small section of pipes buried under concrete which is in conservatory (done over 15 years ago), which I ensured were wrapped around (using an old hose pipe to prevent concrete making contact with copper pipes.

Have had a new boiler (ideal logic H24), new pump (Grunfoss UPS3) and now a new hot water cylinder (Gledhill indirect unvented stainless lite plus) along with new expansion vessel and combination valve, however I’m still getting air in rads. The central heating is fed by an F/E in loft, I have seen it drop water level, by about 10mm height but I cannot be certain if that’s merely expansion and contraction, and/or evaporation related.

British Gas replaced the pump, tried to T the F/E pipes thinking it may be drawing air in, but no joy, now replaced the cylinder thinking maybe that might be the cause, but no joy. I have tried to suggest they do a gas test on the central heating, but seem reluctant… no idea why as that would be my first port of call, but instead they replaced a hot water cylinder. So any thoughts how to figure this issue out? The hot water is mains pressured.

Then now there’s the 2nd issue (caused by this troubleshooting effort by British Gas/Dyno). The new cylinder is made by Gledhill (indirect unvented) and comes with a 19l Zilmet expansion vessel, and a Reliance Combination Valve. All configured and checked to 3bar, and cold mains pressure entering the house is reduced to 3bar to balance the cold and hot supply. When the hot water is used you can hear the water flowing very loudly from around the combination valve, like an aircraft. Also, periodically you hear loud popping noises from the airing cupboard (when the hot water is being used), almost like cylinder is imploding like when a coke can or plastic bottle contracts and expands… is it possible for this to happen on a cylinder, or is the noise possibly from the expansion vessel or combination valve? When it makes a loud pop, it does feel like it’s the cylinder, but I could be wrong, Dyno installed the cylinder and they’re asking Gledhill for support, but I feel that I’m going to get fobbed off, saying it’s normal etc etc. The only reason the cylinder was replaced was because they suspected the air in rads was the cylinder. We had no issues with the old Tribune Premier cylinder, old expansion vessel or the valves. So I have 2 issues now, air in rads, and noises airing cupboard where hot water usage causes unacceptable flow noises and loud popping noises.

#1. Any thoughts how air could be getting into rads? Some of my rads do have white deposits around the blanking and venting plugs.

#2. Any thoughts on the water flow noises and popping noises in the airing cupboard? Is the valve likely to be faulty, or maybe the pipework, and could the cylinder have a dimple inside that is popping in and out as the hot water is being used, or a noises diaphragm in the expansion vessel, or a sticking combination valve?

I have posted a video of water flow noise (might need to increase volume to hear), the initial clicking noise you hear on video is not the loud popping noise, I haven’t been able to get a video of that, just too difficult to be there recording just before it happens).

My knowledge of plumbing is near zero, but I have self learned at lot in the last few weeks! But now I’m at a loss, and feel like that I’m going to get fobbed off by BG/Dyno.

Any suggestions you guys have I’m willing to try….

Thanks!

 

[Ric2013]

Not quite sure I follow the logic of replacing the cylinder either, to be fair.

 

[samba1]

Not quite sure I follow the logic of replacing the cylinder either, to be fair.

Me neither! I was flummoxed too! They said that’s the only component not changed, so worth doing. It was covered as part of my homecare cover so I was willing to go along with anything they suggested if it would cure the rads pulling air in…it hasn’t and now I have more problems!!

 

[ShaunCorbs]

Could be corrosion eg hydrogen

 

[EvilDrPorkChop]

Are your pipes copper or plastic to the rads?

Also i'd consider the sealing the system rather than leaving Open Vent. Sounds like it's drawing air in.

 

[John.g]

Sounds like drawing air in alright, also check setting on UPS 3, if its on constant curve 2 or 3, almost guaranteed to pull in air, would suggest (constant pressure) CP1 which is a 3M setting, if still drawing in air at this setting then look elsewhere or seal/semiseal it.

 

[samba1]

Could be corrosion eg hydrogen

Yeah, I’m a little nervous putting a flame to check when bleeding .. perhaps I ought to try it…

 

[ShaunCorbs]

Yeah, I’m a little nervous putting a flame to check when bleeding .. perhaps I ought to try it…

Use two cups and put it external / garage and use a long poker etc

 

[samba1]

Sounds like drawing air in alright, also check setting on UPS 3, if its on constant curve 2 or 3, almost guaranteed to pull in air, would suggest (constant pressure) CP1 which is a 3M setting, if still drawing in air at this setting then look elsewhere or seal/semiseal it.

It’s on constant curve 1 - had the same thoughts. When the pump kicks in you hear air moving into the upstairs rads, a little gurgle, over time builds up to a fair bit. I have 18 rads, wondering if one or two maybe pulling air in as the rads cool, a small enough gap in the connections to pull air in but not leak?

 

[samba1]

Use two cups and put it external / garage and use a long poker etc

Ok, I’m a little thick, I know hydrogen is lighter than air, how do I get the gas into the cups? Simply hold upside down while venting?

 

[samba1]

Are your pipes copper or plastic to the rads?

Also i'd consider the sealing the system rather than leaving Open Vent. Sounds like it's drawing air in.

Copper pipes, mainly micro bore…is it possible there is a “microscopic” leak which only draws air but not leak? Is that something you experts have previously experienced?

 

[nomad5]

Unless the cleaner and inhibitor were done through a towel rail or radiator I would suggest that the system has not been cleaned properly in the first place or even the inhibitor. Like most companies just putting cleaner in the FE tank and not draining off anything to get it in the system does not work same has inhibitor. Your system is full of crap by the sound it. Take a sample from the drain off point take the first bit and look at it, and I know you should be looking at the second sample. what comes out when you vent rads ? Black ?

 

[John.g]

It’s on constant curve 1 - had the same thoughts. When the pump kicks in you hear air moving into the upstairs rads, a little gurgle, over time builds up to a fair bit. I have 18 rads, wondering if one or two maybe pulling air in as the rads cool, a small enough gap in the connections to pull air in but not leak?

Go up to the attic and get somebody to start the pump, see if any dribble from the vent or movement in the F&E tank, watch again for similar signs when the pump stops, repeat after c/o to CP1.
Systems with the pump mounted high up in the hot press and close to any motorized valves are more prone to air ingress.
Is the cold feed teed to the vent in the form of a H, or preferably, teed in high up adjacent to the F&E tank?.

 

[ShaunCorbs]

Yes

 

[samba1]

Unless the cleaner and inhibitor were done through a towel rail or radiator I would suggest that the system has not been cleaned properly in the first place or even the inhibitor. Like most companies just putting cleaner in the FE tank and not draining off anything to get it in the system does not work same has inhibitor. Your system is full of crap by the sound it. Take a sample from the drain off point take the first bit and look at it, and I know you should be looking at the second sample. what comes out when you vent rads ? Black ?

I was a little suspect of inhibitor being low or even absent with all the messing about BG have done, the water in the rads is crystal clear when venting and all rads heat up very well, no cold spots (apart from the tops where air builds up)… I’d expect some yellowness if it had inhibitor. I will press BG to do a inhibitor test, they seem to be more focused in changing things rather than doing a proper diagnosis.

 

[samba1]

Go up to the attic and get somebody to start the pump, see if any dribble from the vent or movement in the F&E tank, watch again for similar signs when the pump stops, repeat after c/o to CP1.
Systems with the pump mounted high up in the hot press and close to any motorized valves are more prone to air ingress.
Is the cold feed teed to the vent in the form of a H, or preferably, teed in high up adjacent to the F&E tank?.

 

[samba1]

Yes, did a similar test with Dyno yesterday. He went up in loft, got me to start and stop the pump a number of times, and open and close valves. He said he got water coming out of the expansion pipe. Vent and feed is H configuration, though BG did T them to eliminate air being drawn in from the expansion pipe. Had it in T for 2 weeks and still got air in, so it was restored back to original configuration.

Will try CP 1 test though… but am I reading your post correctly, can motorised valves pull air in? It’s an area I’ve not looked at (nor BG or Dyno).

Totally flummoxed!

 

[John.g]

Don't think that M.valves will pull in air, its just that the pump is so close to them that I feel unless they are open when the pump starts/stops that the water then finds it easier to shoot up the vent. Also the H is in a dynamic part of the system, mine is mounted right up at the F&E tank so in a static part of the system but my circ pump is downstairs pumping into the boiler which probably helps as well.

You could blank the cold feed off at the T and tee it in like mine under the F&E tank so you then have a combined vent & cold feed, no guarantee of course that this will work even though mine has for the past nearly half a century, but if handy yourself well worth consideration I think but sealing the system might be nearly as easy except you have worries regarding pipework etc with the higher pressures.