Gurgling and air in central heating

[jim843]

Looks like that but really you shouldn't be getting any air anywhere now IF that is/was the problem, did you or someone say that air might be getting in where the electric heating element is screwed into it?, you might be able to rejoint that.

I said there is a T piece with an electric element. I wondered if the rubber seals could be letting air in?

 

[jim843]

@John.g and @Ric2013 do you think the seals could be the cause?

 

[ShaunCorbs]

Could be corrosion cheap towel rads are know for it

 

[jim843]

Could be corrosion cheap towel rads are know for it

Happy to replace it to rule it out.

What’s the definition of cheap? Can you recommend a good brand?

I did notice that all other rads were fairly clean. The towel rail is coated in black and has bits of black sludge.

 

[Ric2013]

@John.g and @Ric2013 do you think the seals could be the cause?

Well, I like the fact that you're working on ruling that out, I suppose. They could be a weak point, and if the towel rail is running under negative pressure (which the jury is still out on) they could be the point of entry.

 

[jim843]

Well, I like the fact that you're working on ruling that out, I suppose. They could be a weak point, and if the towel rail is running under negative pressure (which the jury is still out on) they could be the point of entry.

I’m not sure how the rad is running under negative pressure?

I do know that if I isolate the towel rail and bleed it for a while it seems to be full of air. If I bleed I’ll get a blast of air, then water, then air. It’ll gurgle and finally lose pressure and the water level in the rad is way below the top of the rad.

If this rad was drawing in air or rusting, surely it would do the same while isolated and running on the electric element?

Happy to replace it but would like to rule it out. The pipes are in the wall so a replacement would mean a bit of smashing out. Would rather avoid if unnecessary.

 

[Ric2013]

The towel rail will not be running negative while isolated (assuming you are isolating both sides...?). If the pressure is only negative at certain times (could happen only on pump start up), it might be hard to see the negative pressure. I'm not entirely convinced the towel rail IS under negative pressure, though, so that's why I like the fact that you are testing it!

 

[jim843]

Happy New Year all!

I didn't get around to replacing the towel rail before Christmas. The towel rail was rapidly filling with air. About 1 bar on the towel rail each day would become cold. I added a couple bottles of inhibitor to the towel radiator as I was concerned that the system was running low.

I got Baxi out and the engineer gave yet another opinion! He said that air in the system would take years to work its way out of the system. I was a bit suspicious as I've never heard this before. He said let the air fill up, bleed it in a few months, don't worry about it, there's no leak.

Anyway, in the run up to New Year about half the towel rail was cold.

At 7am on New Year's Day, I noticed water on a bedroom ceiling. I went into the loft, opened the hatch in the dwarf wall and could see that a speedfit elbow had leaked.

Now, the pipework above behind the dwarf wall was probably the height of the radiator in the loft. What I mean is that this is the highest pipework in the house, nearly level with the top of the radiator. I trimmed the speedfit down a bit so it's roughly level with the bottom of the radiator and replaced the elbow.

Since then the towel rail has been red-hot. I've heard no gurgling. It's been six days.

Could it be that this elbow at the top of the house was somehow pulling in air?

 

[John.g]

Is this pipework part of the primary system? if so then could certainly cause your problem.

 

[Ric2013]

Sounds a plausible reason. Air is more likely to enter at the highest point. 'Years to get the air out'?. Heck of a lot of air, though, isn't it?