Gurgling and air in central heating

[jim843]

My thinking on this, especially in view of the above ongoing air ingress is that negative pressure is NOT required, and that with any slight leak, even a weep, that air finds it far easier to gain access than for the water to seep out?. Maybe not quite alalogous to oxygen gaining access through "solid" plastic (non barrier) piping, who would have believed that but it does happen.

There was a good post on here a few years ago from someone (plumber) who had experience of two houses, one sealed, the other OV, where both had lengths of non barrier piping, the sealed one kept getting air problems but the OV one didn't, he put this down to the fact that the OV one could constantly vent any air continuously through its 22mm vent.
I think I may have a few lengths of non barrier piping in my loft area which has two rads but again never ever get air problems probably because of the OV system?.

So this means the problem could be anywhere, right?

I’ll do what I can do find the problem but short of ripping out pipe work on 3 floors I may never find it.

If the auto air vents work on the towel rail, is this equivalent to an OV system? At least air makes it’s way out of the system?

 

[John.g]

Yes, I think it could be, but if you fix the obvious ones and give the system a thorough cleaning then would think that you will be OK.
I wouldn't compare auto vents with a OV as the auto vent tends to operate more on/off and I certainly wouldn't dream of using them as a cure by installing them on all rads, maybe OK on your towel rad as a temporary measure, remember there was a magic Aladdin lamp but not ditto for Aladdin's auto air vents.

 

[SJB060685]

Can I just say that you have mentioned replacing lots of pipework at least twice and I have never agreed with you, I am not suggesting that. If air is being drawn in then it will be coming from a weak fitting somewhere

 

[jim843]

Can I just say that you have mentioned replacing lots of pipework at least twice and I have never agreed with you, I am not suggesting that. If air is being drawn in then it will be coming from a weak fitting somewhere

ok, so in your opinion it’s a weak fitting. That’s a relief somewhat!

I guess I’m going to “worst case“ scenario which is lift up floorboards and smash out a couple walls!

I may try and find a local heating engineer to do this. I’ve struggled in the past to find anyone reputable.

 

[jim843]

@SJB060685 haven’t had much luck getting an engineer along.

Spoke to a bloke this afternoon who said I’ve either got a leak or the cold water supply is somehow feeding into the system. I said I removed the filling loop and he suggested that the cold water supply is somehow piped into the heating. I don’t see how this is possible!

I need to isolate a couple rads this week to see if they are the source of the problem.

 

[jim843]

@SJB060685 and @John.g struggling to find the time (or a heating engineer!) to deal with the system.

There is a new sound today, though: a whistle/whine from the boiler!

HW was running at the time.

 

[John.g]

Presume there was no noise before with DHW on?. Can you shut down the boiler and just open the same "hot" tap the same amount and see if noise is gone, this may at least prove that the noise is from the primary side.

 

[jim843]

Presume there was no noise before with DHW on?. Can you shut down the boiler and just open the same "hot" tap the same amount and see if noise is gone, this may at least prove that the noise is from the primary side.

What do you mean by shut down? CH off and HW Only?

 

[John.g]

Shut off both CH & HW (or switch off the boiler completely) and open the hot tap, this will just run cold water (now) through the combi and see if noise is gone.

 

[jim843]

Shut off both CH & HW (or switch off the boiler completely) and open the hot tap, this will just run cold water (now) through the combi and see if noise is gone.

@John.g sorry for the delay.

I ran the hot water with everything on. There was the whistling noise.

While the water was running, I switched the boiler off entirely. The whistling sound was still there.

What does this mean?

 

[Deleted member 123817]

If you were still running the cold water through the combi (hot water tap open) tht em the whistling is caused by this and not the primary water (dirty water).
So don't really know what it means in the context of air in your rads etc.

Can't post on my Windows10 laptop for some reason or other.

 

[John.g]

If you were still running the cold water through the combi (hot water tap open) tht em the whistling is caused by this and not the primary water (dirty water).
So don't really know what it means in the context of air in your rads etc.

Can't post on my Windows10 laptop for some reason or other.

If you were still running the cold water through the combi (hot water tap open) tht em the whistling is caused by this and not the primary water (dirty water).
So don't really know what it means in the context of air in your rads etc.

Can't post on my Windows10 laptop for some reason or other.

Have you blanked off that leaking non return valve.

Also just to be sure (again) did you say that with the boiler (&circ pump) ON that you are getting water out of all the rad vents apart from towel rail which emits air initially, does the towel rail also emit water eventually with the boiler/circ pump on?.

 

[jim843]

Have you blanked off that leaking non return valve.

Also just to be sure (again) did you say that with the boiler (&circ pump) ON that you are getting water out of all the rad vents apart from towel rail which emits air initially, does the towel rail also emit water eventually with the boiler/circ pump on?.

@John.g I got a new filling loop and attached one of the isolation switches like this:

When I removed the old filling loop it still had some water in despite not being used for weeks (if not months).

I then switched on the CH system and went round all 9 rads in the house.

Every rad bled water apart from two. The rad in my son's room bled a little air, then water. The towel rail in the bathroom bled quite a bit of air (as usual) and then bled water.

 

[John.g]

Can shut off that towel rad "permanently" for a few days and see does the air appear somewhere else and if noise subsides?.

 

[jim843]

Can shut off that towel rad "permanently" for a few days and see does the air appear somewhere else and if noise subsides?.

I can but we had the same problem before this towel rail was installed. The air just appeared in one of the top floor rads.

I haven’t heard the gurgling for a while now. Just air.

 

[jim843]

@John.g have isolated towel rail and will rely on the electric element for a bit.

I checked the rad in my sons room and there was a little bit of air in that one too.

I also completely turned off rad in the other bedroom after someone said the joint looked like a bodge job.

Will check back in a few days.

 

[jim843]

Can shut off that towel rad "permanently" for a few days and see does the air appear somewhere else and if noise subsides?.

@John.g I isolated the towel rail for 3 days. Switched on the electric element.

On day 1 there was a tiny bit of air in the rad in my sons room. No air in any other rad.

On day 2 and day 3 there was no air in any rad.

On day 3 I checked the towel rail. There was a bit of air in there but not loads.

I opened up the rad valves last night. I checked this morning and there was a bit of air in it again.

So I’m thinking there’s two possibilities:

1. The towel rad valves are cheap/somehow letting in air? This needs refitting.

2. The pipe work before the towel rad is filling up with air.

Which is more likely? With the rad shut off, if there was air getting in elsewhere in the system, would you expect the air to end up in another rad?

 

[John.g]

Wouldn't be surprised at a bit of air in towel rad with element on.
Would suggest repeating test.
isolate the towel rail with the electric element off and the bodge rad off for a few days.
if no air, open up the bodge rad and if still no air after a few more days reopen the towel rail. If you then get air its the towel rail that's the culprit.

 

[jim843]

Wouldn't be surprised at a bit of air in towel rad with element on.
Would suggest repeating test.
isolate the towel rail with the electric element off and the bodge rad off for a few days.
if no air, open up the bodge rad and if still no air after a few more days reopen the towel rail. If you then get air its the towel rail that's the culprit.

Ok, just so I’m clear…

Isolate rad via valves. Leave heating element off. Leave rad for a few days.

After a few days, check if there’s air in the rad.

After a few more days, reconnect rad via valves. If there’s air then the radiator is causing air?

 

[Deleted member 123817]

OK, maybe slightly different method but either way you want to establish if either or both the towel rail &/or the sons rad are the cause of the air.
Shut towel rail isolating valves off both sides then open air vent to ensure valves are tight and not passing. Leave or shut off the electric heating element. After a few days if no air anywhere then towel rail is the culprit, If still getting air shut off the sons rad both sides, if still getting air then problem probebly caused by weeping pipes?

 

[jim843]

OK, maybe slightly different method but either way you want to establish if either or both the towel rail &/or the sons rad are the cause of the air.
Shut towel rail isolating valves off both sides then open air vent to ensure valves are tight and not passing. Leave or shut off the electric heating element. After a few days if no air anywhere then towel rail is the culprit, If still getting air shut off the sons rad both sides, if still getting air then problem probebly caused by weeping pipes?

Ok, I’ve just switched off the isolating valves on the rad. I bled the radiator for quite a while and there was a lot of water then air then water then air. It took a few mins for that to finally loose pressure entirely.

I took the bleed valve off entirely and topped up the rad with 300ml of cold water.

I then opened the isolation valve for a split second to re pressurise the rad. I bled it again for a few seconds. I think this means the rad is now (in theory) without air!

Are you suggesting leaving the air vent entirely open?

I don’t know what you mean by “sons” rad?

 

[John.g]

If you mean the Towel Rail (your description) rad then yes leave the air vent open. and test system again for a few days.

"I also completely turned off rad in the other bedroom after someone said the joint looked like a bodge job." thought this was your son's rad, if you are still getting air somewhere with the suggested test then isolate this rad as well and test for another few days, ie with both towel rail rad and the bodge rad isolated.

I'm not sure if water still seeps from the pipes with the bodge rad isolated? but if so and if you are still getting air after the second test then this possibly the reason?.

 

[jim843]

If you mean the Towel Rail (your description) rad then yes leave the air vent open. and test system again for a few days.

"I also completely turned off rad in the other bedroom after someone said the joint looked like a bodge job." thought this was your son's rad, if you are still getting air somewhere with the suggested test then isolate this rad as well and test for another few days, ie with both towel rail rad and the bodge rad isolated.

I'm not sure if water still seeps from the pipes with the bodge rad isolated? but if so and if you are still getting air after the second test then this possibly the reason?.

The “bodge” rad has been isolated for over a week. I haven’t looked at as the room is fairly warm.

The radiator in my sons room is connected and heating fine.

I’ve opened the air vent on the towel rail.

 

[jim843]

@John.g The bathroom towel rail has been isolated for a week.

Before turning on the bathroom towel rail, I bled all the rads today for between 1-2 mins to be sure that there was no air.

Only one rad had a little bit of air in. On the same floor as the towel rail. It wasn't just straight air but a mix of air/water. Maybe 25seconds worth, didn't seem to be that much air. Certainly a hell of a lot less than we had in the towel rail. All other rads were fine. For reference I have 9 rads in the house.

I've put some inhibitor in the system and opened the towel rail.

I'll give it a few days and check the towel rail? If there's air in the towel rail then it's somehow pulling in air?

 

[John.g]

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.