Could these be air vents?

[amfisted]

Hi Folks

I recently employed the services of a local RGI to fit a bathroom rad. He did a fine, tidy job, but when he refilled the system and fired up the boiler it transpired that there was no auto air vent on the system. The boiler was constantly heating up rapidly and then cutting out, and there was a Niagara-like rushing sound through the pipework. By draining and bleeding each rad in turn he managed to remove enough of the trapped air for the system to work, but there is still significant "gurgling" when the boiler fires up, both for heating or hot water.

Out of curiosity I went up into the loft today to have a look at the pipework. On top of the two 22mm pipes (flow and return?) which lead from the boiler into the cylinder cupboard and thence to the pump, etc, are two lengths of reduced pipework, about eight inches long, and these are terminated by a screw with a knurled edge. Is it likely that these are manual air vents? I can't post a photo right now but if needs be, in the morning I'll set up an inspection lamp and try to get a clear picture to go with this post.

Thanks in advance.

 

[flameport]

Yes, description is exactly that of an air vent. Loosen the knurled bit to let air out.
Somewhat poor that the installer did not look there for vents - it's exactly where you would expect them to be fitted.

 

[amfisted]

Thanks for that. Must admit, given how easily I located these things it surprises me too.

Just to make absolutely sure, I've attached images to this post...hopefully.

Edit: if these are indeed air vents, should I bleed them when the system is running or when its off? Its a conventional open/ vented CH/ hot water set up with expansion tanks and a hot water cylinder, and not a combi.

 

[amfisted]

Well I cracked 'em--clearly the first person ever to do so, given the amount of effort involved--and a smidge of air wheezed out, but the pipework carries on gurgling.

I've recontacted the RGI, and he's going to fit an AAV to remove any air in the future.

 

[Madrab]

In your engineers defense, he maybe didn't realise that the pipework rose into the attic. Not necessarily the place to be looking for CH/HW primaries unless your hot water cylinder is in the attic though he should have traced the pipework to find its high point.

 

[amfisted]

I'm in a bungalow; maybe I should have mentioned that earlier on. The HW cylinder is in a cupboard in the bathroom with the boiler controls, the boiler is in the kitchen along with the programmer and there's a wireless roomstat in the lounge which communicates with a control unit in the cylinder cupboard. The existing manual air vents are on the highest point of the system.

If the RGI is unable to do the job in the near future I'll probably have a go at fitting the AAV myself, because I want to get rid of the air in the system sooner rather than later. I'm guessing that the solution would be to drain down, cut one of the manual valves out and replace it with an AAV?

Edit: is this the kind of fitting I should be looking at?

http://www.directheatingsupplies.co...s-giacommini?gclid=CN_BwY-jpscCFcXHtAodm4IKdg

Thanks.

 

[Madrab]

Ah ok, a bungalow, well yup he should have traced the pipework up above then to confirm the existence or not of vent's for the primaries, so i'll retract my defense for him

That one you've linked to will do the job.

 

[Jackrae]

Have you confirmed that there is actually sufficient depth of water in the header tank and that the system isn't pumping water out of the vent line into the header tank

 

[amfisted]

I'll pop up into the loft later and have a butcher's at the F and E tank. Thank you.

 

[D_Hailsham]

I'm in a bungalow; maybe I should have mentioned that earlier on.

It would have been helpful.

Are the rads fed by pipes dropping down from the attic? If they are, air can get trapped in the horizontal pipework in the attic. So there needs to be an air vent on each horizontal pipe.

Venting should be done with the boiler off and the water cold.

 

[amfisted]

Yes, the bungalow has solid concrete floors and the pipework for all rads drops down from the attic. I'm OK with basic plumbing, so when I spoke to the RGI yesterday I suggested to him that to save waiting until he can fit us in, and also save a little money on labour costs, I might fit the AAV myself.

He said that I should fit two ( one in each location where there is currently a manual vent) and that I shouldn't have to drain off much water because I'll be emptying only two short, vertical lengths of pipe at the highest point of the system. So I've ordered two of these: http://www.screwfix.com/p/bottle-ai...arch-_-SearchRec-_-Area1&_requestid=33264#_=p

I'll go ahead and do that next week, and let the pipes gurgle away happily for another few days.

Edit: what's bugging me a little bit about this episode is this; how much assumption should an RGI make about a system before he or she works on it? OK, he fitted an isolating valve to the F and E feed before he started, because there wasn't one, and didn't charge me for that; and he remained behind for over an hour after completing the job to drain as much air out of the pipework as he could, to make sure the system was working and that we had hot water. However, as Flameport said earlier in this thread, should he not have checked that there was adequate air venting on the system before he started work on the job? Presumably that's what other RGIs who use this forum would do?

 

[FiremanT]

Yes, the bungalow has solid concrete floors and the pipework for all rads drops down from the attic. I'm OK with basic plumbing, so when I spoke to the RGI yesterday I suggested to him that to save waiting until he can fit us in, and also save a little money on labour costs, I might fit the AAV myself.

He said that I should fit two ( one in each location where there is currently a manual vent) and that I shouldn't have to drain off much water because I'll be emptying only two short, vertical lengths of pipe at the highest point of the system. So I've ordered two of these: http://www.screwfix.com/p/bottle-ai...arch-_-SearchRec-_-Area1&_requestid=33264#_=p

I'll go ahead and do that next week, and let the pipes gurgle away happily for another few days.

Edit: what's bugging me a little bit about this episode is this; how much assumption should an RGI make about a system before he or she works on it? OK, he fitted an isolating valve to the F and E feed before he started, because there wasn't one, and didn't charge me for that; and he remained behind for over an hour after completing the job to drain as much air out of the pipework as he could, to make sure the system was working and that we had hot water. However, as Flameport said earlier in this thread, should he not have checked that there was adequate air venting on the system before he started work on the job? Presumably that's what other RGIs who use this forum would do?

No,I wouldn't neccessarily check before starting work. I do, however, try and asses a job and advice on the likely outv=come in terms of cost and future problems. I would have charged for the new valve! That said, I don't understand why he struggled to vent the system, without checking the oft for vents..
You may find that ypu now jhave pockets of air on the system. As it is still gurgling, a full drain and refill may help.

 

[Dan Robinson]

Yes, the bungalow has solid concrete floors and the pipework for all rads drops down from the attic.

Knowing this, as he should have done since he was working on the system, I would have thought it painfully obvious that this problem would occur. We would have fitted decent AAV's to the system as part of the job if only to prevent a phone call later. Would have taken 30 seconds with the system empty.

Now its filled it will take 5 minutes. Probably wouldn't even bother to drain the system at all .

 

[amfisted]

Thanks again.
Since my last post I've also discovered that the F and E tank doesn't have an overflow, so there's yet another reason to leave the lawnmower in peace.

 

[amfisted]

Just one further question, with apologies for harping on a bit. I want to to get this right first time.
I read somewhere else that any AAV(s) should be fitted at least 1m above the bottom of the F and E tank. One metre above that part of my F and E tank is on the sunshine side of the roof, so that's simply not possible. In the place where I intend to fit them, which is currently occupied by the old manual vents, they would probably be about six inches above the horizontal pipework, which would put them about 6 inches below the bottom of the F and E tank. There isn't sufficient clearance between the pipework and the inner roof slope to fit them any higher. Would they still do the job in that position?