Installing Automatic Bleed Vent into CH system?

Andy From Sligo · 12-09-2014 11:43pm #1

Hi there - noise of rushing water in the pipes - sound like rattling/waterfall, pretty sure its air in the system but i just cant seem to bleed it out so thinking of fitting one of these bottle type automatic air vents into the system:

And here is where i was thinking of situating it - in the hot press somewhere rather than on the boiler flow pipe:

Can i put a Tee off somewhere (maybe 28mm to 1/2inch) on the flow pipe there that comes from the boiler or could i add another tee before the pressure relief valve and put the bottle vent before the pressure relief valve will that work it? - or will I have to incorporate the bottle vent near the boiler?

Thanks.

K.Flyer · 13-09-2014 8:16am

In pic 2, is your hot water cylinder upstairs and the attic above it?
Where does the 3/4" vertical pipe that has the pressure relief valve t'eed onto it go to?
This looks like the expansion pipe that would normally terminate over the small feed and expansion tank in your attic.

esox28 · 13-09-2014 8:59am

Plus that safety valve should be located at your boiler.

Can you post a pic of the return pipe lower down on the cylinder, might be a more suitable spot for the 'AAV'

Andy From Sligo · 13-09-2014 1:36pm

K.Flyer wrote: »

In pic 2, is your hot water cylinder upstairs and the attic above it?
Where does the 3/4" vertical pipe that has the pressure relief valve t'eed onto it go to?
This looks like the expansion pipe that would normally terminate over the small feed and expansion tank in your attic.

Its a bungalow, the hot press is downstairs and the cold feed tank is nearly above it in the loft - pretty sure the 3/4" pipe goes vent to cold water tank in the loft

Robbie.G · 13-09-2014 1:47pm

Andy From Sligo wrote: »

Its a bungalow, the hot press is downstairs and the cold feed tank is nearly above it in the loft - pretty sure the 3/4" pipe goes vent to cold water tank in the loft

There is no point to the safety valve in that position as it's on the open vent.
It would be more benificial at the boiler like wise with the auto air vent

Andy From Sligo · 13-09-2014 1:54pm

Robbie.G wrote: »

There is no point to the safety valve in that position as it's on the open vent.
It would be more benificial at the boiler like wise with the auto air vent

I was wondering that myself to be honest - this is rented house we moved in June and I would have thought the safety valve should be at boiler location. What about if safety valve was taken out- bottle AAV put in its place and the safety valve moved to 28mm flow pipe further down? - would that work?

Andy From Sligo · 13-09-2014 1:56pm

esox28 wrote: »

Plus that safety valve should be located at your boiler.

Can you post a pic of the return pipe lower down on the cylinder, might be a more suitable spot for the 'AAV'

heres pic of lower down pipework - pump is on return pipe:

Andy From Sligo · 13-09-2014 1:59pm

Robbie.G wrote: »

There is no point to the safety valve in that position as it's on the open vent.
It would be more benificial at the boiler like wise with the auto air vent

Does a pressure relief safety valve have to be on flow or can it be placed on return pipe instead - does it have a bearing on what pipe its fitted to?

freddyuk · 13-09-2014 3:50pm

1. I would suggest checking where the air is "trapped" as if it is "trapped" it may not find it's way to the AAV?
2. Have you bled the pump? Have you turned it up to full power to see if that shifts it?
3. Better to flush the system properly and expel the air as it can damage your pump.
4. If you are going to install that AAV near the boiler check it can take the potential over heat.

As you are renting this should be for the landlord to sort out especially if the safety valve is incorrect?

Andy From Sligo · 13-09-2014 6:31pm

freddyuk wrote: »

1. I would suggest checking where the air is "trapped" as if it is "trapped" it may not find it's way to the AAV?
2. Have you bled the pump? Have you turned it up to full power to see if that shifts it?
3. Better to flush the system properly and expel the air as it can damage your pump.
4. If you are going to install that AAV near the boiler check it can take the potential over heat.

As you are renting this should be for the landlord to sort out especially if the safety valve is incorrect?

thanks - the noise of rushing water / trickling sound seems to be sound coming from between the pump and either the return or flow pipes - they are hidden behind a wooden panel - the sound is worse on speed 2 and even worse on speed 1 of the pump (its a 3 speed pump)

I have taken out middle screw of pump and bled there.

Have bled the radiators and they had lot of air in them and can hear trickling theough them when rad are on, every now and again, every now and then a whooosh sound of air and water and sounding like a river which makes me think the air is moving around and through the system. I was hoping putting in a AAV it would eventuall get to that and expell the air and keep it vented automatically if i leave the lid off the top of it.

Ah yeah that would be my first port of call, asking the landlord to sort it however we have asked her to get quite a few things sorted so she will be getting fed up with all our demands! - plus she is not the quickest in getting things sorted out. I could install a AAV in one afternoon and I like to sieze the day as the saying goes and once i know something is not right i like to roll me sleeves up (if i feel im competent enough) and get it sorted out quickly, i cant do that if Im waiting for her to get a plumber etc. it would be more than likely she would just get a friend or member of the family that 'knows a bit about plumbing' rather than get a proper plumber to do the job - im not being funny/smart just telling how it is.

Andy From Sligo · 13-09-2014 6:39pm

of course it could also be a lump of solder or a screw/nut/bolt/ piece of metal rattling between the return pipe and boiler rattling as the water passes by it - cant rule that out i suppose - but the way the radiatios are gurgling as well i would say there is some air in the system or getting into the system. - might as well if the system is going to bee drained down any way look into moving the pressure valve and incorporating an AAV into the saystem at the same time - and a couple of the rad lockshiled valves are of the old fashioned screw type with a black rubber washer lockshield cap and grey screw down cap on the lockshield side , they are weeping a bit so a couple of them could do with replacing when the system is drained down

gctest50 · 13-09-2014 6:56pm

Andy From Sligo wrote: »

.......... pretty sure its air in the system but i just cant seem to bleed it out so thinking of fitting one of these bottle type automatic air vents into the system:

if you can't bleed it out - its unlikely an automatic one there will help

might be a radiator or two rotting away internally - gives off gas as it rots and causes much the same

you need a plumber in - have it sorted in no time

Robbie.G wrote: »

There is no point to the safety valve in that position as it's on the open vent.....

be no harm leaving it there and making sure the boiler has one too - some looper might block one off at some stage and it'd pay off ?

Andy From Sligo · 14-09-2014 1:32am

gctest50 wrote: »

if you can't bleed it out - its unlikely an automatic one there will help

its still better to have an AAV into the system than not one at all though isnt it? - what are they something like only 6 or 7euro from the likes of woodies etc

Andy From Sligo · 14-09-2014 1:47am

apart from not wanting to ask her just cannot see our landlord paying out to get all this done properly because it could run into lots of money especially if there are a couple of radiators and pipework to be changed and things added, last time i came up with something to do with maintenance she told us the last tennant were here for years and it was fine for them and said we knew what we were letting ourselves in for before taking the house (well in fairness before you take rent on a house you dont thoroughly check the central heating straight through do you? - i dunno maybe we should have done)

- even the boiler hasnt had a service before we moved in (is that the responsibility of the owner or tennant, i can never grasp who is supposed to pay for it when renting) and according to label on boiler I see it was last serviced in june 2012 (2 years ago) - although the boiler does fire up and run ok,but even so they are supposed to have their flexible oil hoses changed once a year arent they and flue/gas test as well to make sure its running efficent

scudo2 · 14-09-2014 9:45am

Is the arrow on the pump pointing to the boiler or away ?

Another option is useing inhibitor "Fernox" to help stop air forming.

You shouldn't have air as your pipe work already looks self venting in the hot press, just make sure 3/4" pipe is also riseing constantly up and over tank in attic and hasent fallen down into the water of the tank.

Tie up ball cock for a day and see if existing level of water drops, that would indicate a leak = air in pipes.

Or check that water is not been pumped up vent pipe and going into tank, that would also generate air. I'm don't think this can happen as your cold feed seems to be correctly connected in the hot press.

Or change your name to.

"Andy from Sligo, but now lives in Cork"

Plenty of good houses here.

14-09-2014 12:00pm

scudo2 wrote: »

Is the arrow on the pump pointing to the boiler or away ?

Another option is useing inhibitor "Fernox" to help stop air forming.

You shouldn't have air as your pipe work already looks self venting in the hot press, just make sure 3/4" pipe is also riseing constantly up and over tank in attic and hasent fallen down into the water of the tank.

Tie up ball cock for a day and see if existing level of water drops, that would indicate a leak = air in pipes.

Or check that water is not been pumped up vent pipe and going into tank, that would also generate air. I'm don't think this can happen as your cold feed seems to be correctly connected in the hot press.

Or change your name to.

"Andy from Sligo, but now lives in Cork"

Plenty of good houses here.

Inhibitor added to a dirty system can have a negative impact on a heating system, I would only add inhibitor to a clean system with no leaks.

OP if the heating system isn't clean and you add a AAV you may find the AAV leaks.

As your renting I'd be careful as even trying to do the right thing to sort the heating can end in tears that's why I have to have insurance or they wouldn't let me near anything.

Andy From Sligo · 14-09-2014 2:15pm

scudo2 wrote: »

Is the arrow on the pump pointing to the boiler or away ?

Another option is useing inhibitor "Fernox" to help stop air forming.

You shouldn't have air as your pipe work already looks self venting in the hot press, just make sure 3/4" pipe is also riseing constantly up and over tank in attic and hasent fallen down into the water of the tank.

Tie up ball cock for a day and see if existing level of water drops, that would indicate a leak = air in pipes.

Or check that water is not been pumped up vent pipe and going into tank, that would also generate air. I'm don't think this can happen as your cold feed seems to be correctly connected in the hot press.

Or change your name to.

"Andy from Sligo, but now lives in Cork"

Plenty of good houses here.

Never been to Cork :-) ... mind you i dont think Ive ever been to Meath either :-)

Glad it looks in the photo that it looks like the vent / cold feed looks like its correctly fitted anyway - I checked before the vent pipe going into the smaller CH cold water tank and it hasnt fell in its above the water and theres no water pumping up to small CH cold tank in the loft - however i havent gone as far as 'blowing' down the expansion pipe to make sure its absolutely clear, might try that another day, however with combined vent and feed pipe setup like that its not going to be able to blow down it am i because the water up the vent pipe will reach to level at the bottom of the small CH cold feed tank wouldnt it, if its working correctly?

I will try one day tie-ing up ballcock as well and see what happens.

Would really love to get to the bottom of this 'rushing/rattling water noise' one day soon as i like to see things working properly and if its cracked will not only make the central heating sound quieter it should by rights be better for pump especially if air is bad for central heating pump - and you know, knowing our luck the pump will fail in the middle of winter when its -18c outside!!

Thanks for the advice.

Andy From Sligo · 14-09-2014 2:47pm

heres a picture of the other side of the range/boiler - the flow and the return being blanked off by 28mm blanking plugs - could a plumber (or me if it came to it) not incorporate an AAV and PRV on that side using 28mm to 15mm then tee piece and AAV and PRV fitted onto that, rather than in the hot press?

Andy From Sligo · 14-09-2014 3:29pm

Ive just had another idea - i dunno if it will work or if anyone has tried it but it looks like a simpler idea and not require whole system to be drained down. Could a AAV valve be attached to a radiator near to the boiler at the top part of radiator where bleed valve is (these are old fashioned type rads as you can see in the pic) : I know it wont look pretty having a brass AAV sticking out the top side of a rad, but if the air is passing through the rad anyways i am thinking it might expell through the AAV instead of looping around the system - would it work? - all id need to do then s turn off lockshields, drain down just one rad and not the whole system and very little pipework:

K.Flyer · 14-09-2014 5:03pm

To be honest with you, none of this work is your responsibility and is really best left to someone who knows what they are looking at and have the knowledge and Experience to rectify it.
You might be anxious to get it sorted out, but as Gary said earlier, if you mess it up, then you are going to be held liable, as we say amongst ourselves, "you touch it, you own it".
Also, this system is an open vented system. Air should be venting out through the open vent pipe. There could be a lot more wrong than can be determined from a couple of pictures and to stick an aav off the top of a radiator is not going to rectify the underlying issue.
As a tenant your obligation is to notify the L.L. that there is an issue with the heating system. If there is no response from the L.L. send an email or letter requesting the repairs be carried out within a given time frame (say 1 week) as you are afraid to use the heating in case of damage occuring and the weather is getting colder.
You can then offer to hire a good plumbing contractor yourself and deduct his cost from the next months rent.

Andy From Sligo · 14-09-2014 10:39pm

K.Flyer wrote: »

To be honest with you, none of this work is your responsibility and is really best left to someone who knows what they are looking at and have the knowledge and Experience to rectify it.
You might be anxious to get it sorted out, but as Gary said earlier, if you mess it up, then you are going to be held liable, as we say amongst ourselves, "you touch it, you own it".
Also, this system is an open vented system. Air should be venting out through the open vent pipe. There could be a lot more wrong than can be determined from a couple of pictures and to stick an aav off the top of a radiator is not going to rectify the underlying issue.
As a tenant your obligation is to notify the L.L. that there is an issue with the heating system. If there is no response from the L.L. send an email or letter requesting the repairs be carried out within a given time frame (say 1 week) as you are afraid to use the heating in case of damage occuring and the weather is getting colder.
You can then offer to hire a good plumbing contractor yourself and deduct his cost from the next months rent.

yes your most probably right- i will make my first port of call to ask the LL to get it sorted, not yet though because we have asked for too many other things to be done/rectified since we moved into this place in june - so I will let the dust settle a bit first otherwise she will be 'getting fed up with us' as tennants and might end up kicking us out! lol - although I do feel the answer is going to be "theres nothing wrong with the heating, its working, the radiators are getting hot! and the cylinder is getting hot and that is all that is needed" and that will be it! and also I cant see them getting a proper plumber as all things done in the past is by "our own builder/handyman" or "friend" or "member of the family who 'knows a bit about plumbing" and it more than likely wont ever get sorted properly.

scudo2 · 15-09-2014 12:38am

Blow down the expansion pipe and that will clear an air lock out of the cold feed supply pipe, it might be the problem, get a length of 3/4" lagging, hold it over the expansion pipe, squesing it for a good seal and blow into the other end.
It's a similar problem I've discovered before.
No harm in giving it a go.

Andy From Sligo · 15-09-2014 2:00am

scudo2 wrote: »

Blow down the expansion pipe and that will clear an air lock out of the cold feed supply pipe, it might be the problem, get a length of 3/4" lagging, hold it over the expansion pipe, squesing it for a good seal and blow into the other end.
It's a similar problem I've discovered before.
No harm in giving it a go.

thanks i try that tomorrow - what generally tends to block the expansion pipes do you know? - would it/could it be lime-scale or something else?

Andy From Sligo · 15-09-2014 2:10am

really appreciating all the answers everyone - but can we brush to one side about the issue of that because i am a renting tennant I shouldnt touch things to do with the heating because its a rented house and that i should be getting in touch with the landlord to get it sorted, and sort of like concentrate on the questions im asking and the pictures i am doing and maybe answer if you think that would work it or not. I know, and I most probably will end up asking the LL to sort it out, but it would be great to get the feedback on the actual questions im asking, apart from anything its a fascinating/curiosity thing on my behalf on how these things work it would be great to have some idea if she does get a proper plumber out to do the job and maybe pass on the suggestions whilst he is here. But i do appreciate as I say all answers, except for I want to not focus too much on what the tennant is or not supposed to do - i sort of know that part already

- Cheers all

scudo2 · 15-09-2014 8:27am

Andy From Sligo wrote: »

thanks i try that tomorrow - what generally tends to block the expansion pipes do you know? - would it/could it be lime-scale or something else?

Hi Andy.
It might not be the expansion pipe but just a small bit of air blocking/airlock in the 1/2" supply pipe from the tank to the hot press. Blowing would clear that. Without having to get the spanners out.

The other thing that causes air bubbles is boiling water in the boiler.
Any chance you sliped up when at the electrics on the boiler a few weeks ago ?

Again were trying to help, but legaly and insurance wise, if it's not yours and you don't have premission then you can't alter it. (That basic legal law covers a lot)

Were only trying to help everybody here on P&H as best as we can with safe advice.

Andy From Sligo · 15-09-2014 3:55pm

scudo2 wrote: »

Hi Andy.
It might not be the expansion pipe but just a small bit of air blocking/airlock in the 1/2" supply pipe from the tank to the hot press. Blowing would clear that. Without having to get the spanners out.

The other thing that causes air bubbles is boiling water in the boiler.
Any chance you sliped up when at the electrics on the boiler a few weeks ago ?

Again were trying to help, but legaly and insurance wise, if it's not yours and you don't have premission then you can't alter it. (That basic legal law covers a lot)

Were only trying to help everybody here on P&H as best as we can with safe advice.

cheers i appreciate it - yep i understand as well that everyone can only give advice up to a certain level due to insurance etc. I have decided anyway i will ask the LL to get it sorted...when the time is right! , i better not touch it myself even though im itching to do it .. :-) - must resist! must resist! lol

Andy From Sligo · 17-09-2014 4:26pm

basing on the fact that an open vented system, if working properly and there are no blockages in the vent pipe, i am wondering why the last 3 houses we have rented have had AAV's installed near the boiler or in the hot press - anyone know why? - this house we are in at moment is only house to only have a PRV and no AAV at all...

Andy From Sligo · 17-09-2014 5:09pm

ive had a good old inspection of the system today and how its piped up - strange excuse the poor picture i have done - but as you can see in the drawing the F&E tank is not above the hot press where you might expect to find it but well away from the hot press above the bathroom, it looks like at some stage the hot press that housed the copper immersion cylinder was originally in the bathroom but now its in the dining room! (dont ask, why put a hot press in a dining room - i have no idea, weird - only thing i can think of is that it must have been easier for them to plumb it into the oil fired range boiler ..... which again is not in the kitchen where you might exprect to find a range .... but in the dining room instead - well weird!) anyway apart from all that the vent pipe (3/4") then goes vertically from the hot press through the ceiling into the attic and then horizontal all the way to the loft space over the bathroom where the F&E tank is. - Would the facts of horizontal pipe and twists and turns/bends, and being so far run to the F&E have any bearings on the expelled air purging up the expansion pipe or does it not matter that the expansion pipe is horizontal and exits a long way away?:

scudo2 · 17-09-2014 8:10pm

Both cold supply and expansion/vent pipes have to constantly rise slightly (minimum) to expelled air, no need for auto air vent if that's done correctly.

+ I hate Auto air vents, they all leak eventualy !

Installing Automatic Bleed Vent into CH system?

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