Converting to a sealed/pressurised central heating system-Expansion vessel size

[Hot&Cold]

convert to a sealed system to stop air getting into rads

Can the existing air fault not be resolved ?. Should be fairly easy and cheaper that converting to ss

 

[firebladerrw]

Can the existing air fault not be resolved ?. Should be fairly easy and cheaper that converting to ss

Tried mate, but couldn't establish where air was getting in. Posted previously on this.

 

[Mottie]

Funnily enough, air was getting into ours before converting it to a sealed system. Had to bleed it weekly. Been converted to a sealed system since January and just realised that I haven’t had to bleed it once in all that time. Why is that? I did have to change a couple of rads that started leaking when pressurised, only pinholes literally, perhaps air was getting in through them?

 

[firebladerrw]

Funnily enough, air was getting into ours before converting it to a sealed system. Had to bleed it weekly. Been converted to a sealed system since January and just realised that I haven’t had to bleed it once in all that time. Why is that? I did have to change a couple of rads that started leaking when pressurised, only pinholes literally, perhaps air was getting in through them?

Mines is a strange one, it's really only a towel radiator in a utility room, and same in the en-suite. I've posted details in another thread, but couldn't find anything conclusive.

 

[Mottie]

Mine was the towel rail radiator too. It’s a tall one and I just put it down that it was the highest radiator in the house so the air naturally ended up there.

 

[John D v2.0]

Being honest if the pump is only 3m below, if the expansion pipe is on the suction side it could easily be pulling in air. or pumping over. With a sealed system that'll not be possible.

 

[firebladerrw]

Being honest if the pump is only 3m below, if the expansion pipe is on the suction side it could easily be pulling in air. or pumping over. With a sealed system that'll not be possible.

On start up from cold, the pump sucks around 3" from a bottle half filled with water from the overflow, then after a few minutes, some water squirts back in. (See my other post on this). This is the probable cause of air being sucked in and down the vent pipe.

 

[John D v2.0]

On start up from cold, the pump sucks around 3" from a bottle half filled with water from the overflow, then after a few minutes, some water squirts back in. (See my other post on this). This is the probable cause of air being sucked in and down the vent pipe.

Yes that's illustrating the problem, I don't want to go over old ground but either turning the pump down if possible or making sure the feed and expansion pipes are close together and not clogged would be my first check.

 

[firebladerrw]

Yes that's illustrating the problem, I don't want to go over old ground but either turning the pump down if possible or making sure the feed and expansion pipes are close together and not clogged would be my first check.

Thanks mate, done all that. Pump is on minimum and pipes are clear.

 

[John D v2.0]

Found your original thread - did you check the feed and expansion pipes are both connected very close to each other on the heating circuit? And not for example one at each end of the hot water cylinder coil.

 

[firebladerrw]

Found your original thread - did you check the feed and expansion pipes are both connected very close to each other on the heating circuit? And not for example one at each end of the hot water cylinder coil.

Sorry, yes both pipes run beside each other into my airing cupboard and connect quite close into the system. To be honest, I've had this air problem for years in towel rads, however I recently fitted a new towel radiator in my utility room, which seems to collect much more air. It's the furthest rad from the pump and highest rad downstairs.

 

[Hot&Cold]

Has a combined feed/vent or feed only alteration (with air separator) been suggested.

seeing the photo of the expansion tank,it looks like a short open vent pipe liable to sucking & spitting water.

See your pump is set at a very low speed,ignore the above and seal the system then up the pump speed.

make life easy for checking/topping up ,fit the filling loop and the pressure gauge in the airing cupboard,there will be some redundant pipes you can use.

Vessel in the loft,the pressure release valve pipe termination will need consideration all doable.good luck.

 

[firebladerrw]

Has a combined feed/vent or feed only alteration (with air separator) been suggested.

No I haven't considered that....

seeing the photo of the expansion tank,it looks like a short open vent pipe liable to sucking & spitting water.

The vent goes quite high into the loft, but yes it does sucked and spit water during cycles. Following previous advice, I used a half filled bottle and watched it suckling water, then after a couple of minutes some water squirts back into the tank.

"See your pump is set at a very low speed,ignore the above and seal the system then up the pump speed" < Could you expand on this please?

 

[John D v2.0]

Can you photograph the connections of the feed and expansion pipes into the main circuit please?

 

[firebladerrw]

Can you photograph the connections of the feed and expansion pipes into the main circuit please?

Apologies, when I started emptying the loft and airing cupboards, I mistook other pipes for the F&E pipes. The feed pipe vanishes into the floor in the airing cupboard, and the expansion pipe looks like it goes into a pipe chase that runs through my bathroom. Sorry for misleading in earlier posts:

Pics as follows: