How does auto bleed valve work

How does auto bleed valve work

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Discussion

jefword

Original Poster:

182 posts

193 months

Monday 24th October 2011
quotequote all
Hi, I've just replaced one of these types of automatic radiator bleed valves that has been in one of my rental properties and doing it's job for the last eight years. They are the ones that Wickes sell. The old one seemed to be no longer functioning. The new one seems to have solved the problem (well technically the symptom anyway)

I was just intrigued (sad I know) how this type works and is there anything to go wrong inside them. Is it some material inside which swells when wet to give a seal? Also, I wondered if there is a correct technique to set the screw position or is it a trial and error method like the one I used.

I've searched on the net for info but can't find any so I just thought I would ask on here before I grind the old one in half to see (even sadder).

Thanks.


bod27

230 posts

214 months

Monday 24th October 2011
quotequote all
Yes you are right, the fibre washer swells when wet and seals the water in, if the water level drops as when the rad has air in it, it drys and lets the air out until the water level wets the washer again. Simple idea but works well.

jefword

Original Poster:

182 posts

193 months

Monday 24th October 2011
quotequote all
That was fast. Thanks very much.

Gingerbread Man

9,171 posts

214 months

Monday 24th October 2011
quotequote all
I can't help but think these would just mask any issue with the central heating system where air would be getting in.

Paulbav

2,138 posts

236 months

Monday 24th October 2011
quotequote all
Gingerbread Man said:
I can't help but think these would just mask any issue with the central heating system where air would be getting in.
This, and also when I bleed our rads I need to get in the loft and re-pressurize the system or the boiler will display a fault code and lock out??

jefword

Original Poster:

182 posts

193 months

Monday 24th October 2011
quotequote all
jefword said:
The new one seems to have solved the problem (well technically the symptom anyway)
I did actually infer it masked the fault by curing the symptom in my post.

This is also fitted to an open system so no problems with re-pressurising the system.

Paulbav

2,138 posts

236 months

Monday 24th October 2011
quotequote all
jefword said:
I did actually infer it masked the fault by curing the symptom in my post.

This is also fitted to an open system so no problems with re-pressurising the system.
Ahhh, I have no idea what the difference between a open and a non open systempaperbag

Gingerbread Man

9,171 posts

214 months

Monday 24th October 2011
quotequote all
Aye, not blaming you, just think it's a daft idea to put them on your rads. Especially an open system as you can't tell if the header tank is constantly filling up as water is peeing out the other end somewhere.
A sealed system would let you know if pressure was getting out.

All masks an issue that could be rotting out your rads and sludging up your system which mounts up to a protencially bigger bill.

Just my thoughts is all. As you were!

Arthur Jackson

2,111 posts

231 months

Monday 24th October 2011
quotequote all
A constantly venting system means a constantly filling system. Fresh water means fresh oxygen, which means rusting.
It never ceases to amaze me when people say, "Oh, the system loses pressure (on a sealed system), but our plumbers showed me how to top it up."... like that's a good thing.

Rickyy

6,618 posts

220 months

Monday 24th October 2011
quotequote all
Paulbav said:
Ahhh, I have no idea what the difference between a open and a non open systempaperbag
An open vented system uses a cistern to fill the heating system and allow for expansion. The pressure of the system is determined by the height of the cistern and is open to atmosphere.

A sealed system is completely sealed to atmosphere, expansion is taken up using an expansion vessel and is filled by a temporary link between the cold main and the heating system. It is usually operated at higher pressure.

Gingerbread Man

9,171 posts

214 months

Monday 24th October 2011
quotequote all
Love it, the plumbers have been in to give their view, but not to answer the question like the first replier did.

I couldn't resist opening my mouth. Sorry chap!

jefword

Original Poster:

182 posts

193 months

Monday 24th October 2011
quotequote all
Gingerbread Man said:
Aye, not blaming you, just think it's a daft idea to put them on your rads. Especially an open system as you can't tell if the header tank is constantly filling up as water is peeing out the other end somewhere.
A sealed system would let you know if pressure was getting out.

All masks an issue that could be rotting out your rads and sludging up your system which mounts up to a protencially bigger bill.

Just my thoughts is all. As you were!
I tried the trick of setting light to the escaping air to see if it was system corrosion causing the air in it.

However it didn't ignite, leading me to believe it was air being pulled in from somewhere. I understand these minute leaks can be hard to find as air can get pulled in by the pump through gaps where water can't escape. (Perhaps through the pump bearings)

Am I correct. Does anyone have any thoughts on this?

Also it's a bit of a bind going to bleed radiators occasionally because a tenant "can't remember" how to do them, what with all the other minor jobs some of them want doing which would take them two minutes.

Disclaimer: I do have tenants that are very good and do far more than is expected of them.

Rickyy

6,618 posts

220 months

Monday 24th October 2011
quotequote all
Gingerbread Man said:
Love it, the plumbers have been in to give their view, but not to answer the question like the first replier did.

I couldn't resist opening my mouth. Sorry chap!
I'll be honest, I had no idea how they worked until now! Was just passing on some knowledge!

Gingerbread Man

9,171 posts

214 months

Monday 24th October 2011
quotequote all
jefword said:
I tried the trick of setting light to the escaping air to see if it was system corrosion causing the air in it.

However it didn't ignite, leading me to believe it was air being pulled in from somewhere. I understand these minute leaks can be hard to find as air can get pulled in by the pump through gaps where water can't escape. (Perhaps through the pump bearings)

Am I correct. Does anyone have any thoughts on this?

Also it's a bit of a bind going to bleed radiators occasionally because a tenant "can't remember" how to do them, what with all the other minor jobs some of them want doing which would take them two minutes.

Disclaimer: I do have tenants that are very good and do far more than is expected of them.
Depending on how the pump/ vent is setup, it can pull water through the vent. You could try extending it into the water, (22mm pish fit and bit of pipe (6"?) makes life easy) so any pulling on the vent by the pump will suck water not air.

Gingerbread Man

9,171 posts

214 months

Monday 24th October 2011
quotequote all
Rickyy said:
I'll be honest, I had no idea how they worked until now! Was just passing on some knowledge!
Not sure if radiator auto bleed vents ate different but I thought that they worked different to previously described.

I thought it was a matter of bouancy, a float floats if waters present and drops if air, water forcing up on it causes it to create a seal.

But I wouldn't see how this method would work on horizontal plane as it would be in a radiator situation.

Many ways to skin a cat?

Paulbav

2,138 posts

236 months

Monday 24th October 2011
quotequote all
Rickyy said:
Paulbav said:
Ahhh, I have no idea what the difference between a open and a non open systempaperbag
An open vented system uses a cistern to fill the heating system and allow for expansion. The pressure of the system is determined by the height of the cistern and is open to atmosphere.

A sealed system is completely sealed to atmosphere, expansion is taken up using an expansion vessel and is filled by a temporary link between the cold main and the heating system. It is usually operated at higher pressure.
Well there you go, every day is a school day. We must have the latter, mains pressure hot water at all of our taps biggrin

Gingerbread Man

9,171 posts

214 months

Monday 24th October 2011
quotequote all
Paulbav said:
Well there you go, every day is a school day. We must have the latter, mains pressure hot water at all of our taps biggrin
Hot/ cold water is different to heating.

But yes, if you have mains pressure hot, you'll have an unvented system.