Auto bleed rad valves

[opps]

Hi all

My client has a 5 story house, with a boiler and megaflow on the ground floor.

Whilst working at the top of the house I noticed that the two rads and towel rail were completely cold.

The client says that she frequently has to bleed them.

I did suggest that she consider auto bleed valves but after a quick google it seems that they are somewhat Marmite-esque, with both supporters and detractors.

I believe that the problem has existed for as long as she has lived there (8 years?) the current boiler is 2 or 3 years old. The property is an 80/90's build.

I doubt that there is any Fernox in the system, at this moment in time, given that she had some building work done recently. I will recommend that she adds some (unless there is any reason why she shouldn't).

I haven't tested the bleed air for flammability.

I was surprised to see some plumbers claim that autobleed valves can create problems, I don't understand how? I appreciate that they might mask problems though.

Are there any caveats to consider if she wants to add the valves to all 3 top floor radiators? Additionally some retailers suggest adding one to the rad nearest the boiler, is this sound advice or hard sell?

Finally, are there any brands to avoid?

Many thanks

 

[Boilerman2]

The bleed valves you describe use a soft leather washer, which while wet remains fairly water tight, as the water level in the rad drops the leather washer dries out, causing it to leak out the built up air the washer gets wet and swells up again -HOWEVER these must not be used on sealed systems as they are a constant cause of water pressure loss (personally I do not fit these things under any circumstances!)

 

[Charnwood]

Bottle auto air vent.

 

[Dan Robinson]

The bleed valves you describe use a soft leather washer, which while wet remains fairly water tight, as the water level in the rad drops the leather washer dries out, causing it to leak out the built up air the washer gets wet and swells up again -HOWEVER these must not be used on sealed systems as they are a constant cause of water pressure loss (personally I do not fit these things under any circumstances!)

Interesting you say that - I have had them on my old rads (now removed) for several years without a single problem. No pressure loss or drips.


Fugly looking things though.

 

[opps]

The bleed valves you describe use a soft leather washer, which while wet remains fairly water tight, as the water level in the rad drops the leather washer dries out, causing it to leak out the built up air the washer gets wet and swells up again -HOWEVER these must not be used on sealed systems as they are a constant cause of water pressure loss (personally I do not fit these things under any circumstances!)

Hi BM2

So allowing the gas to escape is infact the cause of the pressure drop (in a sealed system)?

Thanks for the heads up, none of the retailers mention the fact that they shouldn't be used with sealed systems...

 

[opps]

Bottle auto air vent.

Hi Charnwood

Wouldn't that also lead to pressure drops?

Tnx