Radiator filling with air

[dwmcn]

nomoss,

Was he Irish?

David

[dwmcn]

Theiere,

Nope, I was just away for a while. pachappa?

David

[Lehaut]

Having been following this thread with a cross between interest and astonishment! I have only installed three central heating systems and have never had one run so hot that it vapourised the water to steam (it does not split to its component molecules of Hydrogen and Oxygen at 100°C even if in a pressurised system the water is heated to above 100°C).

Has it been established that it is a sealed system? Many Brits came to France will full UK open systems and even pipework and had their English speaking builder put in a system they understood. (I have done both types and have never had this particular problem). My current oil burner is in a three storey building and at the ground floor where the boiler is is running at just under 2 bars static pressure. If it is a normal french system, there will be an expansion chamber in it, mine is a big red unit with a valve on top. I have never taken it apart, but expect its like an air loaded accummulator so there will be a diaphram in it, could this be leaking? If its an open system then if the pump sucks too hard, it can pull air back into the system via the expansion pipe. A jar filled with water held over the pipe when the pump is started will help the diagnostic, if it sucks up water, then it is sucking air.

On the more exotic front, if you collect the gas that comes out of the radiator using the pipe and inverted jar in water method, you could try lighting it. If it goes pop, then it is hydrogen/methane, a sign of corrosion?

[Pickles]

[quote user="Lehaut"](it does not split to its component molecules of Hydrogen and Oxygen at 100°C even if in a pressurised system the water is heated to above 100°C). [/quote]

I don't think that the people who were posting about that were talking about splitting water into hydrogen and oxygen: they were referrring to the fact that what makes water interesting from a physical point of view is the hydrogen bonding between water molecules, which gives water some of the characteristics of a heavier molecule. Without hydrogen bonding between water molecules, I'd expect H2O to be a gas at room temperature, not a liquid. 

[Théière]

Absolutely Pickles, completely correct.

Lehaut, I have had in the uk, had a system play up and vaporise the water due to a stuck two port valve, didn't believe it was possible at first. 

I think you could well be correct about the bladder in the expansion vessel, they don't last forever.

[Lehaut]

Théirè wrote

It's jolly handy they decide to split apart at 100 C or we would have to remember an awkward number like 212 F

Its the splitting part that confused, me, too much time spent reading about the LHC!!

The "vaporising" I presume was due to the system wildly over heating without the temperature cut out safey circuit turning off the boiler? Evaporation takes place well below 100°c

H2O can be a gas at room temperature (you can boil it at 1°C if you pull a vaccuum over it!). Its most dense at 4°C (at STP), we take it for granted, but it is very interesing stuff.

This is like the spherical chicken in a vaccuum joke. We will all be disappearing down our own wormholes soon, great fun!

A long time ago, I had to keep filling up the master cylinder on a brake system in a car. Could not find a leak. It was only when I took apart the servo and found a pint of fluid in it that I realised there was a leak in there, hence my ALA logic.

[dwmcn]

Rabies,

OK, how's this?

http://www.uswitch.com/energy-saving/guides/how-to-bleed-a-radiator/

Not that I read it...

David

 

 

 

 

[HoneySuckleDreams]

I thought I would be back with an update

The landlord finally got round to getting a heating bloke in.

There are lots of issues with the boiler setup - a leak from somewhere, no filters, build of crap etc. etc. Which will have to be dealt with another day.

My radiator setup is odd as the bleed valve is next to the thermostatic valve, not the other end (and it's a long rad around 2m), so if there is air in the radiator it's difficult to shift.

However, the radiator issue... The pressure in the system was very low so he increased it, I guess forcing air/water/crap out of the duff rad. Which seems to have sorted things out.