Bloody heating again!!!

skye

GGGRRRH!!! Sorted my recent problem of heaters not warming to the top with advice on here - have used the bleed system and now the heaters downstairs are not working!! All 4 upstairs are scorching.... Don't know if this is relevant but when I blead the upstairs ones no water came out when the air stopped - have checked back several times but still none - but these are working fine. When I now try to bleed the downstairs 3 water comes out but they are cold?? Am I missing something?? Any advice greatly appreciated on this cold wintery night!

rooferPete

Hi,

Presuming the system is full of water and the valves are open, if thermostatic valves were used they can stick when not used, that is not turned on / off adjusting the temperature to keep them moving.

You might want to check if the valves on the other side of the rad are open, these are used to balance the system so if they were not interfered with since the rads were working they should be ok.

Some systems have thermostatic valves fitted to the upstairs pipes that close off the return when the heating reaches the set temperature, these are usually used on fairly large systems but can be used in domestic systems.

If your system is an open (gravity system) the pump may not be working properly, the hot water will rise and circulate without the pump but the ground floor radiators won't work without the circulating pump.

.

JamesM

skye wrote:

Don't know if this is relevant but when I blead the upstairs ones no water came out when the air stopped - have checked back several times but still none - but these are working fine. When I now try to bleed the downstairs 3 water comes out but they are cold?? Am I missing something?? Any advice greatly appreciated on this cold wintery night!

If no air or water comes out when you bleed the upstairs rads, then there is not enough water in the system and an airlock has developed somewhere. If it is a sealed system, find the intake valve. If it is an open system, check the header tank for water, see if there is a valve on the pipe from the tank, or the pipe could be blocked by gunge.
Jim

skye

Hi guys,

Thanks for the help - ended up getting the plumber in - JamesM you were right - not enough water in the system, the plumber went into the hotpress and opened a valve - now in business fully working!!

Thanks again!!

lomb

aye that valve should never have been closed in the first place, it presurrises the system and compensates for water losses. with a lack of water u can cook the boiler and damage it.

JamesM

lomb wrote:

aye that valve should never have been closed in the first place, it presurrises the system and compensates for water losses. with a lack of water u can cook the boiler and damage it.

Lomb, a valve in the hotpress is not as simple as it sounds.
I remember in 1974, in a new house, a Dublin Co. Council inspector insisted that, not only should the valve be closed, but also that the pipe be disconnected. The reason was, that the non return valve might jam and let the contaminated water from the heating system back into the hot water system. The link then was taken from the hot water system. In 2005 the link is now sometimes taken from the mains. If this is so, leaving the valve open will mean that the pressure will be higher than the release pressure of the safety valve and that will mean that the safety valve will release water every time the heating is turned on. (water expands)
There is a pressure gauge on most systems. One should open the valve until the pressure rises to approx 1 bar (no big deal if it is a bit above or below) then shut of the valve. When cold the pressure will be less than when hot (water expands). If there are no leaks, checking the pressure every few months should be enough. If it is down open the valve and let in some more water.
Jim.

rooferPete

Hi JamesM,

I believe you would be going back to the days of building bye laws ? standards that were laid down and enforced, IMO a great system.

When the great rush for natural gas conversions was on, the standard you mention was enforced by taking out about 12" of pipe between the fittings.

It became part of the annual service to top up the system, and for all this time I thought it was the plumbers creating work, Thanks

.

JamesM

Pete, I spent half an hour composing that through a bottle of wine - you answer it in 5 mins

rooferPete

Sincerest Apologies James,

I hope you have a reserve bottle to hand ?

Shucks I answered nuthin, just made a small observation that would be known only to either the "Old School" practioner or the student.

And I is still learning

.

lomb

JamesM wrote:

the link is now sometimes taken from the mains. If this is so, leaving the valve open will mean that the pressure will be higher than the release pressure of the safety valve and that will mean that the safety valve will release water every time the heating is turned on. (water expands)

so what u are saying is that heating water will go back up the mains water pipe? what is the pressure of mains water? surely it must be higher than 1.2 bar as otherwise the heating wouldnt pressurise when hot to this level.
to be honest our heating has had the valve open for 15 years since the house was built sucessfully. why should i close it now?

JamesM

lomb wrote:

so what u are saying is that heating water will go back up the mains water pipe? what is the pressure of mains water? surely it must be higher than 1.2 bar as otherwise the heating wouldnt pressurise when hot to this level.
to be honest our heating has had the valve open for 15 years since the house was built sucessfully. why should i close it now?

I didn't explain clearly (blame the bottle of wine).
If the water supply is from the mains, the pressure of the mains water will bring the pressure in the heating system up too high. When the heating system is off at night the water cools and contracts. If the mains valve is open, it will take in extra water at mains pressure, which is quite high. Then in the morning when the system heats up, the hot water expands and blows the safety valve - hot water all over the place.
If the water supply is from the tank in the attic, usually branched off from the feed to the hot water cylinder, then there is not a lot of pressure in the feed to the heating system and there should be a non return valve fitted. This is to stop the dirty water from the heating system going back into the hot water system when the heat is turned on and the water in the heating system expands. If the non return valve fails (sticks open or something like that), the pressure in the heating system is higher than on the other side of the non return valve, so it is recommended that the valve be kept closed and only opened every so often to top up the system. (best done when the heat is off and the water has contracted)
Jim.

lomb

Thanks, i might consider closing it for safety.