My daughter has central heating with a boiler type doodah in the kitchen.
The pressure guage reads 0 which I'm guessing it should read about 1.5 ?
The gas is on, the boiler turns on, the display reads f.28 no hot water comes out of the taps and none of the heaters come on when you leave it on.
IS there anything else I can try or is it time for a plumber ?
(shes just moved in and was told it was working)
You'll have to re-pressurise the CH system, then bleed the air from the rads, not sure why she's not getting HW though
Ahh sounds a little complicated for me. Might be time for a heating engineer.
hmmm...
Is this something I could do, ... I can bleed radiators no problems, but not sure on pressursing the system. how exactly is that done ?
So the central heating circuit has lost pressure.
Yes. The boiler will refuse to run when there is no pressure in the system.
You need to find a filling loop, which might well be under the boiler. Typically a length of flexible hose (as in theory they're meant to be disconnected when not in use, but rarely are) connecting two of the pipes together, with a valve at one end.
Open the valve, you should hear rushing water and the gauge should rise. Refill it until the gauge is in the middle of its normal range (might have to do it in several "spurts" as the pressure equalises through the system). The boiler should then start when you open a hot tap; if it still shows that error try switching it off and on again first.
Be aware that if the system lost pressure down to zero all on its own, you might have a leak. If you need to do this at all regularly, investigate and fix the leak rather than continually topping up.
Pete
My combi boiler heats the CH water directly, and the HW via a second heat exchanger from the CH. If the CH pressure is down it won't fire up.
Pete
If the filling loop is fitted and working, it's not at all complicated. Trivial, in fact. See my other post.
You might not even need to do that. My central heating used to have a small leak, so the pressure went down and boiler cut out every couple of months or so. I never needed to bleed things when re-pressurising.
You shouldn't normally leave a system that needs continual topping up; I only did because I had some work on it planned anyway. It's fixed now.
Pete
If you look underneath the boiler you will see 5 pipes, gas, cold in, hot out, CH flow and CH return.....they may or may not be labelled, but the cold in is the only one you need to know about. There will be a link from your cold in, to either of the CH pipes, this allows you to re-pressurise the system, sometimes there's a ball valve, or a tap on a flexible pipe, and occasionally (worcester bosch for example) a plastic hexoganal key which is inserted and turned. pressurize up to 3 bar, then bleed all the rads, you may need to re-pressurize if they are all full of air. When you get water from all bleed valves, make sure the pressure is between
1.5 -2 bar and fire up the system (turn it off before you start or it might fire up when you re-pressurize the first time)Phil L wrote on 08/12/2009 :
Some boilers need a special plastic 'key' to be inserted (which completes the water connection), to enable it to be repressurised.
and the leak may not be at all obvious. Some can be quite difficult to trace.
If you have bleed the rads then you have probably released the pressure.
I have read the other posts and they aren't very clear to me.
Many systems have a filler loop. It is a flexible tube, it fits between a valve on the CH flow/return and on the cold water mains and usually just screws on. Then you open the valve on the mains and then slowly open the valve on the other end to let the water in, the gauge should rise, stop when up to pressure and close both valves. Then bleed the rads and repeat as required. If it doesn't have a loop you will need to RTFM. or post back.
PS you may need a screwdriver to open the valves.
Because a combi relies on water in the heat exchanger to run. Repressurise the CH system and it will fire, provided there isn't a leak that depressurises it like mine :-(
Tell me about it. Mine is 'somewhere' under the floor...
In message , Joseph Craine writes
She has a leak ...
refill it (do you know where the filling loop is?) and go and hunt for the leak in the pipework, at the radiators, in the boiler
Why pay a plumber money to do something which you can just as well do yourself ?
Drain it down and pressurise it with air - the air will escape faster than the water and you be able to hear it.
Dumb question from someone who has never had a combi (spawn of the devil) or a pressurised primary system.
With a sealed system that has lost pressure how does any air get in?
As another who has never had either a combi or a pressurised primary I have assumed that there is always a certain amount of air in the water. Fill up and you can't avoid adding some air.
When I drain mine I can hear air being drawn in via the auto bleed valves. In normal use when the pressure drops it isn't enough to let air in.
Through leaks, such as the one where the pressure was lost from. Air actually leaks in through leaks even when the system is under pressure. (I described the process in detail in an old posting.)
Depending how quickly it leaks out again, she might want to challenge the assertion that the system is working, certainly if that was the basis on which she bought the house. Might be worth bouncing this off her solicitor in case it's something (s)he needs to raise quickly. (Raising it in a few days time may be too late to claim it wasn't working when you bought the house.)
Yes but once that has stabilised and been vented there shouldn't be anymore air in the system.
I'm surprised you can get radiators full of air though, a little air drawn in via the leak that let the prssure out I can understand but not radiators full. I guess if someone runs the system until it gives up the battle anything is possible.
It takes time of course. Venting air introduces more water into the system. But I agree neither this nor Andrews explanation seems sufficient for the large volumes of air you mention below. Could be hydrogen of course. :-)
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