Woke up to find no hot water or central heating. The night before I jhad gone around venting every radiator just before the system was due to turn off. Could that have caused it?
Anyway, our fabulous Polish plumber talked me through opning up the valves that enabled the pressure to rise before pressing the firing button.
Before I started the screen showed 0.1 bar. He told me to turn them off when the pressure was above 4.0 bar. It did the trick but why had it dropped in the first place? Woud my venting have caused it? :(
1 to 1.5 bar would be plenty on a cold system. 4 Bar is likely more than the emergency relief pressure relief vale is set to. So you will probably have already lost some water out of the blow off pipe. You certainly will lose more when it gets hot.
I would get a tray under a rad, and crack open one of the nuts on the radiator tails, to drain off some water and lower the pressure.
(It is better not to activate the PRV in the boiler since there is a danger it might not reseat correctly and then let by a bit - that will cause ongoing pressure loss problems)
Chances are it had just about the right amount of pressure in it when cold. Normally it will be set to a bit over 1 bar. As it warms up that will rise to 2 to 3 bar typically.
When you bled the system you dropped the pressure. However because it was hot, it stayed above the pressure that would cause the boiler to lock out due to low system pressure. However once it had called, it will have fallen to below the minimum and caused the lockout.
With a sealed system you can generally get away with bleeding a little bit, and then going back and topping up. This needs to be done when its cold however to properly see the effect you are having. If bleeding lots, or refilling a whole system, then it helps to have someone else watching the gauge, and topping up each time it falls. Otherwise you are in for lots of walking back and forth!
Far from it. There is a pressure limiter and meter on the system. There had to be because our external water pressure is 6.1 bar.
I neglected to mention that as the boiler fired up, the pressure dropped until it was at the pre-planned level. The reason that I neglected to mention it is that my question was about what caused the problem in the first place.
Thank you to everyone that explained.
There was an upside to this. The tiny radiator in our 'guest' loo has been hot since yesterday. The first time since it was installed to my knowledge.
I think every householder should be given in writing information about the electrics, plumbing and drainage to and from their home in a readable. That would prevent them wasting a lot of professional's time with daft questions, like the one I asked.
Yes. But I'd be concerned as to why every rad needed bleeding.
You mean the cold water feed into the system?
If doing this cold, I'd start off low. Say one bar. Then check again hot. Higher pressure than needed for it to work normally is pointless, and may cause problems.
Thinking about all the bits of knowledge that I have about the house and its basic operation, it struck me that my partner, who is significantly younger, and therefore more likely to have to cope with it all sometime, would know little about it.
I have begun a "Home Manual" in which I give details, some with photos, showing stop taps and isolators, fused spurs (a surprising number, and not all in obvious positions), heating system, changing downlights, computer setups and backup processes, and so forth.
I have also gathered together in a binder as many relevant instruction manuals as I can find about the house.
If you think there might be air at thetop , hold the top when tehsystem starts up. Initially, if there's air the top won't get warm, but will by conduction in the metal if you leave it too long.
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