Heating pressure question

StevenE

Before I call a plumber, I thought I would post here a problem that doesn't appear to be a problem.....

Okay, I will try to explain, as again, I still cannot post pictures.

I am in temporary accommodation that has a Grant Boiler Room Condensing Boiler that heats a copper cylinder for hot water and radiators. There is a tank in the loft. The property is a bungalow. The hot water and heating is on a controller and everything works as it should, apart from a motorised valve that had fallen off the pipe as the fitter hadn't secured the electric part to the backplate which I refitted and now the heating turns on and off with the controller.

I bled the rads, some of which were stone cold, others half cold and now all are quite reasonable. I did not repressurise the system after doing this.

So, the problem: There is a gauge fitted to the system, and a gadget that I have tracked down to possibly be an automatic pressure regulator (seems these are frowned upon, but this isn't my property so not something I can change)? The gauge shows zero.

There is a tap/valve fitted to this regulator. It is currently closed. Opening it does nothing to the pressure, boiler running or not, regulator tap open or closed, nothing increases the reading on the gauge, and there doesn't appear to be a second valve on that line, so.....

Regulator open or closed?
Pressure gauge faulty?

Any other checks or tests I can do myself before I call the plumber!

jca

I'd say the filling valve is stuck. On the valve there is a screw in the centre for adjusting the pressure, this screw acts on a spring, with a small screwdriver press down gently on this screw. DO NOT push the screw down too far or it can go over to one side inside the valve and water can pour in unregulated. If you unstick the valve you will hear the water entering the system, watch the gauge carefully to make sure the flow slows off as the pressure rises.

StevenE

I had a look and cannot see a screw. I am a bit nervous poking around, so have an image of the device. I am fairly sure this is the thing stopping the system pressurising, but from what I read, the heating shouldn't be working with no pressure....but it is?

fullsizeoutput_20a by Steven Erridge, on Flickr

jca

The adjusting screw is in the centre of the upside down black plastic piece. I'm assuming you've the tap on top fully open anticlockwise.

StevenE

It was fully off/closed. I didn't want to open it without knowing I should. Up to now I've only lived with electric storage heaters so this is all very new to me.
I opened the valve, but nothing moved. I gave the screw a push, but again, nothing. I gave the screw a half-turn in both directions in case it sorted it out, carefully returning it to the same position, nothing. I still am not convinced the gauge might just be faulty, but bleeding the system makes me think I must have at least lowered the pressure.

Is it time to call a plumber?

StevenE

Just been back to the hot press to find the gauge now reading about 0.7 bar. Perhaps it simply took longer to fill than I expected.

From what I read, 0.7 bar seems to be about right for this boiler?

Though I will be checking regularly to see it doesn't keep going up, I am concerned the valve was closed because it was faulty, being the eternal pessimist I always expect the worst!

Thanks for the advice jca, much appreciated.

jca

0.7 would be the minimum. If it rises to 1.0 I'd turn it off and leave it at that. I'd share your pessimism and wager the valve is knackered and that's why the supply is turned off. Are the rads heating now?

Pete67

You would be better off leaving it turned off except when topping up. If you leave it permanently on you will never know if there is a leak somewhere.

clintondaly

The topup is usually a connection to the mains feed and when it goes so low and you open the valve you should hear a rush of water.
Pressure should usually be about 1.5 bar and valve should be closed after top up so as not to have a constant pressure on the system,however most have an overflow out the side of the boiler to an external overflow pipe,just like the tank in the attic.

StevenE

Thanks to all for the advice.

As I said I would, I rechecked half an hour later and it had reached 0.9 BAR. So I have, as you both suggested, turned the valve off. I will check again when I power the system on again (too hot today) and make sure it doesn't rise further. If it does, I think the rads could do with a second check as some of them were still not getting as hot as they should throughout the area of the radiator, that should reduce the pressure (I am guessing).

Its good to learn about these things. I am in the process of buying a house that is at first fix, and I have to employ a plumber to install a complete system, having some basic knowledge can only help with its overall maintenance in the years following, the interweb is a wonderful place to learn, and you guys rock!

Pete67

The pressure should rise when the system is hot, and drop back down when it is cold. Somewhere between 1 and 1.5 bar cold rising to 2 or max 2.5 hot would be normal.

StevenE

Thank you Pete67, again, shows how much I don't know, I didn't know that!

StevenE

Though I am curious to understand why the heating was still working with zero pressure showing hot and cold. I thought these boilers were supposed to cease working with too low pressure?