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Corinda

Hi,

I've got an external Worcester Greenstar Heatslave combi, installed just over three years ago, regularly serviced, never given any trouble, though .there was a small leak recently due to a pipe/washer/nut coming loose. That was tightened up and the leak stopped.

I have two questions about the internal pressure gauge (ie the one under my kitchen sink that I never look at as often as I should).

(a) There are two black switches (probably the wrong name, but hopefully you'll know what I mean). These are to flick one way or the other so as to increase the pressure if it drops. The one on the left points directly up (ie towards the ceiling - or 12 o'clock). It's the one on the right that I'm not a hundred per cent sure about. Should it point towards the right? (Ie as if the big hand on a clock was pointing towards '3'.) I'm guessing so, as I made a note when the system was installed that if I wanted to alter the pressure, I turned the one on the right towards the left (which would effectively mean down, or the big hand pointing to '6' on a clock), then opened up the one on the left. (Or should the one on the right point down and my note should have read, turn to the right - or 'up'?)

For some reason, I thought the one on the right should point down, but then I couldn't turn it to the left, so I'm probably wrong. (And/or confused!)

The second question relates to fluctuating pressure.

(b) The gauge is set to 1.5 bar. I check it from time to time and it's generally OK. If not, I top it up. However, I'm fairly sure I've never checked it while the central heating is on. (The hot water is permanently on.) Is it normal for the pressure to rise quite a bit when the heating is on? I ask because I've just checked and see that it goes up to about 2.5 bar (and, on one occasion, even closer to 3, though not over).

I wasn't sure if there may be a problem with the boiler, or whether what I've seen is normal.

Hope I've made everything clear - and haven;t got all my rights and lefts the wrong way round.

Any help much appreciated - even if it's 'call a plumber'!

Thanks,

James
 
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Re: Worcester Greenstar Combi Pressure gauge

which ever way the pipe is going say its going horizontal, the valve would be vertical when closed, if the pipe is vertical the valve will be horizontal when closed, and when open it will be in line with the pipe.

your pressure should be sitting at 1-1.5bar when cold, and when heated it should rise to around 2bar there abouts, if it is reaching nearer 3 bar then i would suggest your expansion vessel may need recharged.
 
The black "switches" are taps and are part of the "filling loop".

In case you don't know, the heating system requires water and when you bleed a radiator the pressure of the system drops so you fill it with more water via this filling loop.

They're off when one or both are at 90 degrees to the pipework. To fill the system with more water both need to be in line with the pipework. Best practice to turn them both off when you're not filling the system.

With regards to the pressure, at cold should be a little above 1 bar and normally rises to around 1.5 bar.

The large red container in the boiler is the expansion vessel. This has a diaphram in it and contains air and water. As the water heats and expands the pressure rises and the air fights this pressure to keep things hunky dory.

I'd suggest you keep looking at it and if it approaches 3 bar then call your boiler man out and tell him about it. It could mean a new expansion vessel or it could be that no one's topped the air up for a few years and all it requires is a little more air.
 
Gosh, that was quick. Many thanks. By now you will probably have seen that I managed to mess up and repeat the original post - though I was deleting the content of this one while you were being kind enough to reply. Sorry to anyone and everyone for any confusion I've caused.

I'll do as you suggest and keep monitoring things. Thanks again.
 
Ok, the valve handles will be open if they are in the same orientation as the pipework they are connected to, if they are at 90 to the pipe then they are closed. When you top up the pressure you are opening the mains cold water valve and the central heating pipework casing water to flow into the heating system. When you close these valves the pressure should stop rising. I wouldn't get too excited about them, as long as the valve handles are at 90' to the pipework (i.e.across).
The second question, yes it is the norm for a slight pressure increase as the heating system heats up. This is due to water expansion which is partially taken up by a vessel containing a charged bladder within your boiler known as an expansion vessel. If this loses its charge then the water has no room to expand so there pressure rises rapidly. If it approaches 3bar the PRV (pressure relief valve - a safety device) will be ready to lift and relieve the system pressure (outside if the pipework has been correctly installed).
From what you are saying it is possible that some of the charge has been lost, it may be advisable to get it checked the next time you are getting the boiler serviced.
 
Perhaps it's simply that you're quicker at plumbing and I'm quicker at typing?

bouncy1.gif
 
Again, many thanks for all the replies - and for whoever was able to sort out my duplication of posts! (Which came about because I saw I'd mis-spelt 'pressure' in the heading and wanted to change it. I should have left well alone!)

I obviously made a mistake when I made my original note about how to increase the pressure, as the tap on the right would have had to run in the same direction as the pipe for my instruction to work. But I realise now, from what has been said, that that is the 'open' position. So it needs to be pointing down (which would place it at a 90 degree angle).

It may be that I've always had it in that position, but after fiddling with the taps a few times recently, I was no longer sure about anything.

I'll keep an eye on things and keep my fingers crossed there is no problem - but thanks to everyone for your replies which have all been very clear and helpful. I hardly know one end of a tap from the other - so it's great to be able to ask questions on a forum like this.

I appreciate, too, that people with this sort of knowledge are kind enough to take the time to help out idiots like me. :)

All the best - until my next problem!

James
 
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