F22 low water pressure

Merlin5

Merlin5

Merlin5

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Finchley, London
About 2 or 3 weeks ago, I got a flashing 'F22 Safety switch - off, Low Water Pressure' message on my Vaillant Ecotec 831 plus boiler. I re pressurised it using the two valve knobs underneath it. This morning I got the F22 message again and had to re pressurise it. It only takes a few seconds to do that but I'm wondering if there's an underlying cause for concern? I'm not seeing any leaks. My kitchen floor is all concrete and the pipes were laid in 2012 into the concrete.

When I re pressurised, I set it to 1.5 bar which was the recommended pressure on the youtube videos I watched. Turning the hot water on in the kitchen makes it go to 1.7 bar and then after turning the water off it settles back to 1.5. So I'm guessing that's ok.

I've got the central heating on now and it's showing 2.3 bar, but I'm not sure if it's meant to be higher with central heating. Or do the rads need bleeding and how would I do that?
 
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I presumed you didn't have the manual as you were looking on Youtube.
Personally I would prefer the manufacturer's instructions.
 
It could be that you over pressured it a little bit on the first fill up and the PRV has spit some of that water out. The cheap ones dont like doing that often and can then stick a bit in the open position and leak a bit. TVR`s can leak around the pin so check all the rads. If you have an unvented system with an attached hot water cylinder then you might have an issue with the expansion vessel and it might need to be re-pressured. Need a bit more info really.
 
Slade2 said:
It could be that you over pressured it a little bit on the first fill up and the PRV has spit some of that water out. The cheap ones dont like doing that often and can then stick a bit in the open position and leak a bit. TVR`s can leak around the pin so check all the rads. If you have an unvented system with an attached hot water cylinder then you might have an issue with the expansion vessel and it might need to be re-pressured. Need a bit more info really.
Click to expand...

Thanks Slade2. I'm not sure if I have an unvented system with an attached hot water cylinder, but having just watched a couple of videos, I agree with you about re-pressurising the expansion vessel as this was mentioned as a possible solution. What I'm wondering though is why the water pressure went so low in the first place even before I fixed it for the first time a few weeks ago.

I'm wondering if my radiators are causing the issue. The bar pressure this evening was showing 2.3 with the central heating on. I'm guessing that's too high and I'm assuming it should be at the 1.5 I set it at. I switched the central heating off to see what the pressure would be and eventually the display showed 1.5 bar which is what I set it at. Then putting the central heating on again the bar pressure went back up to 2.1. So maybe the radiators need bleeding and perhaps that would stop the F22 error? I've never bled them since they were installed in 2012.

One other thing. When the bar pressure is at 1.5, if I then turn the hot water on it goes up to between 1.7 and 1.9 bar. I believe it will always go up a bit but I don't know by how much is acceptable.
 
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If its over pressurised and activated the PRV then crap can get into the seal and it may be leaking. There may be a pipe leading outside from the PRV (Usually a "thingy with a red knobby thing on the end). It will be worth checking that.
 
mattyg said:
If its over pressurised and activated the PRV then crap can get into the seal and it may be leaking. There may be a pipe leading outside from the PRV (Usually a "thingy with a red knobby thing on the end). It will be worth checking that.
Click to expand...


Damn missed that advice 2 posts up/3 posts up
 
Merlin5 said:
Thanks Slade2. I'm not sure if I have an unvented system with an attached hot water cylinder, but having just watched a couple of videos, I agree with you about re-pressurising the expansion vessel as this was mentioned as a possible solution. What I'm wondering though is why the water pressure went so low in the first place even before I fixed it for the first time a few weeks ago.

I'm wondering if my radiators are causing the issue. The bar pressure this evening was showing 2.3 with the central heating on. I'm guessing that's too high and I'm assuming it should be at the 1.5 I set it at. I switched the central heating off to see what the pressure would be and eventually the display showed 1.5 bar which is what I set it at. Then putting the central heating on again the bar pressure went back up to 2.1. So maybe the radiators need bleeding and perhaps that would stop the F22 error? I've never bled them since they were installed in 2012.

One other thing. When the bar pressure is at 1.5, if I then turn the hot water on it goes up to between 1.7 and 1.9 bar. I believe it will always go up a bit but I don't know by how much is acceptable.
Click to expand...

You know how they work right? as water heats up it expands. This results in an increase in your boiler and pipes, said pipes and boiler can handle some of that pressure. If you have an unvented system the expansion vessel will expand and contract as the pressure goes up and down and the water heats and cools.

its working ok now then? check your rads, you will notice if they have air in them as when they are on they will have a cold zone which is the air. Start with the downstairs rads and start at the one furthest away from the boiler, then do the same upstairs, you should then be at the last highest rad which is normally a towel rail in the bathroom so check the top of that. Bleed them all (open the little tap at the top slowly, you should hear and even smell some air coming out, let the air out until its water and then close it off) and you should notice a drop in the pressure as you have left some of the air out!. if it drops to 1.5 you should be golden from then on.

If you keep having issues then you probably have a leak somewhere, be that in the expansion vessel, the PVR, one of the rads or a join on the pipe work somewhere.
 
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