Potterton Suprima 60 and CH problem

[hisnibbs]

Hi there, thanks for reading, any advice is greatfully received, and apologies in advance for any non-techinical mis naming!

OK, Potterton Suprima 60 and a closed loop system 2 bed house 7 rads.

Pressure varies from zero to 3 bar, which means I am constantly fiddling with the pressure relief valve and from what I read here that leads to the valve leaking (a vicious circle).
I have had two fill loop ball valves and a pressure relief valve in the past two years.
I've had this problem before and it went away when I changed the valves but it's doing it again and I am not sure why I am getting the same problem, could it be I am missing the bigger picture?
The brown stain down the wall is just so unsightly and getting worse!

Sometimes the system is at zero pressure and I have to re-pressurise and then other days it goes up to 3 Bar and the pressure relief valve does it's job. Other times it sits normal pressure but the pressure relief valve still leaks a bit.

Add to that the new problem whih started a few days ago, the humming/vibration through the house which wakes me but leaves everyone else asleep!!!

Also one rad in the back bedroom stays cold sometimes but not all the time.

So, having bled the system and got little air out what can I do to reduce the humming/vibration? This doesn't seem to be the pump which is running very quitely.

Can anyone suggest a supplier or make of valves to look out for to avoid this problem. I bought both from a local trade supplier who has a good reputation. Have I just been unlucky in needing 2 ball valves and a pressure relief valve in the past 2 years and both now need replacing again? Or is that a normal situation/running cost?

What order do I bleed the rads? I started furthest away downstairs and worked my way towards the boiler going upstairs. That didn't help, I then did the reverse, that didn't help. I then did random radiators that didn't help. Any sugestions?

OK, thanks for reading and I hope there is enough in the post to help you help me. And apologies for the rambling nature of this post and any typos, I've been up since 4.28 with less than 5 hours sleep, uggghhh.

 

[chrishutt]

could it be I am missing the bigger picture?

Yes.

The root of the pressure problem is that your expansion vessel (big red thing) needs recharging or replacing. There's lots of threads on this,, as well as a section in the Plumbing Tips (FAQ) topic and maybe the Wiki.

Basically the expansion (pressure) vessel should have a pre-charge pressure of around 0.8 bar (set with the system pressure at 0). Then the system is pressurised to 1.0 bar or so. As the water is heated the expansion is then accommodated by the compression of the air in the expansion vessel while the pressure remains at only a little over 1.0 bar (say 1.5 bar).

A pity you've never called in a competent heating engineer, who would have diagnosed the problem straight away.

 

[hisnibbs]

Chrishutt many thanks for that, if it turns out to be the red pressure vessel what sort of price am I looking at to replace it? Parts, Labour and Vat? Ballpark would be useful.

 

[chrishutt]

It depends.....the existing vessel may simply need recharging, which might take half an hour. On the other hand it may need replacing, in which case the cheapest option is to fit a generic expansion vessel externally to the boiler, which might cost £150ish.

But first you have to find a competent heating engineer who understands how these things work - not easy. Don't rely on Corgi registration as evidence of this - it means very little beyond strictly gas safety issues. Best to describe your symptoms and then see if the "engineer" can offer an explanation like mine above .

 

[ChrisR]

NB ChrisH it's a Suprima

it will have a generic external PV already, which makes them quicker to check, usually, and easier to change if it IS faulty.