Here we go again.. Sealed system pressure loss when cold

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Ok. So, I've changed everything that might have been leaking, 3 way, pump and pump valves, pressure release valve.

There are no visible leaks. System losing 1-1.5 bar a day, including today with everything off.

Expansion vessel would cause over-pressure blow-off but not pressure loss when cold.

I wondered if it could be the indirect cylinder coil. My system water is so clear I doubt it would even discolour. Is it sufficient to isolate the cylinder via the return gate valve and the 3 way? Well, I did that and it still went down.

So I switched to HW only ... and it still went down. This suggests the 3 way isn't sufficient to shut off the system.

So now I think I have two options.

1) Install some more gate valves to fully isolate the cylinder coil
2) Install some more gate valves to fully isolate the ground floor rads which wouldn't you ff'ing know it run through concrete with tiled floor over the top
http://www.screwfix.com/p/pegler-ball-valve-red-22mm/45277

I don't see the point in a leak test and repair on the concreted pipes as it'll just go again. Of the options, then though I have no idea where the pipes would go, re-pipe seems to be the only way.

Out of interest, what would a ground floor re-pipe cost for 5 rads?

Any other sugggestions greatfully received but I guess this weekend I'll be draining again and installing 3 or 4 gates.

Cheers

:(
 
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Ok, that rules out an unseen leak through condensate pipe due to a leaking heat exchanger. Installing isolating valves is a way of checking the ground floor rads. Do not rely on zone valves as isolators, they are not 100% reliable.
Good luck. Cost of a repipe can vary, depending on many factors, so I would recommend an on site quote.
 
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Thanks. I figured not necessary to isolate boiler as would be able to tell leak at cold. At full temp could have been the exchanger I guess but not cold. Having said that fitter apparently didn't fit isolation valves for the boiler? But then he didn't for anything else so guess shouldn't be surprised.

If by some weird event its not the coil or ground floor rads then I might isolate the boiler too but I suspect is the rads, hope hope hope its the cylinder.

At least if its the rads can isolate over the summer and pretend its fine :D

Figuring 500-750 for repipe. Would consider doing myself but just can't visualise lots of nasty piping round the skirting or how it would get past fireplace / door frames???! Or would I dig some small channels in the floor for those bits -- WITH PROPER SERVICE VALVES AAAG.

Anybody got any pics of this kind of repipe would appreciate some inspiration.

Slightly more positive this morning. Was gutting last night to see the pressure dropped again. Ho hum!

Cheers!

:D
 
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Time to call in a fave from the bro in law methinks... quite handy with the spanners. Reckon we could smash this one out in a weekend.

:evil:
 
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When re piping, consider fitting rads back to back in adjoining rooms if convenient. It might mean altering rad positions but it does save on a drop for each rad and also saves copper. Normally, 2 rads off a 15 mm drop will work ok after balancing.
 
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Not much option to do that on the groundfloor - pretty compact layout. Would be an option to fit zoning though and proper TRVs which could be a bonus.
 
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