a very small drop on my heating half a bar over 6 months

[mooey]

Hi I installed a full heating system last summer but seem to have a very small drop on my heating.before I fitted the boiler I tested all of the system at 4bar over 16 hours no drop but over 24 the needle moved just a touch.After going over every bit of pipework quite a few times and rads I have found nothing at all.there was a bit of pipework that was on the old system only about 3 meters of 15 but can t get to it as it is in some tiled boxing.so I cut some isolation valves in to that radiator before the boxing turned them off and still had a drop.dont really know what more I can do to find it.it is very very small.i had av at the top of the system but had isolation valves on them so turned them off to as it got to September I had to fit the boiler as the temp was dropping and the other half moaning it was getting cold.i have a combi in the kitchen the glow and return go up into the loft runs about 8 meters than drops down into my airing cupboard straight down underneath the floor than spreading out picking up 7 radiator s.its a mystery.its funny fitted loads of heating system and hardly ever had problems . typical doing mine this happens.

 

[ShaunCorbs]

Normal on a new system,

Normally allow 6 months for the water to settle and all the air to be purged

 

[Chuck]

fitted loads of heating system and hardly ever had problems . typical doing mine this happens.

Probably happens to all of them but your customers just top up per instructions and don't bother telling you.

For a typical sized house, the pressure drop corresponds to losing a couple of litres of volume from the water. Probably a combination of trapped air making its way to the auto vent valve, the chemical reaction of the passivating layer being formed in new copper pipework and/or dissolved air reacting with steel radiators. As ShaunCorbs says, this is par for the course and should settle down after 3-6 months of operation. If you've reused existing radiators check the lockshields for signs of leakage. Otherwise, top it up and see what happens over the next 6 months.

I assume that you flushed the new pipework to get rid of flux, etc. and dosed with inhibitor.

 

[Scott_D]

Have you got aavs on the system?

 

[mooey]

Probably happens to all of them but your customers just top up per instructions and don't bother telling you.

For a typical sized house, the pressure drop corresponds to losing a couple of litres of volume from the water. Probably a combination of trapped air making its way to the auto vent valve, the chemical reaction of the passivating layer being formed in new copper pipework and/or dissolved air reacting with steel radiators. As ShaunCorbs says, this is par for the course and should settle down after 3-6 months of operation. If you've reused existing radiators check the lockshields for signs of leakage. Otherwise, top it up and see what happens over the next 6 months.

I assume that you flushed the new pipework to get rid of flux, etc. and dosed with inhibitor.

Yes flushed the whole system and each new radiator individual flushed yes i do have avv s at in my loft but when i was testing they were isolated via to leaver valves inhibitor was put in as well