Central heating pressure loss problem

steveandel

My grandparents are having a major headache with their heating. They bought the bungalow recently and have had the following work done:

• The previous system was removed - the CF wall boiler, flue, cylinder, expansion tank and pipes not in use, lounge radiator rear the kitchen and capped pipes close to the floor.
• New Worcester Greenstar 25si combi boiler installed on 11 July.
• Power flush 14 July.
• Checked 25 August
• Boiler topped up (repressurised) 1 September as pressure dropped
• Pressure dropped 7 September - heating engineer called and they suggested there may be a leak
• Pressure down to zero 16 September
• Heating engineer isolated boiler, left on 1.5bar 19 September
• Boiler remains 1.5 bar 20 September
• Heating engineer checked on 23 September, no change in pressure, advised not boiler problem.
• Trace and Access specialist (ADI Leak Detection) - repressurised boiler, traced pipework using thermal camera, no problems detected. Drained system and pressurised with tracer gases at 2.5 bar for over an hour. Found no drop in pressure. Checked radiators and found most loose and new radiator very loose on fittings so they tightened them. Refilled system. Inhibitor and Leak seal re-added to system.
• 30 September Worcester Bosch engineer - switched off central heating section, to check pressure - isolated boiler, pressure did not drop over 3 days. Unable to check entire boiler as part of kitchen needed to be removed for access.
• Worcester engineer revisted 4 October - fitted new heat cell to eliminate boiler from pressure loss on system, had boiler on test for 4 days, no drop. Checked expansion vessel and P.R.V all ok. Pressure left at 1.5 bar.
• By 5 October the pressure had dropped right down to the red section, by 6 October it was back at zero (previously pressure dropping over 3/4 days).
  

Does anyone have any ideas please as we're running out of ideas and this has been going on a long time now?!:( There are no obvious damp areas or leaks but all the pipes are beneath the concrete screed floors. Shouldn't the leak detection have found any leak if there was one and it was done properly? Has anyone got any experience of the company used (www.adileakdetection.co.uk)?
There were a couple of replacement radiators installed with the new boiler but 5 existing ones remain.

Thanks in advance!

teagan1966

hi
i know it doesnt help but my boiler does the same , i just repressure it myself now !
mine is the same make as urs so im not sure if thats anything to do with it , but if i bleed the rads all the pressure goes st8way and they seem to need bleeding a lot aswell
im lucky that i have a council house and i can get them to look at my heating if i have a problem
maybe its just the type of boiler that is used

gas4you

Has anyone checked the expansion vessel pressure throughout all this?

This being flat would only give the pressure loss when the boiler/heating is on and not whilst standing there isolated under test.

Never assume an expansion vessel in a new boiler has been pressurised properly in the first place.

Canucklehead

Hi.

Are there any external drain off points sticking out of the wall, hidden by plants, earth or paving?


GSR.

nickj_2

don't know if i've got the 25i but my worcester greenstar does the same , tkaes about 3-4 weeks to lose all presure , i just refill it

gas4you

nickj wrote: »

don't know if i've got the 25i but my worcester greenstar does the same , tkaes about 3-4 weeks to lose all presure , i just refill it

Trouble with doing that all the time is that you are putting fresh water into the system constantly so will have no inhibitor left in it to protect it and corrosion will be accelerated.

The cause of the pressure leak should really be found asap.

Plenty of threads in here about things you can check yourself.

de1amo

how long have the pipes been under the screed!-i had a new combi fitted and suffered endless down pressuring and it wasnt resolved until the flat below eventualy got a stain on their celing--the pipes had been under the screed for 30 years(but chromium)--had to replace with above surfice ones and never had another problem

irnbru_2

de1amo wrote: »

how long have the pipes been under the screed!

Presumably the thermal camera would detect the leakage to screed?

steveandel

irnbru wrote: »

Presumably the thermal camera would detect the leakage to screed?

You'd have thought so wouldn't you but not sure how well the leak detection was done now hence my query as to whether anyone had used the company before. We have now managed to borrow some damp probes which seem to have detected an area of damp in one of the bedroom floors, even though there are no visible signs of damage. That's the next area for investigation I think!