Six months ago we had the open vented central heating system (powered by back boiler) in our 3-bedroom semi renewed. We had a Vaillant ecotec plus 831 combi boiler put in the kitchen, and this works very well apart from the pressure issue described here. At the same time all the radiators were replaced with new ones and all the downstairs pipework was renewed (I was concerned about several compression joints, which I installed under the floorboards several years ago, when I modified some of the pipework). Because the upstairs pipework is more difficult to access, I decided to leave this alone. The cold pressure drops at a rate of about 0.1 bar per week. This means I have to top up the system using the filling loop every few weeks. When the radiators are up to temperature (flow target=70 degrees), the pressure rises to 2.2 or 2.3 bar (which Vaillant assure me is normal), and it doesn't seem to make much difference what the pressure was when cold. The radiators have been bled, and are heating up all the way to the top. There is no sign of any leak on the radiators, valves or easily accessible pipework, and no evidence of dampness/staining on the ceilings. I don't want to use leak sealer because Vaillant have told me this will void their warranty (10 years!). What size of leak (i.e. amount of water loss) am I looking for? Any helpful ideas?
N
Newboy
A very small leak!
It might even be small enough and in such a location that it is evaporating off and hot pipe. It might be worth getting the installer back to check connections at the boiler.
It might even be small enough and in such a location that it is evaporating off and hot pipe. It might be worth getting the installer back to check connections at the boiler.
I'm planning to try to install a pair of isolation valves in the pipes which feed the upstairs radiators from the kitchen. I should then be able to establish whether the leak is upstairs (which would give me a real headache especially if iit turns out to be under the tiled bathroom floor) or if it is in the downstairs pipework (or boiler). I wondered about specialist leak detection companies, but I gather they may only be able to find bigger leaks (i.e losing pressure completely over a day or so)
small enough a leak to cause corrosion inside your radiators and block your plate heat exchanger and diverter valve and wreck your pump, and also require a magnaclean or similar, your boiler warranty will be voided by dirty water.
you shouldnt be refilling a sealed system more than once or twice a year. once its filled and bled it should be fine after a couple of months.
refilling constantly = fresh water +oxygen which = more corrosion= new boiler +rads+ a power flush etc etc etc .
Is it OK to use the Hot Water when the CH is isolated at the boiler?