I have a Viessmann 35kw combi boiler with built in 40 litre storage tank, installed and fitted in Feb of this year. Had 3 additional radiators and 2 towel radiators added to the system in Sept as part of an extension build and part renovation of existing house.
Boiler pressure has been dropping from 1.5 bar to zero once or twice a day since we started using the heating in Oct. Homeserve came around and said its a boiler issue as I have a total of 14 radiators/towel radiators on the system and the boiler's pressure relief / expansion tank is insufficiently sized and need to get a new external vessel fitted. The next day I had Viessmann come and they checked the boiler thoroughly and said Homeserve was wrong and its not a boiler issue i.e. no water released in the PRV and that the internal expansion vessel is fine and can handle the 14 radiators - the expansion vessel also registered 0.8 bar.
Builders have come back to check the pipes and cannot locate any leaks in the new GF extension area or where we added new radiators. We have not seen any leaks on the first or second floor.
I have a leak detection company coming around on Mon am (covered through insurance), but Im just wondering if we've missed anything here.
I have to top up from zero pressure to about 1.5 bar at least once a day, but more likely twice a day. have tried using liquid that seals any leaks, but no use and that will have been diluted now due to the top ups. Could adding another expansion vessel really help and should I ignore what the viessman service engineer said? Problem is the condensing pipe is behind feeds a waste pipe behind the washing machine so I cannot determine if any excess pressure from the boiler is being released into it - but the viessman guy said that nothing was dripping when he was testing it with the heating system on (he opened the valve or top of condensing pipe from inside the boiler.
Boiler pressure has been dropping from 1.5 bar to zero once or twice a day since we started using the heating in Oct. Homeserve came around and said its a boiler issue as I have a total of 14 radiators/towel radiators on the system and the boiler's pressure relief / expansion tank is insufficiently sized and need to get a new external vessel fitted. The next day I had Viessmann come and they checked the boiler thoroughly and said Homeserve was wrong and its not a boiler issue i.e. no water released in the PRV and that the internal expansion vessel is fine and can handle the 14 radiators - the expansion vessel also registered 0.8 bar.
Builders have come back to check the pipes and cannot locate any leaks in the new GF extension area or where we added new radiators. We have not seen any leaks on the first or second floor.
I have a leak detection company coming around on Mon am (covered through insurance), but Im just wondering if we've missed anything here.
I have to top up from zero pressure to about 1.5 bar at least once a day, but more likely twice a day. have tried using liquid that seals any leaks, but no use and that will have been diluted now due to the top ups. Could adding another expansion vessel really help and should I ignore what the viessman service engineer said? Problem is the condensing pipe is behind feeds a waste pipe behind the washing machine so I cannot determine if any excess pressure from the boiler is being released into it - but the viessman guy said that nothing was dripping when he was testing it with the heating system on (he opened the valve or top of condensing pipe from inside the boiler.
