Alphacd35c

[Bruce70]

Hello ,I have an alpha cd35c combi boiler fitted with alpha gas save unit. It is 5 years old and under an ;8 year warranty subject to annual servicing by alpha installer. All services have been carried out. The boiler works well apart from persistent de pr essuring problems. This has happened from new and always happens with the first cold weather usually in October. It is easily re pressurised. The time between re pressuring reduces with each re pressuring from about 10 days to about every 2 days. In spring 2016 a new expansion chamber, pressure valve and filler loop were fitted. It worked perfectly from then until the end of October but is now needing re pressuring every 2 days. Over the years occasional leak sealer has been added to the system . There are no obvious leaks on radiators etc. I have also noted that when I 're pressure to the green when the boiler is working the pressure is quickly up to the red zone. Any ideas ?

 

[Bruce70]

Further to above problems with alpha cd35 c boiler. The boiler is located in an unheated garage. This weeks minus temperatures and boiler de pressured overnight. This has gone on for 6 years and installers regularly change boiler parts or 're charge expansion chamber - but winter starts and pressure issues start again . As this seems to be a cold v weather issue could there be an underground leak or would that be ruled out by lack of problems in summer ? If all else fails what are the options for a non combination system? The house is a 3 bedroom bungalow built I 1960 but much developed and extended over the years. The original water tanks are still in the loft but we have had combis for over 20 years.

 

[snb]

how many rads on the system. as the problems only occur when you have the heating it suggests that your expansion vessel fitted to the boiler is too small for your system.

most alpha boilers suggest that if the system holds more than 80lt of water then it would need an additional expansion vessel

 

[Bruce70]

Thanks for that. 12 radiators and a heated towel rail. The real problems always start as soon as colder temperatures start. During the summer we always have rads on in bathroom and en suite and probably a small number of the other radiators - we live in northumberland so not too hot here . I am pretty sure the existing expansion chamber needs to be pumped up and an engineer is coming on Tuesday. I will discuss the possibility of an additional vessel. Again thanks for your advice
.

 

[Bruce70]

Do you think I should have an additional expansion vessel or replace the current vessel with a much larger one? What size do you suggest. Thanks