Model Flamingo rs50
Fuel Type Gas
Boiler Type Conventional
Method Non-Condensing
Flue Type Room-Sealed
Fan No Fan
Output (kW) 13.5 - 13.5
Manufactured From/To Unknown - 1981
SAP seasonal efficiency 65%
Model Promax 24/2 HE Plus
Fuel Type Gas
Boiler Type Conventional
Method Condensing
Flue Type Room-Sealed
Fan Fan Assisted
Output (kW) 22.0 - 22.0
Manufactured From/To 2005 - current
SAP seasonal efficiency 90.9%
Judging from the comments on trade-related web sites if I were replacing my own Potterton boiler I would give serious consideration to a Worcester Bosch boiler (they all seem to like Worcester boilers) - I would be a little concerned because my gas supply is on a 15mm pipe and my belief is that it now needs to be 22mm - this would require digging up concrete floors and extra expense for me. I would never consider a combi boiler because I would lose the benefit of a hot water storage tank. I might consider an unvented system which might give me mains pressure hot water at all outlets still allow me stored hot water in the airing cupboard, the back-up of an immersion heater and the loss of the header tanks in the roof space - but more expense. A friend has just had a Worcester Greenstar 30 CDI & a stainless steel unvented tank installed in his 4 bedroomed house - it cost nearly £5k
My house is 4 beds with 17 radiators - the boiler is 23kW - your existing boiler seems both inefficient and under rated - the 22kW of the new one you propose appears much more realistic.
Good luck with your decision making...
Peccavi, November 2009
