Help With Boiler Output

[Captain Haddock]

Ok my other post regarding a shot Keston 80 has revealed the HE has a hole in it. My dilemma here is should I replace the HE (DIY) or get another new boiler. The engineer today said the HE would be bout £450 and 4 hours labour + flush through.
If I get a new one, I will reposition it into the garage, so the 4" vent doesn't plume by our kitchen window.
How do I calculate the necessary boiler output for the size of property, and should I go down the much trumpeted Vailliant road?
If I do a power flush which machine is best, one that fits around the pump connections or one that goes on the radiator valves.
Thanks.

 

[simond]

I should get rid of the Keston, never a bad move.

Vaillant are a good choice, but none of the German brands have any major problems compared to the opposition.

Power flushing can be attached wherever it suits. Size the boiler using the calculator at www.sedbuk.com

 

[gas4you]

80,000 = 24Kw. If you have been happy with the Keston output you can keep the same, unless you are planning any extra rooms.

Vaillant do a pluming kit as well.