Hi. I've just had a quote from a plumber for a new gas boiler. I don't
understand much about the ins and outs of central heating, so apologies
for any vagueness.

We have an old gravity fed system which we wish to replace with a
combi. He told us the tanks need to come out, some earthing work is
required and the total price for labour and the boiler is £1760. ( It
seems he has a fixed price ) The boiler is a Baxi and that alone will
account for £1050 of the £1760. I believe he said it was a 80,000 btu
boiler. It will also be powering 11 radiators in a small traditional
victorian terrace.

This is the crux, is this claim he made true: "Hot water pressure will
be close to mains cold pressure. You'll have a great shower with a heat
regulator, so the heat and pressure will be constant even when the
heating is on or whatever." To demonstrate, he turned on a cold and a
hot water tap ( from existing tank ) and said the pressure would be
somewhere between the two in the new system.

The shower and labour would cost an additional £190. From what friends
with combis tell me, I was under the impression that the heat output
from the shower would jump all over the place as people turn on and off
taps elsewhere in the house. I had been planning on a 10.8kw electric
shower, but he said it was pointless.

Also, he recommended the radiators be changed as they are 20-30 years
old. He said he could flush them out with chemicals, but it wasn't
ideal. Without measuring, he quoted roughly £1000 for the new
radiators and installation.

Many thanks in advance. Any advice is greatly appreciated. Cheers.