On 30/09/2020 21:20, charles wrote:
In article 2020093020352434361-nospam@nospamcom,
John Smith wrote:
On 2020-09-30 18:58:53 +0000, John Rumm said:

With modern modulating boilers that is less of a problem in the past. A
boiler with a wide modulation range is also desirable. The Vaillant
24kW models often go do to around 6kW.

John, thanks for your suggesting about the PCBs but at 20 years old I
think it's time to replace the whole thing and also it will be quicker.

One possible problem regarding rating and the way new boilers work -
our gas supply pipe to the current boiler is 15mm - is this likely to
be a problem for a condensing system boiler - I know it would be for a
combi boiler. Maybe there is a ceiling on rating or some makers only
specify 22mm.

Digging up the kitchen floor is not a great option...

we have a 75kW boiler with a 22mm supply. The boiler specification sheet
should tell you the size of supply pipe needed.


Gulp. How big is your house ?. Surely anything over 38kW would
put you close to the limit of a domestic meter anyway and usually
need a 28mm supply.