On 01/10/2020 08:58, charles wrote:
In article ,
John Rumm wrote:
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.

It will tell you the size of the inlet, but can't realistically tell you
exactly what you need unless it also knows the length of pipe, the
configuration, and the demands of other gas using appliances.

(basically it would need to reproduce large swathes of BS 6891
"Installation of low pressure gas pipework of up to 35 mm (R1¼) in
domestic premises (2nd family gas) ˜ Specification" to give an
adequately complete answer[1]

(and 75kW is beyond the maximum output of a domestic U6 meter - so


when we bought this house it had no gas supply. It had once, but all pipes
and the meter had been removed. The new supply and was fitted for a "Boiler
exchange" scheme run by British gas.. I assume they knew what they were
doing.

They probably fitted a "bigger" meter - i.e. one more typically used in
small commercial applications.

The normal U6 can do up to about 65kW or 6 m^3/hour. The next one up is
a U16 which will do 173kW or getting on for 16m^3/hour.

What model boiler is it out of interest?


--
Cheers,

John.

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