In message . com,
naffer writes
My boiler has started shutting down too soon. It runs for about 1 min
and then waits 5 mins to start again.

It's a Potterton Envoy 80. The three thermistors which check flow,
return and dry are all OK. The pump is running OK, too.

The result is that the rads warm up very slowly as a "plug" of heated
water circulates followed by tepid water as the boiler waits its
standard 5 mins.

Ideas?
Naffer

1) get another boiler

2) you have a blockage / pump problem
the heat is not getting out of the heat exchanger

--
geoff