On Fri, 26 Apr 2019 11:42:23 +0100, Robin wrote:

We're (still) looking at a new boiler so I'm watching with
interest but thought I'd flag up the issue of guarantees: they
vary enormously but it's hard to judge their value. Eg Vaillant
offer on some boilers 10 years if fitted with a "protection kit"
and serviced annually.

Same guarantee offer here (10yrs) from local supplier/installer
provided we service every year. We have a 40kW WB combi and I
wouldn't get another one - there's an annoying interaction between
the HW and CH that makes for showers running hot or cold for a while
when starting up, no probs in summertime with no CH demand. Even the
wB helpline people only offer the usual "it's because there's
storage in the pipes..." etc, overlooking the fact that it all works
well in summertime. It's also more noisy than I expected, which
might be a prob if the room it's in was occupied at night.