Ed Sirett wrote:
On Sat, 04 Nov 2006 16:25:06 +0000, Tim wrote:

Ed Sirett wrote
Tim wrote:

This year the system is generating hot water and hot radiators. But
something is wrong because in CH mode the boiler often fires up, runs for
between a minute and 10 minutes, shuts down, waits for around 30 secs,
fires
up, ... The pump keeps running even when the burner shuts down. And in
hot
water mode the burner seems to shut down at random unless I keep the tap
very open.
The boiler runs until the water in the radiators is warm (this can be
quite a short while - 10 mins) for a combi boiler in a smallish flat.
Afterwards the burner fires only when the water temperature falls.

The more recent and sophisticated models usually insert a delaying
mechanism to prevent 'short cycling' as you describe.
Thanks, Ed. This is a 6-bed house so the burner should keep on trucking for
a while. The key symptom is probably losing hot water unless the tap is very
open. I'll muse on this, then post a search for a recommended heating guy in
Felixstowe, Suffolk.


I tend to make the assumption that combi boilers are not (arguably
shouldn't be) usually fitted to 6 bed houses.

The symptom you describe is almost always due to some failure of the water
flow detector. I'm not familiar with this model but very often this is a
rubber diaphragm which has a small tear in it.

you could probably get away, as ed said, with a new rubber and seal kit
for the diverter valve. although i have seen the microswitch on an
ariston boiler bieng the problem. DO check the seal kit for damage
before fitting as i have renewed them only to find it was split when
purchased.

hth