My Ferroli Domina combi is 3 years old and has worked well except that the
ignition gap has to be adjusted every Autumn.

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.

My thoughts were no use:

1. Maybe the ignition gap has closed. No real reason for this because the
symptoms are that the boiler totally refuses to fire up, but it has happened
every year.

2. Maybe a bird's nest in the flue ;-) I've seen boilers fire up and down if
the flue isn't installed correctly and the waste gases get back into the
inlet.

Any ideas where I should look next?

Thanks
Tim

On Sat, 04 Nov 2006 11:56:07 +0000, Tim wrote:

My Ferroli Domina combi is 3 years old and has worked well except that the
ignition gap has to be adjusted every Autumn.

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.

My thoughts were no use:

1. Maybe the ignition gap has closed. No real reason for this because the
symptoms are that the boiler totally refuses to fire up, but it has happened
every year.

2. Maybe a bird's nest in the flue ;-) I've seen boilers fire up and down if
the flue isn't installed correctly and the waste gases get back into the
inlet.

Any ideas where I should look next?


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.

If you are in any doubt as to whether the boiler is operating correctly or
not you should get in some professional help.

A bird's nest would so block the flue that it wouldn't fire at all.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

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.

Tim

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.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

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

Ed Siret wrote

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

Interesting. It worked just fine until it stopped working just fine ;-) And
most of the bedrooms are for children who left home ages ago, so the heating
is rarely running hard.

But what do you think is best for these three-floor+basement Victorian
semis?


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.

Thanks. I'll investigate withe Ferroli service and report back.

Tim

"Ed Sirett" wrote in message
news
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.

You should never assume. The CH side may be more than adequate to cope. If
the DHW is one bathroom then a good medium flow combi is fine. Then again
two bathroom models are arounmd that can cope with DHW and CH too.

In message , Tim
writes
My Ferroli Domina combi is 3 years old and has worked well except that the
ignition gap has to be adjusted every Autumn.

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.

My thoughts were no use:

1. Maybe the ignition gap has closed. No real reason for this because the
symptoms are that the boiler totally refuses to fire up, but it has happened
every year.

2. Maybe a bird's nest in the flue ;-) I've seen boilers fire up and down if
the flue isn't installed correctly and the waste gases get back into the
inlet.

Any ideas where I should look next?

Yellow pages - you're way off mark

pumps run on after the boiler has finished heating to disperse the heat
throughout the system You could have a flow switch problem which
accounts for the problem in DHW mode


--
geoff