I have a boiler that is a year old, and I cannot get temperatures at
home much above 18c (the old boiler was ok). I asked Potterton back to
inspect the boiler. They tested the temperature, found it ok (80c) and
said that I should keep it permanently on 'Max'.

The rooms are still nowhere near warm enough, even though the rads feel
hot. I have a boilerman in next week to give the first service. I
notice black sludge when bleeding so I am also going to ask him to
flush this out.

Problem is who do I contact to perform a survey on any heating loss.
The energy companies are only interested in selling you insulation. (I
already have loft insulation - not 10 inches though - and I think my
property is too old for cavity insulation (1920) also I believe that
the cavity is there for a purpose ie to prevent condensation).

Who should I contact to test for draughts, measure heat loss, generally
tell me what's wrong (I believe there is a thermal instrument that
they can use to determine problem areas??)

Any advice would be appreciated

Ross

On 23 Feb 2006 06:57:43 -0800, "Ross"
wrote:

I have a boiler that is a year old, and I cannot get temperatures at
home much above 18c (the old boiler was ok). I asked Potterton back to
inspect the boiler. They tested the temperature, found it ok (80c) and
said that I should keep it permanently on 'Max'.

The rooms are still nowhere near warm enough, even though the rads feel
hot. I have a boilerman in next week to give the first service. I
notice black sludge when bleeding so I am also going to ask him to
flush this out.

Problem is who do I contact to perform a survey on any heating loss.
The energy companies are only interested in selling you insulation. (I
already have loft insulation - not 10 inches though - and I think my
property is too old for cavity insulation (1920) also I believe that
the cavity is there for a purpose ie to prevent condensation).

Who should I contact to test for draughts, measure heat loss, generally
tell me what's wrong (I believe there is a thermal instrument that
they can use to determine problem areas??)


You could try the est.org.uk
Although they'll only be able to offer advice on things which
companies exist to do (loft, cavitys)

You have double glazing? Draft proofing?


Any advice would be appreciated

Ross

--
Get money off vouchers for everything
http://www.moneyoffvouchers.co.uk

On 23 Feb 2006 06:57:43 -0800, Ross wrote:

I have a boiler that is a year old, and I cannot get temperatures at
home much above 18c (the old boiler was ok).

Then the new boiler is too small.

--
Nigel M

Hi mogga - yes I have double glazing and some draft proofing. Also
looked on est.org. which will be good if I decide to increase my loft
insulation. I just feel there must be a professional company somewhere
that specialises in analysing why I get such low temperatures? I wonder
if the surveyor who checks homes when you buy a new house is the way to
go - I'm not sure

Sorry Nigel, should have said that the boilers are identical (50btu).
Strange though, this new one (Profile 50el) goes on and off every 3
minutes even though the temperature has nowhere near reached the main
thermostat (20c/21c). I asked the Potterton engineer if this was normal
and she said yes

Ross wrote:
Sorry Nigel, should have said that the boilers are identical (50btu).
Strange though, this new one (Profile 50el) goes on and off every 3
minutes even though the temperature has nowhere near reached the main
thermostat (20c/21c). I asked the Potterton engineer if this was
normal and she said yes

50 btu ? there's your problem :-)

even 50,000 btu seems a bit on the small side, even for a flat.

On Thu, 23 Feb 2006 15:20:07 +0000 Nigel Molesworth wrote :
I have a boiler that is a year old, and I cannot get temperatures
at home much above 18c (the old boiler was ok).

Then the new boiler is too small.

If the boiler is running continuously. If the boiler is cycling then
the radiator capacity is inadequate.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm
[Latest version QSEDBUK 1.12 released 8 Dec 2005]

What do you mean by cycling Tony?

On 23 Feb 2006 06:57:43 -0800, "Ross"
wrote:

I have a boiler that is a year old, and I cannot get temperatures at
home much above 18c (the old boiler was ok). I asked Potterton back to
inspect the boiler. They tested the temperature, found it ok (80c) and
said that I should keep it permanently on 'Max'.

The rooms are still nowhere near warm enough, even though the rads feel
hot. I have a boilerman in next week to give the first service. I
notice black sludge when bleeding so I am also going to ask him to
flush this out.

Problem is who do I contact to perform a survey on any heating loss.
The energy companies are only interested in selling you insulation. (I
already have loft insulation - not 10 inches though - and I think my
property is too old for cavity insulation (1920) also I believe that
the cavity is there for a purpose ie to prevent condensation).

Who should I contact to test for draughts, measure heat loss, generally
tell me what's wrong (I believe there is a thermal instrument that
they can use to determine problem areas??)

Any advice would be appreciated

Ross


Basically, if you are saying that the old boiler was OK and the new
one is not, it suggests that the radiator sizings are OK.

Had you said that the house had never been warm with the same set of
radiators, then one would need to do a heat loss survey. You could
do that quite easily yourself. The radiator companies have heat loss
programs for the PC which you can load and run. Basically you would
need to measure rooms and know the materials used for construction
(for example in your case probably double thickness solid brick
walls). You enter this data, plus measurements and desired
temperatures and it will give you a heatloss figure for each room.
From that, the radiators are sized and then the boiler.

If you want to do this, send me a mail and I can send you the Myson
calculator - it isn't on their web site right now.

However...... the fact that it *was* OK suggests one or more of a few
things.

- Boiler is smaller, but you said that both are 50,000 BTU models -
just under 15kW.

- Boiler is adjusted for too low a gas rate. A lot are range rated,
meaning that they can be adjusted to a fixed setting within a range.
The engineer can check this and adjust if it is the case

- Boiler has faulty thermostat. The return temperature should be
checked as well. For a flow of 80-82 degrees, the return should be
around 70 degrees. The fitter is correct that the thermostat should
be on max.

- System is sludged and flow rate is therefore inadequate.

- Pump has become faulty or is set too low.

I would look at these areas first.



--

..andy

On Thu, 23 Feb 2006 15:38:29 GMT, Tony Bryer
wrote:

On Thu, 23 Feb 2006 15:20:07 +0000 Nigel Molesworth wrote :
I have a boiler that is a year old, and I cannot get temperatures
at home much above 18c (the old boiler was ok).

Then the new boiler is too small.

If the boiler is running continuously. If the boiler is cycling then
the radiator capacity is inadequate.


Or the flow.....


--

..andy

Hi Andy - I do appreciate all your comments and am interested in your
Myson software. Problem is that I don't post very often, and am not
sure how to find your email address. I looked in your profile and the
bit after the '@' sign said 'hall'. Is that right? (PS mine isn't
teurosshence - thats a fake one I use to prevent spamming)

On 23 Feb 2006 08:06:25 -0800, "Ross"
wrote:

Hi Andy - I do appreciate all your comments and am interested in your
Myson software. Problem is that I don't post very often, and am not
sure how to find your email address. I looked in your profile and the
bit after the '@' sign said 'hall'. Is that right? (PS mine isn't
teurosshence - thats a fake one I use to prevent spamming)


OK. Send mail to andyh at hall dot gl


--

..andy

I sent you an email Andy - I hope that you received it. I put gl after
the dot, which wasn't in your profile

On 23 Feb 2006 09:16:56 -0800, "Ross"
wrote:

I sent you an email Andy - I hope that you received it. I put gl after
the dot, which wasn't in your profile


On its way.


As I say though, if it *was* working OK, then this is not going to
help much.

If you want to do another check, you could measure the CH return
temperature. If the flow rate is low, then the temperature is likely
to be low also.


--

..andy

That's what's puzzling in that the radiators feel very hot, but the
rooms don't. When I bleed the rad upstairs, the water is black, so it
would be great if having them flushed through would solve the problem.
The fact that the rads feel hot makes me doubtful. Thanks again for all
your input Andy - much appreciated.

On 23 Feb 2006 09:35:51 -0800, "Ross"
wrote:

That's what's puzzling in that the radiators feel very hot, but the
rooms don't. When I bleed the rad upstairs, the water is black, so it
would be great if having them flushed through would solve the problem.
The fact that the rads feel hot makes me doubtful. Thanks again for all
your input Andy - much appreciated.

You can check those points easily.


On radiators that are hot, do they feel less hot in the middle near
the bottom? If there is substantial sludging, it tends to form in a
pyramid and you will feel a cooler area as a result. The implication
is that the hot surface area is reduced and hence the output.


Second point is to feel the return temperatures at the radiators, or
better still measure them. This can be done with a boiler
thermometer or infra red thermometer e.g.

http://www.maplin.co.uk/Module.aspx?...ter&do y=23m2

or possibly a clip on boiler thermometer.

In this case, again you are looking for low flow.


Also check the pump. Is it on a low speed setting? Turn it up if
so. Is the system sealed (i.e. with pressure vessel) or open vented?
If it's an open vented one (small tank in loft), do watch out that
doing this doesn't result in air being sucked down or water being
pumped over from the vent into the tank. This would cause corrosion
problems. It's worth checking that anyway.

When you have cleaned the system, some corrosion inhibitor would make
really good sense.



--

..andy

On Thu, 23 Feb 2006 06:57:43 -0800, Ross wrote:

I have a boiler that is a year old, and I cannot get temperatures at
home much above 18c (the old boiler was ok). I asked Potterton back to
inspect the boiler. They tested the temperature, found it ok (80c) and
said that I should keep it permanently on 'Max'.

The rooms are still nowhere near warm enough, even though the rads feel
hot. I have a boilerman in next week to give the first service. I
notice black sludge when bleeding so I am also going to ask him to
flush this out.

Problem is who do I contact to perform a survey on any heating loss.
The energy companies are only interested in selling you insulation. (I
already have loft insulation - not 10 inches though - and I think my
property is too old for cavity insulation (1920) also I believe that
the cavity is there for a purpose ie to prevent condensation).

Who should I contact to test for draughts, measure heat loss, generally
tell me what's wrong (I believe there is a thermal instrument that
they can use to determine problem areas??)

Any advice would be appreciated

Are all the radiators 'nearly untouchable' over almost all of their
surface?

Yes: The then house is too draughty/ badly insulated or not enough
radiators.
No: There is a problem with the primary circulation:
bypass valve set wrong.
sludge.
pump set wrong.
rad valves turned off.
etc.etc.

If 15kW heated before and 15kW is available now then the boiler is not the
problem.


--
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

Received your email thanks. Radiators feel hot all the way down. On
one, it feels hotter on the left hand side, but only slightly - so even
though the water is black, it doesn't sound like 'sludging'. You lose
me a bit in the second part of your email, so I shall show it to the
engineer who is coming next Thursday to perform its first service.

I still don't understand why it goes on and off every 2/3 minutes.
Someone earlier suggested the boiler could be 'recycling'. Do you know
what this means

Thanks

Ross wrote:
Received your email thanks. Radiators feel hot all the way down. On
one, it feels hotter on the left hand side, but only slightly - so even
though the water is black, it doesn't sound like 'sludging'. You lose
me a bit in the second part of your email, so I shall show it to the
engineer who is coming next Thursday to perform its first service.

I still don't understand why it goes on and off every 2/3 minutes.
Someone earlier suggested the boiler could be 'recycling'. Do you know
what this means

Thanks


If all the rads are hot, the boilers ok.
If all the rads are hot, the rads and circulation are ok.

If the boilers cycling all day, the only likely explanation is that the
water temp its putting out is lower than the old one was, and the
solution is to up the temp, presumably by replacing the stat on the
boiler. The other option is to replace the rads with higher output
versions, but thats a lot more work and money.

Its worth checking your room stat too, turn slowly each way till it
clicks, and see its clicking corresponds to the real room temp, and
that turning it down til it clicks stops the heating, and turning up
starts it again.


NT

On 23 Feb 2006 11:18:29 -0800, Ross wrote:

I still don't understand why it goes on and off every 2/3 minutes.
Someone earlier suggested the boiler could be 'recycling'. Do you know
what this means

It's "cycling", and it means going on and off every 2/3 minutes!

If the water is coming back too hot (without loosing heat into the
rooms) it can cause this.

--
Nigel M

Yes the rads are hot so boiler would seem ok. I only have one
thermostat and that is in the hall. When it is mild, this clicks off
when 20c/21c is reached. When it's cold it never clicks off as it never
gets up to temperature. On the old boiler, I remember when elderly
aunts used to be expected, we used to click it up to 23c and it reached
that temperature. Mind you, it was very warm!

I've tested thermometer readings in each room - most are 18c, one is
20c. So it looks like draft proofing, but I come back to my original
question, how can I get this tested? I'm reluctant to have cavity wall
insulation if there's a chance that I end up with condensation when
there might be little heat escaping anyway?

Thanks

On 23 Feb 2006 12:11:52 -0800, "Ross"
wrote:

Yes the rads are hot so boiler would seem ok. I only have one
thermostat and that is in the hall. When it is mild, this clicks off
when 20c/21c is reached. When it's cold it never clicks off as it never
gets up to temperature. On the old boiler, I remember when elderly
aunts used to be expected, we used to click it up to 23c and it reached
that temperature. Mind you, it was very warm!


have a look at the original point and Ed's comment - i.e. are the
radiators hot all over and is the return water temperature cool?
This would be circulation issue. THe only other is if the boiler
burn rate is set low as mentioned earlier. The fitter should be able
to test that.



I've tested thermometer readings in each room - most are 18c, one is
20c. So it looks like draft proofing, but I come back to my original
question, how can I get this tested?


It's possible to work in two ways.

1) Calculate the heat loss. Measurements, materials and temperature
drop. This is reasonably good. What you can't do is to reliably
measure the heat required to heat the air replacing what's there - in
other words, what is lost through draughts. There are typical
estimates for that and these are taken into account when sizing a
heating system - or should be. You could get a heating engineer
to do this work for you but I am not sure that it leads anywhere.

2) If the heating were working properly and you know the temperature
of the radiator on flow and return side, you can look up the output on
a manufacturer's data sheet.


If 1) 2) then you have a problem that heat loss is greater than
supply.

Two solutions to that:

a) Increase heat

b) Reduce heat loss


Draughts and loft insulation are probably the two first places to
start. Cavity insulation and finally double glazing would follow in
terms of return on investment.

However, I come back to the original point. It *was* working. Or
are you perhaps not so sure now?



I'm reluctant to have cavity wall
insulation if there's a chance that I end up with condensation when
there might be little heat escaping anyway?


That happens if you seal up the house by going overboard on draught
proofing and fitting double glazing and not having ventilation.
Having cavity insulation may result in more window condensation
because these now become the coldest surfaces.
It can be resolved with having ventilation, avoiding release of too
much water vapour (e.g. drying clothes on the radiator) or a
dehumidifier.




--

..andy

Nigel Molesworth wrote:
On 23 Feb 2006 06:57:43 -0800, Ross wrote:

I have a boiler that is a year old, and I cannot get temperatures at
home much above 18c (the old boiler was ok).

Then the new boiler is too small.

Or there aren't enough radiators, or the insulatin is crap, or the doors
are draughty..or anyone of a million things dismissed in your
patronising and sweeping statement.

You ARE Drivel and I claim my free combi brochure.

Ross wrote:
That's what's puzzling in that the radiators feel very hot, but the
rooms don't. When I bleed the rad upstairs, the water is black, so it
would be great if having them flushed through would solve the problem.
The fact that the rads feel hot makes me doubtful. Thanks again for all
your input Andy - much appreciated.

If they are too hot to touch, and the house is still 18C, then you are
either in need of more radiators or more insulation.

Nigel Molesworth wrote:
On 23 Feb 2006 11:18:29 -0800, Ross wrote:

I still don't understand why it goes on and off every 2/3 minutes.
Someone earlier suggested the boiler could be 'recycling'. Do you know
what this means

It's "cycling", and it means going on and off every 2/3 minutes!

If the water is coming back too hot (without loosing heat into the
rooms) it can cause this.

The solution might be to _reduce_ the flow rate..

OTOH maybe the problem is that the main thermostat is wonky.

On 23 Feb 2006 06:57:43 -0800 someone who may be "Ross"
wrote this:-

Problem is who do I contact to perform a survey on any heating loss.
The energy companies are only interested in selling you insulation.

To add to what the others have said, there will almost certainly
have a local organisation that gives free advice on energy
conservation, funded by the taxpayer.

(I
already have loft insulation - not 10 inches though - and I think my
property is too old for cavity insulation (1920) also I believe that
the cavity is there for a purpose ie to prevent condensation).

A cavity is indeed there for a purpose, it stops damp from rainwater
penetrating through the wall from the outside. Some of the original
forms of cavity wall insulation did cause problems because they
blocked the ventilation in the cavity. However, modern forms of
insulation avoid this problem.

Internal condensation is due to poor ventilation of the rooms.

What should happen with your new boiler is as follows. Assuming that
the building is cold then it should fire at maximum rate for some
time, say one to three hours, to warm the place up. What happens
next depends on the heating system and the boiler. With a room
thermostat the boiler will go off until the thermostat calls for
heat, which depends on the room. With just thermostatic valves the
boiler will go on and off frequently, cycling. That is for a boiler
with on/off control, a modern boiler may well modulate instead of
going off, it turns down the output to a low level.

If the building was warm enough before then changing the boiler is
unlikely to have affected the heating system enough to make the
building suddenly cold. The problem is undoubtedly with the new
boiler.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

The message
from Nigel Molesworth contains these words:

I still don't understand why it goes on and off every 2/3 minutes.
Someone earlier suggested the boiler could be 'recycling'. Do you know
what this means

It's "cycling", and it means going on and off every 2/3 minutes!

If the water is coming back too hot (without loosing heat into the
rooms) it can cause this.

ISTM that in this case the more likely problem is the opposite - that
the circulation is too slow. I wouldn't totally discount the notion that
the flow rate is too high but that is easily checked by testing the flow
and return temperatures at the boiler. As Andy pointed out earlier the
design criterion is for a temperature drop in the region of 11C but the
temperature drop would have to be much less for the boilers internal
stat to induce frequent cycling.

Either way if the boiler is not firing continuously then it cannot be
giving its maximum output. Given that the previous boiler at the same
rating apparently performed adequately then the radiators should not be
undersized which leaves flow rate to be investigated, sludging (and the
characteristic cool patch) having apparently being ruled out.

So what are the flow and return temperatures at the boiler?

Gas fitter not withstanding boiler malfunction cannot be ruled out
altogether but certain knowledge of the flow and return temperatures
should be the key to solving the problem.

--
Roger Chapman

You ARE Drivel and I claim my free combi brochure.

I'll send you two.

Christian.

On Thu, 23 Feb 2006 21:10:25 +0000, The Natural Philosopher wrote:

Then the new boiler is too small.

Or there aren't enough radiators, or the insulatin is crap, or the doors
are draughty..or anyone of a million things dismissed in your
patronising and sweeping statement.

You seem to have missed an important point in the OP: "the old boiler
was ok". My reply was posted before we were told it was the same size.
Shame, I normally find your posts are well considered.



--
Nigel M

On Thu, 23 Feb 2006 21:14:16 +0000, The Natural Philosopher wrote:

The solution might be to _reduce_ the flow rate..

I was going to say the same thing. Was a new pump fitted?

A lot of folk are going off on tangents about insulation and the like,
but all things being equal, it must be something that has changed.

--
Nigel M

On 24 Feb 2006 03:58:06 -0800, wrote:

and a new (boiler) thermostat that can go
to a higher temp will resolve it.

I wonder if the stat can be re-sited? Or the flow and return mixed up?

--
Nigel M

On Fri, 24 Feb 2006 11:56:52 +0000, Nigel Molesworth
wrote:

On Thu, 23 Feb 2006 21:14:16 +0000, The Natural Philosopher wrote:

The solution might be to _reduce_ the flow rate..

I was going to say the same thing. Was a new pump fitted?

A lot of folk are going off on tangents about insulation and the like,
but all things being equal, it must be something that has changed.


No, reducing the flow rate doesn't help.

At first sight, it might seem that it does, because if there is a
greater temperature drop across radiators the heat given up from them
must be greater.

Unfortunately, it doesn't quite work like that.

Heat released is proportional to mass of water multiplied by the
temperature fall. If the increased temperature drop is achieved by
reducing the flow, then the energy output is not increased.

The only ways that heat output into a room can be increased are by
having a larger radiator surface area or by running the system at a
higher temperature so that the water to air temperature is increased.
Increasing the system temperture to any extent isn't realistic in one
already running at 82 degrees.

Turning down the pump has an equivalent effecet on the boiler. The
heat exchanger will be able to raise the temperature of the water by
so many degrees. On a conventional boiler, the design is around 12
degrees - hence 82 flow and 70 return.

This leaves only two possibilities for the problem if it was working.

1) The water flow has been reduced

2) The boiler is firing at a lower rate than its predecessor.



--

..andy

Andy Hall wrote:
[ radiators ]
The only ways that heat output into a room can be increased are by
having a larger radiator surface area or by running the system at a
higher temperature so that the water to air temperature is increased.
Increasing the system temperture to any extent isn't realistic in one
already running at 82 degrees.

Increase the flow rate until the temperature drop "across
the radiator" is at a minimum, then the heat output from
that radiator will be maximum.

On Fri, 24 Feb 2006 13:12:44 +0000, Andy Hall wrote:

At first sight, it might seem that it does, because if there is a
greater temperature drop across radiators the heat given up from them
must be greater.

Unfortunately, it doesn't quite work like that.

I realise that, heat flow etc. But if the boiler is cycling, it can't
be running efficiently.

--
Nigel M

On Fri, 24 Feb 2006 17:02:40 +0000, Nigel Molesworth
wrote:

On Fri, 24 Feb 2006 13:12:44 +0000, Andy Hall wrote:

At first sight, it might seem that it does, because if there is a
greater temperature drop across radiators the heat given up from them
must be greater.

Unfortunately, it doesn't quite work like that.

I realise that, heat flow etc. But if the boiler is cycling, it can't
be running efficiently.

The reason that the boiler cycles is that either the thermostat is
faulty or that the heat isn't being removed from it fast enough in
comparison to its burn rate.

Given that we know that it *is* cycling, this only leaves faulty
thermostat or low circulation.





--

..andy

Christian McArdle wrote:
You ARE Drivel and I claim my free combi brochure.

I'll send you two.

In Japanese?

--
http://gymratz.co.uk - Best Gym Equipment & Bodybuilding Supplements UK.
http://trade-price-supplements.co.uk - TRADE PRICED SUPPLEMENTS for ALL!
http://fitness-equipment-uk.com - UK's No.1 Fitness Equipment Suppliers.
http://Water-Rower.co.uk - Worlds best prices on the Worlds best Rower.

The message
from Andy Hall contains these words:

At first sight, it might seem that it does, because if there is a
greater temperature drop across radiators the heat given up from them
must be greater.

Unfortunately, it doesn't quite work like that.

I realise that, heat flow etc. But if the boiler is cycling, it can't
be running efficiently.

The reason that the boiler cycles is that either the thermostat is
faulty or that the heat isn't being removed from it fast enough in
comparison to its burn rate.

Given that we know that it *is* cycling, this only leaves faulty
thermostat or low circulation.

Don't discount too high flow rate entirely. If the water can get back to
the boiler sufficiently hot it will cause the boiler to cycle even
though it is doing very little work.

There is another possibility that escaped me before. If the boiler in
question has an automatic bypass valve that could be set wrongly and be
passing hot water directly back into the boiler at all times.

--
Roger Chapman

On Fri, 24 Feb 2006 20:32:14 GMT, Roger
wrote:

The message
from Andy Hall contains these words:

At first sight, it might seem that it does, because if there is a
greater temperature drop across radiators the heat given up from them
must be greater.

Unfortunately, it doesn't quite work like that.

I realise that, heat flow etc. But if the boiler is cycling, it can't
be running efficiently.

The reason that the boiler cycles is that either the thermostat is
faulty or that the heat isn't being removed from it fast enough in
comparison to its burn rate.

Given that we know that it *is* cycling, this only leaves faulty
thermostat or low circulation.

Don't discount too high flow rate entirely. If the water can get back to
the boiler sufficiently hot it will cause the boiler to cycle even
though it is doing very little work.

I understand what you're saying Roger, but it would need a hell of a
flow rate to achieve that if one considers that the original system
will have been (should have been ?) designed for the standard flows
and temperature drops.



There is another possibility that escaped me before. If the boiler in
question has an automatic bypass valve that could be set wrongly and be
passing hot water directly back into the boiler at all times.

That could be, or a manual bypass left open. A stuck diverter valve
could also have an effect, although the DHW would then become very
hot.


--

..andy

Andy Hall wrote:
2) The boiler is firing at a lower rate than its predecessor.

Is it one of dIMMs 120% efficiency types?

Regards
Capitol

On Fri, 24 Feb 2006 21:19:33 +0000, Capitol
wrote:



Andy Hall wrote:
2) The boiler is firing at a lower rate than its predecessor.

Is it one of dIMMs 120% efficiency types?

Regards
Capitol
Nah.

Just a normal one and perhaps the burner pressure is set for less than
max rated output


--

..andy