So, here we are with nice shiny new boiler, system all de-sludged, TRVs on
the rads, the works. Because CORGI man wanted the flushing chemical
circulating as much as possible, I kept the boiler on continuously and the
room stat set to 23 degrees. It was a hot few days, but now the system has
been drained out, flushed and inhibited, I've discovered that setting the
room stat high to keep the pump running continuously, but setting the boiler
temperature control low produces a nice evenly warm house with no cold spots
and is much cosier than having the pump stop and start as it does with the
room stat set to a 'sensible' temperature and the boiler set to produce
water at a high temperature.

The question is: "is this a) bad for the boiler, b) inefficient, c) costly,
d) any combination of the foregoing?" (Subjectively, the boiler seems to be
off for very much longer than it's on, so I don't think I'm burning lots of
gas, but I'd rather not wait until the next bill arrives to find out I'm
being a Silly Billy!) It's a minimal pumped heating convection hot water
system, by the way - no motorised valves etc.

On Sun, 20 Feb 2005 20:49:28 -0000, "Mike Faithfull"
wrote:

So, here we are with nice shiny new boiler, system all de-sludged, TRVs on
the rads, the works. Because CORGI man wanted the flushing chemical
circulating as much as possible, I kept the boiler on continuously and the
room stat set to 23 degrees. It was a hot few days, but now the system has
been drained out, flushed and inhibited, I've discovered that setting the
room stat high to keep the pump running continuously, but setting the boiler
temperature control low produces a nice evenly warm house with no cold spots
and is much cosier than having the pump stop and start as it does with the
room stat set to a 'sensible' temperature and the boiler set to produce
water at a high temperature.

The question is: "is this a) bad for the boiler, b) inefficient, c) costly,
d) any combination of the foregoing?" (Subjectively, the boiler seems to be
off for very much longer than it's on, so I don't think I'm burning lots of
gas, but I'd rather not wait until the next bill arrives to find out I'm
being a Silly Billy!) It's a minimal pumped heating convection hot water
system, by the way - no motorised valves etc.




If it's a conventional, non-condensing boiler, then this may be a bad
idea. They are designed to operate with 82 degree flow and 70
return. If you turn down the boiler thermostat to the point that the
return temperature falls below about 54 degrees then you will get
condensation and eventually corrosion inside.

If it's a condensing boiler, then this is a very reasonable thing to
do. The lower the return temperature, the better from the efficiency
standpoint. In this scenario, you mainly need to be sure that you
have the temperature high enough to deliver enough heat when its cold.



--

..andy

To email, substitute .nospam with .gl

"Mike Faithfull" wrote in message
...
So, here we are with nice shiny new boiler, system all de-sludged, TRVs on
the rads, the works. Because CORGI man wanted the flushing chemical
circulating as much as possible, I kept the boiler on continuously and the
room stat set to 23 degrees. It was a hot few days, but now the system
has
been drained out, flushed and inhibited, I've discovered that setting the
room stat high to keep the pump running continuously, but setting the
boiler
temperature control low produces a nice evenly warm house with no cold
spots
and is much cosier than having the pump stop and start as it does with the
room stat set to a 'sensible' temperature and the boiler set to produce
water at a high temperature.

The question is: "is this a) bad for the boiler, b) inefficient, c)
costly,
d) any combination of the foregoing?" (Subjectively, the boiler seems to
be
off for very much longer than it's on, so I don't think I'm burning lots
of
gas, but I'd rather not wait until the next bill arrives to find out I'm
being a Silly Billy!) It's a minimal pumped heating convection hot water
system, by the way - no motorised valves etc.

If non-condensing boiler, then buy a clamp on thermometer and put it on the
boiler return. If it never goes below 60C, it is fine. If it is a
condensing boiler then you have cracked it and it may be wroth lowering the
temperature as long as the DHW does not suffer. What boiler do you have?



_________________________________________
Usenet Zone Free Binaries Usenet Server
More than 120,000 groups
Unlimited download
http://www.usenetzone.com to open account

On Sun, 20 Feb 2005 20:49:28 +0000, Mike Faithfull wrote:

So, here we are with nice shiny new boiler, system all de-sludged, TRVs on
the rads, the works. Because CORGI man wanted the flushing chemical
circulating as much as possible, I kept the boiler on continuously and the
room stat set to 23 degrees. It was a hot few days, but now the system has
been drained out, flushed and inhibited, I've discovered that setting the
room stat high to keep the pump running continuously, but setting the boiler
temperature control low produces a nice evenly warm house with no cold spots
and is much cosier than having the pump stop and start as it does with the
room stat set to a 'sensible' temperature and the boiler set to produce
water at a high temperature.

The question is: "is this a) bad for the boiler, b) inefficient, c) costly,
d) any combination of the foregoing?" (Subjectively, the boiler seems to be
off for very much longer than it's on, so I don't think I'm burning lots of
gas, but I'd rather not wait until the next bill arrives to find out I'm
being a Silly Billy!) It's a minimal pumped heating convection hot water
system, by the way - no motorised valves etc.

You have found the setting on the boiler which heats the house in the
current weather conditions. It also manages to provide sufficient HW for
your current requirements.

The pump will consume a fair bit of electric over the course of the winter
and there may be some saving by having it on less. You might be talking
about saving £5-10 of electric on the pump.

You don't say shat sort of boiler you have had fitted? if it is open or
balance flue then it is much less efficient to run it all the while as the
warm water in the primary circuit will be cooled in the boiler when it's
not firing.

BTW On what grounds did your fitter replace the existing heating system
with something that is not to current standards? Where is the control of
the HW temperature?

--
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

(snip ..)

You don't say shat sort of boiler you have had fitted? if it is open or
balance flue then it is much less efficient to run it all the while as the
warm water in the primary circuit will be cooled in the boiler when it's
not firing.

BTW On what grounds did your fitter replace the existing heating system
with something that is not to current standards? Where is the control of
the HW temperature?

Thanks for all replies - the consensus seems to be 'good idea for a
condensing boiler, bad idea for mine' (Potterton CFL60 replacing old
Potterton CF60). Having worked in the electronics industry for a good few
years, I am reasonably adept at guessing the temperature of metal surfaces
(from touching heatsinks and hot power transistor cases!) I can just about
manage 60 degrees for a second or two before it becomes too uncomfortable.
I would bet that without measuring with a proper instrument, the return
water temp is below that and the feed not much above, so I've turned up the
boiler temp and turned down the room stat as advised.

The lack of compliance with current standards is entirely down to lack of
money, Ed. It was all carefully explained to me, and he gave me leaflets to
back up what he was saying, but I simply could not afford to do it all in
one go. I need a new cylinder, a tank stat, motorised valve and new room
stat at the very least, but could not afford to do that on top of everything
else. He said he would fit a replacement boiler, flush out the system
(which was sorely needed!) fit TRVs and replace an under-sized combustion
air vent to give me a system that would work better and safer than before,
but only on condition that I signed a 'disclaimer' letter to the effect that
I chose not to make the system compliant at this time against his advice. I
do, as it happens, intend to do the rest when I can afford it, but that may
not be for a while yet. Just gotta get that lucrative new contract ...

Ed Sirett wrote:

BTW On what grounds did your fitter replace the existing heating system
with something that is not to current standards? Where is the control of
the HW temperature?

Slightly misleading choice of words Ed? Not 'Not to Current Standards'
as in gas-speak unsafe situation classification but 'not in accordance
with building regs'.

Wonder what he did about the Benchmark though? No Benchmark, no
warranty, isn't it?

And another CF too - wonder what sort of flue it has? ISTR a
recommendation that a liner should be replaced at the same time as the
boiler unless it can be expected to last the full lifetime of the new
boiler. But then with a new Potterton maybe that's not too long OK ;-)