I have a Glow-worm Fuelsaver 40-50 conventional flue boiler which was
installed in 1984.

Everything works fine except that the central heating circulating pump stops
running as soon as the room thermostat reaches the desired temperature.
This results in some noisy bubbling from the boiler as it overheats for a
short time after the room thermostat switches the pump and boiler off.

Does anybody know if this boiler was designed to have a pump overrun feature
to avoid this problem?

If the boiler was not designed to have a pump overrun feature is there a
control available which can be added retrospectively. e.g. is there a timed
control available which will allow the pump to run for a short time after
each switch off?

TIA

Malcolm H wrote:
I have a Glow-worm Fuelsaver 40-50 conventional flue boiler which was
installed in 1984.

Everything works fine except that the central heating circulating pump stops
running as soon as the room thermostat reaches the desired temperature.
This results in some noisy bubbling from the boiler as it overheats for a
short time after the room thermostat switches the pump and boiler off.

Does anybody know if this boiler was designed to have a pump overrun feature
to avoid this problem?


How bizar I've been wondering about exactly the same problem, with my
Glow-worm Hide Away. It's slightly younger than yours, possibly 1986 or so.

I think it's quite wasteful to have all that recently-heated water
suddenly come to a halt, rather than circulate it for a short time to
spread it around. Also, as you mention, it causes kettling which must in
turn reduce the life of the boiler by a small amount each time.

I've considered building my own overrun feature using a mains powered
relay, a microcontroller and a solid-state relay, so that when the
system turns the pump on, it is actually just indicating this to a
microcontroller, which will delay the turning off. Like so many similar
ideas, it's in my head rather than built...

Ewan

"Ewan MacIntyre" wrote in
message ...
Malcolm H wrote:
I have a Glow-worm Fuelsaver 40-50 conventional flue boiler which was
installed in 1984.

Everything works fine except that the central heating circulating pump
stops
running as soon as the room thermostat reaches the desired temperature.
This results in some noisy bubbling from the boiler as it overheats for
a
short time after the room thermostat switches the pump and boiler off.

Does anybody know if this boiler was designed to have a pump overrun
feature
to avoid this problem?


How bizar I've been wondering about exactly the same problem, with my
Glow-worm Hide Away. It's slightly younger than yours, possibly 1986 or
so.

I think it's quite wasteful to have all that recently-heated water
suddenly come to a halt, rather than circulate it for a short time to
spread it around. Also, as you mention, it causes kettling which must in
turn reduce the life of the boiler by a small amount each time.

I've considered building my own overrun feature using a mains powered
relay, a microcontroller and a solid-state relay, so that when the
system turns the pump on, it is actually just indicating this to a
microcontroller, which will delay the turning off. Like so many similar
ideas, it's in my head rather than built...

Ewan

I too have a design in my head but it only requires one power diode
(rectifier), one resistor, one electrolytic capacitor and one relay.

In message , Ewan MacIntyre
writes
Malcolm H wrote:
I have a Glow-worm Fuelsaver 40-50 conventional flue boiler which was
installed in 1984.
Everything works fine except that the central heating circulating
pump stops
running as soon as the room thermostat reaches the desired temperature.
This results in some noisy bubbling from the boiler as it overheats for a
short time after the room thermostat switches the pump and boiler off.
Does anybody know if this boiler was designed to have a pump overrun
feature
to avoid this problem?


How bizar I've been wondering about exactly the same problem, with
my Glow-worm Hide Away. It's slightly younger than yours, possibly 1986
or so.

I think it's quite wasteful to have all that recently-heated water
suddenly come to a halt, rather than circulate it for a short time to
spread it around. Also, as you mention, it causes kettling which must
in turn reduce the life of the boiler by a small amount each time.

I've considered building my own overrun feature using a mains powered
relay, a microcontroller and a solid-state relay, so that when the
system turns the pump on, it is actually just indicating this to a
microcontroller, which will delay the turning off. Like so many similar
ideas, it's in my head rather than built...

A microcontroller just to give you a 2 minute delay - bit of an overkill
isn't it?


Ewan


--
geoff

geoff wrote:


A microcontroller just to give you a 2 minute delay - bit of an overkill
isn't it ?

Cheap enough these days, and about 30 seconds of programming effort. Why
ponce about with 555 timers (flaky at long delays) ?

Steve·

In article ,
Steve writes:
geoff wrote:


A microcontroller just to give you a 2 minute delay - bit of an overkill
isn't it ?

Cheap enough these days, and about 30 seconds of programming effort. Why
ponce about with 555 timers (flaky at long delays) ?

Low power 555's handle minutes without problems, but this application
probably only really needs around 10 seconds, and it doesn't need to
be accurate.

--
Andrew Gabriel

In message , Andrew Gabriel
writes
In article ,
Steve writes:
geoff wrote:


A microcontroller just to give you a 2 minute delay - bit of an overkill
isn't it ?

Cheap enough these days, and about 30 seconds of programming effort. Why
ponce about with 555 timers (flaky at long delays) ?

Low power 555's handle minutes without problems, but this application
probably only really needs around 10 seconds, and it doesn't need to
be accurate.



The commercial ones use shift registers (40154?)

There is no such thing as 30 seconds of programming

--
geoff

On Sun, 04 Jan 2004 23:35:57 +0000, Andrew Gabriel wrote:

In article ,
Steve writes:
geoff wrote:


A microcontroller just to give you a 2 minute delay - bit of an overkill
isn't it ?

Cheap enough these days, and about 30 seconds of programming effort. Why
ponce about with 555 timers (flaky at long delays) ?

Low power 555's handle minutes without problems, but this application
probably only really needs around 10 seconds, and it doesn't need to
be accurate.

Wouldn't a slow release relay/contactor be suitable?


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at 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

In article ,
Steve wrote:
Cheap enough these days, and about 30 seconds of programming effort. Why
ponce about with 555 timers (flaky at long delays) ?

Maplin used to do a chip designed for car heated rear windows etc on which
you could set the time from a few seconds to a day or so with just one R &
C. It had enough drive current capability for a meaty relay, and could
either toggle on or off, or on at power up. Much less susceptible to
interference on the supply than a 555. Cheap, too, and I bought a load of
them as it's an easy answer to many problems. One of them provides the 14
hour timer for my Ni-Cad charging area.

--
*I have a degree in liberal arts -- do you want fries with that

Dave Plowman London SW 12
RIP Acorn

geoff wrote:
A microcontroller just to give you a 2 minute delay - bit of an overkill
isn't it?

Yes, unless microcontrollers are already being designed into the system.

My house has 4 zones + DHW, yet there is just one thermostat. The zones
must be controlled by flicking switches behind a kitchen unit...! I
think whoever installed it was good at plumbing but knew nothing about
usability.

I'm currently working on controlling these in a more convenient manner,
using one or more PICs.

Ewan

My house has 4 zones + DHW, yet there is just one thermostat.

You should really be installing a programmable thermostat in each zone. Then
each zone can be timed separately AND will hold better temperatures.

Christian.

In message , Ewan MacIntyre
writes
geoff wrote:
A microcontroller just to give you a 2 minute delay - bit of an
overkill isn't it?

Yes, unless microcontrollers are already being designed into the system.

My house has 4 zones + DHW, yet there is just one thermostat. The zones
must be controlled by flicking switches behind a kitchen unit...! I
think whoever installed it was good at plumbing but knew nothing about
usability.

I'm currently working on controlling these in a more convenient manner,
using one or more PICs.

Aah - so it's not just to give a 2 min delay then, I'll let you off
--
geoff

In an earlier contribution to this discussion,
Malcolm H wrote:

I have a Glow-worm Fuelsaver 40-50 conventional flue boiler which was
installed in 1984.

Everything works fine except that the central heating circulating
pump stops running as soon as the room thermostat reaches the desired
temperature. This results in some noisy bubbling from the boiler as
it overheats for a short time after the room thermostat switches the
pump and boiler off.

Does anybody know if this boiler was designed to have a pump overrun
feature to avoid this problem?

If the boiler was not designed to have a pump overrun feature is
there a control available which can be added retrospectively. e.g. is
there a timed control available which will allow the pump to run for
a short time after each switch off?

TIA


I don't know whether the boiler has a built-in pump over-run facility - but
being 1984 vintage, probably doesn't.

In think that in your position, I would implement my own - using a mains
relay and a pipe stat. Connect the coil of the relay to the boiler switched
live. Connect the relay contacts to a permanent live and to the pump.
Connect the pipe stat contacts in parallel with the relay contacts. Install
the pipe stat on the boiler flow pipe and set it a similar temperature to
the boiler's own stat (a bit of experimentation may be required!)

The pump will then run whenever the boiler is firing *and* whenever the
boiler outlet temperature is above the pipe stat setting. This is, in
effect, what a built-in over-run stat would do - and is better than an
arbitrary time delay.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is Black Hole!

In article ,
Set Square wrote:
In think that in your position, I would implement my own - using a mains
relay and a pipe stat. Connect the coil of the relay to the boiler
switched live. Connect the relay contacts to a permanent live and to the
pump. Connect the pipe stat contacts in parallel with the relay
contacts. Install the pipe stat on the boiler flow pipe and set it a
similar temperature to the boiler's own stat (a bit of experimentation
may be required!)

This will work, but you might have to add a second relay to the pump, as
you'll be feeding volts to it which may then go somewhere else that they
shouldn't, as it were, with the system 'off'. That's what happened with
mine. I never bothered working out exactly why, but IIRC it caused the
system to fire continuously.

--
*Hard work pays off in the future. Laziness pays off now *

Dave Plowman London SW 12
RIP Acorn

In an earlier contribution to this discussion,
Dave Plowman wrote:

In article ,
Set Square wrote:
In think that in your position, I would implement my own - using a
mains relay and a pipe stat. Connect the coil of the relay to the
boiler switched live. Connect the relay contacts to a permanent live
and to the pump. Connect the pipe stat contacts in parallel with the
relay contacts. Install the pipe stat on the boiler flow pipe and
set it a similar temperature to the boiler's own stat (a bit of
experimentation may be required!)

This will work, but you might have to add a second relay to the pump,
as you'll be feeding volts to it which may then go somewhere else
that they shouldn't, as it were, with the system 'off'. That's what
happened with mine. I never bothered working out exactly why, but
IIRC it caused the system to fire continuously.


I can't see why you'd need a second relay. I drew a circuit diagram before
posting the above, and satisfied myself that, with the single relay as
described, the boiler firing will cause the pump to run but *not*
vice-versa.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is Black Hole!

"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Dave Plowman wrote:

In article ,
Set Square wrote:
In think that in your position, I would implement my own - using a
mains relay and a pipe stat. Connect the coil of the relay to the
boiler switched live. Connect the relay contacts to a permanent live
and to the pump. Connect the pipe stat contacts in parallel with the
relay contacts. Install the pipe stat on the boiler flow pipe and
set it a similar temperature to the boiler's own stat (a bit of
experimentation may be required!)

This will work, but you might have to add a second relay to the pump,
as you'll be feeding volts to it which may then go somewhere else
that they shouldn't, as it were, with the system 'off'. That's what
happened with mine. I never bothered working out exactly why, but
IIRC it caused the system to fire continuously.


I can't see why you'd need a second relay. I drew a circuit diagram before
posting the above, and satisfied myself that, with the single relay as
described, the boiler firing will cause the pump to run but *not*
vice-versa.
--
Cheers,
Set Square

Thank you for your reply Set Square. Your solution looks very elegant to me
and I see no reason why it should not work. I propose to implement it as
soon as I can.

Malcolm

In an earlier contribution to this discussion,
Malcolm H wrote:

"Set Square" wrote in message
...

I can't see why you'd need a second relay. I drew a circuit diagram
before posting the above, and satisfied myself that, with the single
relay as described, the boiler firing will cause the pump to run but
*not* vice-versa.
--
Cheers,
Set Square

Thank you for your reply Set Square. Your solution looks very
elegant to me and I see no reason why it should not work. I propose
to implement it as soon as I can.

Malcolm


Please let us know how you get on!
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is Black Hole!

On Sun, 4 Jan 2004 10:52:36 -0000, "Malcolm H"
wrote:

I have a Glow-worm Fuelsaver 40-50 conventional flue boiler which was
installed in 1984.

Everything works fine except that the central heating circulating pump stops
running as soon as the room thermostat reaches the desired temperature.
This results in some noisy bubbling from the boiler as it overheats for a
short time after the room thermostat switches the pump and boiler off.

Does anybody know if this boiler was designed to have a pump overrun feature
to avoid this problem?

Yes it did. I used to have one until a year and a bit ago.

The pump over-run is provisioned by a separate set of contacts on the
thermostat. Either the pump was never wired to them, or as on
mine, the thermostat has failed.

When I enquired regarding the cost of a new one it was in the £70
range. Since this followed a failed thermocouple (that admittedly
only cost £2 to replace) I decided that the boiler was at the end of
its useful life. These things are a piece of junk anyway. I
was never able to dismantle it without cutting myself on sharp metal
somewhere.

Considering also that they run at 65% efficiency at best, I felt that
spending money on a new thermostat was pointless and put it towards
the cost of a new condensing boiler instead.




If the boiler was not designed to have a pump overrun feature is there a
control available which can be added retrospectively. e.g. is there a timed
control available which will allow the pump to run for a short time after
each switch off?

You could do this with a stairway lighting timer.

Have a look at rswww.com part number 277-3520

It has a mode whereby the output remains on for a time after the input
drops.



TIA


..andy

To email, substitute .nospam with .gl

In article ,
Malcolm H wrote:
If the boiler was not designed to have a pump overrun feature is there a
control available which can be added retrospectively. e.g. is there a
timed control available which will allow the pump to run for a short
time after each switch off?

I added this feature to mine. ISTR I had to change the pump switching to a
mains relay, as simply feeding mains to the pump after the thermostats
were satisfied caused problems by feeding those volts elsewhere - although
that might well not be the case with others. I made the timer circuit
which is set for 30 seconds. Basically, a small low voltage power supply,
a 555 timer and a relay. Cost nothing as I had all the bits lying around,
but probably no more than a tenner to buy.

At the time, I investigated finding a ready made unit but couldn't. And,
of course, most boilers have these built in now.

--
*If at first you don't succeed, then skydiving definitely isn't for you *

Dave Plowman London SW 12
RIP Acorn

In message , Malcolm H
writes
I have a Glow-worm Fuelsaver 40-50 conventional flue boiler which was
installed in 1984.

Everything works fine except that the central heating circulating pump stops
running as soon as the room thermostat reaches the desired temperature.
This results in some noisy bubbling from the boiler as it overheats for a
short time after the room thermostat switches the pump and boiler off.

Does anybody know if this boiler was designed to have a pump overrun feature
to avoid this problem?

Having spent most of today poring over Glowworm manuals, I can say with
a fair degree of certainty that it doesn't


If the boiler was not designed to have a pump overrun feature is there a
control available which can be added retrospectively. e.g. is there a timed
control available which will allow the pump to run for a short time after
each switch off?


Yes there are several, but if this has started happening recently, it
would make sense to find out why it's happening rather than bodging it

--
geoff

On Sun, 4 Jan 2004 22:41:24 +0000, geoff wrote:

In message , Malcolm H
writes
I have a Glow-worm Fuelsaver 40-50 conventional flue boiler which was
installed in 1984.

Everything works fine except that the central heating circulating pump stops
running as soon as the room thermostat reaches the desired temperature.
This results in some noisy bubbling from the boiler as it overheats for a
short time after the room thermostat switches the pump and boiler off.

Does anybody know if this boiler was designed to have a pump overrun feature
to avoid this problem?

Having spent most of today poring over Glowworm manuals, I can say with
a fair degree of certainty that it doesn't

Mine definitely did, although thinking again it was installed in 1985.

From the Sedbuk web site, there was a Fuelsaver 40-50b (identity
4131583) which was last manufactured in 1983.

There was a Fuelsaver 50Mk2 (4131320) which IIRC is what I had. It was
range rated from 11 to 14kW and I'm pretty sure said something like
40-50 on the outside case.

Perhaps the over-run was the Mk2 feature....

Either way it's time it was in the skip.




If the boiler was not designed to have a pump overrun feature is there a
control available which can be added retrospectively. e.g. is there a timed
control available which will allow the pump to run for a short time after
each switch off?


Yes there are several, but if this has started happening recently, it
would make sense to find out why it's happening rather than bodging it

..andy

To email, substitute .nospam with .gl