Hi,

I really hope you can help me because this problem is driving me nuts!
There is something wrong with our heating system which is causing it to
just do random things. Sometimes it won't turn on and other times it
won't turn off (this morning is a prime example of that). At other
times it will come on maybe for a few minutes and that just turn itself
off.

I come to you in desperation. There is such a shortage of plumbers in
this area that they won't come out unless I can reproduce the fault
while they are here but the fault is random happening for maybe a day a
week. I did manage to talk to one plumber who thought it might be the
circuit board in the boiler (the boiler is a Glow Worm Space Saver 50
MkII and looks quiet old) but I am really sceptical.

Anyway a few more details. The most dangerous thing that happens, IMHO
(please excuse the fact I don't know what all the various bits are
called), is when the boiler fires up but the hot water produced is not
pumped around the hot water tank or the radiators (the pump goes ten to
the dozen and sounds like it's trying to tear itself off the pipe). I
am fairly sure there must be a safety cut off because under those
circumstances the boiler does go off briefly. The Honeywell controller
/ timer box, an ST6400C (http://www.plumbworld.co.uk/acb-1357), has
been bodged on to the wall (previous owners fault) and tapping it, even
very lightly, with my finger can cause the heating or hot water to come
on.

If I had to make a guess I would say that it is the controller / timer
box but I don't know for sure. Any ideas?

Bearing in mind our boiler is quite old I would also be interested to
know how if you think it might be worth ripping it our and sticking in
an instant heat system (or heat on demand)? At some point the house has
had a loft conversion so it has no header tank - it has some
complicated Megaflow thing-m-bob with a little red pressure tank
instead. Removing the hot water tank would give us a lot more storage
space so it is an option if repairing the existing system is going to
be very expensive.
Many thanks for getting this far down my rambling post )

On 1 Feb 2005 02:40:56 -0800, "doozer"
wrote:

Hi,

I really hope you can help me because this problem is driving me nuts!
There is something wrong with our heating system which is causing it to
just do random things. Sometimes it won't turn on and other times it
won't turn off (this morning is a prime example of that). At other
times it will come on maybe for a few minutes and that just turn itself
off.

I come to you in desperation. There is such a shortage of plumbers in
this area that they won't come out unless I can reproduce the fault
while they are here but the fault is random happening for maybe a day a
week. I did manage to talk to one plumber who thought it might be the
circuit board in the boiler (the boiler is a Glow Worm Space Saver 50
MkII and looks quiet old) but I am really sceptical.

Anyway a few more details. The most dangerous thing that happens, IMHO
(please excuse the fact I don't know what all the various bits are
called), is when the boiler fires up but the hot water produced is not
pumped around the hot water tank or the radiators (the pump goes ten to
the dozen and sounds like it's trying to tear itself off the pipe). I
am fairly sure there must be a safety cut off because under those
circumstances the boiler does go off briefly. The Honeywell controller
/ timer box, an ST6400C (http://www.plumbworld.co.uk/acb-1357), has
been bodged on to the wall (previous owners fault) and tapping it, even
very lightly, with my finger can cause the heating or hot water to come
on.

If I had to make a guess I would say that it is the controller / timer
box but I don't know for sure. Any ideas?

Bearing in mind our boiler is quite old I would also be interested to
know how if you think it might be worth ripping it our and sticking in
an instant heat system (or heat on demand)? At some point the house has
had a loft conversion so it has no header tank - it has some
complicated Megaflow thing-m-bob with a little red pressure tank
instead. Removing the hot water tank would give us a lot more storage
space so it is an option if repairing the existing system is going to
be very expensive.
Many thanks for getting this far down my rambling post )

Sounds like an electrical fault to me. Have you checked the wiring
inside the controller box? Perhaps just the tightening of a screw
would solve the problem.

Many people here find unvented systems like the Megaflow highly
dersirable and wouldn't want to rip it out as it provides mains
pressure hot water at a decent flow rate. (If it doesn't then you
probably have a low quality water main!).

M.

I have a Glowworm Mk I. If the pump is going too fast, it suggest a lack of
water in it which could be very dangerous for the boiler and persons
standing too close. The boiler water can't be totally drained in mine as
the feed pipes are at the top and half way down, so in the absence of a
water supply, the burner will heat up what water is left in the boiler,
until the boiler thermostat switches the gas off, which on mine would take
one minute or so.

this is just a worst case scenario....... check the pipes to the boiler for
temperature. If they are cold, they may have no water in them.

"Markus Splenius" wrote in message
...
On 1 Feb 2005 02:40:56 -0800, "doozer"
wrote:


Anyway a few more details. The most dangerous thing that happens, IMHO
(please excuse the fact I don't know what all the various bits are
called), is when the boiler fires up but the hot water produced is not
pumped around the hot water tank or the radiators (the pump goes ten to
the dozen and sounds like it's trying to tear itself off the pipe). I
am fairly sure there must be a safety cut off because under those
circumstances the boiler does go off briefly. The Honeywell controller
/ timer box, an ST6400C (http://www.plumbworld.co.uk/acb-1357), has
been bodged on to the wall (previous owners fault) and tapping it, even
very lightly, with my finger can cause the heating or hot water to come
on.

If I had to make a guess I would say that it is the controller / timer
box but I don't know for sure. Any ideas?

In an earlier contribution to this discussion,
doozer wrote:

Hi,

I really hope you can help me because this problem is driving me nuts!
There is something wrong with our heating system which is causing it
to just do random things. Sometimes it won't turn on and other times
it won't turn off (this morning is a prime example of that). At other
times it will come on maybe for a few minutes and that just turn
itself off.

I come to you in desperation. There is such a shortage of plumbers in
this area that they won't come out unless I can reproduce the fault
while they are here but the fault is random happening for maybe a day
a week. I did manage to talk to one plumber who thought it might be
the circuit board in the boiler (the boiler is a Glow Worm Space
Saver 50 MkII and looks quiet old) but I am really sceptical.

Anyway a few more details. The most dangerous thing that happens, IMHO
(please excuse the fact I don't know what all the various bits are
called), is when the boiler fires up but the hot water produced is not
pumped around the hot water tank or the radiators (the pump goes ten
to the dozen and sounds like it's trying to tear itself off the
pipe). I am fairly sure there must be a safety cut off because under
those circumstances the boiler does go off briefly. The Honeywell
controller / timer box, an ST6400C
(http://www.plumbworld.co.uk/acb-1357), has been bodged on to the
wall (previous owners fault) and tapping it, even very lightly, with
my finger can cause the heating or hot water to come on.

If I had to make a guess I would say that it is the controller / timer
box but I don't know for sure. Any ideas?

Bearing in mind our boiler is quite old I would also be interested to
know how if you think it might be worth ripping it our and sticking in
an instant heat system (or heat on demand)? At some point the house
has had a loft conversion so it has no header tank - it has some
complicated Megaflow thing-m-bob with a little red pressure tank
instead. Removing the hot water tank would give us a lot more storage
space so it is an option if repairing the existing system is going to
be very expensive.
Many thanks for getting this far down my rambling post )

It sounds to me as if the pump is cavitating through lack of water.
Presumably the little red pressure tank is the expansion tank for the
primary circuit (the water which flows from the boiler, through the
radiators and through the heating coil in the hot water cylinder)? If so,
there should be a filling loop for adding water, and a pressure gauge. Is
there? If so, what does the pressure gauge read (a) when the system is cold
and (b) when everything is hot?

Whatever you do, *don't* get rid of your stored hot water system!
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

On Tue, 01 Feb 2005 02:40:56 -0800, doozer wrote:

Hi,

I really hope you can help me because this problem is driving me nuts!
There is something wrong with our heating system which is causing it to
just do random things. Sometimes it won't turn on and other times it
won't turn off (this morning is a prime example of that). At other
times it will come on maybe for a few minutes and that just turn itself
off.

I come to you in desperation. There is such a shortage of plumbers in
this area that they won't come out unless I can reproduce the fault
while they are here but the fault is random happening for maybe a day a
week. I did manage to talk to one plumber who thought it might be the
circuit board in the boiler (the boiler is a Glow Worm Space Saver 50
MkII and looks quiet old) but I am really sceptical.

Anyway a few more details. The most dangerous thing that happens, IMHO
(please excuse the fact I don't know what all the various bits are
called), is when the boiler fires up but the hot water produced is not
pumped around the hot water tank or the radiators (the pump goes ten to
the dozen and sounds like it's trying to tear itself off the pipe). I
am fairly sure there must be a safety cut off because under those
circumstances the boiler does go off briefly. The Honeywell controller
/ timer box, an ST6400C (http://www.plumbworld.co.uk/acb-1357), has
been bodged on to the wall (previous owners fault) and tapping it, even
very lightly, with my finger can cause the heating or hot water to come
on.

If I had to make a guess I would say that it is the controller / timer
box but I don't know for sure. Any ideas?

Bearing in mind our boiler is quite old I would also be interested to
know how if you think it might be worth ripping it our and sticking in
an instant heat system (or heat on demand)? At some point the house has
had a loft conversion so it has no header tank - it has some
complicated Megaflow thing-m-bob with a little red pressure tank
instead. Removing the hot water tank would give us a lot more storage
space so it is an option if repairing the existing system is going to
be very expensive.
Many thanks for getting this far down my rambling post )

Educated guess:
You have a system with a small open header tank (almost certainly).
Either the float valve has scaled up so that no water enters the tank or
the pipe from that tank has blocked (just where it joins the main primary
circuit).
There is now insufficient water in the circuit, the pump is
intermittently going dry (hence the noises) and all the other symptoms.

If you bleed an upstairs rad with the system off you will likely get
nothing out.


--
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

On Tue, 01 Feb 2005 02:40:56 -0800, doozer wrote:

Hi,

I really hope you can help me because this problem is driving me nuts!
There is something wrong with our heating system which is causing it to
just do random things. Sometimes it won't turn on and other times it
won't turn off (this morning is a prime example of that). At other
times it will come on maybe for a few minutes and that just turn itself
off.

I come to you in desperation. There is such a shortage of plumbers in
this area that they won't come out unless I can reproduce the fault
while they are here but the fault is random happening for maybe a day a
week. I did manage to talk to one plumber who thought it might be the
circuit board in the boiler (the boiler is a Glow Worm Space Saver 50
MkII and looks quiet old) but I am really sceptical.

Anyway a few more details. The most dangerous thing that happens, IMHO
(please excuse the fact I don't know what all the various bits are
called), is when the boiler fires up but the hot water produced is not
pumped around the hot water tank or the radiators (the pump goes ten to
the dozen and sounds like it's trying to tear itself off the pipe). I
am fairly sure there must be a safety cut off because under those
circumstances the boiler does go off briefly. The Honeywell controller
/ timer box, an ST6400C (http://www.plumbworld.co.uk/acb-1357), has
been bodged on to the wall (previous owners fault) and tapping it, even
very lightly, with my finger can cause the heating or hot water to come
on.

If I had to make a guess I would say that it is the controller / timer
box but I don't know for sure. Any ideas?

Bearing in mind our boiler is quite old I would also be interested to
know how if you think it might be worth ripping it our and sticking in
an instant heat system (or heat on demand)? At some point the house has
had a loft conversion so it has no header tank - it has some
complicated Megaflow thing-m-bob with a little red pressure tank
instead. Removing the hot water tank would give us a lot more storage
space so it is an option if repairing the existing system is going to
be very expensive.
Many thanks for getting this far down my rambling post )

Sorry I did not read to the end of your post.

The system needing topping up see the FAQ below!

--
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

This is slightly frightening. We have to get certificates to fit you unvented kit over 15 litres, and we have to leave you fully informed about it, but someone is allowed to sell the house to you and leave you clueless as to what you have.

The Megaflow has an internal expansion pocket known as a bubble. This may require re-establishing. It is not your problem but you should learn about that anyway. If you know these things correct me and I'll say no more, if you don't talk and we'll get you informed.

The red thingie is an expansion vessel but not for your megaflow, so we can conjecture your heating system is sealed. Are you aware that you must top up with water via a filling loop? Have you seen one anywhere (silvery looking flexible pipe about 300mm long with a strange thing at one end called a double check valve and a washing machine tap at the other)? In the airing cupboard, near the orange thingy. Shoule be a small circular guage near it which goes from 0 to 6 bar or something like that. When system is cold pressure should be between 1 and 2, depending on your house and installation.

Tighten all the connections in the controller too, like the other guy said.

Have a look around what you have, give the previous owner a good bollocking for being such a prat and handing you over equipment that could blow your house out of the street without a hint of knowledge about it.

Thanks for getting back to me, sorry I've not answered sooner - I
turned on topic watching but for some reason I didn't get notification
of new messages.

When we bought the house a couple of years ago the previous owners
asked us if we would like a lesson on how the heating system worked but
we declined as we didn't realize it was anything special. I wish now
that they had told us what was involved. They did at least leave some
notes tied to various pipes which gave us an idea of what to do.

I know enough to keep the system topped up with water (but thanks for
the reminder because it needs doing - how often should it be checked?).
A note tied to it suggests it should be filled to 1 bar so I fill it to
that (+/- 0.1) when the system is cold. When it is fully hot it goes up
to maybe 1.75 at most and there seems to be an emergency pressure valve
set to 3 bar on top of the red cylinder. I've posted some photos of the
system here

http://www.crazysquirrel.com/images/heating/1.jpg
http://www.crazysquirrel.com/images/heating/2.jpg
http://www.crazysquirrel.com/images/heating/3.jpg
http://www.crazysquirrel.com/images/heating/4.jpg

As you can see the honeywell timer box has been bodged to the wall
using a standard electrical box. I think it must be held on by a piece
of twisted wire or a zip tie - I have been unable to get it off the
wall dispite the fact it wobbles everytime you touch it so I don't
think it is a screw holding it on. The wobblyness is why I suspect
there may be a loose connection on the back of it.

In answer to some questions raised above:

The large (1inch?) pipes running to the boiler come in the top and can
get visciously hot when the heating is on so I don't think it is a lack
of water.

There is certainly no header tank - the system is sealed (I believe
unvented is the technical term)

I spoke to a plumber (who never showed up - grrr) on the phone when the
problem first appeared. He mentioned the bubble at the top of the hot
water cylinder and I have read what it says on the side of the cylinder
about establishing the bubble. It sounded sufficiently difficult that I
decided to leave it alone (I will try most DIY jobs but I know when to
leave it to a pro). There isn't a problem with getting hot water out of
the tank so I think the bubble is ok if I understand the system
correctly. The tank does need cleaning though as we sometimes get a
little dirty / muddy water out when we first draw water after heating
but I am happy to leave that for now. I would like more information
about this system - I had a look on-line but coudn't really find much.
I have done work on vented systems but this is a totally different ball
park.

I would be really supprised if low water pressure was totally to blame.
Even when the the control box has both switches (bottom right in photo
1) flicked to off and the lights are off the boiler sometimes comes on.
I am fairly convinced that the cavatating of the pump (and hence the
noise) is then caused because the three way valve is set in the off
position so it is pumping against the valve. When this is happening
(and thankfully it's been fine for the last few days) we don't get any
hot water or heating but the boiler is going 10 to the dozen.

Many thanks