All,

Having got my oil fired rayburn back in good shape I turned my
attention to why the radiators weren't getting hot yesterday.

During the summer I'd discovered a switch in the utility room which was
live and on, but which I had no idea what it did. I disconnected it.
It turns out that this switch was controlling the pump for the CH.

There is no CH/HW controller, as it's a pretty basic system, and no
electronic control of the heat source (the rayburn). However, I'm
confused with what I've got:

- A DP switch in the utility room, with the supply, the pump and, I
think, the thermostat.
- A pump on the CH feed.
- A cylinder stat (like http://www.screwfix.com/prods/40051) strapped,
not to the cylinder, but to the cylinder feed (which is branched off
the CH return).
- A SP switch in series with the thermostat.
- I think the thermostat was wired in series with the pump, although I
don't have notes of how everything was connected up when I disconnected
it earlier in the year. (Lesson learnt.)
- No diverter valve.

Now, I'm confused. This suggests that the CH pump should only operate
when the feed to the HW is below whatever the set temperature is. Why
would this be? It seems like this might be so that if the HW is cold
then the hot water is fed around the CH and then to the HW, but I've
got two problems with this:
- the thermostat was set to 70 degrees and without the pump running
the thermostat temp was above this, suggesting the pump isn't needed
for the HW
- why would I _not_ want the CH circulating in this kind of system
(and if it isn't where's the heat going to go?).

Right now I've left the pump running 24x7. Are there likely to be any
problems with this?

Thanks,
Piers

In an earlier contribution to this discussion, Piers Finlayson
wrote:
All,

Having got my oil fired rayburn back in good shape I turned my
attention to why the radiators weren't getting hot yesterday.

During the summer I'd discovered a switch in the utility room which
was live and on, but which I had no idea what it did. I disconnected
it. It turns out that this switch was controlling the pump for the CH.

There is no CH/HW controller, as it's a pretty basic system, and no
electronic control of the heat source (the rayburn). However, I'm
confused with what I've got:

- A DP switch in the utility room, with the supply, the pump and, I
think, the thermostat.
- A pump on the CH feed.
- A cylinder stat (like http://www.screwfix.com/prods/40051)
strapped, not to the cylinder, but to the cylinder feed (which is
branched off the CH return).
- A SP switch in series with the thermostat.
- I think the thermostat was wired in series with the pump, although
I don't have notes of how everything was connected up when I
disconnected it earlier in the year. (Lesson learnt.)
- No diverter valve.

Now, I'm confused. This suggests that the CH pump should only operate
when the feed to the HW is below whatever the set temperature is. Why
would this be? It seems like this might be so that if the HW is cold
then the hot water is fed around the CH and then to the HW, but I've
got two problems with this:
- the thermostat was set to 70 degrees and without the pump running
the thermostat temp was above this, suggesting the pump isn't needed
for the HW
- why would I _not_ want the CH circulating in this kind of system
(and if it isn't where's the heat going to go?).

Right now I've left the pump running 24x7. Are there likely to be any
problems with this?

Thanks,
Piers


I'm struggling to get a mental picture of your system from your description.
Any chance that you can draw a schematic diagram of the pipe layout, showing
the boiler, cylinder coil, radiators - with the associated feed and return
pipes, and the pump position. You'd have to upload it somewhere, and post a
link here. Failing that, some photos might help.

It's possible that you have a gravity HW and pumped CH system, but I can't
work that out from your description. It's also possible that the pipe stat
runs the pump when the water temperature is *above* the set point rather
than below it - either to dissipate excess heat, or to run the CH system
*only* when the water is hot enough - I don't know!

Running the pump continuously is no problem - other than the electricity
which it consumes.
--
Cheers,
Roger
_______
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

Roger Mills wrote:
In an earlier contribution to this discussion, Piers Finlayson
wrote:
All,

Having got my oil fired rayburn back in good shape I turned my
attention to why the radiators weren't getting hot yesterday.

During the summer I'd discovered a switch in the utility room which
was live and on, but which I had no idea what it did. I disconnected
it. It turns out that this switch was controlling the pump for the CH.

There is no CH/HW controller, as it's a pretty basic system, and no
electronic control of the heat source (the rayburn). However, I'm
confused with what I've got:

- A DP switch in the utility room, with the supply, the pump and, I
think, the thermostat.
- A pump on the CH feed.
- A cylinder stat (like http://www.screwfix.com/prods/40051)
strapped, not to the cylinder, but to the cylinder feed (which is
branched off the CH return).
- A SP switch in series with the thermostat.
- I think the thermostat was wired in series with the pump, although
I don't have notes of how everything was connected up when I
disconnected it earlier in the year. (Lesson learnt.)
- No diverter valve.

Now, I'm confused. This suggests that the CH pump should only operate
when the feed to the HW is below whatever the set temperature is. Why
would this be? It seems like this might be so that if the HW is cold
then the hot water is fed around the CH and then to the HW, but I've
got two problems with this:
- the thermostat was set to 70 degrees and without the pump running
the thermostat temp was above this, suggesting the pump isn't needed
for the HW
- why would I _not_ want the CH circulating in this kind of system
(and if it isn't where's the heat going to go?).

Right now I've left the pump running 24x7. Are there likely to be any
problems with this?

Thanks,
Piers


I'm struggling to get a mental picture of your system from your description.
Any chance that you can draw a schematic diagram of the pipe layout, showing
the boiler, cylinder coil, radiators - with the associated feed and return
pipes, and the pump position. You'd have to upload it somewhere, and post a
link here. Failing that, some photos might help.

It's possible that you have a gravity HW and pumped CH system, but I can't
work that out from your description. It's also possible that the pipe stat
runs the pump when the water temperature is *above* the set point rather
than below it - either to dissipate excess heat, or to run the CH system
*only* when the water is hot enough - I don't know!

Running the pump continuously is no problem - other than the electricity
which it consumes.

and a shorter pump life.

I'm struggling to get a mental picture of your system from your
description. Any chance that you can draw a schematic diagram of the
pipe layout, showing the boiler, cylinder coil, radiators - with the
associated feed and return pipes, and the pump position. You'd have to
upload it somewhere, and post a link here. Failing that, some photos
might hel

Here's one I drew yesterday once I'd figured it out myself!

http://s737.photobucket.com/albums/x...ting_schem.jpg


It's possible that you have a gravity HW and pumped CH system, but I
can't work that out from your description. It's also possible that the
pipe stat runs the pump when the water temperature is *above* the set
point rather than below it - either to dissipate excess heat, or to run
the CH system *only* when the water is hot enough - I don't know!

Running the pump continuously is no problem - other than the
electricity which it consumes.

"Piers Finlayson" wrote in message
...


I'm struggling to get a mental picture of your system from your
description. Any chance that you can draw a schematic diagram of the pipe
layout, showing the boiler, cylinder coil, radiators - with the
associated feed and return pipes, and the pump position. You'd have to
upload it somewhere, and post a link here. Failing that, some photos
might hel

Here's one I drew yesterday once I'd figured it out myself!

http://s737.photobucket.com/albums/x...ting_schem.jpg


It's possible that you have a gravity HW and pumped CH system, but I
can't work that out from your description. It's also possible that the
pipe stat runs the pump when the water temperature is *above* the set
point rather than below it - either to dissipate excess heat, or to run
the CH system *only* when the water is hot enough - I don't know!

Running the pump continuously is no problem - other than the electricity
which it consumes.


Nice piccy.

I have to agree with Roger. The stat is there to start the pump when the
return from the HW clyinder reaches 70deg and dump the excess heat into the
radiators.

The stat should be wired as "make on temp rise" and should not have any
isolation switch (other than the main one for the Rayburn). The single pole
switch you mentioned should be in parrallel with the stat to allow you to
manually control the pump.

Cheers

Adam

In an earlier contribution to this discussion, Piers Finlayson
wrote:

Here's one I drew yesterday once I'd figured it out myself!

http://s737.photobucket.com/albums/x...ting_schem.jpg


Right, well that certainly helps - but I'm still not *entirely* sure how
it's supposed to work.

It's pretty clear that the 28mm HW circuit is gravity (thermo-syphon) and is
independent of the pump. The central heating is pumped but - in the absense
of any valves - it's not clear as to what happens to the HW circuit when the
pump is running. It there a flow direction arrow on the pump? If so, which
way is it pumping?

In your position, I think I'd convert it to fully pumped - it shouldn't be
too difficult.

You said earlier that there were no electronic controls on the boiler. I
assume that it *is* possible to turn it on and off electrically?
--
Cheers,
Roger
_______
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

On 2010-02-15 13:16:57 +0000, Roger Mills said:

In an earlier contribution to this discussion, Piers Finlayson
wrote:

Here's one I drew yesterday once I'd figured it out myself!

http://s737.photobucket.com/albums/x...ting_schem.jpg


Right, well that certainly helps - but I'm still not *entirely* sure
how it's supposed to work.

It's pretty clear that the 28mm HW circuit is gravity (thermo-syphon)
and is independent of the pump. The central heating is pumped but - in
the absense of any valves - it's not clear as to what happens to the HW
circuit when the pump is running. It there a flow direction arrow on
the pump? If so, which way is it pumping?

Ah, I hand't noticed the arrow - it points from left to right at you
look at it in the picture. I had sort of assumed it was pumping in the
other direction.

When I can turn off the power I'll have a another look at the
thermostat and see when it's on and when it's off.


In your position, I think I'd convert it to fully pumped - it shouldn't
be too difficult.

Does that involve
- moving the pump to the 28mm supply
- introducing a diverter valve?

I'm not keen on doing too much to improve it now. It's all a bit old
and hokey but right now it only heats and supplies HW to the "old" half
of the house, in which I work, but no-one else actually lives. The
"new" half has its own independent fully pumped electronically
controlled system. At some point in the future I plan to merge the two
CH systems together, possibly moving to wood as a fuel. (And possibly
merging in the third CH system which heats attached holiday lets!) But
that's too big a job for the moment!


You said earlier that there were no electronic controls on the boiler.
I assume that it *is* possible to turn it on and off electrically?

Nope. It's an old solid fuel rayburn with back boiler, converted to
run off oil - so it's manually controllable only.

On 2010-02-15 13:00:16 +0000, ARWadsworth said:

"Piers Finlayson" wrote in message
...


I'm struggling to get a mental picture of your system from your
description. Any chance that you can draw a schematic diagram of the
pipe layout, showing the boiler, cylinder coil, radiators - with the
associated feed and return pipes, and the pump position. You'd have
to upload it somewhere, and post a link here. Failing that, some
photos might hel

Here's one I drew yesterday once I'd figured it out myself!

http://s737.photobucket.com/albums/x...ting_schem.jpg


It's possible that you have a gravity HW and pumped CH system, but I
can't work that out from your description. It's also possible that the
pipe stat runs the pump when the water temperature is *above* the
set point rather than below it - either to dissipate excess heat, or
to run the CH system *only* when the water is hot enough - I don't
know!

Running the pump continuously is no problem - other than the
electricity which it consumes.


Nice piccy.

I have to agree with Roger. The stat is there to start the pump when
the return from the HW clyinder reaches 70deg and dump the excess heat
into the radiators.

The stat should be wired as "make on temp rise" and should not have any
isolation switch (other than the main one for the Rayburn). The single
pole switch you mentioned should be in parrallel with the stat to allow
you to manually control the pump.

Makes sense (but the SP switch definitely wasn't wired this way before).


Cheers

Adam

On 2010-02-15 13:32:08 +0000, Piers Finlayson said:

On 2010-02-15 13:00:16 +0000, ARWadsworth said:

"Piers Finlayson" wrote in message
...


I'm struggling to get a mental picture of your system from your
description. Any chance that you can draw a schematic diagram of the
pipe layout, showing the boiler, cylinder coil, radiators - with
the associated feed and return pipes, and the pump position.
You'd have to upload it somewhere, and post a link here. Failing
that, some photos might hel

Here's one I drew yesterday once I'd figured it out myself!

http://s737.photobucket.com/albums/x...ting_schem.jpg


It's possible that you have a gravity HW and pumped CH system, but I
can't work that out from your description. It's also possible that
the pipe stat runs the pump when the water temperature is
*above* the set point rather than below it - either to dissipate
excess heat, or to run the CH system *only* when the water is
hot enough - I don't know!

Running the pump continuously is no problem - other than the
electricity which it consumes.


Nice piccy.

I have to agree with Roger. The stat is there to start the pump when
the return from the HW clyinder reaches 70deg and dump the excess heat
into the radiators.

The stat should be wired as "make on temp rise" and should not have any
isolation switch (other than the main one for the Rayburn). The
single pole switch you mentioned should be in parrallel with the stat
to allow you to manually control the pump.

Makes sense (but the SP switch definitely wasn't wired this way before).

I think I'm talking nonense. I think it probably _was wired_ up this
way before. I need to put the SP SW and Thermostat in parallel, and
the combination in series with the pump. I'll do this once I've
confirmed which way the stat is currently operating.



Cheers

Adam

On 15 Feb, 09:02, Piers Finlayson wrote:
All,

Having got my oil fired rayburn back in good shape I turned my
attention to why the radiators weren't getting hot yesterday.

During the summer I'd discovered a switch in the utility room which was
live and on, but which I had no idea what it did. *I disconnected it. *
It turns out that this switch was controlling the pump for the CH.

There is no CH/HW controller, as it's a pretty basic system, and no
electronic control of the heat source (the rayburn). *However, I'm
confused with what I've got:

- *A DP switch in the utility room, with the supply, the pump and, I
think, the thermostat.
- *A pump on the CH feed.
- *A cylinder stat (likehttp://www.screwfix.com/prods/40051) strapped,
not to the cylinder, but to the cylinder feed (which is branched off
the CH return).
- *A SP switch in series with the thermostat.
- *I think the thermostat was wired in series with the pump, although I
don't have notes of how everything was connected up when I disconnected
it earlier in the year. *(Lesson learnt.)
- *No diverter valve.

Now, I'm confused. *This suggests that the CH pump should only operate
when the feed to the HW is below whatever the set temperature is. *Why
would this be? *It seems like this might be so that if the HW is cold
then the hot water is fed around the CH and then to the HW, but I've
got two problems with this:
- *the thermostat was set to 70 degrees and without the pump running
the thermostat temp was above this, suggesting the pump isn't needed
for the HW
- *why would I _not_ want the CH circulating in this kind of system
(and if it isn't where's the heat going to go?).

Right now I've left the pump running 24x7. *Are there likely to be any
problems with this?

Thanks,
Piers

The Rayburn needs to be protected against boiling therefore the pump
will cut in when the temperature gets high and dump the excess heat to
the radiators, not frequent but a nuisance on a hot day. There is also
a consideration of preventing back end corrosion within the boiler so
it should stop the pump if the temperature gets too low. Normally thus
is achieved by using two thermostats or a dual temperature stat.
You may have a bodge where someone tried to use the hysteresis of the
stat to do both jobs