Does anyone know where i can download an installation guide / wiring diagram
for a Potterton EP2002 heating controller.  I need to fit a hot water
thermostat to the controller, currently have an old mechanical wax type
termostat on the hot water circulation pipes which has seized fully open, so
the hot watter is too hot.

In an earlier contribution to this discussion,
Dopey   wrote:


> Does anyone know where i can download an installation guide / wiring
> diagram for a Potterton EP2002 heating controller.  I need to fit a
> hot water thermostat to the controller, currently have an old
> mechanical wax type termostat on the hot water circulation pipes
> which has seized fully open, so the hot watter is too hot.


Good question - the Potterton website doesn't seem to help much!

Can you give a few more details about the layout of your system, and exactly
how it's controlled. What is the boiler? Do you have a combined hot water
and central heating system? Are there any motorised valves? How much of it
is pumped? etc.

I suspect that you may have a system with gravity (convection) circulation
of the hot water circuit, and pumped central heating - maybe with a Drayton
Cyltrol valve (or similar) on the hot water return, shutting off the
circulation (when it works!) when the water gets up to temperature.

If this is the case, you will need more than a thermostat to achieve what
you want to do. You will need a motorised valve as well - with the whole lot
wired in such a way that the boiler shuts down when both HW and CH demands
are satisfied. Have a look at C-Plan in
http://content.honeywell.com/uk/homes/systems.htm

Of course, I may have it all wrong!
-- 
Cheers,
Set Square
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"Set Square"  wrote in message
news:3p381oF8ganfU1@individual.net...

> In an earlier contribution to this discussion,
> Dopey   wrote:
>
> > Does anyone know where i can download an installation guide / wiring
> > diagram for a Potterton EP2002 heating controller.  I need to fit a
> > hot water thermostat to the controller, currently have an old
> > mechanical wax type termostat on the hot water circulation pipes
> > which has seized fully open, so the hot watter is too hot.
>
> Good question - the Potterton website doesn't seem to help much!
>
> Can you give a few more details about the layout of your system, and
exactly
> how it's controlled. What is the boiler? Do you have a combined hot water
> and central heating system? Are there any motorised valves? How much of it
> is pumped? etc.
>
> I suspect that you may have a system with gravity (convection) circulation
> of the hot water circuit, and pumped central heating - maybe with a
Drayton
> Cyltrol valve (or similar) on the hot water return, shutting off the
> circulation (when it works!) when the water gets up to temperature.
>
> If this is the case, you will need more than a thermostat to achieve what
> you want to do. You will need a motorised valve as well - with the whole
lot
> wired in such a way that the boiler shuts down when both HW and CH demands
> are satisfied. Have a look at C-Plan in
> http://content.honeywell.com/uk/homes/systems.htm
>
> Of course, I may have it all wrong!
> -- 
> Cheers,
> Set Square
> ______
> Please reply to newsgroup. Reply address is invalid.
>

Yes of course you are correct, I had forgot about the need for a motorised
valve, else the central heating would stop when the hot water was at
temperature, which is not much good.  It is a Drayton Cyltrol valve that is
fitted, apparantly the second one in 26 years.  Does that sound about
right?, I expect these valves are inherantly unreliable.  I guess if I
wanted to replace it, I would have to drain the circulation pipes,
presumably at a vent valve by the boiler somewhere (gravity H/W, pumped
C/H).  Before I do any of that though, I'll see if I can adjust it to make
the hot water less hot than it is currently, as I have the installation
guide and on old Cyltrol valve.  I only have a hunch that it is seized open,
as that's what I've been told (its not my system !)

Thanks

>

In an earlier contribution to this discussion,
Dopey   wrote:


>>
> Yes of course you are correct, I had forgot about the need for a
> motorised valve, else the central heating would stop when the hot
> water was at temperature, which is not much good.  It is a Drayton
> Cyltrol valve that is fitted, apparantly the second one in 26 years.
> Does that sound about right?, I expect these valves are inherantly
> unreliable.  I guess if I wanted to replace it, I would have to drain
> the circulation pipes, presumably at a vent valve by the boiler
> somewhere (gravity H/W, pumped C/H).  Before I do any of that though,
> I'll see if I can adjust it to make the hot water less hot than it is
> currently, as I have the installation guide and on old Cyltrol valve.
> I only have a hunch that it is seized open, as that's what I've been
> told (its not my system !)
>

I don't really know how long Cyltrol valves last. I fitted one in my
previous house - and that was still going strong when I sold the house about
8 years later - but I don't know beyond that. I can't remember whether the
wax bit is detachable from the mechanical valve in the same way as a TRV. If
so, you may be able to replace that bit - if needed - without draining down.
If the valve isn't closing when the water temperature rises, it may well
have lost its wax.

As a short term measure, you can reduce the HW temperature by turning the
boiler thermostat down a bit - but the radiators may not then get hot
enough.
-- 
Cheers,
Set Square
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