Separate hot water control?

[ted209]

Background

I installed a Honeywell CM927 in the summer (following advice from this forum!) and am very happy with its performance.
As my house is old and drafty (despite my best efforts to improve it!) and I have young children I want to set the thermostat at around 15deg and leave it on all night.

My System

Thermostat: Honeywell CM927
Programmer: Potterton EP2001
Boiler: Potterton Profile
Plumbing: Gravity Hot Water system (?)

The Problem

I left the heating on all last night, but the boiler and pump kept firing up to keep the hot water to temperature (60deg).
This is noisy and seems like a waste of energy as I won't need hot water from 9pm to 7am.
My programmer allows the hot water to be on without the central heating, but not the central heating without the hot water (I assume it is a gravity system).

The Solution?

Can I just replace my programmer with a more advanced one that can be set to 'ignore' the cylinder stat between certain times?
I understand that I can't have the central heating on without the hot water, I just don't want the whole system firing up just for the hot water during the night.

Any help would be much appreciated.

 

[Boilerman2]

It sounds like your "Cylinder Stat" is not electrical - probably a Drayton Tapstat or a Danfoss equivelent, if this is the case you will not be able to achieve what you want to do you will have to rewire the system to include an electrical cylinder thermostat, it would be possible to connect this to stop the boiler once the new CM control & the cyliner is hot - it would be even better to include a 2 port zone valve into the scheme, but this will all cost money!

 

[yerino]

The short answer is ... No.

Unless of course you wanted to spend the money re-wiring the configuration / altering the system.

 

[bhm1712]

go with a C plan, its cheap (less than £130 if you can do the work yourself)

It involves wiring a cylinder stat and fitting a 2 port valve and associated wiring. depending what wiring centre you already have it could be a doddle.

I did this to my system and it reduced bills by quite alot, and i have full seperate control of CH and HW.

I doubt your system has a cylinder stat or any other sort of stat for the hot water other than the boiler thermostat, as there is no way to control the hot water cylinder temperature with basic gravity hot water system.

 

[matt1e]

perhaps i'm reading this wrong but the short answer would be
set the programmer so that the hot water is off between the hours of
9pm to 7am (or what ever suits)

simples

ps you already know you cant have heating while the hotwater is off so 9pm maybe a bit of an early off time

pps are you sure you are not fully pumped ? it may be advisable to check as these programmers come supplied set for gravity it may be that it just hasnt been set up for fully pumped

Matt

edit ok I think I read it wrong so ignore everything apart from the pps

 

[Whitespirit66]

The trouble with the Potterton EP2001, is that it doesn't give independent timings for the hw and ch.

I'm not completely sure about your system from your description. If it is fully pumped, you may be able to change to the EP6002, which allows independent hw and ch timings.

 

[ted209]

Thanks very much for the replies, I really appreciate your advice - sorry for the delay, I didn't get to reply before I went away for Christmas. I've taken a few photos which may help.

My system from the airing cupboard.

The valve:

The pump:

It appears that the valve is suitable for independent hot water and central heating, though I really don't know if my system is set up for this otherwise.

I've had a look at the EP2001 installation manual ( http://www.gtts.co.uk/EP2001/PottertonEP2001InstallerGuide.pdf ), and it shows different wiring schemes for different systems. I don't mind buying a new one, but ideally I would keep the existing one.

Can anyone advise me as to whether it may be possible for me to achieve independent central heating/hot water control with my system as it is (ie just re-wiring/replacing the programmer)?

Also, my pump is set at speed 3. I'd like to see if it still works fine on speed 2 as it may be quieter (and use less energy). I have 9 radiators in the house over 3 floors. Should I just go ahead and try it, or could I cause damage by changing it?

 

[matt1e]

looks like fully pumped Y-Plan to me
so yes you should be able have independant hot water control, check your programmer settings, you need it set up for fully pumped (there is a switch on the back which needs to be set to 16)
if you want better timing options you may have to upgrade to a better programmer as per Whitespirit66's earlier post.

Matt

 

[ted209]

It's working - thanks all for your replies!

I took out the programmer, and was surprised to see that it was already set to 16. However, there was also a sticker stating that the programme should be set before installing the backup battery. I simply removed the battery for a few minutes, then replaced it and I now have independent control!

Since I plan to leave the heating on constant (with my CM927 controling timing and temperature), the programmer can be used to control hot water alone.

Thanks again for your help.