Looking fora tank thermostat with a built in timer

[Guy Dawson]

I've recently replaced a Honeywell T6360 thermostat with a CM907 Chronostat and I am generally very happy with it.

There is one downside though. To give total control of the heating over to the CM907 the main programmer/timer unit (a Potterton EP2001) has to be set to continous for the heating. Due to the restrictions of the EP2001 this also means that the hot water has to be set to continous. If fact the act of setting the heating to continous on the EP2001 causes the EP2001 to set the hotwater to continous too.

So what I'd ldeally like is a tank thermostat with a bult in timer as for much of the time we don't need hot water but would still like a warm house!

The system is a pumped Y plan BTW.

Any pointers?

Guy

-- -------------------------------------------------------------------- Guy Dawson I.T. Manager Crossflight Ltd [e-mail]

[John Phillips]

Instead of taking the live feed to the CM907 switch (pin A probably) from the timed "CH on" pin of the EP2001 (pin 4 I think) why not take this live feed from a non-timed, permanent live?

Then the timer applies only to the HW and the temperature profile of the CM907 takes care of the timing for the CH.

[Guy Dawson]

That would involve running new wires. The boilder and controller are in new extension (well, new in 1990) while the CM907 is the original (and current) hall.

I guess if I would rewire the switched live at the EP2001 to be a non-switched live then this might be enough.

Guy, who feels guess is not good enough!

-- -------------------------------------------------------------------- Guy Dawson I.T. Manager Crossflight Ltd [e-mail]

[John Phillips]

Yes - that's exactly what I wanted to suggest. Sorry if it wasn't clear which end of the thermostat cable I was writing about.

It should just need the thermostat switch wire moved at the EP2001 from the "CH on" pin (pin 4 I think) to the L pin (or pin 5 if the installer link from L to 5 is there). BTW I'm going on a diagram from the web so please do check your EP2001 documentataion for correctness and safety.

Of course a programmable cylinder stat would also do if available, but the above seems simpler if it can be safely done.

[Ed Sirett]

You should be able to set the CH to continuous and the HW to once or twice.

You may need to reset the device and/or move a mechanincal interlock and/or move a jumper from Gravity/10 to Full/Pumped/16 .

[Guy Dawson]

[snip]

There's my main problem - no documentation for the EP2001.

Indeed.

-- Guy

[John Phillips]

's an installer and a user guide.

I see Ed S. suggests it can be put into separate HW and CH control mode by switching from 10- to 16-program mode. See the installer guide section

1. Note that this seems to be done with the battery disconnected (see section 13).

If so, that would be an easier solution still ...

[geoff]

IIRC, the 10-16 selector is a mechanical interlock on the rear of the programmer, ... screwdriver and a 90 degree rotation

[geoff]

What do you need to know about the 2001 that isn't on the back of the programmer ?

I prolly have a user guide somewhere