"For Q2 M8" wrote in message
om...
Hi All,
I've just moved into a house that has a "Glow worm - economy plus"
boiler (in the kitchen), it also has a controller (in the kitchen -
see below for more details) and a temperature control (in the lounge).


I'd like to replace the controller, currently a Honeywell ST699
controller, unit was not marked with a model but I have looked at
several honeywell units and this seems the most likely.
http://www.grantandstone.co.uk/heati...rols/st699.htm


With this I can program 2 on / off times or manually control the
central heating and the hot water.
I'd like to be able to set:

CH - on at 7am off at 8:30 am on at 5pm off at 10 pm
Hot water - on at 7am off at 7:30am

If I switch the CH to TWICE and the hot water to ONCE, then the hot
water is on from ON1 (7am) until OFF2 (10pm)
not ON1 and OFF1 !

I don't like the way that the hot water and central heating can't be
controlled independantly. Surely if I can control the system manually
then I can replace the timer/controller and have the functionality I
require ?
Could you suggest a suitable alternative controller that will give
more flexiblilty ?
Can I use a Honeywell ST6400C controller instead ?

Many thanks

I'm not sure whether your system is fully pumped or not. As others have
said, if hot water is by gravity circulation, you're stuffed and cannot have
heating without hot water.

Lets assume that it's fully pumped in which case you will have a 3-port
valve (or 2 x 2-port valves) and a cylinder stat. I assume that the
temperature control in the lounge is just a room stat?

One possible solution to your requirement is to replace the room stat with a
programmable stat. You can than set your existing timer to switch the hot
water on and off at the times you wish - and switch the heating to
continuous (manual). The heating will then actually be controlled by the
programmable stat - which enables you to have different temperatures at
different times should you so wish, as well as being OFF when required.

HTH,
Roger