Zoning central heating

[wedginald]

I wish to split my central heating into two zones. Can someone reconmend a progammer that with control two zone valves from two thermostats?
Cheers

 

[Agile]

There are three channel programmers available for HW and two CH channels.

However, its usually cheaper to use two programmers.

But a better and the cheapest solution is to use a programmable thermostat on each of the CH channels.

Tony

 

[wedginald]

Thanks, I thought that might be one of the options and probably better as its a combi anyway. When using two programable stats i presume each one would be wired to a valve and then to the boiler. How would the wiring at the boiler end be done?

 

[D_Hailsham]

I wish to split my central heating into two zones. Can someone recommend a programmer that will control two zone valves from two thermostats?

How do you get hot water? If you have a combi boiler, you will only need a two channel device; but if you have a hot water cylinder, you will need either a three channel device or a two channel for the heating and one channel for the Hot water.

I think the second option (two channel heat and separate HW timer) is better as the HW device can be a very simple time switch, with say two on/off periods a day and an override button, which can be installed in the airing cupboard with the HW cylinder. You do not need the sophistication of a Central heating programmer. A Honeywell ST9100A or ST9100C would be suitable.

Honeywell have a new two-channel programmer specifically designed for two heating zones (most two channel programmers are for heating and hot water).

Honeywell ST9500

The ST9500 is a 7 day two zone programmer designed for individual control of two heating zones and feature the LoT™ display, it also offers up to three "on" periods per day. Additionally each day may be programmed differently.

The thermostats you mention will, of course, have to be wired back to the programmer. Make sure you use digital thermostats e.g Honeywell DT200; they give better control over the temperature.

The alternative is to go the wireless route (for CH only).

 

[D_Hailsham]

Thanks, I thought that might be one of the options and probably better as its a combi anyway.

That's answered my question

When using two programmable stats, I presume each one would be wired to a valve and then to the boiler. How would the wiring at the boiler end be done?

That will depend on whether the boiler needs a switchable 230V supply or has connections for a volt-free thermostat. The valves will require 230V to run the motor, which opens the valve. The difference is the way the valve switch is wired.

Which boiler do you have?

 

[wedginald]

The boiler is a WB Greenstar 37 CDI

 

[D_Hailsham]

The boiler is a WB Greenstar 37 CDI

This boiler switches 230v to control the boiler.

Page 30 of the Installation Instructions shows the electrical connections.

The connection are made to ST10:

Ls = Live 230 volt supply to the wiring centre
Ns = Neutral connection to wiring centre
Lr - Switched return from valve

Here is a basic connection diagram (earth connections not shown). Click to enlarge; right click to save.

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