Zone Valves

[ronald]

Currently I have a 3 port valve controlled by a Time Controller (Honeywell ST799), which controls my heating and hot water.

I want to zone my house to split upstairs and downstairs, and would therefore like to use two sets of the HoneyWell CM67RF Programmable Thermostat and HC60NG relay box, one set for each zone. What I would like to know is what kind of zone valves I need?

I could buy three 2 port valvles (1 for upstairs zone, 1 for downstairs zone, and 1 for the Hot Water (HW)). However at =A345 a valve I would like to know if it is possible to re-use the existing 3 port zone valve for one of the zones and HW, (in which case the CM67RF + HC60NG and the ST799 would need to be able to ontrol the same valve, is this possible?

[Mike]

Or buy both for that price at Grahams.

[John]

I want to zone my house to split upstairs and downstairs, and would therefore like to use two sets of the HoneyWell CM67RF Programmable Thermostat and HC60NG relay box, one set for each zone. What I would like to know is what kind of zone valves I need?

The usual method is to use three two port valves as you intimate above. The wiring is quite simple if you look up the S-plan on one of the manufacturers websites.

I could buy three 2 port valvles (1 for upstairs zone, 1 for downstairs zone, and 1 for the Hot Water (HW)). However at £45 a valve I would like to know if it is possible to re-use the existing 3 port zone valve for one of the zones and HW, (in which case the CM67RF + HC60NG and the ST799 would need to be able to ontrol the same valve, is this possible?

Look around for better prices but to answer your question its possible but you will end up with non-standard systems and possibly a bodge.

[Set Square]

Although it may be *possible* to mix 2-port and 3-port valves in the same system, it's highly undesirable, and the wiring will be an absolute nightmare to sort out. The way in which the boiler is controlled is very different between a Y-Plan system (which you have at the moment) and an S-Plan+ (which you would have with three 2-port valves).

You really need to bite the bullet and go for three 2-port valves. You can almost certainly get them for less than £45 each (maybe not Honeywell, but perfectly adequate). You may also need an automatic by-pass valve if you don't currently have a by-pass circuit. Whereas a 3-port valve always provides *somewhere* for the pump over-run flow to go, a collection of

2-port valves doesn't.

You need zone valves which have a set of volt-free contacts which close when the valve is fully open. The programmable thermostats (and the cylinder stat) switch the zone valve motors. The volt-free contacts switch on the boiler when one or more valves is open. You don't need any relays. Have a look at "S-Plan" and S-Plan Plus" in