wireless stat

[dlt2]

I have just fitted a wireless stat. to my y plan system however it is fed via a acl switchmaster 400 which means the stat. is only on when timed is on or when on constant. However this means the hot water is always on with it because you can not have heating on without water. Do I need to get a new programmer with CH on and HW on or can I just control the water through the programmer and take a perm. feed to wireless stat. to control 3 port valve. Thanks for any info.[/u]

 

[automationman]

Your new stat needs to initiate at least three actions when calling for heat:
1) Set the three port valve to the CH position
2) Turn on the pump
3) Fire the boiler

Your wiring centre should take care of all three assuming it receives a signal (230VAC) at the right terminal..... from the stat.

Do you have a wiring centre? Can you remove the cover and send a picture?

 

[dlt2]

I am struggling for a photo unfortunately . At the moment the wires are; CH ON-live on stat. SW live of stat. to white on 3 port valve. All is working as it should ie. when stat is calling light on valve comes on and carries 240v. However when programmer is set to water only heating is on aswell it never turns off. I have checked all voltages and cylinder stat. etc. turns on and off as it should. Could it be a faulty valve?

 

[ericmark]

Y Plan

• ericmark
• 12 Aug 2008
• 1

Shows standard Y plan are you sure it is Y plan and not W plan which has no motorised valve and can use thermo syphon for hot water?

With that system you can't switch off hot water without also switching off central heating.

My dads old system was like that and I had to fit a motorised valve to limit the hot water temperature and a wireless tank thermostat.

No sooner done it and he had whole lot replaced with new combo boiler.

 

[dlt2]

Definitely a y plan and I am convinced it is wired correctly. I think it is 3 port valve because when water only is on central heating is on aswell. Is there anyway to test the valve?. Thanks for the help.

 

[automationman]

This what to expect on the wires to the 3-port valve:


CH only = White Wire: LIVE (230VAC) with respect to Neutral
Gray Wire: LIVE (230VAC) with respect to Neutral


CH + DHW = White Wire: LIVE (230VAC) with respect to Neutral
Gray Wire: OFF (Assuming tank is cold)
IF Tank at temperature then Gray is LIVE (via cylinder stat)

The orange wire is switched inside the valve and becomes live to enable the pump and boiler.

For detailed info see this: http://www.gasheating.co.uk/Mid-Position-Valve.html

 

[dlt2]

All is as you have described. I just don't know whether the head of the 3 port valve is at fault or the mechanical side of the valve. Also do all 3 port valves have CH ONLY. HOT WATER ONLY AND BOTH TOGETHER or do some have only 2 positions ie. Water only and water and heating together. Sorry my knowledge on heating is not the best.

 

[automationman]

I personally only know of the mid-position type (but I am not a domestic CH expert)

Its usually has three positions:

CH ONLY - Hot Water to radiators

CH+DHW - Hot Water to radiators and coil of tank

DHW ONLY- Hot Water to coil of tank



Some configurations do not use the mid position

The mid position tends to cause motor failure issues since it is essentially stalled at the mid position, held with half wave rectified current.

Testing the valve in position is often a matter of waiting for the pipes to cool and then switching the valve to the three positions to verify a rise in output pipe temperature thus verifying that the valve is working mechanically.