Wiring Room Thermostat to Honeywell ST 7000 Programmer

If it worked before it should work the same now, what was controlling the temperature before? The Room stat should do eactly the same as turning the heating off by the timer. When you turn the heating OFF by timer does the boiler stop, By what you've said I don't think it does because you can only have heating if you have hot water. All the timer heating control is doing is actuating the port valve. Each time the room stat clicks on if you've got both CH and HW set it should pull the valve over from hot water to mid position.
Hot water is controlled by the boiler stat. Hot water and heating is also controlled by the boiler stat BUT won't switch off cos the radiators keep taking the heat.
But then I'm no expert, lectrician seems to know more than me

 

I agree with you madhattter, you're certainly no expert!


Lucia x

 

I know what I mean Lucy, i'm just no good at explaing it. I did write a reply then deleted it to re write and the pc's crashed, now i'm too tired to bother.
But basically Why is zero against hot water off?
A three port valve needs a heating wire a hot water off and a hot water on.

 

I may be wrong but that valve seems to have the hot water off wire missing, which is either designed that way and the programer is new hence it has the hot water off but no wire to connect or its been cut off because the valves sticking when it goes into hot water only, or its not three port, but we;ve already been told that it is.

 

What is the make/model of your valve?  Can you photograph it and post the photo here?  If it is a true mid port 3 position valve, you should have complete independent control of the HW and CH, and should have a cylinder stat (often behind a cover if you have a modern pressurised cylinder).

Photos would help.

 

Its always nice to whip in a towel rad, and indeed bathroom rad ''across the boiler primaries'' Lec..I emphasize the word ''across''..the reason being obvious.

 

People don't like that these days JP - Not being able to control that one rad can frustrate some people.

I did make a wording error above - with a y plan you do need to have a rad with lockshields on, usually in the hallway with the room stat. A mid position valve cannot close both ports ever, so there is no need for a heat dump rad or bypass, aslong as you have a lockshielded rad on the heating circuit.  

To get you thinking JP - we have had several plumbers who install a second heating circuit for UF heating, towel rails, or an annex etc, and just tee off the primaries, sticking in a 2 port valve and they just ask you to wire it up.  There is a very good reason why this cannot be done that simply with a Y-Plan mid position.  You need to either swap the mid position for two two port valves, or fit a 2 port valve in front of the mid position and wire it up as a "blocker" valve.

So, to get your brain working JP, why can't it be done as I mentioned first, and how would you wire a "blocker" valve?

 

Lec - Y Plan as in my house for instance. Whipping a towel rad and a small rad in the bathroom across the boiler primaries was never designed as a heat dump. Both rads can be turned off or just the towel rad used as indeed the ordinary rad..I used lockshields and Terrier wheels on mine, some people might want to use TRV's and of course lockshields (what the heck its there dosh)..but once again it is not designed as a heat dump.

All this double lockshield business on the last rad is poppycock tbqh..a simple bypass blown in under the floorboards works wonders..if you want you can use a lockdown valve on this bypass -  but what the heck if you adjust stuff properly then well it works like a goodun..