Need to identify 2 zone heating system issue

[Robin Martin]

Hi all i've come cap in hand to ask for help identifying a heating issue i've found myself involved in. Backstory is all the pipework is done and the system is operational. Zone 2 valve is operated by a flowmasta wireless thermostat. The boiler has a switched live and is not operated by flow alone. The issue is that when Zone 2 heat is called the heating in Zone 1 comes on as well.

I was called in after plumber no.2 said it needs a relay to work properly. The diagram of the system as i understand it,

I went with the task of adding a relay and came out thinking pipework wont allow the system to work as 2 independent zones regardless of relays. Told the builder this and just had a call from a new guy on site who says it needs a 3 channel controller (it currently has a 2) and all will be well.

Now, sure my knowledge is limited but wont that achieve exactly the same thing as is already happening?

We're 2 visits in and i still don't think this will work but I seem to be the only one who thinks this can't be solved electrically. A very experienced handy guy said it needs the 3 port replacing with 2 x 2 ports or another pump to operate zone 2 alone, that makes sense to me it logically checks out.

So my plea is that you guys can shed some light on the best solution for this system before I go get opinion number 3...which i think is madness.

 

[doitmyself]

Which is zone 1; and which is zone 2?

 

[Robin Martin]

the extra zone valve is zone 2, zone 1 off the 3 port

 

[Robin Martin]

thank you so much for replying

 

[Last Plumber]

Hi all i've come cap in hand to ask for help identifying a heating issue i've found myself involved in. Backstory is all the pipework is done and the system is operational. Zone 2 valve is operated by a flowmasta wireless thermostat. The boiler has a switched live and is not operated by flow alone. The issue is that when Zone 2 heat is called the heating in Zone 1 comes on as well.

I was called in after plumber no.2 said it needs a relay to work properly. The diagram of the system as i understand it,

I went with the task of adding a relay and came out thinking pipework wont allow the system to work as 2 independent zones regardless of relays. Told the builder this and just had a call from a new guy on site who says it needs a 3 channel controller (it currently has a 2) and all will be well.

Now, sure my knowledge is limited but wont that achieve exactly the same thing as is already happening?

We're 2 visits in and i still don't think this will work but I seem to be the only one who thinks this can't be solved electrically. A very experienced handy guy said it needs the 3 port replacing with 2 x 2 ports or another pump to operate zone 2 alone, that makes sense to me it logically checks out.

So my plea is that you guys can shed some light on the best solution for this system before I go get opinion number 3...which i think is madness.

View attachment 32268

Hi Robin
I may be reading this wrong.
Is the Diagram at the bottom how things are or how you think they should be?

 

[Last Plumber]

If It were me, personally I would use a three channel clock, the relevant stats change to an S plan (three zone valves) and fit a by-pass.

 

[Robin Martin]

Sorry that's how it is right now

 

[Robin Martin]

Ok great thank you Last. That's put my mind at ease. If that is ideal world then is there another way to achieve zoning with the methods already described? or is s type the only way?

 

[doitmyself]

You only need a 3-channel programmer if you want separate timings for the two heating zones; otherwise a 2-channel programmer will do.

You will have to get rid of the mid-position valve and replace it with two zone valves. If you don't, whenever zone 2 is calling for heat either zone 1 or the HW zone will be heated at the same time. The reason for this is that a mid- position valve always has one port open, even when the valve is not in operation.

You will also need a bypass.

A second pump won't help.

 

[Robin Martin]

Cheers doit that's very clear. Zone 2 already has a programmable wireless thermo so it's effectively already 3 channel system, at least in my head. So adding a 3 channel controller will do very little. I think.

I think the idea of the extra pump was to t off before the existing pump and replace the zone 2 valve so pump 2 only feeds zone 2 making the Y plan a standard setup. But 2 zone valves makes more sense.

 

[Robin Martin]

Thinking out load now if the existing 2 channel is kept and the mid position valve is replace with 2 zone valves the heating will be n/c but the water would be n/o?

I ask as i noticed the controller had 'water off ' but 'heat on' wires so i guess it's geared up for a mid position.

 

[doitmyself]

So adding a 3 channel controller will do very little. I think.

That's correct. The 2- channel controller will control zone 1 and HW; the prog stat will control zone 2.

I think the idea of the extra pump was to t off before the existing pump and replace the zone 2 valve so pump 2 only feeds zone 2 making the Y plan a standard setup. But 2 zone valves makes more sense.

Teeing -off before the existing pump might work, but it's adding to the complexity. Replacing the 3-port with two zone valves, is the tried and tested way - and cheaper

Thinking out load now if the existing 2 channel is kept and the mid position valve is replace with 2 zone valves the heating will be n/c but the water would be n/o?
I ask as i noticed the controller had 'water off ' but 'heat on' wires so i guess it's geared up for a mid position.

It doesn't work like that. For a 3-port to work correctly, there must also be a wire to the water on terminal. The wire from heating off tells the valve to move over to the heating only position. A 3-port works like this:
HW On + CH Off = HW Only
HW On + CH On = Both On
HW Off + CH On = Heating Only

When you use separate 2-port valves for CH and HW, they are supplied from the CH On and HW On terminals of the programmer, via their thermostats. The HW Off terminal is not used.

 

[Last Plumber]

Zone 2 already has a programmable wireless thermo so it's effectively already 3 channel system, at least in my head. So adding a 3 channel controller will do very little. I think.

I meant, get rid of the programmer and Prog RM stat and install a three channel. Not install a three channel as well as the things you have now.

 

[Gasmk1]

just make it 3 x 2 ports simple