Heating zoned on a three port

[jonny5isalive]

Hi. Went to a job where they wanted a new thermostat for the downstairs as it wasn't working properly. Having looked at the controls it was a 2 zone system where they'd used a 3 port to differentiate between them. Bizarre.

Anyone seen this before?

 

[Ray Stafford]

I take it there was no cylinder?

 

[jonny5isalive]

I take it there was no cylinder?

No cylinder, Wierdly it looked like a relatively new install and I don't think it was even adapted from a system that used to have one.

 

[Ray Stafford]

Well if its wired up right, I don't see why it shouldn't work. I'm assuming that if its a new install is a mid-pos valve? The old hot-water priority valve would have made things a tad awkward 🙂 Upstairs stat calling? Shut off downstairs heating!

 

[jonny5isalive]

It's not wired up right at all. Only the upstairs stat calls for heat and thankfully for them the mid position valve is stuck in the middle so it is really only one zone at the moment.

 

[Aquazone]

I suppose it could be done in theory, as there's 3 positions on the valve, so could do downstairs, both or upstairs on it's own.

However, I'm sure you would need an off circuit from one of the room stats, and that would mean a perm live to the stat. I think?????

Probably best save yourself a headache and retire to S plan.

 

[jonny5isalive]

I suppose it could be done in theory, as there's 3 positions on the valve, so could do downstairs, both or upstairs on it's own.

However, I'm sure you would need an off circuit from one of the room stats, and that would mean a perm live to the stat. I think?????

Probably best save yourself a headache and retire to S plan.

Good plan I reckon. I like a challenge so spent a bit of time trying to work out what they'd done. They've put what looks like a capacitor across the orange. And although they've used a wiring centre they've not followed it at all.

I think you would need the DHW side to say that it was satisfied as you say and then it could work in theory.

 

[Nostrum]

You'd need a live from the satisfied terminal on the stat to motor across from mid position to A port only. The calling signal from that stat would run straight to fire the boiler & pump. It's the exact same principle as a cylinder only it goes through a room stat instead of a cylinder stat.

 

[jonny5isalive]

You'd need a live from the satisfied terminal on the stat to motor across from mid position to A port only. The calling signal from that stat would run straight to fire the boiler & pump. It's the exact same principle as a cylinder only it goes through a room stat instead of a cylinder stat.

Thanks. Have done a wiring course since and it has all become clear. . Tutor advised against as said it wasnt right but seems relatively simple once you understand . As you say as long as i have a satisfied feed for my programmer from the stat all will be good. Customer happy as is atm which is a shame as now i know how i fancied proving it could be done. And rewiring the mess so its easy to understand.

Thanks everyone for their help

 

[Reg Man]

It would have been so much easier with an s plan. At least everyone else that turns up when things go wrong will understand what's going on. The cost difference between Y plan and S is diddly squat.

 

[jonny5isalive]

It would have been so much easier with an s plan. At least everyone else that turns up when things go wrong will understand what's going on. The cost difference between Y plan and S is diddly squat.

I agree. Customer having none of it tho. Would have been perfect for three zones and easier to fit a filter.

 

[jonny5isalive]

It would have been so much easier with an s plan. At least everyone else that turns up when things go wrong will understand what's going on. The cost difference between Y plan and S is diddly squat.

If and when I rewire a tip I picked up is to use heatshrink to label the wires. And maybe a wiring diagram next to it if I've time.