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Discuss 2 zone CH but 1 zone heats whole house in the Plumbing Jobs | The Job-board area at PlumbersForums.net

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I’d really appreciate some advice.

We moved into a new build 3 story town house last Monday. It’s got a Worcester boiler & 2 wireless thermostats (one by the front door, the other on the first floor landing).

When the downstairs thermostat asks for heat (to warm up the kitchen & lounge) every radiator in the house on all 3 floors gets hot. The upstairs thermostat is definitely not asking for heat.

I’ve checked in the boiler room and there are 2 RF receivers which seem to be paired correctly with the thermostats.

We’ve had the plumber who installed the system & the developer round - but when I tried to explain the problem, they both went straight upstairs and set the upstairs thermostat to ask for heat. The upstairs radiators started warming up (which they should do) and they turned the upstairs thermostat down again.

When I turned the downstairs thermostat up and took them back upstairs to show them the warm radiators, they explained this away as ‘residual heat’ from when they had just turned the upstairs thermostat up.

I’ll definitely be getting both the developer & plumber back again and demonstrating the fault to them properly.

My question is - why is this happening? Any ideas would be greatly appreciated to help me have it out with them!
 
Thanks Scott - I took a photo yesterday (when the downstairs thermostat was calling for heat). As you may be able to make out - one of the motorised valves is on A & the other on B - so I didn’t think this was the problem. But could there be something going wrong inside the unit itself that I can’t see? Thanks again for the advice

#can’t post photo, think file is to large. Will repost in a sec
 
Thanks for your responses so far.

One thing to add - after setting all the upstairs radiators to zero last night, i’ve come downstairs this morning to find all the downstairs radiators barely producing any heat at all. The downstairs thermostat is reading 18c but calling for heat to make the downstairs rooms 20c. The boiler is fired so downstairs should be warmer than it is. Has turning my upstairs radiators to zero affected my downstairs radiators?
 
Is it a combi boiler or do you have a big hot water tank.

If it's not a combi, and the upstairs valve is not open you my have an installation problem.

One, the bypass may be linking the two different zones.

Or two, you may have reverse circulation, this is where the hot water return pipe ISN'T the last pipe T'd in to the boiler return pipe.

Get the guys round again, DON'T let them call for first floor heat, have all the rads cold and call for downstairs heat.

Then check to see if the outlet side of the first floor zone valve is heating up, test is a couple of feet away the valve not right next to it.

This will show if the first floor zone valve is passing to stuck open. If there is not heat at the outlet side of the zone valve, you have an installation problem.
 
Hi Bibbs - thanks for the reply. The plumber has promised to return today so it’s good to have some ideas about what the problem might be.

It’s a combi boiler (brand new) - i’ve added a photo of what the system looks like when the downstairs thermostat is calling for heat but the upstairs thermostat is off (although as i’ve mentioned this still heats up the upstairs radiators)

Would you mind explaining which side is the outlet valve? I remember feeling all the pipes coming out of the boiler when I took the picture & all were red hot.

Many thanks

0B892A7B-9B40-4C77-AB4D-0AAB2F881074.jpeg
 
Hi Bibbs - thanks for the reply. The plumber has promised to return today so it’s good to have some ideas about what the problem might be.

It’s a combi boiler (brand new) - i’ve added a photo of what the system looks like when the downstairs thermostat is calling for heat but the upstairs thermostat is off (although as i’ve mentioned this still heats up the upstairs radiators)

Would you mind explaining which side is the outlet valve? I remember feeling all the pipes coming out of the boiler when I took the picture & all were red hot.

Many thanks

View attachment 33420
Hi, below is the outlet side of the zone valve
 
CAnt see a bypass so I’d assume that the valve is letting by. Could even be a wiring fault
 
It’s a Greenstar 30i ErP NG Combi

Thanks for all your contributions. The plumber came round again this morning & was here for over 3 hour’s trying to sort it all out.

Having pulled up the flooring in the boiler room, he said the return pipe was incorrectly plumbed in & sending hot water straight into the upstairs heating pipes (or something like that!)

That would explain why the upstairs radiators were getting hot when the downstairs thermostat called for heat.

I’ve been out all afternoon so haven’t had a chance to test the system for myself yet & check that the upstairs radiators don’t get hot when the downstairs ones do, but will do that later.

He’s definitely coming back anyway as we also have a downstairs radiator failing to heat up at the bottom. It’s been flushed through twice now on the driveway, so he is planning just to replace the radiator.

The other reason he’s definitely coming back is that he left his drill behind!
 
I spoke to soon!

The downstairs thermostat just called for heat to warm up the lounge & kitchen radiators. They’re now hot but problem is - so are the upstairs radiators (where the thermostat controlling the zone is turned off!). We can stop upstairs getting to warm by turning down the TRV’s on each radiator but i’ll be asking the plumber back for another go at fixing the problem. So do please keep your suggestions coming!
 
CAnt see a bypass so I’d assume that the valve is letting by. Could even be a wiring fault

Looks from the picture the upstairs valve is closed when downstairs is calling. I'm betting the two zones are linked, installation fault.


(I didn't read posters post about the plumber being back.....honest)
 
Thanks again for all the help with this - firstly the pipes. Yes they are both hot both above & below the valve.

The plumber came back again today (I think it’s his 4th visit!). He’s suggested that both of the valves (the ones that switch from A to B) have been incorrectly fitted, so hot water was going through to the upstairs radiators when it wasn’t being called for. He said it wasn’t worth trying to fit them correctly now as they’re basically broken, so he’s going to buy two brand new ones and come back to fit them properly (we hope)
 
Thanks again for all the help with this - firstly the pipes. Yes they are both hot both above & below the valve.

The plumber came back again today (I think it’s his 4th visit!). He’s suggested that both of the valves (the ones that switch from A to B) have been incorrectly fitted, so hot water was going through to the upstairs radiators when it wasn’t being called for. He said it wasn’t worth trying to fit them correctly now as they’re basically broken, so he’s going to buy two brand new ones and come back to fit them properly (we hope)


Do not pay for this work. I very very doubt they are either broken or fitted incorrectly.

If they are fitting incorrectly that can only mean upside-down, a nice clear pic of both sides of both brass housings will show this .AND having water going thru them in the wrong direction is very unlikely to break them .

I'm still going with incorrect pipe work, which I thought one plumber had identified under the floor? Keep us posted.
 
Hi - my Electrician's 20p internet bet will be on the wiring, as that's the bit I do sometimes find has been left wrong (I guess sometimes mistakes with pipes are made, but I've never seen one :) ). I agree with @Bibbs118 that neither piping or wiring errors will have damaged the 2 port valves, sorry.
 
Hi - my Electrician's 20p internet bet will be on the wiring, as that's the bit I do sometimes find has been wrong :) . I agree with @Bibbs118 that neither piping or wiring errors will have damaged the 2 port valves, sorry.


Check out the pic, shows valve closed and the one Stat calling with its valve open. This to me rules out Wiring .
 
Post some pics and a detailed description of the fault.

Same situation, new build house, multi zone heating but only on 2 stories.
Turn downstairs heating on, valve does not actuate as in the arm does not move but heating does come on downstairs, but also upstairs on all radiators except the main bathroom (which is directly above the valves if that makes a difference)
House builder has agreed to change the valve as it is clearly not actuating suspecting the spring has gone (danfoss valve) however i suspect the issue runs deeper than this i.e pipework or electrical turning the rads on upstairs.

Any help appreciated or some ammo to throw at the house builder.
 
Same situation, new build house, multi zone heating but only on 2 stories.
Turn downstairs heating on, valve does not actuate as in the arm does not move but heating does come on downstairs, but also upstairs on all radiators except the main bathroom (which is directly above the valves if that makes a difference)
House builder has agreed to change the valve as it is clearly not actuating suspecting the spring has gone (danfoss valve) however i suspect the issue runs deeper than this i.e pipework or electrical turning the rads on upstairs.

Any help appreciated or some ammo to throw at the house builder.


So are you saying, you turn the downstair heating on, the arm doesnt move, but the downstair rads get hot?
 
Changing the valve will do absolutely nothing, it may not be visiblly moving over but its bringing the rads on so its working fine.

You have a piping issue, namely its been piped up incorrectly.

That level is there to manually move the valve if the motor inside fails, its not a visual tool to tell you its moved over.

It you push it over when the stat is calling for heat it will be slack, turn the stat down and you will need to push it fairly hard to move it.
 
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Changing the valve will do absolutely nothing, it may not be visiblly moving over but its bringing the rads on so its working fine.

You have a piping issue, namely its been piped up incorrectly.

That level is there to manually move the valve if the motor inside fails, its not a visual tool to tell you its moved over.

It you push it over when the stat is calling for heat it will be slack, turn the stat down and you will need to push it fairly hard to move it.

Thanks Bibbs, you have confirmed what i suspected regarding it is the pipework.

Now im no plumber but i assume to rectify this the builder will have to start lifting floor boards and ripping the house apart to find the issue as to where the downstairs pipework is meeting the upstairs?

Thanks for your help so far
 
Not necessarily show a picture of your airing cupboard. Cylinder pipework and valves
 
Is that the only visible pipework? Do you have a cylinder
 
A thermal image camera may be required.

It may be something a simple as moving the cylinder return so that it's the last return to the boiler, but yes, it may need some serious mess making then making good .
 
A thermal image camera may be required.

It may be something a simple as moving the cylinder return so that it's the last return to the boiler, but yes, it may need some serious mess making then making good .

Thanks Gibbs, your help is much appreciated and certainly given me half a chance to blag the builder into thinking i know what im talking about. It seems they will take any oppertunity to avoid snagging on our site and have pulled the wool over many of the owners eyes but not me.

I will update the thread once the plumbers have visited
 

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