Motorised Valves Activating When Heating Off??

deadduck

Hi,

Wondering if someone can advise?

We have 2 rooms stats, one upstairs, one downstairs. Each controls it’s respective 2 port motorised valve, both of which are located just under the boiler.

Issue is, even when the heating isn’t running (I.e. outside of the times set by the main programmer), if either of the room stats call for heat, the valves activate, and just sit there open, as the demand won’t be satisfied, as the boiler is off, as per the main programmer.

Is this a simple wiring issue, or is there something else going on that I’m not aware of?

Also, please let me know if any more info is required, if the above isn’t fully clear

John.G

The normal wiring is if the main switch is on and CH is selected on via programmer the supply goes to respective zone valve via roomstat, its the zone valve end switch that then calls in the boiler/circ pump so something strange all right.
Can you just switch on the CH system as per normal but with both roomstats turned to minimum and ensure both zone valves closed and then see if the boiler fires up occasionally, you may have to wait for awhile for the boiler thermostat to be satisfied.
The attached wiring diagram will show how it should be wired.

deadduck

John.G wrote: »

The normal wiring is if the main switch is on and CH is selected on via programmer the supply goes to respective zone valve via roomstat, its the zone valve end switch that then calls in the boiler/circ pump so something strange all right.
Can you just switch on the CH system as per normal but with both roomstats turned to minimum and ensure both zone valves closed and then see if the boiler fires up occasionally, you may have to wait for awhile for the boiler thermostat to be satisfied.
The attached wiring diagram will show how it should be wired.

Hi John, thanks for the info

I’ll have a proper check later, but I believe the zone valves don’t switch the boiler on either when the boiler is running, they simply activate until the room stats is satisfied and then close again. And just to be clear, we have a single channel system, so water is on all the time ( by which I mean, whenever programmer’s timed programme is running), and room stats decide when heating is on.

(we actually have one of those trv type valves on the cylinder, plan is to add a proper stat there too and another motorised valve for the water, but that’s a separate topic)

John.G

So how was your boiler supposed to be switched on/, was it if either CH or/and HW is programmed on or is there any hot water programmed channel?, I understand the cylinder tap stat control which used to be fairly common.

deadduck

John.G wrote: »

So how was your boiler supposed to be switched on/, was it if either CH or/and HW is programmed on or is there any hot water programmed channel?, I understand the cylinder tap stat control which used to be fairly common.

My understanding of it is there is only a h/w channel programmed. When this is running, it heats the cylinder to whatever the cylinder tap stat will allow and then shuts off. At the same time, if one of the room stats calls for heat, this causes the water in the CH zone to circulate, and the heat transfer from the cylinder water to the CH water in turn causes the boiler to fire up again, to bring the cylinder back up to temp. Does this sound right?

Just to add some further info, the flow pipe from the boiler is split to 3 further pipes, 1 for CH d/s, 1 for CH u/s, and one for HW (at least I expect that’s where that 3rd pipe is going, otherwise we wouldn’t have hot water?)

deadduck

Added some pics in case what I’m describing doesn’t tally with what’s actually present in the system

John.G

From what I can see, the programmer only switches on the boiler, during this programmed time the CH demand is satisfied by either or both zone valves opening via their respective roomstats and the HW demand is satisfied by the tap stat. If this is so then if all 3 heating demands are satisfied during this programmed period then the boiler will still fire up occasionally vis its own thermostat which certainly isn't ideal as it wastes energy and also unless the boiler has a internal by pass or there is a external ABV (automatic by pass valve) fitted then the water has no means of circulation.

Your original query was re the roomstats opening outside of the programmed time, the only difference this makes IF your system is installed as I have interpreted it, above, is that the zone valves may be consuming power when not required which may also shorten the lives of the actuators,

deadduck

John.G wrote: »

Your original query was re the roomstats opening outside of the programmed time, the only difference this makes IF your system is installed as I have interpreted it, above, is that the zone valves may be consuming power when not required which may also shorten the lives of the actuators,

Exactly, this is the thing, I don’t want the actuators wearing out prematurely, they’ve already been changed out before. I’ll have a look later and see if the wiring is as showed in the schematic you provided. My suspicion is the motorised valves aren’t connected to the boiler at all, and therefore don’t know when the boiler is off, and also don’t switch it on when they should.

Thanks for all the advice and I’ll report back on what I find.

wizardman

Instead of the motorized having a permanent live, change it to the switched live. Should a wiring centre its simple to do. Many house built like that 15-20 years ago. Blanchardatown, clonee, lucan etc.

Usually a manual thermostat on the cylinder (TCV) usually myson was used.

deadduck

wizardman wrote: »

Instead of the motorized having a permanent live, change it to the switched live. Should a wiring centre its simple to do. Many house built like that 15-20 years ago. Blanchardatown, clonee, lucan etc.

Usually a manual thermostat on the cylinder (TCV) usually myson was used.

That certainly sounds like a simple fix to the issue I’m having, so thanks for the input.

However, and this is going to sound silly, when I went looking for the wiring Centre I couldn’t find it! Took the 3a spur off the wall to be sure it wasn’t somehow hiding behind it, no joy. Where are they usually located?

deadduck

After further investigation, I found the ‘wiring centre’, but it’s not what I expected. You can see in the pics, as John said, the boiler is connected directly to the programmer’s back panel, along with black and grey. The motorised valves’ neutrals are also wired into the back panel, and their lives are going into the terminals in the pics, but the orange and black wires have both been cut back.

That said, I’m guessing their’s still no reason I can’t wire the valves’ live wires to the programmers switched live on the back panel, as this will have the same result as Wizard suggested, I.e, valves will only operate when heating/boiler is on?

wizardman

deadduck wrote: »

After further investigation, I found the ‘wiring centre’, but it’s not what I expected. You can see in the pics, as John said, the boiler is connected directly to the programmer’s back panel, along with black and grey. The motorised valves’ neutrals are also wired into the back panel, and their lives are going into the terminals in the pics, but the orange and black wires have both been cut back.

That said, I’m guessing their’s still no reason I can’t wire the valves’ live wires to the programmers switched live on the back panel, as this will have the same result as Wizard suggested, I.e, valves will only operate when heating/boiler is on?

Yes that's what I said above.

John.G

The wires that are being changed to the programmer switched live are the room stats?.

deadduck

John.G wrote: »

The wires that are being changed to the programmer switched live are the room stats?.

No, Wizard has said the valves’ live wires should go to the switched live on the back panel instead, so they’ll only activate when the heating is running.

John.G

If your room stats aren't in the picture then you may as well have no zone valves as the heating is full on to both zones for the full programmed time?.

wizardman

Once the clock is switched on, a live will go to the boiler, live to each room stat. If the room stat is calling for heat it will open the motorized valve. When the stat is satisfied the valve will close.

When the clock goes off, timed or manually switched off. The live to the boiler and stat and valves if they are calling for heat will be cut. So your valves are now not permanently live.

Very simple

deadduck

John.G wrote: »

If your room stats aren't in the picture then you may as well have no zone valves as the heating is full on to both zones for the full programmed time?.

Yeah, you’re right, if I go that route the valves will be open all the time

deadduck

wizardman wrote: »

Once the clock is switched on, a live will go to the boiler, live to each room stat. If the room stat is calling for heat it will open the motorized valve. When the stat is satisfied the valve will close.

When the clock goes off, timed or manually switched off. The live to the boiler and stat and valves if they are calling for heat will be cut. So your valves are now not permanently live.

Very simple

Hmm... I don’t think that will work in my case. The room stats are digital, and for some reason, they default to ‘standby’ when powered back up.

John.G

You could install programmable stats but at a cost.

Another "solution" might be to buy a few relays, powered from the boiler switched supply and installed in the live to/at the zone valves, it might be relatively easy to install these in a JB close to the valves, does one of your photos above show the two zone valves installed close to the boiler?

deadduck

John.G wrote: »

You could install programmable stats but at a cost.

Another "solution" might be to buy a few relays, powered from the boiler switched supply and installed in the live to/at the zone valves, it might be relatively easy to install these in a JB close to the valves, does one of your photos above show the two zone valves installed close to the boiler?

Yes, the 2 valves are directly under the boiler.

Do you mean to use some dual input relays, and feed the programmer’s S/L to it, and the S/L from the room stat also, and when both are ‘on’, this would activate the motorised valve?

John.G

Yes, I think that should work OK, if the programmer isn't giving a switched supply to the boiler and the relays then the room stat supply to the zone vale(s) is open irrespective of whether the room stat is calling for heat or not.
In other words the relays are only closed during the programmed times, the room stats then open/close the zone valves as required through the (now) closed relays.

wizardman

Is there batteries in your stats? If not swap for simple on off stats or get stats will batteries to hold setting.

deadduck

Thanks very much for the responses and advice guys, it’s much appreciated. Gonna either go with John’s idea with the relays, or maybe even go one better and fit a proper Wiring centre to house all the connections and get the system running properly.

wizardman

deadduck wrote: »

Thanks very much for the responses and advice guys, it’s much appreciated. Gonna either go with John’s idea with the relays, or maybe even go one better and fit a proper Wiring centre to house all the connections and get the system running properly.

No need for relays, think that's a mad idea but each to their own.

Rewire the whole thing and use the micro switch on the valves. Fit a motorized valve and cylinder stat on hot water and have the whole system interlocked. That's the best thing to do.

But for quick job change the stats, job done.

Good luck whatever you choose

John.G

deadduck wrote: »

Thanks very much for the responses and advice guys, it’s much appreciated. Gonna either go with John’s idea with the relays, or maybe even go one better and fit a proper Wiring centre to house all the connections and get the system running properly.

Obviously, as stated above, a "proper" S plan is the ultimate way to go but in the interim, one relay, a single coil double pole, will do the trick while you are making your mind up and prolong the life of the actuators.