There's a wiring diagram here which a quick glance at seems to show the BDR91 firing the boiler.?
Odd zone valve problem
- Thread starter Ben565
- Start date
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Yes there's a few different configurations possible.
In my setup BDR91 is controlling the zone valves. I have one for HW and one for CH.
My installer said it makes no difference if BDR91 triggers the boiler directly. Or triggers it via a zone valve.
Personally I would have configured it so BDR91 connects directly to the boiler, but he was on the phone to Honeywell and they talked him through this configuration. So I guess its acceptable.
In my setup BDR91 is controlling the zone valves. I have one for HW and one for CH.
My installer said it makes no difference if BDR91 triggers the boiler directly. Or triggers it via a zone valve.
Personally I would have configured it so BDR91 connects directly to the boiler, but he was on the phone to Honeywell and they talked him through this configuration. So I guess its acceptable.
My understanding is that the BDR91 is just a switch, sending power to either the boiler or the 2 ports valve, everything else should be connected and work as any normal S Plan, unless there's a wireless controller/relay at the boiler. I think you need to go back to basics, remove the evohome temporarily and connect it all up as a normal S plan, check that it all works then work your way back to installing the EVOhome clean.
There are some basic wiring/circuit checks that can be done without that if it can be understood what's being looked at, sometimes it can be quite confusing looking at a wiring centre with all those connections. Always be careful with leccy and work confidently and safely.
Evohome manual - page 46
BTW, the 'pink' wire may actually be the brown live wire, with some valves the brown live can actually look 'pinkish'
There are some basic wiring/circuit checks that can be done without that if it can be understood what's being looked at, sometimes it can be quite confusing looking at a wiring centre with all those connections. Always be careful with leccy and work confidently and safely.
Evohome manual - page 46
BTW, the 'pink' wire may actually be the brown live wire, with some valves the brown live can actually look 'pinkish'
It is connected up as a basic S-Plan system, just switched live for the zone valve is coming from a BDR91 instead of a thermostat or controller box. Theres no difference.
I could disconnect the BDR91 and put a manual switch to the zone valve, but what would that prove ?
We already know BDR91 is switching live to the zone valve like it should. Its going make no difference if I disconnect it and put a different controller on or even manual switch.
With evohome connected, live gets switched to the zone valve
With original dumb controller, live gets switched to the the zone valve
The signal to the zone valves isn't the issue here. Both zone valves were getting live switched to them. Thats it thats evhomes part in this done and dusted.
I could disconnect the BDR91 and put a manual switch to the zone valve, but what would that prove ?
We already know BDR91 is switching live to the zone valve like it should. Its going make no difference if I disconnect it and put a different controller on or even manual switch.
With evohome connected, live gets switched to the zone valve
With original dumb controller, live gets switched to the the zone valve
The signal to the zone valves isn't the issue here. Both zone valves were getting live switched to them. Thats it thats evhomes part in this done and dusted.
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If it's not the BDR's, then testing of the rest of the system is straightforward. Power runs into the wiring centre, that runs to each BDR91, they switch the power out to energise each valve, on demand, when the valve is energised then the valve's microswitch switches the PermL out through the SL to the boiler/pump.
If there is strange switching going on and the BDR's aren't a problem then it has to be either a crossed/short wiring issue or one or both valves. The easiest way is to take it back to the start, disconnect the 2 port valves and test at each stage of calling, that way it can be seen where the problem is being introduced and live power test each component - PermL in (G) and SL (O) and work back from there.
If there is strange switching going on and the BDR's aren't a problem then it has to be either a crossed/short wiring issue or one or both valves. The easiest way is to take it back to the start, disconnect the 2 port valves and test at each stage of calling, that way it can be seen where the problem is being introduced and live power test each component - PermL in (G) and SL (O) and work back from there.
Its going to be hard to do any more because its working normally now. Which is what makes me think something mechanical was stuck/sticking. And zone valves are prime candidate for this.
The end switch(s) mustn't have been .making IMO, pulling on the levers manually probably gave the ball and contacts that extra few mm required.
Might be no harm to check the voltage on that purple wire with both valves engined and with one energised in case it's too low for whatever reason and not enabling the motor to supply sufficient torque.
Might be no harm to check the voltage on that purple wire with both valves engined and with one energised in case it's too low for whatever reason and not enabling the motor to supply sufficient torque.
They are known for sticking yes but they wouldn't normally cause one to switch when the other was disconnected, they normally either switch or they wouldn't. That being said it may be the SL from one that's causing a problem in the other. The microswitches may be getting sticky/intermittent, if they continue to be problematic then best approach would be to replace the head(s) if they are replaceable.
Cant see from the photo but if it has Honeywell stamped into the case below the warning label then it's as good as they get, if it doesn't then it may be a generic valve which tend to made of cheaper bits
Honeywell used to be the best, but they’re not as good as they once were. Others still rate them.
They are Honeywell which are still probably as good as any, I'd say the chances of the two going faulty together are almost nil and looks to me like a supply voltage problem not driving them hard over,may still be worth checking the voltage with both energised even though both operating normally now.
How old are they?
How old are they?
With valve in manually open position, microswitch will not operate. It only operates under power.
Prudent thing to do is to check what voltage is on orange wire ( white would bE isolated if you have 6 conductors in the motorised valve cable) in each either heating or hot water demand. Brown and blue run the valve motor, grey would sometimes have 240 on it, other times a low voltage if the demand terminal is for non mains operation. When valve fully open, the switch within the valve operates and runs the boiler.
There are times when a priority schedule might be chosen which will require, say hot water cylinder be upto temperature before heating will come on
Easy enough to do when you know grey wire voltage needs to run the boiler when relevant switch in the valve operates.
BDR is a demand switch that tells the control system to get on with it. If the light on BDR is green, brown of connected valve will run till valve is open. Switch now energises and boiler will run.
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