Downstairs heating turning itself on, upstairs fine?

[ianmcd]

If it was asticking micro switch the boiler and pump would constantly fire but the downstairs circuit wouldnt heat up, if you want to test the micro switches, you need to open the wiring centre , with power off check for continuity, there will be 3 orange wires into the same terminal and 3 grey wires into another terminal, if you get continuity between the two terminals you will have to split them into individual pairs to see which pair has continuity

 

[Jajodu]

The microswitch is operated by an internal arm operated by the syncron motor. It's internal to the switch. You can pop off the cover and observe it
Due care as it's mains voltage in there.

 

[ianmcd]

The microswitch is operated by an internal arm operated by the syncron motor. It's internal to the switch. You can pop off the cover and observe it
Due care as it's mains voltage in there.

Cant be done that way unless you seperate all the other valves as you will get 240v feeding back to the orange from the faulty micro switch

 

[b0ng0]

Taking apart the valve is starting to get to the edge of how far I'm prepared to go before calling a professional.

I put the programmer back on the wall (rads didn't turn on again while it was removed from the system) and it was able to correctly fire up the rads but after it was supposed to be off they still have some heat. Any further diagnosis on the valve I could do? Even if the lever feels normal could it still be sticking?

 

[Jajodu]

Cant be done that way unless you seperate all the other valves as you will get 240v feeding back to the orange from the faulty micro switch

I meant he could see if it was stuck using a mark 1 eyeball first of all, plus with the power off continuity could be measured.

 

[ianmcd]

plus with the power off continuity could be measured.

Not without splitting all the oranges and greys it couldnt

 

[Jajodu]

If power was off all the microswitches should be off. You should then be able to detect if it switches when manually operated.

 

[b0ng0]

If power was off all the microswitches should be off. You should then be able to detect if it switches when manually operated.

Just so I understand correctly, you suggest turning off the power, removing the Honeywell valve cover and manually moving the arm from Auto to Man and seeing if the microswitch actuates?

 

[Jajodu]

Yes

 

[ericmark]

That seems a good idea, full marks. Remove head ensure valve off, does it still heat?

I had the same problem rooms getting warm when they should not, the problem was simply discharged batteries in the TRV heads, the eQ-3 heads it seems are designed so when the batteries get low, it opens the valve, it is considered as fail safe. So today fitted 8 AA batteries and now other rooms heating up as rooms not in use have stopped getting warm.

Now I know why we use two motorised valves in series, the batteries in the TRV heads can go flat. But in the main the only reason for the motorised valve is because it acts as a relay. In theory the TRV does same job, but it relies on batteries.

 

[ianmcd]

Just so I understand correctly, you suggest turning off the power, removing the Honeywell valve cover and manually moving the arm from Auto to Man and seeing if the microswitch actuates?

You are getting completely wrong advice, moving the lever from auto to MAN will not connect with the micro switch

 

[Jajodu]

If the lever is manually moved to the fully on position are you saying it won't operate the switch?

 

[ianmcd]

If the lever is manually moved to the fully on position are you saying it won't operate the switch?

Correct the MAN position is simply for initial filling of the system with water, it will not go as far as to make the end switch, only the synchron motor does that

 

[Jajodu]

But you can operate the switch with a small screwdriver

 

[b0ng0]

One other thing I just noticed (could be unrelated) is that downstairs one or two of the rads are really hot (almost as if they were set to max and the rest are just warm (the TRVs are all set to the same level, 3 out of 5). This seems to have coincided with the CH not turning off downstairs.

Quick search of this problem and I found this old thread (https://www.diynot.com/diy/threads/one-hot-radiator-all-others-lukewarm-or-cold.19291/) where the last post was the original poster saying it was a motorized valve failure.