Motorised valves

[diezeltruck]

Hi,

The programmer that controls my central heating and hot water fails t communicate with the boiler and the boiler is continually 'ON'

The programmer is set at 'OFF' but the boiler still fires

The RET Electronic Room Thermostat that controls the central heatin also fails to switch the boiler off even when turned fully down.

Because of this my central heating is continually 'on' and th thermostat fails to switch do anything in controlling the room temp a the boiler fails to switch off.

It has been suggested that I have a faulty motorised valve which i stuck in the 'on' position.

I assume that the motorised valve operating the central heating may b faulty.

There seems to be 2 motorised valves beside my water tank:-

1 - Synchron HPA2 Actuator/HPV26 valve(plastic box/white cover) 2 - Synchron 272848 Honeywell Motorised valve(metal box)

But which valve of the two is faulty?

1 is situated just above and in line with the pump and feeds into th top of the cylinder tank

2 is situated off of the main pump and and then travels down to th ground floor.

I guess that 2 is the one that controls the central heating?

All the wires that serve both valves go into a junction box so it i easy to isolate each valve but which one?

Will changing just the actuator resolve the problem because having ha both actuators off each valve appears to turn except that 2 valve i what I could say a little stiff and jerky.

Will I have to drain the system?

There appears to be alot of 'stop taps' above and below each valv which sould facilitate removing of the valve.

I am tempted to just change the actuator!!

What does anyone think?

please advise

Cheers

Dieze

-- diezeltruck

[The Wanderer]

Do a google for 'S plan'. You should be able to come up with wiring diagrams for all the common variations of heating system.

Wiring mistake, possibly

Wiring mistake, possibly

That alone won't give rise to the symptoms you describe. If the system has been wired properly, then the controller overides any other auxiliary switches (like the thermostat, the aux switches on the valves) in the circuit.

Start with the junction box if you're happy to investigate the wiring.

[Roger]

The message from The Wanderer contains these words:

I don't think that follows. Surely the microswitch on the valve is fed from the permanent live and the controller provides a switched live for the thermostat. (That is certainly the way my controller should be wired).

If the system worked properly once and the wiring has not been disturbed a miss-wiring fault should not be present.

To the OP if the valve is difficult to move then that is the likely culprit but it is the wet part that is at fault so you will have to change the whole unit. The actuator can be tested easily enough by seeing if the symptoms persist while the actuator is mechanically disconnected to the valve which should, if faulty, remain open when the actuator is disconnected. If the actuator is not faulty the thermostat should then control the firing of the boiler.

[The Natural Philosopher]

Either. They are wired 'or'

That one (in an Andy voice)

Maybe. Take the actuatoir off and try wiggling the valve stem

Sometimes swarf or scale causes them to jam. If you can free it up enough the actuator motor may be able to move it again, or if its burnt out, new actuator.

Certainly remove it and check the spindle moves. Mine did this and only needed a new motorised bit.

If you disconnect the actuator switch contacts temporarily, at least the boiler won;t come on all the time.

[The Natural Philosopher]

Completely WRONG. The controller does not have the power to drive the boiler. The controller drives the thermostat and the valve motor: The switches on the valve body control the boiler. That is why they are there.

[The Natural Philosopher]

It's wired from permanent live on the switched fused spur that should run the whole heating system..

[The Wanderer]

Bollocks. As usual, you pontificate on things with such conviction , and it is *you* who is wrong. Do your homework, and take a google for 'S plan' wiring diagrams. The info is out there if you take a look for it, it might save you from looking so bloody stupid in future.

[Roger]

The message from The Natural Philosopher contains these words:

How come? The microswitch only closes when the thermostat powers up the actuator.

[Sparks]

[The Wanderer]

Yes, you are correct, I had mis-read the wiring diagram I was looking at.

[Roger Mills]

The microswitch is closed whenever the valve is open. The valve is opened by a motor - when told to do so by the programmer and stat. It is closed by a spring when the demand is removed.

HOWEVER, if the wet part of the valve jams open such that the return spring is unable to close it, the microswitch remains closed, and the boiler continues to fire - regardless of what the programmer and stat are doing.

[Roger]

The message from "Roger Mills" contains these words:

I am not disputing that as a particular fault and, if you read my earlier messages, that is exactly what I had previously suggested. What I was challenging was the NTs suggestion that wiring the microswitch that way was wrong as it would lead to the whole system being permanently on. However it seems I may have misinterpreted what the NT actually meant.

[The Natural Philosopher]

Correct. Your point being?

[The Natural Philosopher]

Correct. The live feeds the timer and the valve SWITCH. The valve MOTOR is fed via the thermostat from the timer OUTPUT. The SWITCH OUTPUT feeds the boiler.

[diezeltruck]

Thanks Roger! You're confirmation of what i'd thought was right and th Wanderers advice was incorrect

How could it be a wiring problem if the sysem has been working for th last 8 years without any probs and no wiring altered?

Having removed the actuator attached to the valve and manually turne the valve using my fingers hopefully freeing it and replacing th actuator appears to have solved the issue.

I've been on hols for 3 weeks and the CH has been off causing the valv to seize up.

Turning the valve does appear to be a little stiff and jerky bu hopefully now the system is up and running it should stay that way.

Thanks for your sound advice

Dieze

-- diezeltruck

[The Wanderer]

I did say in another post in this thread that I had misread the wiring diagram.

[roger]

The message from The Natural Philosopher contains these words:

Sorry about that. I thought you were saying that wiring the microswitch that way would result in the heating being permanently on.