Honeywell V4073A

[fluxcapacitor]

I wonder if one of you could explain the purpose of the lever on the front of the 4073 marked Auto/Man. Although it might appear obvious.
I moved into my current house 10 years ago. Soon afterwards the central heating radiators failed to heat up when the system was running. After a bit of fiddling I found that moving the lever across to Man and lifting it so it locked fixed the problem. Until the last couple of days that is. Now the lever, cunning little devil, unlocks itself and gradually makes its way to auto. Thus no heating. I assume something has changed i.e. a fault has developed.
Any information gratefully recieved. Previous posts/data sheets on the web don't seem to address this question.

 

[seco services]

change the motor in the top of the actuator valve for £10 saves keep moving it across for the next ten yrs.

by pushing the lever across will give you heating when the motor fails in the actuator.and also help the system refill when its been drained.

 

[fluxcapacitor]

Thanks for that rapid response. I have one on order.

 

[MANDATE]

The valve/motor moves over 2 stages ie 1st half then 2nd half but uses power from different source for each half.
The power for 1st half comes from 'white' wire. power for 2nd half comes from 'grey' wire.
If the motor is duff, then it won't travel the 1st half and it's got to get to mid position before the 'grey' wire can takes over.
You have used the lever to turn the valve/motor to mid position (although thats not its true purpose) and you've had some form of sucess.
What is not clear is! When the HW gets satisfied does the valve/motor go to CH only position.
Well obviously it can't if the motor is duff and the lever only takes it mid position(for filling). But if it has been going to CH only and being controlled by the room stat, then the motor may not be the problem.
Suppose there is a wiring fault or the room stat is at fault and there is no power at the 'white' wire.
Also within the 'actuator head' are two micro switches. Burnt or dirty contacts can also cause problems. Also the valve spindle, if stiff makes it too hard for the motor.
So Its not easy to pin point the real problem, but at least you can check spindle and available power at the 'white' wire.
Best to test it with the head removed off the spindle.

 

[fluxcapacitor]

Thanks Mandate. Fingers crossed it is the motor however I'll check out the voltage values tomorrow hopefully.
Found the following link in another post giving the mechanical and electrical operation. It won't hurt to reproduce it here.

http://content.honeywell.com/uk/homes/FAQ/v4073aop.pdf

 

[fluxcapacitor]

Finally managed to check voltages and found the following:
heating only - white 240 grey 64
hot water only - white 9.4 grey 94
heating + hot water white 240 grey 67

Does this suggest any particular area at fault? PCB components? The values certainly do not conform to those in the link in my previous post.

 

[MANDATE]

Well the 'grey' wire seems to be the problem area.
This 'grey' is required to be 240 volts to power the motor over the final stage.
Power to the 'grey' comes from the 'satisfied terminal' of the cylinder stat, but it would not work if the HW was not switched on.
So an additional source is provided and this comes direct from the programmer, known as the HW OFF terminal.
So with HW and CH both off, the 'grey' should have 240 volts.
With HW on but not satisfied, the 'grey' should not be live.
With HW on and satisfied the 'grey' should have 240 volts
With CH on. 'grey' has to have 240 volts to keep it energised andin the correct position (even if the room stat cuts power to the boiler)
With both HW and CH on. Now here's the difficult bit, both are switched on, but are they both in demand or are they both satisfied or is one satisfied and one still in demand.
From cold both may well be in demand (valve at midway, grey not live)
Say HW gets satisfied, then the cylinder stat makes 'grey' live so valve moves to CH only.
Say room stat cuts the supply to 'white', Yes it stops the boiler, but 'grey' stays live.
Say there is now demand for HW, the 'grey' no longer live, neither is 'white so valve unwinds to HW only.
So you have to know more about the actual valve position. It does not mean its at midway just because both are switched on. It's designed to flutuate according to demand.
I see there is no result for both HW and CH off.
Also you may have to check the two feeds to the 'grey' separately.
If you start with 240volts at the programmer and you're down to 67 it's highly likely theres a bad connection in the 10 terminal box.
Hope all this makes sense, I will watch with interest

 

[seco services]

i recon he'll be scratching his head if he can take all that in first time. LOL

 

[gavinda]

i struggled and i know that stuff like the bak of my hand

 

[MANDATE]

i struggled and i know that stuff like the back of my hand

But did you find it incorrect?

 

[fluxcapacitor]

Thank you for that very detailed post Mandate. The initial impression was 'What on earth does that lot mean'. However, in conjunction with the information in the Honeywell pdf document it all made sense.
The situation seems to be resolved. Your comment about the programmer prompted me to open it too. There was presumably a bad contact within as I'm suddenly getting 240V on the grey wire now.
For completeness the satisfied/unsatisfied voltage values follow:

HW CH White Grey
off off 1 1
ON(unsat) ON(unsat) 240 113
ON(sat) ON(unsat) 240 240
ON(unsat) ON(sat) 24 93
ON(sat) ON(sat) 2 240