No CH, HW OK. Y Plan system.

[MartyMalabu]

The system is about 9 years old, fitted in a domestic residence, and has worked fine up until a few days ago. I believe it is a Y Plan system. It has a tank in the airing cupboard and a T shaped valve fed from a pump. One side of the valve goes to the tank, the other to the 14 radiators. Boiler is a glowworm Micron 60FF.

Hot water is fine.
When I call CH the boiler does not fire up (programmer light comes on for CH and room stat is turned up).

If I move the valve lever over to the RHS, the boiler fires up and the rads start to get warm. Not sure if this is the valve midpoint or it is in the CH position.

I have measured the voltage on the white wire in the junction box in the airing cupboard and this goes to 240VAC when the room stat is set to max, and 0V when set to min.

I therefore conclude that the non mechanical part of 3 port valve is at fault. However, I pulled the head off the valve and measured the motor coil and it is 2K ohms. Which looks like a good motor to me.

I know the fault is not the boiler (HW OK), not the programmer or room stat (240V called from stat).

How likely is it that this is the 3 port valve, and can I get away without changing the mechanical part. There are no model names on the valve so I cant identify it for replacement purposes (motor has synchron on it though).

I am reasonably technically able, and have done some plumbing in the passed, but am concerned about having to drain down and remove air locks etc, so would prefer not to change the mechanical part if possible. There are isolators on the Tank and CH sides of the valve which might help.

Advice sought please. What should I do next.

 

[D_Hailsham]

Advice sought please. What should I do next.

1. Read Mid-position valve working and Diagnostics and carry out the tests given. This will confirm if it is the valve actuator (the box on the top) or something else.

2. All current valves (which should include yours) have detachable actuators, which makes it easy to fit a new one without draining down. If you post a pic of your valve we will be able to identify it - though there should be a number somewhere.

3. Synchron motors are used in all motorized valves; it's just a case of getting one with the correct terminals.

4. The lever only opens the valve mid-way; it's real purpose is to open the valve when filling/draining the system.

 

[MartyMalabu]

Thank you for your speedy and clear reply.

I will carry out the tests and post back with results and picture of motorised valve.

 

[MartyMalabu]

Results from CH test

white and grey tied to permanent live.

I am not sure how I can tell if the valve has moved. What I can say is that the override lever(s) sticking out of the actuator did not move, the boiler did not light. However there was an oscillating noise which I assumed was the pump, but turned out to be coming from the valve motor.

I removed the motor from the the actuator and noticed that the gear which interlocks with the arm in the actuator (presumably to drive the valve) can be turned freely while the white and the grey wires are connected to the permanent live (test conditions). Furthermore, if I switched the power off to the system, and switched it back on again there was no movement from the gearing. Should there be any ?

Other things worth mentioning are that the motor is not open circuit (2K ohms) and is very hot to touch. My initial thoughts were that the internal gearing might be broken, but surely the problem is more likely to be down to circuitry feeding it? Note that 240v was confirmed on the grey and white in the terminal block.

Images

Complete unit in situ
//www.diynot.com/network/MartyMalabu/albums/8578/33276

Synchron motor removed showing connector and gearing
//www.diynot.com/network/MartyMalabu/albums/8578/33275

Actuator with motor removed
//www.diynot.com/network/MartyMalabu/albums/8578/33274


I would appreciate any suggestions on
a) where I go next, and
b) what the motorised valve model is.

Many thanks.

 

[matt1e]

thats a Siemens actuator
cant recall the model number but parts centre will Know tell them its off a mid position
if you have 230v on white and grey and the neutral is ok then it should power fully open to central heating
If it does not, the motor, or the actuator circuitry is knakered
or the valve is jammed

 

[D_Hailsham]

Actuator with motor removed

Untitled

• MartyMalabu
• 19 Apr 2011
• 1

You should be able to turn the spindle (in the middle with a circlip round it) easily by hand. It won't turn a complete circle; probably about a quarter turn.

If it's very stiff, some silicon lubricant round the shaft may help.

It's a Siemens MA-V322C actuator

 

[MartyMalabu]

Thanks for the info chaps.

... the motor, or the actuator circuitry is knakered or the valve is jammed

If I move the top level right over the boiler fires up and the CH pipe from the valve gets hot. Can I assume the valve is not stuck, and this is a motor or actuator problem ?

You should be able to turn the spindle (in the middle with a circlip round it) easily by hand. It won't turn a complete circle; probably about a quarter turn.

I cannot turn the spindle (to slim to grip by hand), but if I move the levers it moves with them. What can I conclude from this.

It looks to me that the 22mm pipe is soldered into a larger adapter before it joins the valve - can I assume that this is probably a MA-V328C rather than a MA-V322C ?

Are the Actuators the same for these two valves ?

Are they easy to change ?

Thanks again for your time and wisdom.

 

[D_Hailsham]

If I move the top level right over the boiler fires up and the CH pipe from the valve gets hot. Can I assume the valve is not stuck, and this is a motor or actuator problem?

Yes

I cannot turn the spindle (to slim to grip by hand), but if I move the levers it moves with them. What can I conclude from this.

It's not stuck. You can always use a pair of pliers to turn the shaft.

Are the Actuators the same for these two valves?

Yes.

Are they easy to change?

Yes. Just follow the instructions. Here they are:

1. Before working on the synchronous motor housing replacement you must switch off the electrical supply.

2. Lift up fully the two coloured locking sliders.

3. Press in simultaneously on both plastic tongues and lift up the plastic cover.

4. Disconnect the electrical internal connector.

5. Now remake the electrical internal connector from the new motor housing unit.

6. Hold the coloured sliders up and locate the plastic tongues in their respective slots, push down firmly until the tongues are fully located then push down the coloured locking sliders.

7. Turn on electrical supply and test for operation.

 

[MartyMalabu]

Thanks for your reply.

This procedure looks as if it will just change the motor/housing unit is that correct ?

1. What if the problem is in the electronics which is left fastened to the valve (i.e. part of the same plastic unit which contains the levers). How can I change this without having to take the valve out ?

2. Bearing in mind the symptoms and evidence gathered thus far, which is more likely to be at fault, the electronics or the motor?

3. Where is the recommended place for a non trade person to obtain a replacement parts from ?

Thanks again.

 

[D_Hailsham]

Reading your opening post again you said:

Hot water is fine.
When I call CH the boiler does not fire up

Are you referring to CH by itself or with HW?

Do the "lever test".

Turn of the power to reset the valve. The lever should give resistance when you move it across - it's opening the valve against the springs.

When the valve is powered (CH with HW) the lever should move across very easily.

If no resistance, the motor is opening the valve to mid-way.
If there is still resistance the valve has not opened - faulty motor.

If the valve opens to mid-way but not full over (CH only), the micro-switches or one of the other components is faulty. That means a complete new valve

Any plumbers merchant will sell you a valve or actuator.

If you have to change the complete valve, get a Honeywell V4073. The micro-switches are in the actuator, which can easily be replaced.

You said that the pipes are 22mm but then enlarge to 28mm where they enter the valve. Seems strange - unless a 22mm valve wasn't available so the installer put in a 28mm as a bodge. I could understand the other way round - 28mm pipe sized down to 22mm for the valve - it would suggest an old gravity HW system converted to fully pumped.

 

[MartyMalabu]

Reading your opening post again you said:

Quote:
Hot water is fine.
When I call CH the boiler does not fire up

Are you referring to CH by itself or with HW?

Just CH.
I.e. Just the CH button switched on on the programmer (+ room stat all the way up). HW button on programmer turned off.

Boiler does not fire up.

If I switch HW on, (with or without the CH button) on the programmer, the boiler does fire up.

I will carry out the test you suggested.
Thanks

 

[MartyMalabu]

I did the lever test.

There is no difference between the resistance of the lever when the system is off, and when it is turned on calling for CH and HW.

This would therefore point to a faulty motor ?

A couple of points here though.

1. The motor is not open circuit, is it still possible it has failed ? It does make a quiet rattly noise when powered up, and with it connected and not fitted the valve, the gear is free to spin by hand, and I have never seen it drive - this does not seem right.

2. I imagined that the resistance was the resistance of the spring. Presumably this would be the same which ever position the valve was in ?

Is a faulty motor the favourite suspect ?

Thanks again.

 

[D_Hailsham]

If I switch HW on, (with or without the CH button) on the programmer, the boiler does fire up.

That's expected as the valve is not involved when you are only heating the HW. (Read the explanation how the valve works in the link I posted.)

If you turn on the CH and HW at the same time, do the radiators get hot?

If the answer is YES, then the motor is OK.

If the answer is NO, then the motor is faulty.

 

[MartyMalabu]

The radiators do not get hot in any combination, except if I manually override the valve using the lever.

I have a new motor coming today. I will need to modify the flying lead, before I fit it though.

I will post my results.

 

[MartyMalabu]

Fitted a synchron motor from ScrewFix (£13.00 plus delivery). Heating system is now working again.

The fault with the motor seems to be mechanical. I could spin the output gear cog of the broken motor - the new one was much harder to turn. The old motor was obviously running flat out (it was very hot) but was not coupled mechanically to the output gear.

Many thanks to all who replied on this thread, but in particular to D_Hailsham for all his advice.