Motorised Valve Faulty?

[MartyJ76]

Hi all, hoping someone might be able to shed a little light on a 2 port motorised valve that I dont think is operating correctly on the CH side of my system.

The system was installed only 2 years ago. The valve on the DHW side of the system is operating correctly. However, on the CH side, am getting only minimal heat to rads. 

With the valve lever set hard left to Auto, it appears the valve lever seems to revert after a while to a position off left of centre. Is this where it should be? Not hard, full travel left? 

 

If I push the lever to manual, there is resistance to complete hard right. But nothing will make the lever sit in the groove to keep it locked to manual, it reverts to a position just to the left of full right (apologies for this description, dont have the terminology).

 

In the latter scenario therefore, the closing lever plate inside the head unit is pushing the red microswitch, but it moves back and therefore the tiny red switch does not remain pressed?

 

An audible click can be heard in the electrical controller box when the manual lever is fully depressed, and a second click when it moves away from the microswitch. Its turning on, and then off, right?

 

I understand the lever should remain in Auto at all times, whilst when demand is pressed on thermostat the system deliver heat for 5 mins, and thereafter nothing. I should add, and most will have guessed, this is on an Air Source Heat Pump set up. But my query is only upon knowledge of working 2 port motorised valves. Any suggestions as to whether this unit is functioning as it should?

 

Thanks so much, this site is a lifesaver, every time.

[Mattg4321]

Is this a Honeywell valve?

[ProDave]

What make of valve, different makes behave differently?

 

If you remove the actuator head from the actual valve, does the actuator move correctly off the valve?  does the valve spindle rotate freely with the actuator head off?

[MartyJ76]

The valve is a Neomitis MTV222a. The valve spindle rotates freely, its movement is only something like 20degrees either way...which I understand to be normal? The actuator moves when off the valve, but it won't remain fully depressed and on the manual latch, so its not holding the microswitch down. In auto, where it should be, it does move marginally off of its fully left location....

 

[MrPotts]

6 minutes ago, MartyJ76 said:

The valve is a Neomitis MTV222a. The valve spindle rotates freely, its movement is only something like 20degrees either way...which I understand to be normal? The actuator moves when off the valve, but it won't remain fully depressed and on the manual latch, so its not holding the microswitch down. In auto, where it should be, it does move marginally off of its fully left location....

 

I dont think the micro switch operates when the manual is moved to MAN, it just opens the valve.

[John Carroll]

That's the valve, below, operates like any 2 port valve, you can see the lever in the Auto position, on the end to the left, when you pull on this you should feel a fairly stiff resistance while pulling it across to the right, when its almost fully over, just push the lever up and let it move back towards the left, the lever will then latch in (up) and keep the valve open, but, as stated above,  will not operate the micro switch as its only latched open when draining or refilling the system and you don't want your boiler, that you forgot to switch off!, firing up with no water in it.

When energised open the valve will move fully across and engage the micro switch to fire the boiler.

If the lever feels loose and floppy without any resistance when pulling across when NOT energised then the actuator is kaput and needs renewing.

Another feature of these valves is that if you have it manually latched open say when refilling the system and its then energised, when its deenergised again the valve will close automatically as the lever will  have fallen down, out of its latch, when motorised fully across.

 

Edited Friday at 21:32 by John Carroll

[ProDave]

If that is the actual valve being discussed, it looks like a clone of a Honeywell.

[ProDave]

1 hour ago, MartyJ76 said:

The valve is a Neomitis MTV222a. The valve spindle rotates freely, its movement is only something like 20degrees either way...which I understand to be normal? The actuator moves when off the valve, but it won't remain fully depressed and on the manual latch, so its not holding the microswitch down. In auto, where it should be, it does move marginally off of its fully left location....

 

I meant when you remove the actuator head, and energise it by electricity, i.e. demand heat, does it operate fully and turn the boiler on?

20 degree movement seems too little for a 2 port valve, I would expect a lot more so suspect a mechanical issue in the valve.

[John Carroll]

49 minutes ago, ProDave said:

If that is the actual valve being discussed, it looks like a clone of a Honeywell.

 

https://www.wolseley.co.uk/product/neomitis-2-port-zone-valve-22mm/?srsltid=AfmBOoqv_ENIV53nUqWT0o_kPleTlp7Vrj29abrEn4EMV9R9BhMx7LT7