Weird problem with 3-port valve - affecting CH

[DavidFox]

hi,

Realizing that my radiators were still very hot after 10pm when CH was off (from the Programmer), I checked the 3-port valve. The lever was floppy - easily back and forward.

I flapped the lever from the 'Auto' and 'Man' about 10 - 15 times - then heard a sound and the lever was back to the 'Auto' end. The strong resistance can be felt if I tried moving it. About 15 minutes later, the radiators became cold. Next morning, CH was on and off at 10pm. The radiators were cold as expected. Checking the lever. It was in the 'Auto' end - right position (HW only, I suppose).

Everything seems working. However, one week later, the exactly same problem occurred again. I did the same, except more times on flapping the lever to make it back (or firmly staying in) to the 'Auto' end.

Like this, it comes and goes, about once a week since last month. Can anybody give me some advices? I am afraid, sooner or later, I am not able to bring the lever to the right position anymore......In fact, the head (actuator) was just replaced in June 2014, due to similar problem, as I posted at //www.diynot.com/forums/plumbing/radiator-is-always-hot-even-with-ch-off.402776/. It has been working perfectly until last month (Jan 2015)...

(This morning, when both CH and HW were on in the Programmer, I was feeling the lever. It has some resistance - can be moved a bit in the middle. Correct positioning? Then I 'OFF' CH through the programmer and checked the lever. It was in the 'Auto' end. Then, 'ON' the CH, checking the lever again - it has resistance, seems normal. However, a 'tick', 'tick' sound can be heard, about once per second. About 30 minutes later, the 'ticking' sound was gone. Is this abnormal?)

Thanks a lot for reading this a bit long message, and look forward to your suggestions and helps,

Cheers,
David

 

[picasso]

What make and model of boiler do you have ?

 

[DavidFox]

What make and model of boiler do you have ?

Vaillant ecoTec Plus 624. So, something with the boiler?

 

[picasso]

Some worcester bosch boilers are affected by stray voltage from the 3 port causing the boiler to fire up with no demand, I dont reckon this is your problem,its more likely the actual valve is sticking so changing the head will only temporary cure it.

 

[DavidFox]

Some worcester bosch boilers are affected by stray voltage from the 3 port causing the boiler to fire up with no demand, I dont reckon this is your problem,its more likely the actual valve is sticking so changing the head will only temporary cure it.

Thanks. Is there an approach to verify whether the valve is sticking? I am also keen to know if my understanding above is correct about the positioning of the lever for HW only or CH/HW, so giving me a good clue.

 

[picasso]

This should explain.

https://www.youtube.com/watch?v=Yyn_fBEH90U

 

[DavidFox]

This should explain.

https://www.youtube.com/watch?v=Yyn_fBEH90U[/QUOTE]

Many thanks, Picasso, for your prompt reply and help. Do appreciate it!

To be honest I watched the video before posting this message. I didn't understand well, so wrote the long message to see whether some experienced plumbers can point me the right direction, more straightforwardly.

So, could you or some other plumbers give me more clues? or simply advise me whether my analysis in the first message is correct? Thanks.

 

[dcawkwell]

3 port valve is sticking change the whole valve.

 

[stem]

Was the problem during the icy weather? if so, do you have a frost thermostat somewhere such as your garage / loft? If you do, they override the programmer and turn the heating on to prevent the pipes freezing. Often only becoming apparent when the weather is unusually cold.

 

[picasso]

I wonder how he manages to overcome the frost stat by moving the lever back and forward.

 

[DavidFox]

3 port valve is sticking change the whole valve.

Thanks. It seems the whole valve has to be replaced. Does the system have to be drained to do so? 2~3 hours work?

 

[DavidFox]

Was the problem during the icy weather? if so, do you have a frost thermostat somewhere such as your garage / loft? If you do, they override the programmer and turn the heating on to prevent the pipes freezing. Often only becoming apparent when the weather is unusually cold.

Thanks, Stem.

No, I don't have a frost thermostat. The problem occurs randomly, regardless of weather.

 

[DavidFox]

I wonder how he manages to overcome the frost stat by moving the lever back and forward.

True

Actually, I do wonder that, if it's due to the valve's sticking, how I could manage to get the lever back to 'normal' or 'correct' position by moving it back/forward?

 

[oilhead]

What is the make and model of the valve?
If the head is removeable, then remove it and see how stiff the valve is. It may only be a worn synchron motor.

 

[DavidFox]

What is the make and model of the valve?
If the head is removeable, then remove it and see how stiff the valve is. It may only be a worn synchron motor.

Thanks, Oilhead.

I can't see the model/maker of the valve. It looks like being made of copper - with ends marked as 'A', 'B', etc., and comes with a date '01/01/2013'.

Yes, the head is removable. As mentioned earlier, it's just replaced half a year ago, due to similar symptom.

How may I check if the valve is very stiff or not?