No CH. Only works when HW is on

[Fredy]

Thanks for looking and appreciate anyhelp

Now that Winter is approaching, I have set the HW and CH programme to start at same time, the HW programme is to set to stop after 1 hour and the CH to run on for another 3 hours. Previously the CH was off.

However the CH only runs for the same time period as the HW programme.
Boiler switches off but Programme light still shows active for CH.

The Valve is a Honeywell Mid-Position Valve 22mm
Following threads I replaced the Syronised Moter, However Problem still persists

1) I wondered it it had anything to do with the connectors to the Synchronous Motor ie two wires connecting to two other wires, does it make any difference which way it connected.

2) Or any diagnostics I could undertake incase it was the Vavle itself or another part of the system.

The system as far as I can tell is gravity fed oil fired boiler.
There are no room temperature thermostats. Only Thermostat is attached to the Hot water Tank.

 

[hi-spec plumbing heating]

check if you have power from the ch side of the programmer.

 

[Fredy]

Sorry, When you say CH side of the programmer

Could you elaborate

Thanks

 

[hi-spec plumbing heating]

you should have a box where all the wires connect together.
when you select heating at programmer the wire from programmer becomes live then activates mid pos valve that activates pump,boiler.

 

[MANDATE]

From your description, it sounds as though your problem is similar to the one I experienced some time ago.
CH only possible with HW. After verifying room stat was ok, the head of the valve was removed and operated to establish if valve would move to all three positions. This was ok, so there should have been 230volts on the orange wire (when using CH only). There wasn't and this indicated a fault on one of the microswitches.
Acutator head changed and problem cured. Old head dismantled and microswitch proved to be the problem ( now repaired).
You must not do check with HW on, because the feed to boiler from cylinder stat joins the same wire as orange. This will show live and mislead you.

 

[Fredy]

Thanks to you both

I checked the HW controller and its live. It lights up to indicate that its trying to do something.

I did a few other tests on the Manual/Auto Lever.

When you push the Lever in the Manual Position, switch on HW and then CH the lever moves back to the mid position and cuts out

If you hold it in the manual postion it continuous to fire both the HW and CH.

When you say Actuator head I assume this is the Honeywell 3 point Mid Position Valve

Thanks again

 

[MANDATE]

The actuator head is the top part of the valve, which houses the motor that drives a quadrant that fits on the valve spindle.
You can usually change the actuator head and leave the existing valve body and valve in situ.
When you cannot get CH on its own ( assuming wiring and room stat is ok) it is usually due to either (a) stiff spindle (b)faulty motor or (c) faulty microswitch.
If the head can be removed the spindle can be tested. Also it can be seen from the underside if all three positions can be achieved. In my case all three positions were achieved which meant the microswitch was not functioning. This was proved as there was no power on orange wire coming from the valve to fire the boiler.
Power to fire the boiler when HW is involved does not come via this orange wire. It comes from the cyinder stat
Although you may select both HW and CH, it does not mean they are both receiving heat. They do until one of them is satisfied and then that side is closed off.
Because HW is not in constant use and the cylinder is insulated HW gets satisfied sooner than CH where heat is being lost through the radiators.
When this happens the valve moves to CH only but if microswitch is faulty boiler cannot operate.
You can try a couple of things. Up the cylinder stat. This will now operate the boiler and you will get HW and CH but only until HW is satisfied.
Or if you run off some HW it will have the same effect.
You say there is no room stat but I don't understand how your system can function without one. It's the room stat that supplies the power to drive the valve from the HW position.

 

[Fredy]

Thanks Mandate

I just around to have a look following your post.Painting the weekend as the weather was good!

The Actuator Head and Valve is a Grundfos type model.

I took off the plactic top cover
This revealed the wiring, A spindle type control which I believe is the speed control and a white cylinder.

A couple of questions. Sorry if they are a bit stupid

When I set the HW/CH to come on the Live terminal became Live. Assume this is correct seems logically from your explanation.

The Cyclinder I assume is the Microswitch

I assume the Spindle is the steel type Screw which you can see on the front off the Valve. This spindle could not turn at all.

From the above and your notes the spindle is stiff in my case stuck fast.
Therefore I assume I need a new Grundfos Valve or Take out and Check and free spindle.

On the room stats, The only stats I can find in the house are On the Hot water Tank x 2 and on the boiler

Thanks In advance

 

[MANDATE]

I don't quite follow your last post! I understood your valve was a honeywell 3 port mid position valve, where you have already replaced the motor in the actuator head. The microswitch I refer to is mounted within the actuator head (in fact there are 2 microswitches).
When you mention Grundfos, I'm now not clear what you are looking at.

 

[Rob]

Sounds like he's talking about the pump!

With CH only selected check to see what voltage is present at the grey wire which goes to the honeywell motor valve.. you will need a multi meter

 

[Fredy]

Sorry for the confusion Mandate

As you say I replaced the motor within the 3 position valve and the problem persisted.

When you talked about the Actuator Head, I thought this was a devise futher upstream so to speak which is in fact the Circulating pump as Rob884 pointed out

When I checked the Circulating pump spindle it would not move. Looking at the Technical Notes online if should move freely. This is stuck fast.

So I assumed(Maybe) wrongly that the Circulating pump was in fact the problem area

Thankyou

 

[MANDATE]

You will have a problem if the pump does not rotate, but that would mean you would have no circulating water in both the HW side and the CH side.
If you start from cold and call for both HW and CH the valve should go to mid position. (even if it's only till HW is satisfied) If the radiators now start to get hot, it would prove the pump is working.
The problem that seems to arise is when CH only is demanded. That is either by selection or when HW has been satisfied if calling for both.
There are two main points. the motor you replaced must drive the valve to the CH only position and whilst doing so it triggers an internal microswitch to provide power to light the boiler.
If motor moves valve to CH only position and boiler does not light, then problem is most likely the microswitch.
You should be able to lift the actuator head off the valve spindle ( after removing screws) and observe the underside as someone trys the different modes. You can also test valve spindle for stiffness.
If you find valve will not go beyond mid point you need to test gray wire as suggested.

Hope this make some sense.

 

[Fredy]

Hi

The actuator head is in a awkward position so could observe how the switch operates. Took the step of buying a new like for like mid-position valve and replacing the actuator head element. Rewired to the controller area like for like etc.

Same problem

HW and CH called at the same time everything ok.
Call CH nothing

Could it be the pump?

 

[Softus]

Fredy, you're doing far too much guessing.

You need to read MANDATE's post dated Wednesday last week and work hrough it, following the advice and answering the questions.