3way heating and hot water issue

[Groovejet]

Ive been told they are having to put 3 way valve into manual to get heat , but then when the cylinder gets to temperature the boiler goes off.
They apparantly then run some hot water off to get the boiler to kick back in , thus in turn heating the radiators as the actuator is still in manual.

This has only been a recent issue they said. As theyve lived there 4 years but the room stat is in the upstairs bedroom?? Ehhh?

Stat issue?? Getting to temp and thats whytheres no heating demand?
Stat is one of those BG rs1

 

[stem]

That is exactly what I would expect to happen with the valve in the 'manual' position. I assume that it has been put in 'manual' because it is not working properly. This position is not designed to be used when the system is in operation.

When the valve is in the 'manual' position, it will hold it in the middle position, so that water from the boiler flows to supply the heating and hot water. However, the valve will not have moved far enough across to operate an internal switch inside the valve that controls the boiler when the central heating is required. So the boiler won't come on. [When in the 'Auto' position if the valve is working properly, the motor will wind the valve fully across past the mid position to heating only operate the switch and start the boiler.]

However, when the hot water is 'on' the boiler is controlled from the hot water cylinder thermostat and so the boiler will come on and water will also flow to the radiators because the valve is locked open.

The manual position is only there to allow the system to be left 'open' so that it can be initially filled with water, it is not supposed to be selected during normal use.

It is possible that the thermostat is not telling the valve to open, or it could be the valve that is faulty. Both can be tested by a competent person with the appropriate test equipment.

It is unusual to have the thermostat upstairs, only the original installer will be able to tell you why that position was selected.

 

[Daveydub]

To keep it going just remove the cylinder stat from the cylinder

 

[MANDATE]

The room stat is not the problem., Because it moves the valve to mid position.
The problem is the actuator head.
Two actions are required to obtain CH only. The valve has to move from mid position to CH position. Secondly the valve has to trip a microswitch to light the boiler.
If valve moves to CH position and boiler does not light, microswitch no 2 is the cause.
If valve does not move beyond mid position, microswitch no 1 is the cause.
Other considerations are " stiff valve spindle' ' worn gear teeth on quadrant'.
Microswitchs do fail in two ways. Contacts become dirty and fail to make contact.
Also burnt contacts get welded together and fail to break.
In the valve the requirement is that a failure to break a pair of contacts also prevents the making of other contacts.
I would not recommend removing the cylinder stat. Just replace the actuator head

 

[stem]

The room stat is not the problem., Because it moves the valve to mid position.

The OP doesn't actually say that it 'moves to the mid position' it's in the mid position because it's been put there manually. Although I agree, the head is the most usual culprit, the thermostat and programmer much less frequently so.

 

[Wildcat1961]

The OP doesn't actually say that it 'moves to the mid position' it's in the mid position because it's been put there manually.

The actuator has been moved to the heating position.

 

[stem]

It is not in the 'heating position' it's in the 'mid position'. With the valve set to manual, both ports are open (ie hot water and heating) This can be seen from the original post.

they are having to put 3 way valve into manual to get heat , but then when the cylinder gets to temperature the boiler goes off.
They apparantly then run some hot water off to get the boiler to kick back in , thus in turn heating the radiators as the actuator is still in manual.

The OP says that the valve has been put into 'manual' and the hot water cylinder is still being heated up so that it switches off the cylinder thermostat. That would not happen if...

The actuator has been moved to the heating position.

because the hot water port would be closed and the hot water cylinder would not heat up. Only in the mid position are both the heating and hot water ports open.

In any case, it is irrelevant to the point I was making which was that the OP didn't say the valve was moving by its motor, but rather that it had been put there by the lever.

 

[Daveydub]

I would not recommend removing the cylinder stat. Just replace the actuator head

Yes replacing the actuator head IF it is in fact the problem. It could still be cylinder stat, programmer or room stat. What I was saying, with valve manually opened, remove cylinder stat to keep hw &ch running pending test & replace failed component.

 

[Wildcat1961]

If the actuator is warm to the touch this usually indicates the motor is ok and possibly a seized/tight valve spindle.

 

[Groovejet]

Pump was full of sludge and ticking loud( bearings) but this was a extra as its evident it's got nothing to do with problem.
So it ended up being the ****e 240 v British gas stat. That only makes contact when powers there.
Changed like for like and tested and it was fine.
They also went for new 3 way valve actuator and body. When u manually turned it , it was very stiff and stuck when it got to certain position?? Just when the valve was trying to open full bore for either h/w or c/h.
Inside the valve there is the spindle!!! And it has blades onit(rubber or something) these were deformed and catching as it turned.
Anyway everyone's happy now. Thanks
One thing I ain't gotta clue about is when I tested to see if I was getting power from programmer htg on to ch stat. I got nothing.
I linked htg on to live in prog. Went to stat and nothing.
So then I linked hw on to live and tested at ch stat and got 240v ??? Ehh
Any ideas