Replacing Drayton three-way valve

[PaulXX]

I have an Ideal Classic conventional gas boiler with Drayton thermostat, valve, controller and pump.

The boiler is working absolutely fine with hot water but the heating won't come on. When I try pushing the three-way valve switch over to H, the boiler fires up momentarily but the switch forces itself back towards W.

So does this indicate a motor fault?

The valve is a 679H340-30L0, which I believe is one of the ones where you can't replace the motor. Is it likely to be salvageable? Any checks I can make to try and repair it before giving up and replacing it?

If I have to replace the whole unit, it is no longer made but some online stores say the Drayton MA1/679-3 is a direct replacement.

I'm slightly worried about having to replace it as this does not appear to be a clip-on type and DIY guides I've seen say I'll have to cut pipework if I can't get it off.

Now I'm fine about draining down the system (I've never done it before - but it seems a straightforward enough job), but I think cutting pipework is a little bit too daunting for a novice like me.

So does anyone have experience of replacing this model of valve? Have they had to cut out the pipework or was it not too hard to remove?

If I have to cut pipework, I'd rather call a pro plumber - but I lost my job a couple of weeks ago so can't really afford to do that.

 

[seco services]

check the power to the motor.
if its got power and not moving then the motors faulty.

 

[PaulXX]

check the power to the motor.
if its got power and not moving then the motors faulty.

Guess I'll need to remove the cover and use a multimeter to do that?

When I do try to move the switch, there's a lot of physical resistance to it and it does force its way back again, with a slight whirring sound as it does so.

If the motor is faulty, I understand it can't be changed on these and the whole valve head has to be replaced. I just hope this can be done without cutting pipes.

 

[seco services]

it will force its way back as they are on a spring, in the relaxed position they fall to hw only your pushing against the spring to open the heating port.
you should be able to push the lever across and lift slightly and it will clip in and hold.

yes you'll need to remove the lid.
if the motor is faulty just change the motor not the head. motors are under a tenner.
if the teeth or any other part of the actuator are faulty then you'll have to change just the actuator.

you'll only have to change the brass valve if it is jammed which yours isn't.

 

[PaulXX]

I left this alone for a while as I didn't need the heating. But now autumn is creeping up fast, I'd better get my finger out.

I did take the lid off and was able to move the switch back to the heating position. The heating fired up just fine.

Unfortunately, the switch was now stuck in this position and when I tried to move it back towards HW the switch seemed to have become detached. I didn't snap it or anything, it just seems to have come off whatever it was attached to.

I could have a bash at changing the motor myself (I presume the switch will be easy to re-attach once the motor is out of the way) but I'm not entirely confident about doing it, especially as the actuator is in a pretty awkward position to get at (see pic) and I can't see what I'm doing.

View media item 4195
Will I be able to change this motor without having to drain down the system? And how exactly do I get it out? From what I've managed to see, there are a couple of screws inside the case, anything else I need to get at to change the motor?

I might still have to give up and call in a plumber to do the job - but the problem is finding one round here (Selby) willing to take on such a small job. The ones who advertise all seem to be of the sucking teeth and "that'll be £200" variety.

 

[seco services]

the motor is only two screws and two wires.

 

[D_Hailsham]

Unfortunately, the switch was now stuck in this position and when I tried to move it back towards HW the switch seemed to have become detached. I didn't snap it or anything, it just seems to have come off whatever it was attached to.

If you mean that the lever is loose, then there may be nothing to worry about. When a mid-position valve is at rest the HW port is open and the CH port closed. Moving the lever across will open the CH port and close the HW port. You will feel resistance as you are working against a spring. If the valve is stuck in the CH open position the lever will feel loose.

The valve can be stuck in the CH open position for two reasons, mechanical (the shaft is stiff or the ball/shoe stuck) or electrical (the valve is being held open by the motor).

The first thing to do is to turn off all electricity to the system. This will reset the valve to its default HW port open position. The lever should now be hard to push across. If it is still loose then you have a mechanical problem, i.e the ball/shoe in the valve is jammed. If your valve is the type which does not have a removable actuator, then you will need a complete new valve. If you can remove the actuator (button on the side which you push in), you may be able to free the innards by rotating the shaft with pliers (moves about 10-15 deg).

The valve does not look to difficult to get at, if you stand on a chair or a pair of steps.

 

[PaulXX]

The valve does not look to difficult to get at, if you stand on a chair or a pair of steps.

Trust me, it was far more awkward than you might think. I was having to balance on one leg to get my head round enough to see what I was doing - a disaster waiting to happen.

Anyway - I should have posted ages ago to say mission accomplished and thank seco!

One slight snag is that I didn't fiddle about with the wires to get them to align nicely enough for the lid to snap properly shut. But it's working, that's the main thing.

Or at least it was until the fan jammed today...

 

[seco services]

as they say if it ain't one thing its another.

so you changed the motor then and all ok.