Drayton valve 'sticking'

[Paul Drawmer]

S plan system. One of the two port valves is sticking. The valves are only about 4 years old.

What happens is the CH gets up to temp, 'stat switches off, but system still runs.

First found out when I came home and realised that the CH pump was running whilst boiler was off, and the timer was past the all off time for the night.

If I tap wallop the valve cover, it switches off, all is fine and it returns to normal operation next time the stat calls for heat. I don't know if the boiler switches off due to over heat, or if the boiler is switched off by the 'stat.

Is this a body or motor problem? Are the motor units user serviceable?

[Troubleatmill]

Is it a Drayton VA5?

[Paul Drawmer]

Having photographed the cover in a mirror(!) it's a ZA5

[Troubleatmill]

That's the one.

I have this also.
They are renowned as crap by those in the trade.
They stick all the time.

I asked on here a question as to why my heating came on at very odd hours
After some good advice from members on here.
The advice I got was to replace it with a Honeywell unit.
You will have to drain your system.

In short the Drayton is junk.

[LookAtMyCat]

Troubleatmill said:

That's the one.

I have this also.
They are renowned as crap by those in the trade.
They stick all the time.

I wouldn't say that's true, actually. I fit Drayton valves and they're decent. I used to fit Honeywell and saw failures within a year on some of them. The Draytons I rarely get problems with and they have the distinct advantage that you can change just the head instead of the entire body.

[Gingerbread Man]

LookAtMyCat said:

The Draytons I rarely get problems with and they have the distinct advantage that you can change just the head instead of the entire body.

The Honeywell's can have just the head swapped, or just the motor. So not a unique advantage.

[frisbee]

In theory you could just replace the microswitch. If you can find one.

I was tempted just to fit a multifunction relay and use that to control the pump and boiler.

[Rickyy]

Draytons aren't crap, but they do occasionally stick. I prefer them to Honeywells as they have position indicators and quick release actuators.

Just do a like for like replacement on the actuator.

[Murph7355]

Whatever you do, do not procrastinate. Get it fixed quickly.

It took me a while in our house to work out that one of ours (can't recall the make) had failed. Fixing it made a MASSIVE difference to our energy costs. Especially over winter (nearly a third reduction in oil utilisation).

[Paul Drawmer]

OK - thanks folks. I'll do a top swap on it then.

[CorradoTDI]

Give them a call, they might send one out FOC if it's only 4 years old.

[Gingerbread Man]

CorradoTDI said:

Give them a call, they might send one out FOC if it's only 4 years old.

Classic

[Paul Drawmer]

Update. Replaced actuator only this morning. Oddly enough, the valve body inc actuator is cheaper than actuator only - mad.
swapped the tops over, replaced the new wires one by one for the old one, control restored. Thanks PH for the info.

[Paul Drawmer]

UPDATE. Grrrr. it's doing it again. CH pump running and boiler cycling even though all controls are calling 'off'.

Haven't got round to tapping each valve to see which one isn't switching off yet. And I remember getting to the wiring centre is an arse. And I'm stiffer now than I was at 69! May have to pay someone this time.

[Gary C]

Just replaced the microswitch in our ZA6.

They get sticky but are an off the shelf part if your that way inclined. At £3, a lot cheaper than a £70 new head. Fairly simple solder job but make sure you dont loose the springs. Also these bodies age, the plastic cracks and the springs detach, you can hook them back through the holes in the body where the hooks for the springs sit.

https://uk.rs-online.com/web/p/micro-switches/1616...

Edited by Gary C on Saturday 19th November 10:11

[Lincsls1]

Paul Drawmer said:

UPDATE. Grrrr. it's doing it again. CH pump running and boiler cycling even though all controls are calling 'off'.

Haven't got round to tapping each valve to see which one isn't switching off yet. And I remember getting to the wiring centre is an arse. And I'm stiffer now than I was at 69! May have to pay someone this time.

So it seems you have mistakenly diagnosed the wrong head as the one keeping the system running.
Either get another new actuator and replace the other one, or if you've got the old one, put that on.
What the boiler out of interest?

[Gary C]

Lincsls1 said:

So it seems you have mistakenly diagnosed the wrong head as the one keeping the system running.
Either get another new actuator and replace the other one, or if you've got the old one, put that on.
What the boiler out of interest?

Note, its been 7 years since he replaced the head, so I think its safe to assume he got the right one, just that its failed again.

[PositronicRay]

Paul Drawmer said:

Update. Replaced actuator only this morning. Oddly enough, the valve body inc actuator is cheaper than actuator only - mad.
swapped the tops over, replaced the new wires one by one for the old one, control restored. Thanks PH for the info.

If the valve is sticking it could be burning out the actuator.

[Gary C]

PositronicRay said:

Paul Drawmer said:

Update. Replaced actuator only this morning. Oddly enough, the valve body inc actuator is cheaper than actuator only - mad.
swapped the tops over, replaced the new wires one by one for the old one, control restored. Thanks PH for the info.

If the valve is sticking it could be burning out the actuator.

It will be the microswitch rather than the valve not travelling, also the ZA6 when open maintains power on the motor at the end of travel and it doesn't 'burn out'

[Paul Drawmer]

Gary C said:

Just replaced the microswitch in our ZA6.

They get sticky but are an off the shelf part if your that way inclined. At £3, a lot cheaper than a £70 new head. Fairly simple solder job but make sure you dont loose the springs. Also these bodies age, the plastic cracks and the springs detach, you can hook them back through the holes in the body where the hooks for the springs sit.

https://uk.rs-online.com/web/p/micro-switches/1616...

Edited by Gary C on Saturday 19th November 10:11

That's interesting, thank you.