Drayton ZA6 zone valve actuator microswitch problem

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I have had repeated problems with one of my 2 ZA6 actuators, with its microswitch not switching when the actuator is commanded to close the valve. The result is that the pump and burner continue after the flow has stopped. The condensing boiler doesn't like that, obviously. I have sourced and fitted several new microswitches (SAIA-Burdgess XCG3Z1) - each time the new switch behaves for 6 months and then becomes intermittent. I'm about to do the same again but wonder if I'm the only one this has happened to, and has anyone any advice?

Martin
 
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That is Danfoss for you using micro micro switches. Common problem I would change to a different valve Like Honeywell or Drayton/ Iflo as they use proper sized micro switches.
 
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Thanks, the actuator is a Drayton ZA6. You suggest Honeywell as a better alternative? Will alternatives be interchangeable to be used on the same valve?

Martin
 
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Sorry my mistake regarding the Drayton. No heads are not interchangable so the body would have to be changed too. Honeywell is about the best there is as I had one that lasted 24 years untouched.
 
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Hello Martin.

I realise that this thread is over a month old, but my contribution might be worthwhile.

I've had this problem with two consecutive Drayton 2-port zone valves. The first one lasted about 12 years, and yes, I did have to replace the whole unit, even though the valve itself was still perfectly serviceable, because the actuator was not replaceable. However, the new one (779-2) does have a replaceable actuator. The actuator is very easy to remove on this model by manually opening the valve with the lever at the top, holding in the release button on the side and pulling it free.

The microswitch on my new valve has recently begun to malfunction in the same way as the one you describe, and I think I'll need to replace the actuator ... unless anyone can suggest a way to change only the microswitch??
 
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Hello Martin.

I realise that this thread is over a month old, but my contribution might be worthwhile.

I've had this problem with two consecutive Drayton 2-port zone valves. The first one lasted about 12 years, and yes, I did have to replace the whole unit, even though the valve itself was still perfectly serviceable, because the actuator was not replaceable. However, the new one (779-2) does have a replaceable actuator. The actuator is very easy to remove on this model by manually opening the valve with the lever at the top, holding in the release button on the side and pulling it free.

The microswitch on my new valve has recently begun to malfunction in the same way as the one you describe, and I think I'll need to replace the actuator ... unless anyone can suggest a way to change only the microswitch??

I have changed microswitches by de-soldering the connections an soldering them to a new switch. It's a bit fiddly since the parts are so small, but can be done. I've uploaded a photo of the microswitch in situ.

Martin
 
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Hello Martin.

I realise that this thread is over a month old, but my contribution might be worthwhile.

I've had this problem with two consecutive Drayton 2-port zone valves. The first one lasted about 12 years, and yes, I did have to replace the whole unit, even though the valve itself was still perfectly serviceable, because the actuator was not replaceable. However, the new one (779-2) does have a replaceable actuator. The actuator is very easy to remove on this model by manually opening the valve with the lever at the top, holding in the release button on the side and pulling it free.

The microswitch on my new valve has recently begun to malfunction in the same way as the one you describe, and I think I'll need to replace the actuator ... unless anyone can suggest a way to change only the microswitch??

I have changed microswitches by de-soldering the connections an soldering them to a new switch. It's a bit fiddly since the parts are so small, but can be done. I've uploaded a photo of the microswitch in situ.

Martin
 
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Mine's just packed up after about 6 years. Do you replace yours with the genuine Saia XCG3Z1 switch or just the regular offering from Maplins?
 
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Given the other moving parts, springs etc on the actuator, I think I'd just replace the whole actuator.
 
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Mine's just packed up after about 6 years. Do you replace yours with the genuine Saia XCG3Z1 switch or just the regular offering from Maplins?

I have used the genuine part (currently offred on eBay here http://www.ebay.co.uk/itm/BURGESS-X...l_Components_Supplies_ET&hash=item3f2375cacd) but haven't considered an alternative. What is the Maplin's alternative? (Might be worth a try since the genuine switch is the source of the problem!)

Martin

I couldn't find anything on Ebay and there they are! The maplin offering http://www.maplin.co.uk/miniature-microswitch-34835#specification is only 3A rated which is fine for me but more to the point there is a Maplin on my way home from work, right now i've got nothing. The sizes look good but no heat range stated. I've ordered off Ebay but i'm going to try Maplins switch as well, i presume they'll be open Monday, i'll let you know. Thanks for the reply.

DickieP, I couldn't scrap off a perfectly good valve for the sake of a microswitch, i just couldn't do it. I had considered just replacing the head, but you can't buy them, you have to buy the whole actuator, which also means i have to drain the system to change the valve, otherwise it's a bit pointless buying it. Sorry mate, but i welcome your contribution.
 
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Sorry I didn't realise you can't get a replacement head(actuator) & generally the whole valve is replaced. Perhaps when anyone is in Maplins they should consider buying a new diode & resistor then.

If it were me; I think I'd plan a Mid-Summer job & replace the complete valve, fit a Honeywell(though not as good as they once were) & also fit lever ballvalves on the pipework at the same time, incase of future problems.
 
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The Maplin switch doesn't fit. it's slightly thicker one end and it won't quite fit into the molding. never mind, it was worth the try, i'll just have to wait for the Saia switch to turn up.

I can't find a resister or diode in my ZA5 actuator, mine looks the same as U33446z's image, just the micro switch and the motor.

I did find a vendor who sells just the actuator,

http://www.uk-plumbing.com/drayton-za5-2-port-valve-actuator-only-p-42968.html

But for just £1 more Screwfix will sell you the whole valve, and i've seen them almost a tenner cheaper on Ebay.
Still, i'm perfectly happy with the repair and i'm grateful for this site for pointing out that there's an issue with these switches and that i hadn't actually cooked it running the water to hot. Thanks to all that have contributed.
 
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Just bought a new house that has the Drayton zone valves fitted to the HW & CH circuits and found the same problem. The actuator shuts but the pump and boiler run, the water flow goes through a bypass valve and the water is pumped around the loop and controlled by the boiler stat until the zone valve opens again. Problem is micro switch that is sticking in the on position, the current rating of switch is 3 Amp resistive / 1 Amp inductive. The switch is providing power to the switched live of the boiler and also a grunfoss circulator pump. I believe this to be the problem so I rewired the micro switch output signal to power a relay coil and used the relay contact to provide the power to the switched live of the boiler and the pump since doing this I have had no problems with the pump / boiler staying on.
 
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The load on the micro switch is the problem, asking a tiny switch to start pumps and boilers and other ancillaries in 'heavier loaded' system is oviously asking too much. In these situations i have fitted relays as mark55uk mentions with excellent problem solving results.
I use an octal base and octal plug-in module fitted in a plastic box with plastic gland seals mostly. These !0amp or 20amp relays will last a lifetime.

Relay...

http://uk.rs-online.com/web/p/latch...eproducts-_-FeaturedProductsContent-_-0352480

there are cheaper versions on ebay.
 
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