electroválvula fault

[Miro]

A couple of weeks ago, one of the electroválvulas in our community riego system sprung a leak. It's not the first one to break in this way - a fine jet of water was shooting out of a pinprick sized hole on the actual plastic casing - not from any joints or screws etc., which seems strange enough.
Anyway, the maintenance guy replaced it with a new one. The system is programmed to come on at 1:00am, for 10 minutes each zone, but when I went out at 9:00 the zone with the new electroválvula was still on (high water bill coming!) It would appear it had a mechanical fault, and never closed at the end of its 10 minute cycle. That area of garden was somewhat moist to say the least. The maintenance company put it down to faulty part & replaced it again.

This morning I went out to find the same thing happening, but in the next zone. This zone still has one of the original (10 year old) electroválvulas. I know they haven't fitted the previous faulty part, because I checked in the box where the electroválvulas are, and can see this is an old one.

In 10 years we have never had the problem of electroválvulas not closing. Now in the space of a fortnight, we have had it occur with a brand new one, and then a 10 year old one. Am I being over suspicious in thinking that summat ain't quite right?

(apologies for the Spanglish)

[El Cid]

I have had a similar problem occasionally with our system.

I think it is caused by a small piece of crud getting behind the rubber diaphragm and causing it to stay open. I just take the cover off the valve, clean the rubber diaphragm and that usually solves it.

I have 6 valves and it probably happens to one of them every couple of years.

Sid

[Miro]

Thanks for the reply Sid. Interesting.
If it was mine, I'd fiddle around with them and sort it out, but this is the community garden & system, and although I'm the only one who even notices when things go wrong and seems to give a s**t, I'm not prepared to get my hands dirty since nobody appreciates it.
However, I did cut the water off & notify the gardener (nobody else would have bothered and the sprinklers would no doubt still be on now). I've been out all day, but he just called me to say he's tested the system both manually & with the programmer, and everything's working fine.
When I checked the valves this morning, I think (but can't swear by it or prove it) the offending valve was not fully closed. My suspicion is that the gardener yesterday opened the valves manually to check the sprinklers, and if he didn't fully close one, when the programmer turned it on at night it may not have shut properly. Sound possible/plausible?

[El Cid]

Assuming that the system has a separate pump, then that is the best way to see if a valve is leaking. The pump should kick in in even the slightest amount of water is leaking through the valve.

One solution is to put the pump on a timer so that it only comes on during the period that the irrigation is active.

Sid