Rain8 problems turning certain valves on

[UniKyrn]

Has anybody noticed a problem with the Rain8 not being able to turn a valve on?

I replaced an older controller that used relays with a Rain8 about a month ago and it had been working fine with my four valves up until a day or so ago. Now it can't manage to turn one of the four on.

If I short the wires together with a jumper the valve opens and even if I move that valve to an unused zone the Rain8 still fails to open it. I'm guess that one valve is more sensitive to the voltage being sent to it and however the Rain8 works hardware wise, it's not enough to work that one valve now.

[Michael McSharry]

check the rain8 eeprom to make certain the timeouts etc are not preventing the zone from working

[UniKyrn]

That isn't/wasn't the problem, I think I've got a clue now as to what is going on. There is a note in the install guide that mentions the 250ma current limit on valves. It also mentions that the surge current when first opening can be higher as long as the holding current is under 250ma. For some reason the one valve is now requiring more current to open than the others.

Another interesting item I found was that the 24VAC supply has to be wired a specific way, but I couldn't find a note to that effect in the install guide. When I'd originally wired it, it didn't work and I ended up supplying the voltage from the old mechanical controller that is still wired in parallel with the Rain8 for emergency use. I disconnected that, reversed the two wires from the 24VAC wall wart and suddenly the Rain8 was able to power the valves as I thought it should have in the first place.

The wall wart is 24VAC, it should be nothing more than a step down transformer, but for some reason the leads from it are position sensitive. The Rain8 will work either way but the valves only work one way. A note from WGL mentions testing using pin 11 of the two power positions to test with, maybe that relates to this somehow.

So I think my problem is that the Rain8 simply doesn't have enough current to open one of my 5 year old valves. I've asked WGL if the 250ma limit is a function of that 300ma wall wart they supply, or if a heftier supply will simply burn out the triacs in the unit when the valve opens up using a higher surge current.

I suppose I'll have to juryrig a small 24VAC relay to the Rain8 and let it handle the higher current load of the valves. Hopefully WGL will consider changes to let the Rain8 handle a higher current itself.

[rocco]

Brian:
You may have diodes in there messing with your mind.

Some solenoids, if they are meant to work with DC only, will have diodes wired in anti-parallel to absorb the flyback when they are turned off.

Your old mechanical controller probably has diodes in it as well, to protect the contacts from the afore mentioned flyback. The Rain8 may be powering diodes rather than the solenoids. I would not risk wiring both controllers up at the same time.