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Tuesday, July 25th 2017, 1:44pm

Square Solenoid Replacement?

Hi all,

I've got a zone that isn't coming up. I inherited this system from previous owners and I'm not sure which solenoid to replace it with. Any chance someone can give me a recommendation from the this visual?



Posts: 2,365

Location: USA


Wednesday, July 26th 2017, 12:14am

A bad solenoid is rarely the problem.
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Supreme Member

Posts: 5,325

Location: Metro NYC


Wednesday, July 26th 2017, 8:08am

The solenoids are almost certainly the discontinued Weathermatic M24E - replace them with the new S20P - but don't fiddle with the valves until you clean out the valve box and remove more dirt

A wiring check for continuity would be in order. If you are going to handle maintenance on this system, you should own a multimeter. They're cheap enough. In fact, Harbor Freight actually gives them away on occasion, as a sales promotion.


Wednesday, July 26th 2017, 10:35am

OK Thanks!

I already shop-vac'd out quite a bit of loose dirt, but I'll do some more. I have the multi-meter, but haven't gotten in there to check it out yet. I know there is water coming through that valve and it doesn't appear to be the controller as it works for my other zones. But I'll keep after it. I wish I lived closer to Harbor Freight though.

Thanks again!


Supreme Member

Posts: 5,325

Location: Metro NYC


Thursday, July 27th 2017, 12:14pm

If you already have a multimeter, it is automatically superior to the HF freebie. :)


Thursday, August 17th 2017, 4:54pm

Well multi-meter reads at the controller show high resistance (relative to other valves) on the two valves which aren't working. So that's - I guess - good. I'll do a reading tonight at the actual valve to see if it is a wiring problem or a solenoid problem. I guess if the reading at the solenoid itself comes back the same as at the controller - I'm pretty sure I just need to replace the solenoids with the s20p.

If you already have a multimeter, it is automatically superior to the HF freebie. :)

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