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Tuesday, May 20th 2014, 4:44pm

Possible to design to avoid winter blow-out?

I might be going about this all wrong, I don't know.

Hello. Every fall I pay to get my system blown out, and every spring there's some damage... usually a cracked elbow somewhere. This year, the damage is quite extensive. I had to tear out my whole manifold because of poor access, because of a cracked fitting between two valves. After fixing that, I find out there's a line broken somewhere in the yard. I don't know if its a poorly designed/built system or if the blow-out guy just has no clue what he's doing... but anyway, this year I'm planning on an extensive overhaul of my landscaping anyway so I may as well re-do the irrigation. I was seeing SprinKler Warehouse's "Automatic Drains" section and wondering if its possible to use those to avoid having the system blown out at all? Or is it for something else? Thanks.


Supreme Member

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Location: Metro NYC


Wednesday, May 21st 2014, 6:42am

Replace the system shutoff valve. Yours is probably leaking when it's shut off, and the water gets into the system and breaks things when it freezes. The plumbing should be configured so that an open drain can let this leaking water drip out of the plumbing, before it can get into places where it will damage the system when it freezes.


Wednesday, May 21st 2014, 6:24pm

I appreciate the response.

Tell me... am I asking too much of the new fancy "smart" digital water meter then? Because from time to time I'll check it to tell me if there are any leaks. I do that by ensuring nothing is (deliberately) running, then I activate the meter (you shine a flashlight at the sensor so the display turns on) and it shows me that the flow is 0.000000 cubic meters per minute. So for it to not detect a leaky shut off valve, the flow would have to be extremely minimal, or its just not as sensitive as it appears (6 decimal places... let's see, that's 1/1000th of a litre in a minute).

And now that I think about it... it would have to be two faulty shut-off valves.

Its plumbed like this: we're in Canada so the pipe comes in from the ground beneath the house. I have a main shut off there. It then goes to the mechanical room where there's another shut off just before the meter. From the meter it branches with one going to the PRV and then the rest of the house while the other goes to the double check valve. After the check valve is the first irrigation shut off and then it goes about 15 feet and exits the building. Immediately outside there is another irrigation shut off. From there it goes to the valve box, etc.

Both shut offs are closed for the winter (inside first, then system blown out, then outside is shut)

I've been reading on and making my way through that trove of info. I'm learning that there are a million ways these systems are designed. From what I'm reading (there and here), it seems rather unusual for the check valve to be inside the house? It also seems rather unusual to have two shut offs, right?


Supreme Member

Posts: 5,279

Location: Metro NYC


Thursday, May 22nd 2014, 5:02am

Until you have a low-point drain valve in the sprinkler system supply line, downstream of the system shut-off valve, you are only guessing. Install that drain valve, and you will have visual evidence, and real protection against water getting into the outdoor sprinkler plumbing.


Thursday, May 22nd 2014, 10:54am

I don't know what you mean. I think you mean to install this drain inside (so it doesn't freeze) at the lowest point on the line after the shut-off... but I'm not sure how that would give me any "visual evidence" for two reasons: First, the low point is inside a wall, presumably immediately before it exits the building. I can't tell exactly, but it appears to grade down as far as I can see, and I think the exterior pipe is a foot or two lower than the interior one... but I can only see the pipe for the short section that is in the mechanical room. It disappears into the bedroom wall before getting outside. Second, even if I could have access to the pipe at the low point, of course I'd want to plumb it to a drain, right? So I still am not clear how that would provide any visual evidence.

So I must be missing your suggestion.


Supreme Member

Posts: 5,279

Location: Metro NYC


Thursday, May 22nd 2014, 1:23pm

Maybe you need to post some photos. If your plumbing exits the house foundation below grade, it would make sense to cut in a drain on the inside plumbing, where you can see right away if there's a drip through the shutoff valve. The whole idea is to make it physically impossible for leaking water to get into the outside plumbing.

Should it happen that the supply exits the house above grade (and I'm guessing that it doesn't), then you could place a drain on the outside plumbing.

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