# Draining Sprinkler System



## SeminoleRail (Oct 11, 2018)

I recently moved into a new house with a sprinkler system. I believe it has automatic drain valves since I can't find manual drains valves anywhere. I've been reading up on how to drain the system for winter and it seems pretty easy to do but I do have one question. Most websites I go to say to open the drain cap on the stop and waste valve in order to drain water that is trapped between the water source and the backflow preventer. However I have no idea where this would be. My stop and waste shut off valve is several feet underground and I use a key to operate the valve. Is a drain cap not necessary since the line from the water source to the backflow preventer is all underground and (I'm assuming) below the frost line?


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## g-man (Jun 15, 2017)

Are you sure it has drain valves? In our weather, we normally have to blow the system with a compressor.


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## SeminoleRail (Oct 11, 2018)

g-man said:


> Are you sure it has drain valves? In our weather, we normally have to blow the system with a compressor.


Since I can't find any manual valves, I think it's a safe assumption that it has automatic ones. I may have it blown out but for now I'm just wanting to make sure it's gets drained properly.


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## SeminoleRail (Oct 11, 2018)

One other question. Is it normal for some water to remain in the chambers of the pressure vacuum breaker after draining it? I opened the test cocks and drained water from them, but gently shaking the pvb assembly reveals some water is left behind.


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## Delmarva Keith (May 12, 2018)

Colorado + no Winter blowout = irrigation repairs in your future. :nod:


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## SeminoleRail (Oct 11, 2018)

Delmarva Keith said:


> Colorado + no Winter blowout = irrigation repairs in your future. :nod:


I'm not even sure how my system would get blown out. There is no place to hook a compressor up to, unless it's possible to do it through the test cocks.


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## Delmarva Keith (May 12, 2018)

SeminoleRail said:


> Delmarva Keith said:
> 
> 
> > Colorado + no Winter blowout = irrigation repairs in your future. :nod:
> ...


There is always a way. There has to be a connection somewhere, likely in one of the valve boxes. There should also be a plug somewhere in the basement or in a valve box to drain any remaining water in the PVB and supply pipe to it. It might be worth it to hire a local pro and ask if you can observe what they do so you know where the connections are and what the procedure is. If there are no such connections, they should be added. Even if there are automatic drains at all the low spots in the lines, they don't always work, plus the main line has to be emptied.

Blowing it out yourself is not recommended anyway because a high volume compressor is needed and most homeowners don't have access to that type of equipment.


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## Anthony Drexler (Apr 23, 2018)

If you don't have a chuck on your back flow, you'll need a hose with the bibb already on it. You'll need this to hook up air, to your blow out port.

This is what mine looks like. It's the port on the left.


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## Delmarva Keith (May 12, 2018)

How do you open the port on the right?


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## Anthony Drexler (Apr 23, 2018)

They're plastic caps


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## Delmarva Keith (May 12, 2018)

Anthony Drexler said:


> They're plastic caps


There's a valve you need to be able to access with a screwdriver. Test port on the right needs to be turned 180 degrees.


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## Anthony Drexler (Apr 23, 2018)

Yes, you need to open the the valve so you can blow the system out. That can be seen in the same image. Plastic cap on the left with the screw to open, and close the valve. Sorry wasn't doing a full tutorial.


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## Delmarva Keith (May 12, 2018)

Anthony Drexler said:


> Yes, you need to open the the valve so you can blow the system out. That can be seen in the same image. Plastic cap on the left with the screw to open, and close the valve. Sorry wasn't doing a full tutorial.


No problem. You're not supposed to blow through the PVB. The test ports are used for testing. Blowing a compressor into the left test port risks contaminating your domestic supply and damaging the PVB. Blowing a compressor into the right test port risks damaging the PVB and once it's damaged, contaminating your domestic supply. I wouldn't suggest using the test ports to blow out the irrigation system. What comes out of a compressor isn't just "air." There's always a little condensed water vapor that will flush whatever crap is growing in the hoses right into the piping, plus a little oil vapor depending on the type of compressor. Isolate the domestic supply after the PVB (by closing the ball valve) and blow out the system downstream of that. If you don't have a blowout tap downstream of the PVB, add one.

The valve on the test port on the right is not accessable. The little valve is turned towards the house so you are not able to see it and it would be very difficult if not impossible to open it also. Out of curiosity and before I say any more, who installed it? Has it ever been tested?


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## Still learnin (Sep 9, 2017)

> I'm not even sure how my system would get blown out. There is no place to hook a compressor up to, unless it's possible to do it through the test cocks.


The company that installed my system said they blow it out through the sprinkler head...? That's what they said...


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