Blowing out irrigation system for winter


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My irrigation system was inspected and winterized by a pro a couple weeks ago but then we found the main shut off valve was faulty.  I replaced the valve myself, but in doing so had to allow water back into the system. 

Our usual sprinkler company can't make it out within a few days and it's supposed to dip below freezing this weekend. 

I'm contemplating blowing it out myself. Has anyone done this?  My main concern is where to attach the compressor to the backflow preventer and what fittings to use.  

My preventer only has four test cocks, no hose cock.  

Can anyone tell by looking at this where I should attach the compressor? 

20171023_212522.jpg

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I do mine every year. From the pic it looks like all your connections face the wall is that right? Anyway you want to blow through the preventor but not into the house so you close the valve going to the house and blow out from there. On mine the bottom valve would be closed the others open You can see I leave my air hose connection on year round and just open that ball valve with a screw driver to blow it out. I also have a drip system for rid o rust and I have to close that ball valve as well. Once you blow out the system leave everything cracked valves, ball valves, and in my case the water faucet

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Keep in mind you need a big tank to blow out a sprinkler I have a 60 gal tank and it works fine. If for some reason you can't get it blown out and you are only talking a couple degrees below freezing wrap it with and insulating blanket until they can get out there.

 

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10 minutes ago, Eric. said:

So many cocks.  I'm no help.

I know. That was a difficult post to make. 

 

4 minutes ago, pkinneb said:

I do mine every year. From the pic it looks like all your connections face the wall is that right? 

IMG_2369.jpg.61e12d5b4bdbaab898cb047f6aeb28a4.jpg

Keep in mind you need a big tank to blow out a sprinkler I have a 60 gal tank and it works fine. If for some reason you can't get it blown out and you are only talking a couple degrees below freezing wrap it with and insulating blanket util they can get out there.

 

Yup, that's right, they aim toward the house unfortunately. 

I know that draining between the house and the preventer is easy, and I essentially did that when I replaced the valve anyway.  

To blow out the preventer and toward the sprinklers, can I use any of the test...cocks?  I noticed they are all different, two are female threaded, one is male threaded, I forget what the fourth was. 

 

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1 minute ago, Jfitz said:

if it's just a few days, you could wrap the piling in a blanket, maybe with a heating pad to keep it warm.  The stuff in the ground should be fine if it just dips below freezing overnight.

Yeah, I know that's last resort and would likely get us by. 

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The air compressor is another point of contention with my wife.  My compressor is good only for a nail gun and bike tires.  My wife wants to borrow our brother in laws compressor, which is just 8 gallons...however turns out it's a piece of crap and needs an hour in between fill ups to keep from blowing up the motor.  That would make this process take forever. 

Would the harbor freight 21 gallon compressor be reasonable?  Our system is 8 zones, but only 2-3 sprinklers per zone. 

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34 minutes ago, bleedinblue said:

 

To blow out the preventer and toward the sprinklers, can I use any of the test...cocks?  I noticed they are all different, two are female threaded, one is male threaded, I forget what the fourth was. 

 

In your photo which is the house side and which is the yard side? I would want to use the one just after the shut off to the house side and before the BF valve so your blowing through the valve but not into the house. 

10 minutes ago, bleedinblue said:

The air compressor is another point of contention with my wife.  My compressor is good only for a nail gun and bike tires.  My wife wants to borrow our brother in laws compressor, which is just 8 gallons...however turns out it's a piece of crap and needs an hour in between fill ups to keep from blowing up the motor.  That would make this process take forever. 

Would the harbor freight 21 gallon compressor be reasonable?  Our system is 8 zones, but only 2-3 sprinklers per zone. 

A pancake will definitely not work I don't think a 21 gallon is going to get it done either, is renting one an option? I have a 60 gal and it runs a lot to catch up takes about 5 minutes per zone. I have enough in the tank to get about 90 seconds before it starts to recycle. Having said that I am on acreage so my longest run is in the 400-500' range.

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I used to do lawn sprinklers for a living.

Yes, that HF compressor will probably work if your lines are 1 inch diameter. Over an inch you probably want to rent a tow behind size compressor.

You want to shut the up-stream valve and connect your compressor to the nearest stop cock. Charge up the compressor to 100psi and open zone 1. It should blow the water, then vapor, and then just air. If you're not sure the zone has emptied sufficiently do each zone twice. After you're through all the zones crack open each of the stop cocks on the double check valve to make sure the water is out (this can be done as the last zone is blowing), turn off your compressor, and shut the downstream ball valve on the double check so that if the first valve leaks the water will go out the stop cocks and not into the sprinkler system main.

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15 minutes ago, pkinneb said:

In your photo which is the house side and which is the yard side?.... .

From the picture, the closest is the house side. 

My property is much smaller than yours... I'm in a subdivision with a typical suburban sized yard, probably in the 7k square foot range.  I bet my furthest run isn't 100 feet. 

11 minutes ago, davewyo said:

I used to do lawn sprinklers for a living.

Yes, that HF compressor will probably work if your lines are 1 inch diameter. Over an inch you probably want to rent a tow behind size compressor.

 

Yup, all 1" lines. 

Thanks for all the info guys. 

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1 hour ago, bleedinblue said:

From the picture, the closest is the house side. 

My property is much smaller than yours... I'm in a subdivision with a typical suburban sized yard, probably in the 7k square foot range.  I bet my furthest run isn't 100 feet. 

Yup, all 1" lines. 

Thanks for all the info guys. 

I should add that you should be charging up the compressor and then letting it blast for each zone, not just going through the zones while the compressor runs.

I generally try to blow the zone which is furthest away first (if you have more than one valve box). That way the main is cleared first, and it's easier to clear the rest of the zones.

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24 minutes ago, davewyo said:

I should add that you should be charging up the compressor and then letting it blast for each zone, not just going through the zones while the compressor runs.

I generally try to blow the zone which is furthest away first (if you have more than one valve box). That way the main is cleared first, and it's easier to clear the rest of the zones.

Yeah, at least a couple of the YouTube videos I watched said it's best to start with the zone furthest away.  

Realistically, I don't see how there is much water in the system anyway.  When we opened the main valve (what we replaced) for a leak test, it was only on for a short time.  All test cocks were open and the valve between the bf preventer and sprinklers was closed.  I know there is water in the bf preventer, but I think most of the rest sprayed on the side of the house. 

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4 hours ago, pkinneb said:

In your photo which is the house side and which is the yard side?

 

4 hours ago, bleedinblue said:

From the picture, the closest is the house side. 

 

I just realized this is backwards.  From the picture, the closest is the sprinkler/yard side.  I think that kills my theory that little or no water made it to the sprinklers.  It was the valve on the house side that was closed, but a lot of water made it to the test cocks.  The valve on the yard side was open to 45*.

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I may be seeing this totally wrong and open to corrections. One of the connections towards the house looks like it has fresh Teflon tape on it and it also looks like it is between the main valve and the check valve/backflow preventorI would remove it and add a 90* ell, turned up so that you can get to it, and replace the connection that’s on there now with a small ball valve and quick connect like @pkinneb has on his. Then close your main and use your compressor or air cylinder to blow it out. 

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No sir. Leave all as is but replace the outlet with the threads on it with an ell, valve and quick connect and blow thru the preventer. I’m assuming the preventer is just a flap valve or check valve (for lack of better words)?

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I had something like that I mind, it might be necessary anyway just to get the hose in it. 

Been fighting with the wife all day over the stupid air compressor.  She's too cheap to want to spend $200 on a new compressor, even though we wouldn't even notice a $200 purchase.  Our brother in law convinced her his compressor is big enough so she went and got it.  It's not even the 8 gallon I thought, it's 5.  And it needs an hour to sit between refills. 

Anyone want a spare wife?

Lesson learned, again.  Just go buy the damn tools I need without involving her. 

  

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30 minutes ago, bleedinblue said:

it might be necessary anyway just to get the hose in it. 

 

  

I always installed my double-check valves with the cocks pointing down. That usually gives room to hook on and allows gravity to drain the double check if the shut-off valve dribbles during the winter.

You can try screwing off the first stop cock and then thread your compressor quick-connect fitting directly into the body of the double check. Go easy, it's brass on brass and will fracture if you yard on it too much. That may give you enough room to hook in. Replace the stop cock when you're done.

If the stop cock won't budge or there's still not enough room, get a short 1/4" NPT threaded nipple (what's called a close nipple) and an elbow to thread your compressor fitting into. Take the stop cock to the hardware store to check the thread. It should be 1/4" inch, but you never know.

You have to connect to the upstream stop cock or you're not clearing the double-check valve entirely (and it will likely crack from freezing).

The 5 gal. compressor is too small. Eight was going to be a stretch. Rent a twenty or forty gal compressor would be my recommendation, or wait for the guy to come out. Jfitz was correct earlier in saying that a first frost of the year probably isn't going to burst the double check, especially if you put on some insulation.

 

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All good info Dave.  As far as the compressor, I'm just going to go buy the 21 gallon.  I need a real compressor for the house anyway.  I may or may not hook up the 5 gallon borrowed compressor just to prove to the wife that it's not big enough. 

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