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1

Monday, September 28th 2015, 3:12pm

incorrect plumbing?

My sprinkler connection is similar to the one pictured here. I have a Febco 765 breaker.

My plumber looked at it and claimed it was installed incorrectly, because the valve for blowing out the lines is on the wrong side of the vacuum breaker. The breakers are not meant to take the blowout pressure, so after a few winterizations they break. He said they are installed like this because it they like to guarantee future repair business.

Is that correct? Can it be safely winterized as-is, without harming the breaker?


SunCoLawns

Advanced Member

Posts: 111

Location: Omaha, Nebraska, USA

2

Monday, September 28th 2015, 9:41pm

Technically, you are not supposed to have a threaded hose connection before the back flow because it creates a potential unprotected cross connection. I have winterized systems through the backflow for years without problem, though it is certainly more desirable to have the connection after the backflow. if the piping downstream of the backflow is PVC it would be simple to cut in a drain. the backflow in the picture is missing the bonnet, so you would be unable to blow it out from before the backflow.

3

Tuesday, September 29th 2015, 10:16am

pressure adjustment

Thanks for the comments. Mine has a bonnet, so no worries there. I'm not sure if the downstream pipe is PVC. It is black plastic, maybe 3/4 or 1" diameter. Probably your comment is still valid, that it would be simple to cut in a drain valve.

If I don't do that upgrade, and blowout as-is, do I need to limit the compressor pressure initially so the breaker doesn't get damaged? I'm confused about this point, because I thought the breaker would be engaged already since the system is already pressurized.

Also, I'm considering purchasing this compressor, and was wondering if it would be adequate:
http://www.lowes.com/pd_470442-30449-0300841_0__?productId=50129758 (Kobalt 1.8-HP 8-Gallon 150-PSI 120-Volt Horizontal Electric Air Compressor)

SunCoLawns

Advanced Member

Posts: 111

Location: Omaha, Nebraska, USA

4

Tuesday, September 29th 2015, 1:40pm

If that is the compressor you are going to use you probably don't need to worry about the pressure being so high it damages your backflow. More likely, you may struggle getting the poppet to seat against the bonnet. It would definitely make your life easier to put a tee in downstream of the backflow with a 1/4" female threads that you can screw an air chuck into.

When I first started in this business I used a compressor about that size. You'll want to make sure to plug it into a 20 Amp circuit that isn't already loaded with a big draw like a freezer or refrigerator. You'll need to let the pressure build up to it's maximum before you open the first valve and, if the pressure drops too much before the zone is empty, you'll have to shut the valve and let the air pressure build back up again. Depending on how large your system is it may take a while, but it should be possible.

Wet_Boots

Supreme Member

Posts: 5,147

Location: Metro NYC

5

Tuesday, September 29th 2015, 1:56pm

Don't buy the 8-gallon compressor. Go bigger. You need more air to get the job done. On your intended scale of operation, it is the air tank that does most of the work.

By the way, the 'rule' about not blowing through the backflow preventer harkens back to old jackhammer compressors that put out air hotter than boiling water.

6

Tuesday, September 29th 2015, 7:48pm

fitting

The downstream portion on my rig is 1 inch black polyethylene pipe.
What fitting / other parts should I use for the tee?

I have three zones, maybe 5 heads per zone, and the lawn is small, maybe 24ft x 10 feet in the front and 20ft x 30ft in the back. Do you think a 20 gallon compressor would be good? 30?

This post has been edited 1 times, last edit by "msprinkles" (Sep 29th 2015, 8:58pm)


Wet_Boots

Supreme Member

Posts: 5,147

Location: Metro NYC

7

Tuesday, September 29th 2015, 8:25pm

20 gallon will get it done. Even a 12 might do it with repeats.

8

Wednesday, September 30th 2015, 1:55pm

fitting

How would I add a blowout fitting to a 1 inch polyethylene pipe? Can someone point me to the right fitting?

SunCoLawns

Advanced Member

Posts: 111

Location: Omaha, Nebraska, USA

9

Wednesday, September 30th 2015, 5:03pm

RE: fitting

The downstream portion on my rig is 1 inch black polyethylene pipe.
What fitting / other parts should I use for the tee?

I have three zones, maybe 5 heads per zone, and the lawn is small, maybe 24ft x 10 feet in the front and 20ft x 30ft in the back. Do you think a 20 gallon compressor would be good? 30?


With poly ethylene pipe you could tap a threaded saddle http://www.sprinklerwarehouse.com/Blazin…ee-p/bs7000.htm and attach a threaded hose bibb.

Wet_Boots

Supreme Member

Posts: 5,147

Location: Metro NYC

10

Thursday, October 1st 2015, 6:54am

Just blow through the PVB. There does not exist the compressor you could purchase at a Home Depot or a Lowes that can do damage to the PVB, so long as your pressure is set below 60 psi (which is really protecting your sprinkler heads, not the PVB, which can endure much higher)

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