Irrigation system blowout

[DTro]

I've had the company that installed my system blow it out the past 4 of 5 years, but wouldn't mind trying it myself this year.

How many CFM's is recommended?

I have a small Porter Cable Nail Gun compressor. I'm guessing that is too small.

But I bet I could justify the cost of a bigger one if needed.

Suggestions appreceiated.

[ScoutII]

Depends on the number of and type of heads on a zone. With 185 CFM, 4 rotors on a zone, and a short main line it takes about 2-3 minutes a zone, on my first round threw. I always hit each zone a second time because the air passes over the water in the pipe causing slugs of water in low spots (pipe is not level). If time is not an issue go for it.

Let us say you spent $5,000 on your system, $50, 1% each year to winterize is cheap maintenance. If you have rust in your water, a larger compressor will push a lot of the slimy rust out, like flushing the cooling system in your car.

[CFRay]

I have an eight zone system that I use a 30 gal., 6 hp elect. to winterize my system. Have not had any freeze problems. I believe I've paid for that compressor by doing it myself long ago. I use that compressor for other tasks as well around the house. I let the tank pressure build up to 100psi then open a zone. The water and rust residue leave in a hurry. I go through the system twice, takes an hour.

Good Luck.

[ottertailguy]

The first year I did it with my own 15 gal.,3 1/2 hp compressor. But then I paid for someone else to go through the system to see if I did a good enough job. He told me I did a great job and his services weren't needed in the future. I've done it now for 6 years without a problem. It takes awhile but I usually clean out the garage at the same time. I also put my own system in and my yard is 1/2 acre. Get the biggest compressor you can but use only 80 psi or you may damage your heads. Or check online for the max. pressure for your heads. Also make sure you get all the air out of the back flow and leave the 2 little screws open afterwards.

[Quetico]

Yeah i know a lot of guys that charge a flat rate of $45 to do the blow out. Figure $45 times a few years, theres your compressor costs right there.

[DTro]

yeah, I've paid $65 the past 5 years.

[echotrail]

I did mine last week with a rented a 8 hp compressor for $39. No blown lines or heads. I just don't trust the hire-out jobs because they will blow 120 lbs of preasure into the lines to get done fast and blow a head or two and then tell you it was a faulty head. Or if your not there to oversee the job they step the head back down and you won't notice it til spring and they deny they did it.

[DTro]

I've had a good experience with the company that has done it for me in the past.

Having said that I'm always a do it yourself guy when it makes sense and I have the know how.

[Shack]

Quote:

I have an eight zone system that I use a 30 gal., 6 hp elect. to winterize my system. Have not had any freeze problems. I believe I've paid for that compressor by doing it myself long ago. I use that compressor for other tasks as well around the house. I let the tank pressure build up to 100psi then open a zone. The water and rust residue leave in a hurry. I go through the system twice, takes an hour.

Good Luck.

I did this same exact situation for the first two years I had my system.

Now I have a very large comp, set it at about 90psi and blow out system with a long hose I have.

Dtro,

With your comp. it might take a little time, but it will get it done. I would not let it run for very long periods of time. Do a couple zones, let it cool down and hit the rest. For you first time, go threw the zones a couple times. Then if you want, hit it a third time the next day. All you have to do is make sure the heads drop down, then move on. Let sit and water collect and hit it again.

Remember, if you have a booster pump (outside) and your blow out point is after pump. Make sure you drain your pump and I leave my drain plug out.

Good luck dude if you do it.

Once you do it, you will never hire it out again.

[DTro]

Well after much research I decided to forgo purchasing a new compressor and just flagged down a guy running around our neighborhood on Sun.

$40 and 15 minutes later I was done (actually tossed in an extra 10 for his time)

[Fazerfish]

I was wondering if the psi needed is determined by the size of your system. I have been blowing 150 psi thru my system for the past 7 years and never had a problem. When my tank gets down to about 120 psi, the heads won't even come up. I think I have about 2/3 acre lot....

[ScoutII]

Compressor volume, CFM,cubic feet per minute is what determines if you can blowout a zone or not. For a given pressure say 20 psi to hold a head up. It takes 10 times the volume of air to hold the head up than if you were using water to hold the head up.

[Fazerfish]

I was thinking about it and remembered that I have a regulator that is set at about 115 psi, so I guess I wasn't shooting that much thru my system as I thought.