Winterizing in-ground irrigation

Joined
Mar 21, 2004
Messages
29,554
Location
Near the beach in Delaware
The company came today with a trailer mounted air compressor and went through zone by zone.

Does one really need that big a compressor?

Another reason to keep my 5hp two stage 60 gallon compressor? Most tools now Milwaukee M18 cordless.

If you use a smaller compressor (I have small HF one I can carry) does it just take longer?

Next year I will winterize it myself.
 
I have a drip irrigation system as part of my septic system and it never needs to be winterized. But the drip tubes are buried 1 foot below ground level.
 
Smaller compressor will just take longer, and it might run longer than you might want. Each zone of the system should get at least 4 minutes of blow out, but keep in mind that water expands 11% with freezing so you don't need all that water out of the system to sleep fine.
 
The company came today with a trailer mounted air compressor and went through zone by zone.

Does one really need that big a compressor?

Another reason to keep my 5hp two stage 60 gallon compressor? Most tools now Milwaukee M18 cordless.

If you use a smaller compressor (I have small HF one I can carry) does it just take longer?

Next year I will winterize it myself.
Subscribed, I'm tired of paying for winterizing. I should have bought a compressor at Costco, it seemed reasonably priced, but it's OOS.
 
I’ve been doing mine for 10 years. I have 18 zones with two timers and three manifolds. I use two - 2 gallon compressors manifolded together as shown. At worse you might need to build it up a second time on some zones.

7FCEB5D5-C334-4BB0-9D74-D2E4B3994E6F.jpeg
 
Last edited:
I'd say there are a lot of factors to consider.
How long are the runs?
Are there any major low spots?
What are the diameters of the piping?
Commercial services must be equipped to handle any config they encounter, so they need to deal with worst case scenarios.

I'm guessing that a 60 gallon tank would be sufficient, but I'd have a large outlet on it to make sure you get plenty of volume.
 
It is a tradeoff - the large compressors can deliver a large volume of air at a lower pressure.

I do my system with a 20 gallon tank compressor. It takes me roughly 1 to 1.5 hours to complete the 8 zones in my system. After the initial blast of water comes out, my setup will only keep the sprinkler heads up for about 25-30 seconds -it can't deliver the volume needed to run continuously...

On the flip side, this made the payback on my air compressor less than 5 years if I don't even consider the other things I use it for. 17 years later... its all money in the bank.
 
Figure they are probably also doing large commercial properties where the lines run a lot greater distance than your typical residential yard system.
 
It is a tradeoff - the large compressors can deliver a large volume of air at a lower pressure.

I do my system with a 20 gallon tank compressor. It takes me roughly 1 to 1.5 hours to complete the 8 zones in my system. After the initial blast of water comes out, my setup will only keep the sprinkler heads up for about 25-30 seconds -it can't deliver the volume needed to run continuously...

On the flip side, this made the payback on my air compressor less than 5 years if I don't even consider the other things I use it for. 17 years later... its all money in the bank.
From experience over 10 years in an area with temps to -25 F and sometimes , -40 , you do not need the sprinkler head to stay up after the blast of water is out. Running continuously is not required. If you think you have a sprinkler head lower than the others, give it a second blast. My sprinkler lines are about 6 inches underground and the frostline is about 2 feet.
 
I'm guessing you didn't check my location before commenting... Frost Depth here is 3 to 4 feet with the same temps you were describing. After 17+ years, I've also determined what it takes to properly winterize my system - through some hard knocks in the early years.

If you leave enough water in the system, it will all drain back to the lowest point where it will freeze and crack the pipe. Been there, done that, got the T-shirt, as have other family members and friends.

There is a reason with a high volume setup most companies here will blow for 3+ minutes per zone. Since my setup cannot keep the heads up that long, it takes 3 pulses minimum to ensure enough water is out - and for good measure I do four.

And as others have pointed out, it all depends on the length of the runs, size of piping, and sprinkler heads as to what you will need to do and how long.
 
If the system is designed correctly water from one leg cannot enter the adjacent leg so it will not gather at the low point. A proper manifold has the valves at the same elevation. Opening one valve, blowing it out and closing the valve is the procedure I use. I build up the pressure in the tank to 50 psi and open to the manifold.

I do the highest manifold first, then middle elevation, then lowest elevation. The last valve is at the end of each line and the last of the water goes rushing out followed by a burst of air. Never had a problem even with four gallons of compressor capacity. Now if a person has parallel lines coming off a single valve, yes, that will require more air. As for the frost line, having lines 6 inches deep means it’s seeing surface freezing temps regardless of frostline depths.

There is a lot of stuff play in the system design so just saying a volume and pressure number does not do anyone a favour. 4 gallons and 50 psi works fine for me but may not be enough for many others. However, do not be intimidated by those commercial guys with trailer mounted compressors.
 
Last edited:
When I lived in Maryland I winterized my irrigation system myself. You definitely don't need a huge compressor. I used a 2-hp portable compressor with a 20-gal tank.

I built myself an adapter to connect the air line to the PVC pipe. I set the regulator on the compressor to around 40 PSI. I would open the valve on each zone for about a minute, going through all of them. Then I went through each zone again for about 30 seconds each. I figured that a few drops left in the pipes here and there are not going to cause a problem.
 
When I lived in Maryland I winterized my irrigation system myself. You definitely don't need a huge compressor. I used a 2-hp portable compressor with a 20-gal tank.

I built myself an adapter to connect the air line to the PVC pipe. I set the regulator on the compressor to around 40 PSI. I would open the valve on each zone for about a minute, going through all of them. Then I went through each zone again for about 30 seconds each. I figured that a few drops left in the pipes here and there are not going to cause a problem.
I used a small less than $100 compressor with roughly a 2 gallon tank and blew the lines out one by one as you did. Also agree, some left over water wont damage, the object is to clear out most all water so any little remaining water that freezes has enough room to expand and contract.
 
I have a 60 gallon 11 or so cfm compressor ands I turn off the water valve and run the sprinkler test run cycle for 5 minutes per zone. It works well and takes about ten minutes of my time to find the Adapter and hook up the air hose and turn on the timer and less to unhook the hose and adapter and turn off the timer and compresser.
 
Back
Top