Winterization, What Sets Us Apart?
There are three schools of thought on proper sprinkler winterization. You could spend all day on the internet reading hundreds of articles, but all of them base their opinions on what Rainbird and Hunter suggest. The crazy thing about these 2 sprinkler experts is their answers are extremely different. Rainbird suggests that "air pressure (PSI) should not exceed 50, and your CFM (cubic feet per minute) should range from 10-25. Air volume should be high, and air pressure should be low." Hunter on the other hand suggests that" your air pressure should not exceed 80 PS,I and 80-100 CFM." This will clear lines faster than rainbirds suggestion, but has long term impacts on your system. One of the main things that both companies agree on is that a 1-3 HP air compressor will not do the job efficiently. These small compressors can turn a ½ hour job into an all day ordeal. The main problem being that air heats up when you run through a compressor for extended periods of time. Heat as you can imagine is hard on plastic pipe, and rubber seals. A compressor should not push air through any pipe for more than 2 minutes at a time. So with this information what can one deduce? Air volume should be high, and air pressure should be low. Now I’ll introduce the 3rd school of thought. A few landscape professors came up with the ideal answer. Find out what your water pressure is, and how many gallons per minute your system was designed for. Then take your GPM, and divide it by 7.5, and that will give you your CFM. Clear as mud right? During winterization season you will see landscape companies driving around with tow behind air compressors. These compressors at a minimum push 175 CFM, and can run 150 PSI. Does anyone see a problem with that? Most sprinkler pipes are rated for 120 PSI for cold water. Hot compressed air acts different in pipes than cold water. This can lead to pipes bursting out of their joints, and rubber in backflows and valves can melt or warp. I have seen the top of sprinkler heads blow off, and shoot 30 feet straight up and I have scars to prove it. I have also seen the gears in rotors strip out because they were rotating so fast. The reason behind using these tow behind compressors is they blowout water fast while this may be a good thing for the company's bank account it may not be so great on your investment. Now that we have powered through all that info here is my recommendation. Since most homeowners don’t have a copy of their sprinkler plan to figure out the optimal CFM for your system (It can be done without your plan, but I find it’s not necessary). A 6-10 HP gas air compressor that can push 10-25 CFM is what you need, and what we use. Each valve should be opened for no more than 2 minutes. The air from the compressor needs to be shut off in between valves otherwise that hot air we talked about is pressurizing your mainline, backflow, and valves. After all zones have been blown cycle through again, and double check for excess water. This process may take 5-10 minutes longer than the typical company, but we put customers before fast profits.