Tired of paying to have the sprinkler lines blown out every winter,
but I also don't want to have to replace lines and sprinkler heads in
the spring :-)
I am wondering if I could buy one of those 150 psi "Husky" compressors
from Home Depot and do it myself. Is that doable? And if so, where
would I get the adapters to connect the compressor tube to the outside
check-valve? Any ideas?
Thanks for any advise or any "alternate" ideas anyone might have.
I purchased a compressor about 10/12 years ago for this purpose and it
has been a successful investment. I presently shut off gate valve
feeding the outside water line for the sprinkler system and two hose
valves, connect the compressor air line to one of the hose lines and
fire away at about 45 psi. The air line connection to the hose bib is
via the female end of a washing machine hose connected to an air line
coupling fitting secured by a hose clamp.
Well, I should have asked the *right* questions, I guess :-)
I went to Home Depot and got a compressor. 155 psi, 3 gallons. I
got the appropriate couplers, and run home to blow out the lines.
Turned the water to the spronkler off and connected the compressor to
one of the check valve inlets. I turned the first zone of the
sprinkler valves on and started my new toy... The first zone, has
three sprinkler heads, with about 35 feet of pipe to each head. A
little bit of water came out of the first two sprinkler heads and then
the pressure of the compresson dropped and no more water. Run back to
home Depot, and talked to the guy in hardware (Seemed knowledgeable).
Well he says, with such long rung and multiple sprinkler heads, you
need a lot more that a 3 gallon compressor. I returned the small
compressor and got a 6 gallon one. Went back home and tried again. I
had a bit better luck this time, but still was not able to blow out
some of the longer runs.
I don't know about the cold factor, but to be self draining it would
seem to require a uniformly sloping area. If you have areas that are
basicly flat, then what? Here in NJ the sprinkler trucks are all
very busy pulling around rented air compressors every Fall. However
part of that could be that not designing them to be self-draining,
even when easy to do, means more $$ in their pockets to blow them out
Around here, almost all the systems are installed by pulling the pipe
using a machine that does that instead of actually digging a ditch.
It's less work, nothing to fill in, less mess, etc. But that means
you can't change the depth gradually along the way. And depending on
where the soil is more compacted, roots, etc, that the pipe might wind
up buried 7" in one spot, 3" in another spot along the same run.
All you need for connection is a male air hose quick connect
fitting. That you should be able to find at any auto parts store,
HD, or online. Harbor Freight Tools has them cheap. The fitting
has male pipe threads, generally 3/8" on the other end so you just use
whatever pvc plumbing parts necessary to make up either a permanent or
temporary fitting that you can connect to your system at the
appropriate spot. I added a permanent one together with a ball valve
to my system.
Whether you can successfully blow out the system with a small
compressor is a different story. I do mine easily with an old Sears
shop compressor,that has babye a 15 gallon tank and does 9 CFM at
40psi. I let the tank get up to about 80psi, then turn on a
zone. I only have 3 rotors per zone and 7 zones so it works OK.
Used it one year on a friends house that had 10 zones, from 6 to 10
heads per zone. That was much more difficult and took a very long
time because these smaller compressors can't deliver the air volume to
do it effectively and quickly. The pros use large gas powered
compressors that can blow out several zones at once in a couple
I've got a 7-zone sprinkler system at a small commercial office
building. Each zone has about 6 or 7 heads. Each time the system comes
on in the summer, every head in each zone belches air for about 15
seconds before water starts shooting out of them. This doesn't just
happen the very first time the system comes on for the season - it
happens every time the system comes on.
I'm thinking that the heads or the lines have an automatic drain
function that always kicks in when the system turns off, and therefore I
don't need to blow the lines out in the fall.
You are most likely correct. A well designed system has no need for
compressed air. I live in Denver, and used to design and sell the parts for
irrigation systems. We always tried to design for gravity drainage of the
system. The common pipe for laterals here is polyethylene (poly) pipe. It
can take a lot of water frozen inside of it, as long as the pipe is not
completely full of water. One office building I had, the north zone in the
shade sometimes still had ice in the pipe when we would turn the system on.
It would melt out with no damage. That system was in use for well over
twenty years, until the highway department widened the road, and dug it out.
The sprinkler guys love to convince you that compressed air is required to
keep from freezing damage. My current home has a very old system, but it
does gravity drain.
Although it's too late for a lot of you that have already bought
You would have been better off buying just a small, portable air tank (5
or 10 gallons) and rig it up with the appropriate gate-valve and
connectors to attach to your sprinkler plumbing.
To fill the tank, either take it to a service station or buy a small
I rigged up a 5 gallon tank so that I have a medium-sized electric
compressor connected to the tank as well as having the tank connected to
the sprinker system at the same time. This minimizes the time it takes
to disconnect / reconnect the tank to recharge it.
What you need to purge a sprinker line is a massive blast of
high-pressure air - which some of you now realize comes mainly from
having a large tank that's been pre-charged. And only turn on 1 zone at
a time when you do it.
And you need a low-restriction gate or ball valve to let the air out of
the tank and into the line with as little restriction as possible.
If you connect a low-capacity / low-volume air compressor to your system
and find that you can't exceed a pressure of 30 psi then your sprinkler
system is probably self-draining and the air is bleeding out the drain.
You need more than 50 psi to force the heads up.
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