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View Full Version : blow out sprinklers, I can do that, right?


CardinalFJ60
09-28-2009, 07:33 PM
I got a pancake compressor last spring...can I blow out my own sprinklers? I think I can, but don't really know the process. Here's my thought:

1. get two quick connects for the back side of the anti-backflow valve thingie (the thing with the bell on top that cracks every other year ;) )
2. get really wet then realize I have to turn off the supply. :lmao:
3. connect my compressor hose to the top quick connect -= What PSI?
4. have my 'operative' cycle the zones upon my command with the FMRS radios to then next one when one seems clear.
5. what do I do with the bottom one? (I can take pics tomorrow for those unlucky souls who are unaware of the joys of replacing a backflow valve thingie)

Any tips? advice? or is it worth the $$ to just have someone come over so I don't have to do it? (I can't imagine that's the case)

thanks! :cheers:

(4 weeks and counting until the stork arrives in Lousiville. :thumb: )

nakman
09-28-2009, 08:14 PM
Yeah you can do this Shawn, and you don't even need a helper it just doesn't go fast enough. I think the inside is all connected so it really doesn't matter if you use the top one or the bottom one, I have always used the bottom one too though, yet opened the top one while blasting it out and a little water will spray out. My procedure:

1. Shut water off to sprinklers. Drain whatever you can, from whatever drains you have.
2. Completely close the valve between the backflow thing and the house, if you have one there. that way you won't squirt air back into the house, not that it would really matter though since you shut the water off inside.
3. Turn on the compressor to 100-120 psi, until it shuts off on its own.
4. Turn one of your zones on manual. Connect to top quick connect for about 5-10 seconds- the water will squirt out, then air mixed with water, by this time your compressor will be on again, you're done.
5. Remove hose, drink half a beer. :drink: turn that zone off.
6. Once compressor shuts off again, turn another zone to manual. :drink:
7. connect hose again, watch the water, air, after 10 seconds you're done. :drink:

go back to step 5 and repeat for all of your zones. I wouldn't get hung up on removing all the water personally, you want that backflow valve to be pretty dry but you've got a good 6 weeks before anything will really freeze, it'll dry. And all you need to do is create enough air space to allow the water to expand inside the lines.

nakman
09-28-2009, 08:20 PM
couple other anal points:

If you have one of those little brass caps at the shut off inside the house, take that off and put a little bucket below it after you shut off the water. Then go outside and open (turn the screwdriver slots horizontal) the little valves on the backflow thing. This will allow air in and your line will drain nice and quick, beer bong style.

Some folks will remove that bell thing completely and put it in the garage, and then cover the backflow deal with a plastic bag. I think this is overkill, but I have also had to replace more than one of those, so what do I know. :confused:

Some folks will also leave the valves before and after the backflow half-open. I'm not sure why to be honest, I can see leaving them open all the way, but I don't know what "half open" really buys you. However I've seen that on a lot of houses that were "professionally" blown out.

I'm sure our other irrigation experts will chime in and correct all of my misguided assumptions..

RicardoJM
09-28-2009, 08:25 PM
Easy job:D. Did mine yesterday, my sisters last Thursday and will do my brothers this weekend. My clock is in the basement so I do use the FRS radio to signal my clock assistant to start/stop the zones. Basically, I follow the same procedure that Tim outlined; minus the beverage. Go through the zones twice and it will be plenty well blown out.

Hmm, I might have to give the beverage thing a go next year. :beer:

CardinalFJ60
09-28-2009, 08:32 PM
I will be adding the :beer: piece for sure. ;)

"Some folks will also leave the valves before and after the backflow half-open."

yeah! mine were halfway in the spring, I was scratching my head, too

RicardoJM
09-28-2009, 08:51 PM
I will be adding the :beer: piece for sure. ;)

"Some folks will also leave the valves before and after the backflow half-open."

yeah! mine were halfway in the spring, I was scratching my head, too

I should have posted here for Nakman instructions before doing the job. I'm now thinking I've missed out on an important part of the experience of the last 18 years of doing this job:D.

I also leave my valves halfway. Why? Don't know have never stopped to ponder it. :o

Shark Bait
09-28-2009, 11:49 PM
Is it time already? :eek:

nuclearlemon
09-29-2009, 08:24 AM
rip up your old system and put in the valves that self drains:D

Maddmatt
09-29-2009, 10:45 AM
Leave those little valves half way open - and don't forget to open the ball valve below the backflow valve when you're done. That way there's no chance of any water getting trapped inside a little brass valve.

Otherwise it can hold a little ball of water inside that brass fitting. If it gets cold enough, water will win and then next spring when you start up the system water will shoot out from where there used to be brass and you'll get your shorts all wet.

And then that $50 you saved goes to Home Depot. But at least you get to use a torch while you're sweating the system back together. DAMHIK.
-Matt
edit - or leave them all the way open, I don't know why "half" is the standard either. Just don't leave them closed.

nakman
09-29-2009, 10:48 AM
Yeah but why wouldn't you just leave the valves all the way open? still don't get what the halfway buys you.. :confused:

wesintl
09-29-2009, 10:50 AM
Turn the water off. It'll drain and evap enough that by the time for the first freeze you'll be fine.

Jacket
09-29-2009, 10:51 AM
Maybe an indicator that they are neither open nor closed? :dunno: I've wondered that myself....

ScaldedDog
11-07-2009, 03:10 PM
Yeah you can do this Shawn, and you don't even need a helper it just doesn't go fast enough. I think the inside is all connected so it really doesn't matter if you use the top one or the bottom one, I have always used the bottom one too though, yet opened the top one while blasting it out and a little water will spray out. My procedure:

1. Shut water off to sprinklers. Drain whatever you can, from whatever drains you have.
2. Completely close the valve between the backflow thing and the house, if you have one there. that way you won't squirt air back into the house, not that it would really matter though since you shut the water off inside.
3. Turn on the compressor to 100-120 psi, until it shuts off on its own.
4. Turn one of your zones on manual. Connect to top quick connect for about 5-10 seconds- the water will squirt out, then air mixed with water, by this time your compressor will be on again, you're done.
5. Remove hose, drink half a beer. :drink: turn that zone off.
6. Once compressor shuts off again, turn another zone to manual. :drink:
7. connect hose again, watch the water, air, after 10 seconds you're done. :drink:

go back to step 5 and repeat for all of your zones. I wouldn't get hung up on removing all the water personally, you want that backflow valve to be pretty dry but you've got a good 6 weeks before anything will really freeze, it'll dry. And all you need to do is create enough air space to allow the water to expand inside the lines.

OK, I think I need more explicit instructions... :D

I finally tried to do mine today, but I'm either not doing it right, or something is wrong. I had my regulator set to 80psi, but it had to go through 100' of hose, so I suspect the delivered pressure was something less than that. The air all seemed to come out from underneath the backflow bonnet, or whatever that thing is called. I was connected to the top quick connect, and tried it with the bottom quick connect ball valve both open and closed.

I'm doing this by myself and can't see the heads from the backflow device, but I don't think they ever came up.

School me, please...

Thanks,

Mark

nakman
11-07-2009, 03:37 PM
try connecting to the bottom inlet, not the top one. Mine did the same thing until I hooked it up to the bottom. Also you can use the little screw to turn the air off & on while it gets back up to pressure between zones.

Mendocino
11-07-2009, 03:39 PM
My bottom inlet feeds the rear lawns and the top the front. I have to blow out all the front and rear zones with the air attached to the respective zone feed.

PabloCruise
11-07-2009, 09:15 PM
My source at the plumbing supply store said to blow at 60 psi to avoid over pressure and breaking things... (water supply at 65 psi)

LARGEONE
11-08-2009, 09:32 AM
A pancake compressor will not produce enough volume to blow out the line. I've had to borrow my neighbors compressor in the past...and even his (35 gal, I think) needs to recharge too often and really doesn't produce enough volume of air. 60 PSI is plenty BTW. I'm going to do mine today. I had to repair a head that I ripped off last weekend trying to cut my lawn super short for the winter. My lawn mower caught on the head and broke it off.

When I installed my sprinkler system a few years back, I put drains at both valve manifolds as well as under the backflow preventer. I can usually drain all of the expensive stuff and wait until late in the fall to actually blow it out. That way, if we get a warm spell like we're having now, I can turn it back on in ten minutes. I'm going to run my sprinklers and then blow them out.

Good luck!

Inukshuk
11-08-2009, 09:55 AM
Its all about volume, not pressure. I did a bunch of online research before buying my compressor years ago because this was one use I wanted. I have a home depot husky, 22gal tank, 6.5 cfm at 40 PSI which was about the minimum volume recommended for sprinkler purging.

But as for the backflow device, like Tim said your air has to be downstream from it. And I'll add that it has to be isolated. Downstream from my backflow preventer/vacuum breaker I have a shutoff valve and then downstream from that is a T with a valve that leads to an air line quick connect. I have used this system successfully for 7 or 8 years.

ScaldedDog
11-08-2009, 04:32 PM
try connecting to the bottom inlet, not the top one. Mine did the same thing until I hooked it up to the bottom. Also you can use the little screw to turn the air off & on while it gets back up to pressure between zones.

Thanks man, that did the trick. I set the regulator at 90psi, since I had a 100' of hose, and some really long runs. I can't imagine doing mine with a pancake compressor. As it is my 5hp/80g one ran 'till it was blazing hot. There was still a lot of water in some of the lines.

I still don't know how to drain the up (supply) pipe that goes into the backflow preventer, though. It's plumbed off the house supply before the latter enters the house, so there's no drain on it.

Mark

nakman
11-08-2009, 04:39 PM
I still don't know how to drain the up (supply) pipe that goes into the backflow preventer, though. It's plumbed off the house supply before the latter enters the house, so there's no drain on it.

Mark

Is there not a little drain thing on the valve that shuts it off? You can turn it with your fingers- that's all I have..

Uncle Ben
11-08-2009, 05:04 PM
Is there not a little drain thing on the valve that shuts it off? You can turn it with your fingers- that's all I have..

Should be a bleeder on the shut off valve in the house.

ScaldedDog
11-08-2009, 08:35 PM
Should be a bleeder on the shut off valve in the house.

That's the thing: The shut off valve for the sprinkler system isn't in the house, it's in the yard. The copper pipe between the valve and the backflow preventer, including the 2' sticking up out of the ground, is full of water.

Mark

nakman
11-08-2009, 08:54 PM
So no way to drain it inside? man that doesn't sound right... this isn't a new house, right? what did you do last year? Can you access the pipe at all inside?

Worst case it would be worth it to sweat in a nice ball valve that drains, IMO.. much better than leaving a pipe full of water outside all winter.

Inukshuk
11-08-2009, 10:21 PM
That's the thing: The shut off valve for the sprinkler system isn't in the house, it's in the yard. The copper pipe between the valve and the backflow preventer, including the 2' sticking up out of the ground, is full of water.

Mark

Mine has an underground valve (like for a water main) that I turn off with a 6' T pipe with a slot at the end. Any round access caps nearby? Can you follow the pipe into the house. That pipe sticking up will freeze if full.

ScaldedDog
11-09-2009, 09:55 AM
Mine has an underground valve (like for a water main) that I turn off with a 6' T pipe with a slot at the end. Any round access caps nearby? Can you follow the pipe into the house. That pipe sticking up will freeze if full.

Yep, mine's exactly the same, and I shut it off back in October. I don't see a drain between that underground valve and the backflow preventer, though.

The house is 30 years old, but the sprinkler system was redone when the landscaping was back in 2005. We bought the place in 2008, but had a bunch of construction going on last year, and the sprinkler system was largely torn up, though this part of it was untouched.

Mark

Inukshuk
11-10-2009, 08:46 AM
Yep, mine's exactly the same, and I shut it off back in October. I don't see a drain between that underground valve and the backflow preventer, though.

That part should self drain out the bottom. Can you hear any water flow out there when you turn the valve? Turn slowly. Can you shine a light down there?