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View Full Version : 1/2 vs 3/4 outdoor frost free sillcock



mjm
06-17-2011, 11:03 AM
Hi,
Have a question I'm hoping to get some enlightenment on.

I currently have a 3/4 line going to my outside faucet, that needs replacing due to the fact that the cartridge in the shutoff valve going to it inside, is pretty much disentegrated, and the valve outside split over the winter.

So the supply line is 3/4 and it goes into a 3/4 valve outside that then branches into 2 other lines(valves). 1 for an everyday 1/2 garden hose, but the other line feeds a 3/4 underground sprinkler system. The sprinkler system is not big, 3 legs with about 3 - 4 sprinkler heads on each. All of the line outside is soldered copper, except for the black tubing that feeds into the underground sprinkler manifold.

So I want to replace with a frost free unit. 3/4 are just not all that available and I finally found one at a plumbing supply place, but I am starting to wonder about the whole setup. I don't think there is really going to be that much difference in water flow compared to a 1/2, by looking at the inside of this. I can also buy a fairly good 1/2 one anywhere, where as this 3/4 one did not come with the pressure valve on top or the plastic gasket to mount it on an angle, so I'm kind of wondering about reliability and then replacing it up the road.

So wondering if any comments on whether I should stick with the 3/4" setup or change everything to 1/2"

Thanks

cwhyu2
06-17-2011, 11:18 AM
My first question is do you have a backflow device on the line to the sprinkler?
I do not think you would notice the volume change that much if you went to 1/2".

LLigetfa
06-17-2011, 11:28 AM
Most frost-free units are only frost-free if there is nothing attached to the end of them so that they can drain. If you mount a shutoff on the interior and properly drain the exterior portion, it too is frost-free. You can also buy insulated protectors to slip over them.

mjm
06-17-2011, 12:10 PM
My first question is do you have a backflow device on the line to the sprinkler?
I do not think you would notice the volume change that much if you went to 1/2".

backflow device, I am not familiar with, so I guess the answer is no.


Most frost-free units are only frost-free if there is nothing attached to the end of them so that they can drain. If you mount a shutoff on the interior and properly drain the exterior portion, it too is frost-free. You can also buy insulated protectors to slip over them.

I think what you'e saying is I could just stick with what I have and it would accomplish the same thing as the frost free. that's right, but I have to replace the shutoff inside and the main sillcock outside, so I might as well put in a frost free anyways, since it has to be replaced. Just wondering about the 1/2 vs 3/4

cwhyu2
06-17-2011, 12:35 PM
A backflow device prevents contaminated water from being siphoned back into your potable water.Like a sprinkler,if you turn off your main and drain the system you have the possability pull contaminated water it to the water you drink,cook and bath in.
Google back flow preventers it will tell you more.

mjm
06-17-2011, 01:10 PM
wouldn't just shutting off the tap outside prevent backflow from the sprinkler system or garden hose. I can't see doing any work that would create a backflow situation while the valve going to either would be open.

cwhyu2
06-17-2011, 01:56 PM
Yes that is true.It just that it is required on hose faucets here and is to protect you and your family.Just in case.
But should be ok going to 1/2"

jadnashua
06-17-2011, 02:52 PM
Backflow can happen if there is a hiccup in the supply pressure where the hose that is sitting in a puddle then sucks up insecticide, fertillizer, dog poop, etc...they are REQUIRED, not optional, as they protect not only your house, but the whole supply network.

The internal port may not be that much different, but assuming they are proportional, a 3/4" pipe can flow about twice the volume of a 1/2" pipe. Since you want good flow for your sprinklers, I think you should stay with a 3/4" valve.

There are a few companies that make a frost-free silcock that drains (and maintains the frost free aspect) even if you leave a hose on. Check out www.woodfordmfg.com (http://www.woodfordmfg.com).

mjm
06-17-2011, 03:24 PM
Have to admit I am not too familiar with the backflow situation, but it is obviously a subject or we wouldn't be talking about it. I will have to look a bit closer, google shows it in industrial situations but not so much residential.

3/4 ff sillcocks are hard to find here.

cwhyu2
06-17-2011, 03:30 PM
This will work just fine.

dlarrivee
06-17-2011, 04:56 PM
Most frost-free units are only frost-free if there is nothing attached to the end of them so that they can drain. If you mount a shutoff on the interior and properly drain the exterior portion, it too is frost-free. You can also buy insulated protectors to slip over them.

Explain how the insulated cover would do any good?

LLigetfa
06-17-2011, 05:32 PM
Explain how the insulated cover would do any good?First, it forces you to remove the hose so that the bib can drain. It also has a foam gasket to reduce air infiltration. Lastly, it is insulated so it keeps a small amount of heat in.

Gary Swart
06-17-2011, 05:44 PM
A note to MJM. The picture of the valve cwhyu2 post is an excellent example of a back flow device on a sillcock. You can quickly identify them by the cap on the top. That's the backflow part. As you know, the frost free part is on the inside end of the fitting. But, always remember the frost free is defeated if you leave a hose connected in freezing weather. I learned this the hard way several years ago.

dlarrivee
06-17-2011, 06:41 PM
First, it forces you to remove the hose so that the bib can drain. It also has a foam gasket to reduce air infiltration. Lastly, it is insulated so it keeps a small amount of heat in.

Where does the heat come from?

mjm
06-18-2011, 06:50 AM
I found this which explained it all to me.

http://www.structuretech1.com/blog/category/vacuum-breaker/

I thought the "vaccum breaker" on the top of the sillcock was a pressure relief thing and in conversation with someone they even referred to theirs as the same. Pretty sure the guy at HD even said the same when I asked. I don't think this is a very common topic here in Canada.
So, having seen the pictures in this article, definitely the 3/4 one I bought has no vacuum breaker built in.
So that leaves me with 3 choices.
Go pretty much anywhere and pick up a decent 1/2 " one.
Keep searching for a 3/4 " one, which is proving, pretty tough.
Install the 3/4 " one I got and replace it when I can finally find a decent one, or order one I guess.

cwhyu2
06-18-2011, 07:10 AM
If you install the one you have,you can put a vacuum breaker on it.
You can get them at a plumbing supply and mabey a big box store.
Or from the web site you posted.
It attaches right on the hose connector.

http://www.terrylove.com/images/arrowhead_breaker.jpg

http://www.terrylove.com/images/arrowhead_breaker2.jpg

hj
06-18-2011, 07:50 AM
The only difference between a 1/2" and a 3/4" one is the pipe thread and some come with a 1/2" female-3/4" male thread so they can go either way. The only thing that MIGHT affect the flow is the size AND length of the pipe feeding it.

LLigetfa
06-18-2011, 08:08 AM
I think it is a bit of a misnomer to call them backflow preventers. They are an anti-siphoning device, not a checkvalve. Picture a couple hundred feet of garden hose that has a bit of stretch to it. It acts much like an expansion tank would to store water and this water can flow in either direction as the pressure varies. Most garden hoses are not approved for potable water and the water stored in the hose at the highest pressure will reverse flow back into the house when the pressure drops.

mjm
06-18-2011, 09:20 AM
The only difference between a 1/2" and a 3/4" one is the pipe thread and some come with a 1/2" female-3/4" male thread so they can go either way. The only thing that MIGHT affect the flow is the size AND length of the pipe feeding it.

I was just looking at mine more closely and that is exactly what it is 3/4" male x 1/2" female. I am starting to think that as far as frost free sillcocks are concerned I am looking at 1/2" if that is what I want. Or I forget about FF and go with my own soldered setup and get the 3/4. The size of the existiing pipe is 3/4 and it is about 15'. I'm not sure anymore this hassle of trying to accomplish staying with 3/4 is worth it. I may go with downsizing the feed to 1/2 for a couple of feet before the FF unit goes in.

Once again, my intentions of just heading to HD and buying an off the shelf product, a 3/4 x 3/4 x 1/2 T and some fittings has turned into calling a bunch of plumbing supply stores and scouring the internets and not getting it done in a timely fashion

mjm
06-18-2011, 09:22 AM
I think it is a bit of a misnomer to call them backflow preventers. They are an anti-siphoning device, not a checkvalve. Picture a couple hundred feet of garden hose that has a bit of stretch to it. It acts much like an expansion tank would to store water and this water can flow in either direction as the pressure varies. Most garden hoses are not approved for potable water and the water stored in the hose at the highest pressure will reverse flow back into the house when the pressure drops.

I still don't see this being an easy thing to have happen when the outdoor valve would be closed unless it is being used. But like I said it is obviously a concern or there wouldn't be any backflow/anti vacuum devices in stores. I just don't think the odds of it happening are high.

Not that I don't believe you, I'm just having a hard time wrapping my head around it.

jadnashua
06-18-2011, 11:45 AM
You at the minimum want a vacuum breaker, either built-in, or add-on. In many places, a backflow preventer is required, and in many places, it must also be tested by a certified tech as often as annually to ensure it is protecting the water supply. Yes, it takes a special set of circumstances to happen, but you can contaminate your home's water supply. One possible scenario is if there's a fire nearby and they are using all of the fire hydrants to maximum flow while your sprinklers are on. You could suck up stuff into the supply lines. It could be something that you do, but more often something that happens in the system. A certified backflow preventer is moderately expensive, but the price many people pay to protect their and their neighbors' water supply.

jadnashua
06-18-2011, 12:17 PM
13333The Woodford Model 27 has both a vacuum breaker and a ASSE 1052 backflow preventer built-in.
http://www.woodfordmfg.com/woodford/Wall_Faucet_Pages/Model-27.html

dlarrivee
06-18-2011, 03:11 PM
Pretty sure the guy at HD even said the same when I asked. I don't think this is a very common topic here in Canada.


So because the guy at HD didn't know what he was talking about, all of Canada doesn't have a clue?

No wonder the Americans think we live in igloos.

mjm
06-18-2011, 05:22 PM
So because the guy at HD didn't know what he was talking about, all of Canada doesn't have a clue?

No wonder the Americans think we live in igloos.

whoa whoa whoa, that's not what I was insinuating. I'm just saying after searching and talking to about 4 or 5 people about these units, this is the first I heard of backflow concerns. Had I talked to a real plumber first they may have set me straight right from the get go. Or maybe they all assumed I already knew about it. and I do live in an igloo, something wrong with that?

jadnashua
06-18-2011, 05:30 PM
Codes differ not only from town to town, but especially from one country to another. Canada's plumbing regs are similar to those in the USA, but by no means identical. Here, most places require a backflow preventer precisely because there have been situations where installations without one has gotten people sick. With that in mind, since there is a valve available with that built-in, and not too expensive...personally, I think it's worth looking into. Not sure if Woodford stuff is readily available there, but they do sell direct on their website - if, they'll deliver to Canada, I don't know. I did see some vendors that also sell them at less than suggested retail and they're also on Amazon.com.

hj
06-18-2011, 05:42 PM
IT IS definitely a "back flow preventer" as well as an anti siphon device. The disc that prevents it from leaking is held in place by the incoming pressure. IF that pressure disappears, which it would have to in order to all siphoning OR backflow, the disc seals the "inlet" port and opens the vents around the perimeter. This either interupts a siphoning condition INTO the house, (but, not through the antisiphon device if the siphonng source is above the hose bibb), or prevents back flow.

jadnashua
06-18-2011, 05:55 PM
Woodford Model 27 has an approved double-checkvalve as opposed to a conventional vacuum breaker which is why I mentioned that one. It was specifically designed for applications like where you use the hose bib to feed a sprinker system and meet US codes for that application (at least what I read in their specs).

mjm
06-18-2011, 08:08 PM
IT IS definitely a "back flow preventer" as well as an anti siphon device.

Is this the knob on top, we are talking about here?

btw, I am not questioning this whole thing because I do not want to do it. I'm all for doing things right and above code. This is why I am asking so many questions. I do plan on having the backflow protection one way or another, but I want to know what I am talking about for my next trip to a plumbing supply place.

re: amazon I did check there and may have found what I am looking for.
http://www.amazon.com/Industries-104-619HC-Anti-Siphon-Sillcocks/dp/B000H8U4F6/ref=cm_cr_pr_product_top

It's twice the price to ship to canada, but driving around lookiing for one adds up with the price of gas too.

1 question is 3/4 MIP x 1/2 FIP wouldn't that allow the same amount of water through regardless of 3/4 or 1/2 line going into it. Doesn't this unit just put the 3/4 down to a 1/2 flowing through?

Gary Swart
06-18-2011, 08:32 PM
There seems to be some confusion between the terms "anti-siphon" and "back flow preventer". Gentlemen, the function of this feature to to prevent siphoning. Now certainly, the back flow preventer on an underground sprinkler system is more complex than what is use on a hose bib, but the end result is the same. You don't have to believe me, just go to a hardware or plumbing shop and look at one and read the label on the package. If you ask the clerk for an anti siphon frost free hose bib, or a hose bib that is frost free and has a back flow preventer, you will be directed to exactly the same thing. End of story.

jadnashua
06-19-2011, 01:45 PM
There seems to be some confusion between the terms "anti-siphon" and "back flow preventer". Gentlemen, the function of this feature to to prevent siphoning. Now certainly, the back flow preventer on an underground sprinkler system is more complex than what is use on a hose bib, but the end result is the same. You don't have to believe me, just go to a hardware or plumbing shop and look at one and read the label on the package. If you ask the clerk for an anti siphon frost free hose bib, or a hose bib that is frost free and has a back flow preventer, you will be directed to exactly the same thing. End of story.
You may be directed to the same place, but in fact, they are NOT the same. It is the level of the protection that they provide that differs. The Mansfield product I pointed to comes in many forms. Only one of their models (I think, at least in the residential line) has a dual-check valve that is certified for use on a sprinkler system. All of the others have vacuum breakers. Both provide some backflow prevention, but only the dual check valve version is approved for use with a sprinkler system. A nice feature of the Mansfield products is that they also have internal features that will prevent frost damage even if you DO leave a hose connected during freezing temperatures. On some, with just a vacuum breaker, they'll drain when you shut the valve off. On the others, there's an internal check valve that opens if the pressure exceeds 300# - low enough to not damage the valve, but high enough to not regularly open except in that freezing sitution.

mjm
06-24-2011, 09:53 AM
So I just called a small plumbing company and talked to the guy there, and he said he should be able to get me a 3/4 no problem. Then I explained what I was doing and we talked about the backflow situation. He said what I need, to be up to code is a double check valve assembly.
I am going to show him pictures of what I am working with and he should be able to set me up with everything I need, hopefully.

jadnashua
06-24-2011, 04:29 PM
And, the one I pointed you to awhile ago is exactly that...it has a code compliant double checkvalve.

mjm
06-24-2011, 05:40 PM
And, the one I pointed you to awhile ago is exactly that...it has a code compliant double checkvalve.

Thanks, I thought that might've been a bit of overkill, but now that I know it is code, I guess it's what I need.

ballvalve
06-26-2011, 05:07 AM
You would be a lot safer in life without any hose 'protection'. .... by washing your bean sprouts and lettuce twice or having them irratiated at the packing plant.

All this backflow protection on residential hoses is just industry lobbying to give them a new and essentially useless new market.

You have 60 DEAD people in Germany from a bean sprout, but no one is going to start a bean sprout protection industry.

Much ado about nothing. Put in the hose bibs you grew up with as a kid.

Overkill? Yes, but way beyond. Misapplied and a result of overeducated and industry tainted government robots creating jobs for themselves and brass casters.

Check your seatbelts and air bags. Forget your garden hose.

Terry
06-26-2011, 08:15 AM
We installed a double check valve on a home in Medina, they were blowing out the irrigation system in the yard, and it was forcing the water back into the main and causing problems to the plumbing in the homes nearby. We're talking homes worth millions. They weren't liking it.

So we installed a double check valve on the incoming water. City required after the neigbors complained of the problems.
Being hooked to a city main does not make someone independent.
Maybe on a well, but not on a street with other homes.

Any irrigation system should be on some sort of back flow prevention.
It it's at the high point, you might get by with a vacuum breaker.
Lower then that and they may insist on a double check valve.

ballvalve
06-27-2011, 10:37 AM
Irrigation and city water with a chance to go backwards for special reasons make sense, but we all grew up without anything on our garden hoses except a valve and our mouths on a hot day.

And most of those were on city water.

Sort of lke the genius that drains a resevoir because some drunk peed in it. Even though a dead skunk is likely laying on the waters edge.

Terry
06-27-2011, 11:37 AM
When the city shuts off the mains, everything siphons backwards.
There have been cases when resturants have left a hose into god knows what, and during a water main repair, sucked whatever the hose was placed in and back into the main, to be respread to the neighbors. And people did get sick.

As long as nobody ever shuts off the main, then yes it would be safe. These measures are taken because leaks happen, shutoffs happen and sickness as a result of that happens. It's part of being joined at the hip.

One Winter when my younger brother was living in Preston, He was getting freeze breaks.
There was no shutoff on his home, so we turned off the entire city of Preston to fix his leaks. We did this for several days, finally getting smart, digging up the water service outside and adding a shutoff to his incoming copper line.

LLigetfa
06-27-2011, 04:07 PM
There was no shutoff on his home, so we turned off the entire city of Preston to fix his leaks.

These days some professional plumbers have liquid CO2 systems to deliberately freeze pipes to shut off the flow in order to effect a repair. I saw it done on Bob Villa.

http://www.dryicesource.com/dryice/fixpipes.php

Terry
06-27-2011, 04:38 PM
I don't know too many plumbers that have those.
I would use one once in a Blue Moon.

BobL43
06-27-2011, 06:58 PM
maybe conducted heat through the copper tubing that gets some warmth from the house interior, but you can't depend on that for sure to prevent freezing even with the insulated cover. Got to drain that baby.