Sizing main water line for manifolds

[5030tinkerer]

I need help sizing a main line plumbing distribution system for my new home. I have the following:


Five bedroom
3.5 bath

Extras include a wet bar, laundry sink, and garage sink.

I want to avoid pressure and volume drops associated with toilet flushes, laundry running, etc. I am 800 feet from my water meter and have 60 psi at the house. The line from the meter to the house is 2 inch PVC.

The plumbing is all Wirsbo PEX with home runs to the 2 inch water service entry in the basement throughout, with the exception of the 2nd floor main and master baths, which are served from a hot and cold water manifold in the attic. These manifolds are served from 1 inch PEX lines from the basement.

Originally, I had the attached layout designed (you'll have to imagine copper lines going between the copper fittings and 2" Sch 40 PVC going between the PVC fittings). The four manifolds have 1" mains and are for filtered unsoftened drinking water, unsoftened cold water for outside spigots, softened cold water, and softened hot water.

I am concerned about the possibility of a PVC failure in the future, however, and am looking to migrate to another material (perhaps copper). The question is what size lines do I need? With 2" PVC main line distribution, I wasn't concerned about a sprinkler running outside, a load of laundry going, dishes being cleaned in the dishwasher, and two showers going all at once, but if I drop my 2" PVC line size down to copper of 1", 1.25", or 1.5", will I have a problem? Ideas appreciated.

 

[heehaw]

i bet there are several of us looking forward to an answer to this from someone that understands how to figure this stuff out!! as far as switching from pvc to copper, i've had more trouble with copper than i ever have pvc. i would never put copper in a house again. cost to much, slower to install, an with our water, it sometimes gets pin holes in it: never had that with pvc or cpvc. i hope someone solves this one for you..
heehaw

 

[EddieWalker]

I agree with HeeHaw about copper. I do allot of home repairs and remodels, and copper is always a problem. Most of the time is leaks to such a small degree that you never have an idea that it's leaking, then 20 or 40 years later, the bathtub falls through the floor or the tile starts to crack or ???? The most common place seems to be the tub faucets where they are sweated together, but I've seen leaks in all sorts of places. I work with copper all the time, consider myself pretty good with it and have never had a callback for a leak. That said, I would never run copper in anything I owned.

A rule of thumb when figure water supply is that for every half inch increase in pipe size, the increase in water flow/volume is 2 1/2 times. So a half inch line has so much water going through it, then a one inch line has two and a half times as much water.

Start at each faucet and work your way backwards. Half inch fitting for those and increase the size accordingly. Most homes work great off a 3/4 inch line with normal usage. A one inch line is more then enough water to supply an entire house. A 2 inch line is considered a county water main here, and is enough to supply a dozen homes.

Eddie

 

[gotrocks]

I'm not sure how far your baths are from HW heater, BUT I do know when we built I directed the plumber to use 3/4" throughout.
After occupied the house I found that was not a good idea.
The main bath is in front and HW in back of house.
It takes tooooo long for hot water to the lav when washing my face.
Smaller pipe would help but a better solution would have been what was done on my Dad's house.
This was all the way back in the 50's and the plumber ran a "loop" out of the top up through the attic back under the floor to the bottom of the HW tank. Insulated all pipe and the natural movement of hot water keeps hot water at the faucet all the time.
No pump required.

2nd edit for Eddie
I enjoy your posts but I think your list should have #10 moved to #1.
Happy New Year !

 

[5030tinkerer]

My hot water manifold in the attic is 120 line feet from the hot water manifold in the basement. I have a 1" PEX line between the basement manifold and the attic manifold that is presently sitting loose. While I had wanted to place a 2" section of PVC conduit between the basement and the attic for any low voltage runs I may had forgotten about, sheetrock guys were ready before I was and I was unable to get to this before the rock went up.

Plans now are to slide a 1/2" piece of pex into the 1" pex (using the 1" pex as a conduit) along with two runs of some low voltage wire that will be used to setup two motion sensors (one each in each of the second floor baths). The 1/2" pex will be teed into the main branch of the hot water manifold upstairs and tied into a hot water recirculator at the supply side of the hot water heater. I'm planning on using the Metlund pump here (Metlund D'MAND Recirculation Pump Systems by ACT - Metlund - HVACQuick.com.

This way, when someone walks into a bathroom upstairs, the pump in the basement will kick on and get hot water up to the attic manifold. The pump also has a check valve in it to prevent gravity from continuously allowing the water to flow and therefore have the hot water heater have to keep the water in the main supply line hot all the time. Hope it works!

As far as never using copper again, that *was* the thought, but I am concerned about the amount of torque that will be placed on the 2" PVC if I ever were to bypass my water softener - 2" quarter turn ball valves don't turn easily. While I plan on clamping the 2" ball valve down pretty tight against the plywood backer, if the PVC were to crack, I'd be stuck replacing all of it since my joints are so tight (no way to slide a coupler in there later).

I am also (and mostly) concerned about the 2" to 1" threaded PVC adapter connections. These connections will accept a 1" male copper adapter. If I get too crazy on the tightening of the copper adapter, the PVC will develop a hairline crack and leak. The trouble is that I won't have a way to tighten the copper adapter after everything is put together and have water in there (the only way to get the adapter to turn would be to re-sweat the connection, but the PVC couldn't take that amount of heat). So...I'll have to tighten the copper adapter just enough but not to much right off the bat. Teflon tape only does so much.

If a PVC connection were to catastrophically fail, it would be really, really bad 2 supply into the house would flood the basement in a hurry. Am I too concerned about this or would a move to copper ASAP as it comes into the house be a wiser move?

 

[EddieWalker]

As far as never using copper again, that *was* the thought, but I am concerned about the amount of torque that will be placed on the 2" PVC if I ever were to bypass my water softener - 2" quarter turn ball valves don't turn easily. While I plan on clamping the 2" ball valve down pretty tight against the plywood backer, if the PVC were to crack, I'd be stuck replacing all of it since my joints are so tight (no way to slide a coupler in there later).

If a PVC connection were to catastrophically fail, it would be really, really bad 2 supply into the house would flood the basement in a hurry. Am I too concerned about this or would a move to copper ASAP as it comes into the house be a wiser move?

Two things cought my attention here.

Never use PVC ball valves for anything important. The very best of them are junk. Brass ball valves are ok, but for anything bigger then 1 inch, not something I'd use. Use brass gate valves for all your bigger fittings. They have female theads that you put your male PVC fittings into before gluing the to your pipes. This way, you can get the fittings super tight!!!

Why are you bringing a 2 inch water line into the house? That's a rediculous amount of water and more then any household will ever come close to being able to use. The negative to having such an oversized pipe is stale water. You will be creating a storage tank with your pipe from water that will stay in there for months and years at a time.

If you run that large line, you will need a way to flush it out at least once a year. Maybe more, depending on your water. My home is the only use off of a 6 inch water main. There is a valve on that line that's flushed out about four times a year. They just turn it on and let the water out for about an hour.

Eddie

 

[5030tinkerer]

Hey Eddie -

I am not using PVC ball valves - I agree that they are junk. Check out my images in my prior post - copper with female threads, just as you suggested. The gate valve option is something that I'd considered as well since operating it would place zero torque on the line, but they take an awfully long time to close if you need to close them in a hurry for whatever reason. It's certainly something to seriously consider, though.

Re: using 2" line. I was concerned about the stale water (and really still am), but it's about a 50 foot rise over an 800 foot run to get up to my house and I didn't want to have pressure problems (the utility said that I might only have 50psi at the meter pit to begin with...). I've got 60psi at the house now with the 2 inch.

I can deal with the periodic flushout to have 60psi every day...had I been thinking I would have installed a 2 inch tee outside at the house to aid in the flushing. Oh well, we'll see how bad of a problem it turns out to be. If flushout from running a few outside spigotts concurrently with a long shower isn't effective, I can dig up the line and install one without too much trouble.

My biggest concern remains that one inch male copper adapter into the PVC flush bushing reducer. Any thoughts there?

 

[EddieWalker]

My biggest concern remains that one inch male copper adapter into the PVC flush bushing reducer. Any thoughts there?

I did notice the ball valves in your picture, but was more worried about the 2 inch line and how you were going to turn that off. Odds are that if it ever fails, a few seconds turning it off wont matter. You will have thousands of gallons of water to deal with and another couple hundred wont matter. A year or ten from now, when you want to do something on that 2 inch line, you will really appreciate a quality gate valve on the line.

I don't have any first hand experience with reducing down from 2 inch PVC to 1 inch copper. I would think that standard fittings would do the job easily enough.

At 60psi, you don't have allot of preasure, so that's not a big issue. If you were over 100psi, I'd be more concerned. If it's something that will keep you up at night, go to the plumbing supplier. The box stores only have the commmon stuff. The suppliers have all the specialty items, and the high end products. Tell them what you want and that you want it to be 1,000% solid, and they will have it.

Eddie

 

[heehaw]

i switched from brass gate valves to pvc ball valves several years ago, an haven't had any trouble with the ball valves, yet: i also used 2inch pvc ball valves on the plumbing for the wifes pool 4 years ago: they are a little tough to turn, but have worked flawlessly so far, note i said, so far. the brass gate valves were a joke, they started failing within a year of installation, usually wouldn't turn off or when off, the stem would strip from the gate so they wouldn't open...an these were suppose to be quality valves from a plumbing supply, not a warehouse store.
heehaw

 

[Kays Supply]

I will start off by saying I have been a plumber for 30 years. There are good gate valves BUT, if you don't get a red brass valve, you will have the problems described by a previous post. If you can find one it will cost more than the ball valve.Yellow brass will go bad in most water types in just a few years. One issue you will have to address is what size your water meter is. If it is a 3/4" meter like most water disticts use, you have wasted quite a bit on 2" line,and fittings. 3/4" @60psi will give you X gallons per minute, no matter what size line you run. Friction loss is all that is helped by size. Fristion loss is directly related to volume. You can't get enough volume at 60psi to get much help from a 2" line. Your best bet as far as your 2" to less size would be to reduce your 2" as soon as you can to 1" and adapt everything from that. All your fittings and valves would be much cheaper and easier to work with. Once you get down to 1" you can use a McDonald fitting to connect the PVC to any other type material you like. It is a friction fit red brass coupling that clamps the pipes so they can't be pushed out by water pressure. I have never had one fail. You can take or leave my advice. I am just passing on what I have learned.