Domestic Water

Jackchips

should be sized for static and residual pressure, velocity (fps-feet per second) and pressure loss. Pipe sizing can not increase pressure, it can though decrease pressure loss. Whatever the pressure is from the source can only be decreased by a PRV if to high, or increased by mechanical means-a booster pump.

If you are experiencing pressure loss this can be minimized by increasing the size of the piping from the meter or well expansion tank. You can check with the local supplier to find out what the static and residual pressure is in the line that you are connected to. If the residual (flowing) is fairly high (above 50 psi) you should have plenty of pressure in the house and increasing the piping will help.

You could put a pressure gauge on one of your outside sillcocks, with nothing flowing, to check the pressure in your house. Then open a few fixtures and check to see how much the pressure drops. If the initial pressure is close to what the supplier tells you and you notice a large drop you could have a problem with the line from the street into the house (obstruction or kink).

Good luck

Jamie Pompetti

The domestic water line coming into my home is 3/4" L copper which has been reduced to 1/2". I was wondering, if I where to increase all the mains into the house would that increase the amount of "usable" water I have? Would it reduce the loss of water when someone is in the shower and you run a fucet or flush a toilet? Or is it really not worth doing.

Floyd

Yup,Yup, and NO

Yes!!! change the trunk lines and especially to the HWH. It will definetly make a big difference
in your water pressure! Also check to make sure that the lines ARE L copper, I find a lot of domestic
lines that are M copper. Seems the OLD people did about anything to save 2 cents!!!!

Floyd

Frank_3

If you're willing to change out the piping, then I'd suggest you take 3/4" L from where the service enters the house and run it throughout the house, as needed. Take individual 1/2" L feeders off of that cold water main to the kitchen sink, bathtub, bathroom sink, toilets, etcetera.

If you have outdoor spigots then make each of them a 1/2" L feeder from the 3/4" L main as well. However, if you're running an inground sprinkler system and/or have a seperately piped feeder for a swimming pool keep them at 3/4".

At the hot water heater, take another 3/4" L main from the hot water supply and run it through the house. Again, take individual 1/2" L feeders from that pipe to each fixture.

Just my opinion.

Jim_7

Rule of ten.

Back when I started in this trade, I was told to follow the rule of ten. Each fixture was never to have more than ten feet of half inch pipe supplying that fixture. If it was a sink, that meant two five foot half inch lengths. Five feet of cold supply and five feet of hot supply. A toilet fixture could have one ten foot length of L copper. Fittings were not entered into the equivalent length. The rule of ten not being exceeded in pipe length eliminated the pressure loss complaints common in todays's buildings. Pressure losses,ungh, another reason why I detest plastic supply piping. Holding to this rule prevented the lazy installers who wouldn't or couldn't ream pipe and who over soldered their joints from causing us callbacks.

Rob Garcha

Water Piping

Why, not change it out with Aqua-Pex, you will get much beter flow rates through the Pex than you will with copper and because it is flexable it will make retro-fitting much easeier.

What do you think.
Rob

hr

These days

with the low flow faucets and flow restricted tub/ shower valves on the market, smaller line sizes work ok. An exception would be a roman tub filler valve or hose bibs.

If it were me I would look at one of the pex manifold systems. Every fixture gets it own supply 3/8 or 1/2" generally. Pressure drop and pressure imbalance scald issues disappear, quick hot water to distant fixtures is handled, no more DHW recirc problems.

Individual shut off in the mechanical room is very handy feature, especialy for tub or shower valve repairs. It allows you to shut off just the fixture you need to work on. Flux, solder and noise issues disappear. Easily retrofitted, much more resistant to unusual water quality conditions (pin holes, electrolis, etc) Freeze tolerant.

Just be sure to drive a copper ground rod for your electrical service

hot rod

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Stef Davis

Jim,
You just made a brief allusion to plastic pipe. I assume you meant PVC, not Pex?
Is there any reason not to use home runs with PEX, insulated of course, instead of copper? Seems like that skirts the issue of pressure drops and facilitates running water line over long and circuitous routes?
stef

chuck shaw

Local codes

Rob,

that might depend on local codes, in Massachusetts the code revision that would allow pex, has still not passed. You may want to know where someone is, before you tell them to use something they cant. To the best of my knowlege, copper is universally accecpted.

Chuck Shaw

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Jamie Pompetti

Thanks for all the replies today guys! I really appreciated it. Since I was board first thing this morning I ripped out all those 1/2" mains and repiped them 3/4". Not to mention I hooked up to my new Instantaneous Hot Water Heater. Only took about 4 hours and 50' something foot of pipe.

Tony_4

Whats wrong with type m

I dont understand your reasoning for condeming type M.
The burst pressure seems to be ample, much better than some plastics.
It may be thinner and will leak from acidic water faster but this is a water problem and it would leak no faster than L would compared to k. Am I missing something?

Floyd_2

basically no, but yes you are

and you did anwser your own question.....
L copper IS heavier so therefore if you have marginal water quality or have velocity issues, or turbulence inside the piping... yes it will last longer simply because there is more meat there to wear on......
Heating situations do not require the extra thicknes because of the static nature of the water after being nuetralized rather quickly in a heating system. Therefore type M copper is fine for that......
Type M can be used for domestic water with no problem pressure wise, but you are going to be limited as far as the expected life of the piping.....

Hope this hasn't totally confused the issue here!

Mike T., Swampeast MO

Simple thing that works

Mike T., Swampeast MO

Simple thing that works well

Pressure balance the cold line. Make a little square or octagon loop in a central location at the END of the cold water main. Do this before any takeoffs except possibly hose bibs.

Size these (at a minimum) from the loop: DHW supply; toilets; laundry; rest of house. Each of these should supply ONLY what is mentioned.

By looping the cold water supply back to itself you create a region where the pressure IS IDENTICAL TO EACH BRANCH SUPPLIED--regardless of flow rate in each branch.

Impossible for toilets/washing machine to scald you in this circumstance!

You can take this as far as you like and the common connection location makes a GREAT place to put your branch service/drain valves.

If you don't believe this simple thing works try it and you'll likely be amazed. With a touch of planning, it doesn't take much extra pipe.

I'm certain it won't negate the requirement for those cursed pressure-balance shower valves, but it's nearly as effective and WON'T break down. (Thermostatic shower valves are another matter altogether.)

This principle is used all the time--fire protection systems, irrigation systems, human "car wash" showers are good examples.

Tony_4

So it would be safe to asume

Based on the premise of thicker being better...type K would be better than L.

larry mintz

changing the mains to 3/4" will increase your volume the pressure stays the same. maybe the mineal content of the water in your area needs to be considered for "M" or "L". for domesic mains i use m, for recirculating lines, i use l

Roger Litman

L versus M

In some states, L copper is the code and the cost is not much more than M especially when you consider the labor cost, this is for domestic water especially the hot water side.A loop system will work well and you should consider an instant draw hot water system. If you have a large(two person) tub, it shoud be done with high flow faucets and be fed with a 3/4 line

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Frank_3

Because of its thinner walls, Type M is, in my opinion, more easily damaged during handling and installation.

I took apart the baseboard heating in my house and found all sorts of bends and kinks in the supply piping that appear to have been made while it was being installed through the floor joists. Not a pretty sight, nor was it good for the heating system as the kinks bring a restriction to flow with them.

Dave (Canada)

Type \"L\" verses type \"M\"

I recently installed a hydronic system in my home
and I used PEX and type M 3/4 copper for the baseboard runs.
While working with my SlantFin/30 rads I became aware very eary during the install that the 3/4 copper they supplied was not type M, it was very twistable when tightening up my unions connecting the Type M and their copper, upon observing the end cuts it was considerably thinner.
Just my observation guys.
Great site to exchange thoughts
Dave

Eric Taylor

baseboard

I did the same thing. While planning the job I toyed with the idea of using L with the baseboard "just to make sure", but once I looked at how thin the fin tube pipe was it just made no sense. A chain is only as strong as the weakest link. Considering the pressure in a static system, type M still gives a very good safety factor, and a closed system should not corrode as fast as an open system.

Domestic water on the other hand......My 3/4 M main was only 35 years old and when I replaced it I could break the old pipe with my bare hands. It didn't flex, kink, or bend. It just broke with no effort at all. I'm glad I was able to diffuse that time bomb before it went off.

Jackchips

Having attended

a seminar with CDA a few years ago, we were assured type-M copper could and should last many years in a domestic water application (although it is not allowed in Mass. per code).

The major reason M does not last, even L in many installations, is velocity. Piping should be designed to keep cold water movement under 6 feet per second and hot water under 4 fps. This is true in ALL buildings. There is no "old timers" formula for sizing water systems for residences. They should be sized based on demand, velocity and pressure.

This doesn't mean that all homes are sized improperly or that what many of us did based on training is wrong. It's just to clarify that piping wears out for a reason. We could install DWV tubing at minimum velocity and it would out live K at extreme velocity.

Roger Litman

Velocity of water

There is no argument that velocity coupled with heat and constantly changing water will erode piping. But the fact is that most homes and most commercial buildings are built for a cost budget and the piping is the smallest that they can get away with. I recently worked on a building where 12 apartment units were being fed hot water with 1/2 inch tubing and yes it isn't right, but I had to live with what is existing. So to give a little more life to the system using L is necessary.

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