Pressure Balancing Loop for an Entire Home

[jeff.sani]

I have implemented pressure balancing loops for shower jets before in bathroom renovations. It got me thinking about this principal for an entire home. If you have 3/4 mains that run the length of the house and all the fixtures are tapped off of these, wouldn't it be advantageous to have return loops at the ends of the mains to balance out the pressure to reduce pressure differences between fixtures at opposite ends of the mains? I did not find much googling around on this topic other than the application of this type of design for shower jets. Is this idea crazy?

 

[Twowaxhack]

Yes it works, I’ve done it before. It balances the flow more evenly between fixtures

 

[jeff.sani]

Cool, that was my initial thought. The basement is unfinished and we are going through a reno at the moment and I have been staring up at the mains for a while thinking about how we could make the setup better. We have the issue where someone is showering and it on one end of the house and then another person is using the sink in another bathroom and there is a noticeable pressure drop and I wanted to see if there was anything I could do to make it better. Appreciate the reply.

 

[wpns]

If you are just talking about pressure drop, then either upsize the 'mains' that run around the house, or run separate 3/4" runs to each (of the important) fixtures. This also assumes you have enough capacity in the city water main, and that it's large enough (and has a sufficiently capable pressure regulator where applicable) to supply all your large demands at once.

Not sure what a pressure balancing loop is in this context but if you are just running two pipes in parallel out to the last shower (for instance), then it'll have the same effect as upsizing the 'main'.

Engineering Pro Guides has a table for pressure drop versus pipe size that seems to say that 1" pipe has 1/3 the pressure drop of 3/4" pipe at 10GPM, for instance. [This is not as easy as electrical engineering!]. I thought there were tables of Equivalent Diameter but I just got into a long Google Rathole about the physics of water flow...

 

[wpns]

We have the issue where someone is showering and it on one end of the house and then another person is using the sink in another bathroom and there is a noticeable pressure drop

Is that 'someone on the same side of the house', or 'someone on the other side of the house'? If the former then upside the 'mains', if the latter then upsize the supply.

 

[Twowaxhack]

Making a loop will balance what flow he does have between the fixtures.

Sure, you could upsize the main but that’s a lot of expense compared to making a loop and balancing what water you do have.

It’s the same principle as a body spray loop in a custom shower.

 

[MicEd69]

Running a "house wide loop" will provide two paths for the water flow to the fixtures. The flow in each line of the "loop" will vary based on the flow rates through the various fittings and pipe lengths such that the friction drop in each path equalizes based on the flows going to the fixture(s). One would have to have the piping layout and perform calculations based on the various scenarios that could occur to see if upsizing the main to 1" would yield different fluctuations in flow than installing a pair of 3/4" pipes. If we are talking about copper lines, then upsizing the main to 1" would definitely be cheaper than running two 3/4" lines. And even upsizing to 1 1/4" copper pipe mains would likely be cheaper that two 3/4" lines if you have to hire a plumber to solder and hang the pipe, as the material costs would be less than a dollar per foot more and the plumber would only be working with a single pipe run.

 

[Twowaxhack]

Look up body spray balancing loop.

The principle is exactly the same on a larger scale.

It works…..

 

[Twowaxhack]

And even upsizing to 1 1/4" copper pipe mains would likely be cheaper that two 3/4" lines if you have to hire a plumber to solder and hang the pipe, as the material costs would be less than a dollar per foot more and the plumber would only be working with a single pipe run.

I’m all in…….where we buying it ?
I think I just paid $3 per ft for 3/4” copper type m at the Home Depot.

Type L 1.25” copper will run you around $8.40 a ft right now. Fittings are outrageous too.

 

[MicEd69]

Look up body spray balancing loop.

The principle is exactly the same on a larger scale.

It works…..

Yes, that's what I said.

 

[Twowaxhack]

Yes, that's what I said.

Oh, I thought you were contemplating on a major piping job to increase water main size to balance the flow. I guess I missed it.

Balancing flow versus increasing overall flow capacity are two different animals.

 

[MicEd69]

I’m all in…….where we buying it ?
I think I just paid $3 per ft for 3/4” copper type m at the Home Depot.

Type L 1.25” copper will run you around $8.40 a ft right now. Fittings are outrageous too.

Menards:

3/4" type M = $2.70/ft. Two lines = $5.40/ft.
1" type M = $4.84/ft.
1 1/4" type M = $6.48/ft.

I meant to say 1 1/4" was a little more than a dollar a foot not a little less than a dollar a foot.

Apparently, you misread my post. What I said the price for a single 1 1/4" main would be slightly more than the cost of a pair of 3/4" lines. However, that additional material cost would likely be offset should one require a plumber to install the system.

 

[Twowaxhack]

Menards:

3/4" type M = $2.70/ft. Two lines = $5.40/ft.
1" type M = $4.84/ft.
1 1/4" type M = $6.48/ft.

I meant to say 1 1/4" was a little more than a dollar a foot not a little less than a dollar a foot.

Apparently, you misread my post. What I said the price for a single 1 1/4" main would be slightly more than the cost of a pair of 3/4" lines. However, that additional material cost would likely be offset should one require a plumber to install the system.

You can’t use M for a water main.

1.25” fittings are way higher that 3/4. . Check for yourself.

A 1.25x 1.25x .5” tee will run you around $19. And that’s a solder type.

I’d hate to buy 1.25” press fittings and pipe just to balance my flow when I could just run a simple loop with 3/4”.

 

[MicEd69]

Oh, I thought you were contemplating on a major piping job to increase water main size to balance the flow. I guess I missed it.

Balancing flow versus increasing overall flow capacity are two different animals.

Maybe two different animals, but it would be like the difference between a quarter horse and a thoroughbred.

Two 3/4" lines will provide increased flow capacity. And a larger main will balance flow. As I said, it would require calculations to determine the size of the main that would equal the balanced flows that could be obtained with two 3/4" lines. It's all a balanced pressure drop calculation on how much flow is coming through each leg of the two 3/4" lines.

 

[Twowaxhack]

Some people do not like to see the volume drop when they’re using a fixture even though they still have plenty of water.

To combat this you can install large pipes

Or you can install a balancing loop.

For a typical 3/2 American home, I’ll pick the balancing loop every time.
Especially so in an existing house.

 

[MicEd69]

You can’t use M for a water main.

1.25” fittings are way higher that 3/4. . Check for yourself.

A 1.25x 1.25x .5” tee will run you around $19. And that’s a solder type.

I’d hate to buy 1.25” press fittings and pipe just to balance my flow when I could just run a simple loop with 3/4”.

Yep, the fittings will kill you. Home Depot has a 1 1/4" x 1 1/4" x 3/4" reducing tee for a cool $25!!!

When I said, "water main", i was only talking about the primary supply line running towards the water users in the house. Are you saying that cannot be type M, but if that line is only 3/4", and there are two of them, they can be type M?

 

[Twowaxhack]

Yep, the fittings will kill you. Home Depot has a 1 1/4" x 1 1/4" x 3/4" reducing tee for a cool $25!!!

When I said, "water main", i was only talking about the primary supply line running towards the water users in the house. Are you saying that cannot be type M, but if that line is only 3/4", and there are two of them, they can be type M?

Last I checked the minimum grade copper for new construction was type L.

It may have changed and as you know codes vary all over. I shouldn’t have made a blanket statement but it is a “ thing “ in a lot of places.

 

[jeff.sani]

So just to follow-up on this thread. Last night we implemented this: We ran 2 3/4" lines parallel to the existing H/C mains and looped them (just as you would with shower jets). The returns in the loops on each end were past the last fixture tap. I can tell you the end result was like night and day. The loops resulted in equalizing the pressure across all the fixtures as it seems to to lessen the back pressure generated from having another fixture open which then causes the flow rate to be reduced to the open fixtures. Showers are the main problem since they have higher flow rates so they are impacted more than other fixture types. Anyway, for anyone else with this problem, this solution definitely worked.

All in all it took about 3 hours to get it all implemented. Only needed to buy 2 x 75' rolls of R/B Pex-B, some elbow and tee fittings, and pinch clamps. Total cost < $100. BTW, for what it is worth, 3/4" is a lot easier to work with than 1" when you are dealing with overhead joist bays and have to thread the tubing through holes 14" apart. I realize each application is going to be different, but I would not have wanted to work with 1" tubing for mine. Many thanks to Twowaxhack for confirming it would work.

Jeff