Water pipe going up then down

[austin]

I have water pipes that leave the furnace room, pass horizontally through an unheated basement garage, then go up to the ground floor bathroom which is located above the garage. I would like to reroute them to go directly up to the ceiling of the ground floor (through the heated part of the house), across the ceiling, then drop back down to the ground floor bathroom. Is this a workable solution? What would it do to the water flow and pressure?

[HayZee518]

depends how many ninety degree fittings you have.

[austin]

Right, but all else being equal, is there a problem with having the pipe go down 8 feet to the faucet after a 16 foot rise?

[LazyPup]

For all intents and purposes the pressure could be said to be exactly the same.

Vertical static head loss is 0.434psi/ft vertical

From your description you would have a 16' vertical rise to the ceiling overhead, then an 8' drop from the ceiling back down to the faucet location. From this I conclude that the faucet is actually 8' higher than the source of water.

If you run the line horizontal from the source level then directly up to the faucet the vertical static head loss would be 8' x 0.434psi= 3.472psi less than the pressure at the source.

If you run the line up 16' the vertical static head loss is 16x 0.434 = 6.94psi to the overhead line, however when the water drops down from the overhead line there is a vertical static head gain of 0.434psi/ft x 8' =3.472psi therefore the additional rise is offset by the opposite drop, thus the pressure at the faucet remains the same either way.

To compute the additional friction loss we would need to know the size of the pipe and the rate of flow.

By example, 1/2" copper pipe is rated for a maximum flow rate of 3gpm and at 3gpm the friction loss is 0.062psi/ft.

The fitting insertion loss is expressed in the equivalent length of straight pipe that the loss represents. A 1/2" 90deg elbow has a fitting insertion loss of .5feet of pipe.

Obviously the horizontal distance from the source to the bathroom will remain the same whether you run the pipe under the floor or overhead so the only pipe we need to concern ourselves with here is the 8' vertical rise, the 8' vertical drop and a 90deg elbow on each end of the overhead horizontal line.

The total additional friction loss would then be (8' x 2)+(.5' x 2)=17'.
The increased friction loss from running overhead would then be 17'x 0.062psi = 1.054psi

From these figures you can easily see that there is no cause for concern if you run overhead,

[numberQ]

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