I need to run hot water pipes to the various appliances in my home. Some
of the appliances (lavatories, and sinks) will use relatively small amounts
of water at a time but will be used frequently, while others (tubs &
showers) will be used less frequently but will use much more hot water at a
time.

I would like to minimize wasted energy and the time spent waiting for hot
water at sinks and lavatories while still providing sufficient flow. At
tubs & showers, having a good flow rate is more important and the wasted
energy & wait times do not matter so much because of the less frequent use
and large amount of water per use.

Running different size how water lines to the same room is no problem at
all. I realize that, occasionally this will result in having to fill two
pipes but in our situation this will seldom happen. A recirculating system
is not ennergy efficient so I don't want to go that way.

Given the above, what size pipes should I run to:
Sinks & Lavatories:
Tubs/Showers:
Dish washer:
Washing machine:
(Whirlpool tub: 3/4" since valve inlets are 3/4")

Many thanks for any help!

On Apr 3, 6:35 am, wrote:
I need to run hot water pipes to the various appliances in my home. Some
of the appliances (lavatories, and sinks) will use relatively small amounts
of water at a time but will be used frequently, while others (tubs &
showers) will be used less frequently but will use much more hot water at a
time.

I would like to minimize wasted energy and the time spent waiting for hot
water at sinks and lavatories while still providing sufficient flow. At
tubs & showers, having a good flow rate is more important and the wasted
energy & wait times do not matter so much because of the less frequent use
and large amount of water per use.

Running different size how water lines to the same room is no problem at
all. I realize that, occasionally this will result in having to fill two
pipes but in our situation this will seldom happen. A recirculating system
is not ennergy efficient so I don't want to go that way.

Given the above, what size pipes should I run to:
Sinks & Lavatories:
Tubs/Showers:
Dish washer:
Washing machine:
(Whirlpool tub: 3/4" since valve inlets are 3/4")

Many thanks for any help!

1/2" for all. At typical pressure, you can get 5-7 GPM from a 1/2"
pipe.

JK

I prefer 3/4 for house piping and 1 1/4 for a main line to the house and to
outside water valves (idea with large main is that you can water outside and
also get good flow inside).

I lived in house once which had all 3/4 pipes. It was great. Water flowed
fast everywhere. I have preferred this ever since.

Keep in mind that crud builds up on the inside of water pipes. So perhaps
with all the crud, the 3/4 pipe actually has 1/2 of remaining space whereas
the 1/2 pipe has maybe 1/4.

"Bill" wrote in message

Keep in mind that crud builds up on the inside of water pipes. So perhaps
with all the crud, the 3/4 pipe actually has 1/2 of remaining space
whereas the 1/2 pipe has maybe 1/4.

Where do you live? Over 30 years and my copper tubing is a clear as the day
it was installed. You do get buildup in galvanized pipes.

1-1/4 is unrealistic for a supply. It's just not done. IF you really did
it, you wasted money. The meter (at best) will only be 1". And it's
probably a 5/8". A one inch feeder line would be optimal, and 3/4 is most
common. (unless you're going over a hundred feet)


s


"Bill" wrote in message
...
I prefer 3/4 for house piping and 1 1/4 for a main line to the house and to
outside water valves (idea with large main is that you can water outside
and also get good flow inside).

I lived in house once which had all 3/4 pipes. It was great. Water flowed
fast everywhere. I have preferred this ever since.

Keep in mind that crud builds up on the inside of water pipes. So perhaps
with all the crud, the 3/4 pipe actually has 1/2 of remaining space
whereas the 1/2 pipe has maybe 1/4.

Bill wrote:

I prefer 3/4 for house piping and 1 1/4 for a main line to the house and to
outside water valves (idea with large main is that you can water outside and
also get good flow inside).

SMALLER pipes to outdoor valves would make more flow indoors.

Nick

On Apr 3, 5:10 pm, wrote:
Bill wrote:
I prefer 3/4 for house piping and 1 1/4 for a main line to the house and to
outside water valves (idea with large main is that you can water outside and
also get good flow inside).

SMALLER pipes to outdoor valves would make more flow indoors.

Not unless the outdoor valves were open when you went to use the
indoor plumbing. As in most things, it's better to plan ahead and use
a head, than forge ahead.

R

RicodJour wrote:

wrote:

Bill wrote:

I prefer 3/4 for house piping and 1 1/4 for a main line to the house and to
outside water valves (idea with large main is that you can water outside
and also get good flow inside).

SMALLER pipes to outdoor valves would make more flow indoors.

Not unless the outdoor valves were open...

Doh :-)

Nick

On Apr 3, 7:41�pm, (Nick Pine) wrote:
RicodJour wrote:
wrote:
Bill wrote:
I prefer 3/4 for house piping and 1 1/4 for a main line to the house and to
outside water valves (idea with large main is that you can water outside
and also get good flow inside).

SMALLER pipes to outdoor valves would make more flow indoors.

Not unless the outdoor valves were open...

Doh :-)

Nick

PEX is so cheap your better off running larger diameter......

Thanks to all who replied. I used 3/8" pipe home runs to all sink &
lavatory hot water valves. Water flow decrease was measurable, too small
to notice in normal use. Wait time for hot wated decreased sharply due to
shorter runs and the fact that a length of 3/8" pipe holds only 56% as much
water as the same length of 1/2" pipe.

I don't know if code approves of the 3/8" pipe, but I love it!

On Thu, 03 Apr 2008 07:35:34 -0400, wrote:

I need to run hot water pipes to the various appliances in my home. Some
of the appliances (lavatories, and sinks) will use relatively small amounts
of water at a time but will be used frequently, while others (tubs &
showers) will be used less frequently but will use much more hot water at a
time.

I would like to minimize wasted energy and the time spent waiting for hot
water at sinks and lavatories while still providing sufficient flow. At
tubs & showers, having a good flow rate is more important and the wasted
energy & wait times do not matter so much because of the less frequent use
and large amount of water per use.

Running different size how water lines to the same room is no problem at
all. I realize that, occasionally this will result in having to fill two
pipes but in our situation this will seldom happen. A recirculating system
is not ennergy efficient so I don't want to go that way.

Given the above, what size pipes should I run to:
Sinks & Lavatories:
Tubs/Showers:
Dish washer:
Washing machine:
(Whirlpool tub: 3/4" since valve inlets are 3/4")

Many thanks for any help!

After about two months in my new home, I re-installed new PEX hot water
pipes to all locations. I used 3/4" to the whirlpool tub, 3/8" all sinks
and lavatories, and 1/2" elsewhere. I measured flow rates before and after
and found no (or insignificant) decrease in maximum flow from the
sink/lavatory faucets but substantially reduced wait times for hot water in
every case. Since I made more home runs to the water heater, some wait
times were decreased because of shorter length of pipe. However, even
where the distance was the same, hot water arrives at the sinks lavatories
much faster than it did before because of the smaller volume of water in
the pipe.

I am not a plumber, but just from the physics of the flow I thought I would
be a good move and we are very happy with the result.