Ask Me Help Desk - Min. Distance between hot/cold plumbing and MORE.

I have a variety of plumbing questions, and hope someone in-the-know can help out. Here goes:

This house is 43 years old, with 3/4" galvanized plumbing. We're moving the washer, dryer and water heater from an area that was once a garage (but has become interior finished space) to another part of what was the old garage that was left as an enclosed 'storage area'.

1) I'm in King Co. (outside city limits) WA State. Is there a minimum distance that hot and cold water plumbing can be from each other as they come from the crawl space to the inside of the house? This will be 1/2" copper.

2) We will be going from 3/4" galvanized (the existing pipe) to 1/2" copper in a short run (maybe a couple of feet) in the crawl space, instead of staying with 3/4" (I think...we keep changing our mind). Is it against code to have 1/2 inch under the house?

3) I have read pros/cons about dielectric unions. There will be a brass gate valve between the galv. and copper. I had a plumber come out once and say that my water pressure was 75 psi (or whatever the measuring unit is), however I had very high water VOLUME. Is this of issue with the whole dielectric thing?

4) I'm moving my washer, dryer and water heater We have to come up through the concrete sill of the 'garage' and about 4" of wood. I thought about using malleable copper to go up through this mess once holes are somehow drilled through all of this with a gigantic drill. Is there any reason we should NOT do that? I thought it would be easier to work with in this one iffy location, rather than lots of elbowy-angly stuff going on with all the soldering and stuff. Thoughts on this?

5) Drain questions:
a) is 1/4" rise per foot of distance code? I have about 15" rise available over 20'. Is this good enough?
b) we have 2" cast iron right now as the drain exists the house. There's a short section of 2" galvanized connected to it right now. Can we just switch up and go to galvanized (is it cheaper)? Or is there a way to go to PVC for the new install (about 20')? Is one quieter or easy to insulate for sound? The pipe will run under the dining room and living room, near the family room. Easier to install? Going to last till I turn 80? Issues I'm not thinking about? Do you need a dielectric union between galvanized and cast iron or PVC?

I'm not sure, but I think I'm all questioned out. If I'm way off base :o or you have good ideas, please let me know! Thanks so much!
Wendy

Hey Wendy:

1) No.. no minimum distance to keep hot and cold water pipes.. just use common sense... don't let pipes touch is all. I usually maintain a 3 or 4 inch spread between pipes.. but only because I think it looks nice.

2) It is not against code to have 1/2" under the house...but if you are in a cold area (like me..Boston)...then running pipes under house may not work well (could freeze).

Also, why reducing to 1/2".. Now is the time to run 3/4" copper pipe to feed water heater so hot water coming out will be full size 3/4", too... gives greater volume to entire house when using fixtures.. It is not required to be 3/4"...just recommended if you have 3/4" galvanized.

3) Dielectric unions and VOLUME have absolutely nothing to do with each other. Check out this link on dielectric unions... I would recommend installing the dielectric union to transition between the disimilar metals, and then install a copper/sweat BALL VALVE (not a gate valve).

Plumbing System Components - The Dielectric Union

4) You can use SOFT COPPER TUBING to go through this... will work fine... or could also PRESOLDER fittings to pipe and just stub up and through the wood.

5a) 1/4" rise per foot of drain is correct... so 20 feet only requires 5 inches pitch overall.

5b) You definitely want to switch over from the galvanized pipe to PVC plastic pipe and fittings... PERIOD!! Be sure to use the PRIMER and cement to join pipe to fittings. You can make the transition from the galvanized pipe to the pvc pipe using a 2" mission or proflex shielded clamp or a 4 band 2" extra heavy clamp... see pictures below.

Dielectric unions are not common on household drains... and should not be needed here.

MY THOUGHTS:

You want to be sure the remaining galvanized is cleaned using long screwdriver to reach up inside and make sure all is perfectly clear (use flashlight to confirm)... then install the transition clamp, then install a DANDY CLEANOUT just after that (so can clean drain line easily if need to in the future)... see pic.#3 I would prefer to see the galvanized waste line removed completely, but probably not an option here.

Then you want to install cleanouts at every major change of direction in the drain line... and especially one at the end of the line at washing machine.

The washer will require a vent pipe to be installed and connected into other vent in the house or may need to penetrate the roof of the garage (or may be able to use a mechanical vent (AAV... air addmittance valve) in its place, but they are not allowed in some places).

Washer also requires a 2" ptrap and a standpipe that is say, 30" tall coming out of the p trap.

And then I have all kinds of other thoughts... but let's start with this info.

Let us know if need more... glad to help... Mark

If this helped please RATE THIS ANSWER. Thank you

.

Quote:

1) I'm in King Co. (outside city limits) WA State. Is there a minimum distance that hot and cold water plumbing can be from each other as they come from the crawl space to the inside of the house? This will be 1/2" copper.

Not that I know of. They should not be touching. Here we place out hot and cold at about 4" apart.

Quote:

2) We will be going from 3/4" galvanized (the existing pipe) to 1/2" copper in a short run (maybe a couple of feet) in the crawl space, instead of staying with 3/4" (I think... we keep changing our mind). Is it against code to have 1/2 inch under the house?

No, but it's not a good idea to reduce the size of the main. With older galvanized piping you need all the volume you can get.

Quote:

3) I have read pros/cons about dielectric unions. There will be a brass gate valve between the galv. And copper. I had a plumber come out once and say that my water pressure was 75 psi (or whatever the measuring unit is), however I had very high water VOLUME. Is this of issue with the whole dielectric thing?

No! Pressure has nothing to do with a dielectric union. Dielectric Unions are there to prevent electrolysis.
However, at 75 PSI you're putting the fittings and valves under a strain. The average house pressure's 45 PSI.

Quote:

4) I'm moving my washer, dryer and water heater We have to come up through the concrete sill of the 'garage' and about 4" of wood. I thought about using malleable copper to go up through this mess once holes are somehow drilled through all of this with a gigantic drill. Is there any reason we should NOT do that? I thought it would be easier to work with in this one iffy location, rather than lots of elbowy-angly stuff going on with all the soldering and stuff. Thoughts on this?

No, Soft copper is used all the time for water piping.

Quote:

5) Drain questions:
a) is 1/4" rise per foot of distance code? I have about 15" rise available over 20'. Is this good enough?
b) we have 2" cast iron right now as the drain exists the house. There's a short section of 2" galvanized connected to it right now. Can we just switch up and go to galvanized (is it cheaper)? Or is there a way to go to PVC for the new install (about 20')? Is one quieter or easy to insulate for sound? The pipe will run under the dining room and living room, near the family room. Easier to install? Going to last till I turn 80? Issues I'm not thinking about? Do you need a dielectric union between galvanized and cast iron or PVC?

a) Your fall should be 5 inches for a 20 ft. run. Maintain your fall until you get to the connection and then 45 down to it. Too much fall and the solids get left behind, too little fall and the solids will build up and clog.
b) Remove the galvanized and convert to PVC. Convert using a No-Hub Coupling,(see image) It will be easier to work with and last until you're 180.
I see Mark's posting at the same time as me. Between us you should get your answers. Good luck, Tom

Quote:

Originally Posted by AsthaB

3) I have read pros/cons about dielectric unions. There will be a brass gate valve between the galv. and copper. I had a plumber come out once and say that my water pressure was 75 psi (or whatever the measuring unit is), however I had very high water VOLUME. Is this of issue with the whole dielectric thing?

My only comment regarding the use of dielectric unions is to remind you to 'jumper' the two dissimilar metals with grounding straps to maintain the continuity of your homes electrical grounding system.

Comcast, Summit, Qwest, DishTV, alarm companies et al are notorious for installing small ground straps to water piping as a means of bonding their equipment -- After receiving a few late night phone calls regarding interrupted cable, phone, security alarm or internet service after a repipe, I've made it a policy to bridge any use of dielectric unions with ground straps and a short section of copper wire.

Hey Tom... could our answers here have been any more similar... ;)

And more good information from Iamgrowler! Did not think of that... very important!