Sizing CPVC or PEX Galvinized Replacement

[WTunick]

Tried to read up as much as I could on this site about my question (and have learned a lot), but have a particular set of circumstances and thought I might post them to see if anyone had any advice.

My question is basically what size pipe should I use in replacing galvanized water lines in our house.

By way of background, the house was built in the 50's, only two bathrooms over a crawl space. Moved in two years ago and upgraded the services from the meter to 1" copper (have about 70 psi coming in from the street). Also one of the bathrooms is already plumbed in copper (3/4" line with 1/2" to all the fixtures). We are currently remodeling the other bathroom and since it is back-to-back with the kitchen, thought it would be a good time to replace the old pipes. I am relatively handy and have soldered copper before, but the idea of soldering copper under the house did not appeal to me so decided that I would use either CPVC or PEX in the crawl space and use copper where the supply enters the house and in the walls. In any event decided to go with CPVC since I had never worked with PEX and did the replacement last weekend.

Now I have 1" copper from the meter to 1" CPVC which splits to into two 3/4" CPVC lines. One goes to the hot water heater, transitioning to 3/4" copper on the way, and the other goes on to feed the rest of the house. The hot water comes out of the water heater as 3/4" copper and then transitions to 3/4" CPVC to feed the rest of the house. Each fixture is fed by a 1/2" CPVC line coming off the 3/4" feeds.

Now that I have all the CPVC in place, it seems that the flow throughout the house (both hot and cold) is less than it was before I replaced the galvanized pipes (which were 3/4" for the most part and only partially corroded). Got me thinking that I should have paid more attention to the I.D. of CPVC and maybe upsized all of the CPVC to 1" with 3/4" feeding the fixtures or gone with PEX and done the same thing.

Anyway, my question at this point is would I see a noticeable difference in flow if I changed out all the 3/4" and 1/2" CPVC for 1" and 3/4" CPVC or PEX, so that the system would be entirely 1" or 3/4" Copper and CPVC/PEX. It isn't that much work or money to make the change, but if it isn't going to make much of a difference I won't bother.

Figured there is so much experience on these forums that someone might have a little insight.

Thanks,
William

 

[Cacher_Chick]

Some fixtures, like a lavatory or toilet would not be notably effected by the undersized lines, but at a tub or hose spigot, it would be very noticeable.

 

[Sponsor]

 

[WTunick]

Thanks cacher_chick, that makes sense. As a matter of fact the one place I think I have noticed a change has been the flow in the shower. Guess the question is, is 3/4" & 1/2" CPVC really undersized and if so will moving to 1" and 3/4" PEX or CPVC make a real difference.

 

[Jadnashua]

Unless you have an old, non-conforming showerhead, 1/2" pex should supply more water than it can use, so the pressure shouldn't be degraded. A 1/2" pex or cpvc line shold be able to flow around 5-6 gpm, and a showerhead (new ones anyway) are spec'ed to be 2.5gpm max. So, same idea as putting your finger over the end of a hose...as long as there's more water pressure available than the volume needed or allowed to go through, it shouldn't make a difference. But, if other things are running at the same time, then the overall system's ability to provide the required flow may be degraded. In reality, what you have should be better than with the old galvanized.

 

[hj]

Increasing the pipe sizes would only help IF the low pressure/volume is being caused by the i.d. of the CPVC, and not some other factor which we do not know about.

 

[WTunick]

Thanks hj, that makes sense although not sure what other factors could be causing it. I don't think there are any more/less L's and T's between the supply and the shower than there were previously. The only other thing I can think of is that there is still debris in some of the valves from when I replaced the pipes which is causing the reduced flow, although I have flushed them a few times. Any other factors I should be looking for?

I guess an better/more straightforward question would be, assuming all else is equal, when replacing a system comprised of 3/4" and 1/4" galvanized should I be using 3/4" and 1/2" CPVC/PEX or 1" and 3/4" CPVC/PEX.