In real world usage, what happens now when you are in the shower, and others are doing things like flushing a toilet, or filling a pot in the kitchen?
It's all OK when just one thing is running. I say OK but in reality I've never seen everything in this house run with a large, clean pipe so not sure if one thing running would work even better with a larger pipe. Currently from what I see where it starts to have problems is when more than one thing is open and turned on. A good demonstration of this is turning on the shower and washing machine at the same time while I turn on and off the hot water on the main bathroom sink. Doing this I can make the water dance like it's the water display in front of the Bellagio hotel in Vegas.
After Terry's Friday post above I was up till 1am Saturday and spent much of yesterday printing pages off and reading the IPC. I am going to post my figures and a graph I have drawn up of my house to hopefully give an indication if I understand and have done this correctly. My community uses IPC 2009 so that is what this is based from unless noted.
First from TABLE E103.3(2) here:
http://publicecodes.cyberregs.com/icod/ipc/2009/icod_ipc_2009_appe_sec003.htm
TOTAL WFSU
---------------------------
Bathroom Group - 3.6
Water closet - 2.2
Lavatory - 0.7
Kitchen Sink - 1.4
Dishwasher - 1.4
Washing Machine- 1.4
Hose Bibb - 2.5 (Figure from IRC 2012 TABLE P2903.6
http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_29_par034.htm)
Hose Bibb - 2.5 (Figure from IRC 2012 TABLE P2903.6
http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_29_par034.htm)
Total: 15.7
HOT WFSU
---------------------------
Bathroom Group - 1.5
Lavatory - 0.5
Kitchen Sink - 1.0
Dishwasher - 1.4
Washing Machine- 1.0
Total: 5.4
Following calculations based from here:
http://publicecodes.cyberregs.com/icod/ipc/2009/icod_ipc_2009_appe_sec004.htm
MAXIMUM DEVELOPED LENGTH
-------------------------------------
Meter to front of house - 32'
Front of house to water heater - 49'
Water heater to furthest hot faucet - 32'
Total: 113'
multiplied by 1.2 for fittings loss = 136'
TABLE E201.1
Based on the 150' "Maximum Developmental Length" column and WFSU of 15.7, 1/2" pipe is up to 1.5 (too small), 3/4" is up to 6.5 (too small), but 1" pipe is up to 25 so the main distribution pipe in my house, according to code, would be 1". Would that be a 1" line all the way to the water heater?
Based on the same "Maximum Developmental Length" of 150' and a hot WFSU of 5.4, 1/2" pipe is up to 1.5 (too small), 3/4" is up to 6.5 so my hot water main line from the water heater would require 3/4" to meet code. If I did do this correctly I do have one question. Once the main hot passes the dishwasher, kitchen sink and washing machine, it just goes to the 2 bathrooms that have a WFSU of 2. Does that mean the 3/4" changes to 1/2" on it's way to the bathroom or does it stay 3/4" for the entirety of its run? One thing I am worried about if 3/4" is taken all the way to the bathrooms is that the hot water will take longer to get there. That is one thing that is MUCH improved since the new lines is the hot water getting to the bathrooms much quicker. I'm assuming that's because it's a small 1/2' PEX pipe that is flushed of cold water quickly when a hot tap is opened.
Also of note is the plumber used a mini-branch and put the cold shower and main bath toilet on the same run. Since a toilet is 2.2 and shower is 1 that would equal 3.2 and would be a code violation (maximum of 1.5 on 1/2" @ MDL of 150') and that branch should be changed to 3/4".
Here's a drawing of the plumbing layout of my house:
http://imageshack.com/a/img835/8051/uqiv.jpg
Thanks for the help everyone!