The new code 2012 changed the flush valved WC fixture units from 10 to 40, second WC is 30, etc... then should I enlarge the cold water main to the water closet? This change is strange. How to modify my design of water piping? Should I keep the same like before, 1"? or I must make it larger?
Thanks.
Are you talking about the requirement to use high efficiency toilets that have a maximum flush rate of 4.8LPF?
The last Building Code required a maximum flush rate of 6LPF, so if anything you need less water.
I am sure you did not read the new code carefully. If you go to OBC 2012 Part 7 Plumbing: read Table 7.6.3.2 A, B,C you will see the fixture units for water closets / urinals with flush valve changed. (on page B7-44 of the code 2012). So from now on, how to size the pipe based on the 2012 code ?
Follow Table 7.6.3.4 - Water Pipe Sizing. You have 3 options when it comes to sizing;
1. Use the detailed engineering analysis method.
2. Use the average pressure loss method.
3. Use the simplified method.
Quote7.6.3.2. Hydraulic Load
(1) Except as provided in Sentence (3), the hydraulic load of a fixture or device that is listed in Table 7.6.3.2.A. shall be the number of fixture units given in the Table.
(2) Except as provided in Sentences (1) and (3), the hydraulic load of a fixture that is not listed in Table 7.6.3.2.A. is the number of fixture units listed in Table 7.6.3.2.D.
(3) Where fixtures are supplied with both hot and cold water, the hydraulic loads for maximum separate demands shall be 75% of the hydraulic load of the fixture units given in Tables 7.6.3.2.A. and 7.6.3.2.D. when using a detailed engineering design method.
(4) The hydraulic load of urinals and water closets with direct flush valves shall be the number of fixture units listed in Tables 7.6.3.2.B. and 7.6.3.2.C.
Quote7.6.3.4. Size
(1) Every water service pipe shall be sized according to the peak demand flow but shall not be less than 3?4 in. in size.
(2) Except as permitted in Sentence (3), the size of a supply pipe that serves a fixture or device shall conform to Table 7.6.3.2.A.
(3) For fixtures listed in Table 7.6.3.2.A that have a permitted supply pipe size of 3?8 in., a connector not more than 750 mm long and not less than 6.3 mm inside diameter may be used to supply water to the fixture or device.
(4) No water system between the point of connection with the water service pipe or the water meter and the first branch that supplies a water heater that serves more than one fixture shall be less than 3?4 in. in size.
(5) Where both hot and cold water is supplied to fixtures in residential buildings containing one or two dwelling
units or row houses with separate water service pipes, the water system may be sized in accordance with Table 7.6.3.4. where,
(a) the hydraulic loads for maximum separate demands on water distribution system piping are not less than 100% of the total hydraulic load of the fixture units given in Tables 7.6.3.2.A., 7.6.3.2.B., 7.6.3.2.C. and 7.6.3.2.D. for private use,
(b) the minimum water pressure at the entry to the building is 200 kPa, and
(c) the total maximum length of the water system is 90 m.
BTW you are posting on an HVAC forum when your question pertains to plumbing. You need to ask a plumber.
Try posting your plumbing questions here,
http://www.terrylove.com/forums/forumdisplay.php?29-Canadian-Plumbing-Code-Questions
Thank you for your info. Please let me solve this topic here ,then I will ask for help for other topics in the plumbing forum.
Table 7.6.3.4 is for residential. My concern is for public, say, office building where flush valve water closets are used.
For example, there are 5 toilets, the fixture units will be 115 not 50(old code). From the 115 FU, I can find 72gpm, then from the regular sizing procedure that every designer knows, I should use 2.5" pipe. for a 50FU , i can only use 2" pipe. I think the new code increases the pipe size this way.
Am I right?
unbelievable...