Preface: I'm a self taught hydraulic calculation dweeb and I always thought I had a handle on the basics. I also should take the hydraulics course on-line, not a plug but I'm sure there's a lot I don't know.
I got a written review of a set of plans and calcs I submitted by mail today. The AHJ's reviewer is anonymous and mails his reviews via the AHJ. First for me and that's fine. It's a 4 unit attached residential building. Full Basements, 775 SF/flr, 2 floors with a small loft, attached garages. Single 2" copper supply to a doghouse on the end, single zone system, steel in the basement, cpvc upstairs. Just a description of the system as it bears little to my questions, but good for background. Comment #1 states my calculations are completely wrong. No citing of section, just wrong. He backs it up by saying that I include the downstream fitting in each segment and I should be including the fitting at the start of the segment. I've just opened this up and I'm stunned. He goes further to ask where my training is in hydraulics and who (by name) taught me. Not nice in my book. Let me explain how I do these and would you kind folks (and George too) tell me if I'm off-base or not. My first segment is the underground. 2" copper, annealed, 1 piece from the corporation stop on the main up into the doghouse. I input 34' of type L, a gate valve and a 90 degree elbow with the tap as the inflow. I know it's closer to 30' and the tubing is rolled and unrolled so I really have a l o n g sweep but I usually go a little conservative. He says I have to include the tee. I disagree in principle for now. My next segment is the compression fitting (I actually braze a male adapter on) to a 90 to a 2" horizontal backflow with ball valves (all copper because it's still potable). I input a 1' of vertical, a 90, 1' of horizontal copper, 2 ball valves and use 8 psi for the backflow non-linear loss (guessing at the time but checked and adjusted for the basement demand of 150 gpm) and put a 100 gpm (inside and/or outside) hose demand at the elbow. He says the base elbow must be included but says the hose demand should be after the backflow. There are no hose valves, why? Anyway.. Fast forward to the last segments where again he says I'm incorrect, again. I show 7.5' of 1" cpvc, and elbow and a head with 224 SF of area on it. He says I have to include the branch tee feeding it but I included that in the segment feeding that segment! Am I doing this all wrong? Another thing. I have a 4 head and a single head calc. (plus the basement and garage). I always used to do this when they had separate demands and I just still do but that's not my question. I have 4 heads with different areas being served by each. 2 are in bedrooms, 212 SF and 224 SF, one in a hall with 90 SF and one in a walk-in closet with 56 SF. He says they all have to "provide the same density at similar dimensions". WTF! I have to base all 4 heads (or all heads in the building for that matter) based upon my most demanding head which is the 224 SF bedroom that is 16x14 using 16x16 flow and pressure requirements for all 4 heads. I've got almost a gallon/sf in the closet and that's incorrect according to my reviewer. I'm not going to start a reply now as I just poured three fingers of single malt but more because I want to re-read his comments and see what you folks think. I submitted these on Dec. 10th and I'm getting angry phone calls because we haven't started yet and I get home and find this monkey-poop (ok, I'm sipping now). Have I been doing these wrong all this time? There's some more but I'm starving. Dazed and confused. Tom Duross Go Red Sox! _______________________________________________ Sprinklerforum mailing list http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
