I just finished a job that has already gone astray- due to the exhaust fans being imprpoerly sized.
This has me thinking- perhaps I ought to, in the future, be able to "size" such fans (as well as other HVAC equipment) so that I can make sure I can do my job properly.
With this particular job, I 'dodged the bullet.' I have room in the panel, room in the pipe, and adding contacts to the Ansul system is no big thing.
Can anyone suggest a site, or method, for sizing range hoods?
John I always figure on the plans being wrong. This goes double for HVAC. I could tell some tales.
That is why I recommend using pipe, not MC, for such loads.
That's it: provide extra pipe capacity.
Don't waste your time trying to perfectly engineer something that the 'pros' can never seem to get right. Stay on your own game.
I follow the prints and if they are wrong we get paid for the correction.
We are not going to provide more capacity for free.
I always try RFI or visually check ACs. EFs and water heaters. A good super should be checking also. If whats installed is different than what is on the plans, then I have no issues with a change order.
If you have prints, don't the specs include a (CYA)pre bid site visit, that covers the architects /engineers, while transferring all responsibility to the bidder. They do in my parts. This always makes me wonder if the total responsibility is mine why are they getting paid in the first place. Oh yea; now I remember, its so I can spend my time and money to bid the job according to their rules, and then wait for them to disreguard their bidding process and start the reverse auction for the contract.
Oh, this job was truly devised by the spawn of Satan. I am actually quite proud that MY stuff works!
As luck would have it, I did run pipe. At one point, I got confused, and ran an extra 3/4 pipe to the Ansul contactors- which turned out to be a truly lucky break, as (surprise) something was added. It's much easier to pull wires into an empty pipe, than a full one!
The current blower is fed by a pair of #12's in 1/2 pipe. I can probably run 3-#10's in their place, without much bother.
My "learning experience" here is that I ought to be able to 'figure the odds' when I make my first runs, as to the likely hood that there will be corections made. This time, I think I've lucked out.....making the change will not involve replacing an existing run of pipe, just pulling wires. This is a real consideration when your work interferes with the operation of a business.
I try to learn a little about the other trades so that I can better work with them. On this very job, my (limited) refrigeration experience led me to realise that the ice machine was missing a remote condenser- a major complication to wiring the unit! A last-minute panic was avoided as a result.
I guess what I really need is to find an HVAC forum comparable to ECN- not an easy act to follow!
renosteinke:
Here are some NFPA publications that you may want to look up: NFPA 86, NFPA 90A, NFPA 91, and NFPA 96.