220.87 +HVAC replacement

[cyriousn]

I've read a few of the posts before but I'm still a little unclear about it.

I'm working on a renovation of a school where we are replacing window-shaker air conditioners and through-the-wall trane units with one big chiller, a ton of air handlers, and a make up air unit.

I have the max demand from the past year's utility bills, it was not surprising it was at it's highest in June, right before school lets out.

Can I subtract the load of the units that are being taken out before I take 125 percent of the peak load and then add the new load to determine if the existing service size is large enough?

Also, my reviewer is saying that I should apply an assumed power factor of 0.85 to the max demand for all of the computers, lighting ballasts, motors, etc. Would the power company's max demand already have this in to consideration? Thanks.

 

[steve66]

Can I subtract the load of the units that are being taken out .....

I don't think so. All the units probably didn't run at once, and the units may not draw their full nameplate rating. So you would be overestimating the load you are taking out.

It would seem reasonable to deduct some load (a modest amount) for the units you are removing, but I don't think the code specifically allows that.

STeve

 

[cyriousn]

Thanks Steve66, I was kind of wondering the same thing. That's a mighty big assumption to go with and I don't really want to get the phone call next June when the service trips out in the middle of the school day.