I am curious on how people who use Manual J for load calculations addresses the quirky issues that arise in high end custom home issues such as how to calculate the load for: a screening room that seats 20, a personal gym, a dinning room that seats 35-40. How does one correctly size a unit when the baseline load for the house will be very different than the peak loads in certain rooms? 

Tags: JSD, Manual, right, size

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Hi Dav, since all of my work is custom, much of it high end, these types of scenarios come up from time to time. Extra people and exercising (gym) generates extra cooling loads, not heating loads. Zoning those rooms doesn't help because a) the capacity required to address those loads may be significantly larger than the baseline load, and b) in a confined space like a home theater, it's easy to end up with a cooling load in the winter. So the only viable option is to install a separate system specifically to address the "impulse" loads.

I typically use mini-splits for this. The mini would only be used when the additional loads are present. Depending on the space, I use ductless or ducted minis. The whole house HVAC would handle the loads in those spaces when they're unoccupied or lightly used.

As for calculating the load, you'll find the following site helpful: http://bit.ly/2Ah4SHH

Feel free to contact me privately if you need support on a specific project.

Thank you David. I will check out the link. BTW, I tried to email you; did you get it?

what time of year?  If mid summer late afternoon -Yes add a unit just for the party room.   I just did a very low energy house that has a bridge party each monday at 3 pm with 16 extra body's - extra drinks - extra food - ended up with extra 1.5 tons of cooling


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