Package unit/electric heat for apartment bldg?
Getting ready to finalize HVAC system for new 58,000 s.f., 3 story wooden frame 36 unit condo building in Columbia,SC.
Mechanical engineer has recommended a centralized roof top air cooled package unit to handle AC for apartments with electric resistance heating in each apartment's airhandling closet. Another option mentioned was to use individual heat pumps for each apartment mounted on the roof...although we're not real excited about doing that. Cost is of course a factor in our decision. We don't want to use any thru-the-wall type systems although magic-pak type might be a consideration if no ther good options.
No problem with centralized packaged unit, my question is the method of heating. I'm concerned about electric cost for heating. I realize that having the electric resistance heating in each airhandler gives each apartment control over how much heating they need which is important plus.
Is my climate reasonable enough not to be concerned with this configuration vs. something else or am I in for major eelctric bills in the winter?
So a chiller on the roof providing cold water to each condo and electric strip heat? That's one way.
I would think the Magic Pak way would probably be lower first cost plus shift the repairs, maintenance and all utilities on to the condo owners. In SC I wouldn't worry too much about electric heating though a Magic Pak or 1st Company heat pump may be better than unit with straight cool and strips. Most new Residence Inns use 1st Comany TTW heat pumps. Last one I stayed at worked out well.
What he said ^^^Another option would be hot water reheat, but I'm not from your area and don't know what your fuel prices are. But considering recent events it might be cheaper just to set the place on fire in the winter, rebuild it the rest of the time.
I'd also have questions about a single pkg that size on a wood frame. It would make me nervous, not to mention the value of having multiple units that won't all go offline at the same time. Engineers don't have all the answers, or consider all the possibly better alternatives, so throw some his way. Not saying what he proposes won't work, just that in 20 yrs I've only seen a few multi-res with a single unit. Usually a steel hi rise with a cherry, er I mean cent. chiller on top.
Cause when its done and still doesn't work as expected, funny how I've yet to see an engineer on a call back.