Residential AC Split System for Small Commercial Office Space?

Paul Fredricks_3

We always looked at it from the amount of time it will run. Commercial settings usually need the A/C to run many more hours than a residential setting. On the extreme side, a computer room A/C unit can run non stop, 24-7. For that situation you can expect a residential unit to last 5 to 10 years. A commercial system, like a Leibert, can last 20 years. Lots more $$ up front, but better performance over the life of the unit.

If there is not much extra heat gain in the area, from people, computers and office equipment, the residential unit may work out.

Tom_99

Residential AC Split System for Small Commercial Office Space?

I need to have a 4-ton split system installed in a small office space. Several manufacturers offer systems that size both as a residential product and as a commercial product. In the few cases I have seen, the residential product has a higher SEER (as high as 21) while the same size commercial system in only as high as 13. Also, new R-400 refrigerant seems to be available for residential units while the few commercial units I looked at seem to only offer R 22.

Are there reasons not to put a 4 ton residential unit in a commercial office space where the load calls for a 4 ton system? Is the pricing much different? Thanks for any insight.

Tom

John Mills_5

single phase & 3 phase

That's the only difference between what you are calling residential and commerical. Due to little demand for small 3 phase units and the fact that much of that market is tenant paying the bill, there's been virtually no development of high SEER units. No reason not to go with a single phase in a 4 ton. Just watch low ambient operation and make sure the unit can handle as cold out as you want to run.

Tom_99

Residential AC Split System for Small Commercial Office Space?

Paul and John,

Thanks for the feedback. The office space does not have a computer room and only 2-3 people work in it with a PC and small refrigerator. The biggest load comes from the 300 CFMs of outside air ventilation. The OA is only needed during the 7:00 a.m. to 6:00 p.m. Monday to Friday time period. No weekends.

Given this, I am inclined to try the residential unit, and the most efficient possible. For the compressor, I am looking at two-stage units that have two compressor inside, one small for most summer days, one large for the dog days. Also, a variable speed air handler.

The only hurdle I see is that while most manufacturers list detailed specifications for their commercial units at their websites, only very general specs are given for residential units. So I want to confirm that the 4-ton units I select, say a Trane or Carrier, in fact can handle the load we have come up with.

Tom

John Mills_5

Specs

The dual compressor unit is a A-S or Trane unit. I can get you specs on the Allegiance 18 unit if you'd like. The dealer site is password protected due to ecommerce.

http://www.scacd.com/dealerInfo_carrierCatalog.asp is a good source of Carrier specs.