hey guys if you have a rooftop unit with 15 ton cooling capacity, you get the KW consumption by multiplying by 2000W right?
so that would be 15 x 2000 = 30kW
does this sound familiar? I think this is the conversion I used to apply just want to get confirmation
thanks!!
Please look for the energy efficiency rating of your heat machine (EER). EER is expressed in BTU/Watts. Assuming an ERR of 10, and a ton of cooling is equal to 12,000 BTU; your 15 tons of cooling translates into 15 tons x 12000 BTU per ton = 180,000 BTU; Your electrical input requirement will be 180,000 BTU/ 10 BTU per Watt = 18,000 Watts or 18 kW (a rule of thumb of tons X 1,200).
However, if your heat machine is not very efficient, say EER=8, then your electrical requirement becomes 22.5 kW (15 X 12000/8 = 22,500 W, or a rule of thumb of tons X 1,500). IMO, tons X 2,000 Watts is an over-design.
I found other people use a 1kW per ton of cooling too. It is so because it seldom happens users operate a cooling unit to its rating. HVAC designers usually do provide extra cooling capacity for every space considered. Hope that helps.