HOW HOT IS HOT?

With more high rise buildings using a heat pump type apartment A/C unit and providing condenser water from cooling towers, ground water or lake or ocean water through flat plate heat exchangers, the question comes up as to how hot is hot?

That is,  how much above design temperature can the condenser water go before it causes increase operating costs for the individual apartment owner?

Of course not all heat pump units operate the same way but below gives you an idea as to how much individual apartment A/C operating costs can increase as the condenser water temperature to their heat pump A/C unit increases.  Let’s assume for discussion purposes that the design temperature is 80 degrees F.

Condenser Water Temperature.      Percentage Increase in operating Cost

80 design
85.                                                                             6%
90.                                                                            12%
100.                                                                          24%
110.                                                                          39%                  

So, as the above simple chart indicates allowing the condenser water temperature to significantly increase above design operating temperature can cause large increases in apartment A/C operating costs.  This can cause an increase burden on the renter or apartment owner when they are responsible to pay the electric bill.  Of course if the building owner is paying all of the electric they will bear the increase burden.   And yes, if you are wondering there have been some significant lawsuits over this one type of situation.