HAC 165-350 ASSIGNMENT 3 Air Source Heat PumpsInformation: Heat Pumps are an interesting piece of mechanical equipment. They are able to change the direction of refrigerant flow during cold weather, so in effect the hot gas that went to the outside condenser now would go to the inside evaporator coil in winter months. There are a bunch of convoluted engineering formulas to predict how much heat these things can generate, but the simple way is to take the rule of thumb that this type of heat pump runs at about a 3.5 COP, or co-efficiency of performance at ideal operating conditions.So, if we take a typical 3 ton heat pump that moved 36,000 btu in the summer (3 tons x 12,000 btu per ton) and multiply it by 3.5, we get 126,000 btu of =usable winter heat. This sticking point is ideal winter conditions. This type of heat pump looses efficient as the outside air gets colder. Its best at 65 degrees, but when the temperature fall to about 38 degrees it has lost all its efficiency and is now providing that initial 36,000 btus of heat. But wait, it gets worse.....at about 34 degrees outside the outside coil actually s=freezes up because th refrigerant in the heat pump has gotten too cold. So the general rule is to turn the dang thing off at 38 degrees and just run back up heat.This back up heat can be either electric or gas, depending whats most available and cheapest to use.A typical performance chart would look something like this for a typical 80,000 btu design heat loss house.Heat BTU 126,000 Heat pump heating capacity 80,000Design Heat Loss 36,000Note: Lined area indicates backup heat need038 65Outside Air TempAs you can see from the above chart, at about 40 degrees or so the heat pump can no longer provide the amount of BTUs needed to heat the house, and back up heat is now needed.Assigned ProblemA homeowner in Chicago ahs determined he wants to install a heat pump after watching a Sierra Club special on Channel 11 where they explained how energy efficient heat pumps were in a house in California that is located close to L.A. Using the above graph with its 80,000 btu design heat loss, and 3 ton heat pump unit, select a back up furnace to heat the house when the heat pump cant do it any longer, and select what the backup heat form will be ......gas, or electricHint: To determine the least expensive form of heat, simply take the heat content of the energy source (3113 btu per Kw for electric, 100,000 btu per therm for gas) and divide it into the cost per unit of energy

($.14 for Kw electricity and $.50 per therm of gas). The resulting numbers will be quite small (your calculating $ per BTU after all) and just simply take the least expensive. Show your work below, and turn in to your Instructor for credit.How big of a back up furnace will you install?At what temperature will you disable the heat pump and simply run back up heat?What fuel source will you use for back up heta?