HVAC techs: Should I replace A/C crankcase heater?
I have a Trane XL 1200 split system air conditioner (cooling only, no heat pump). It's 14 years old.
Earlier this week, it tripped the circuit breaker. The breaker would not stay reset, even with the thermostat set to "off". The HVAC technician immediately suspected a shorted crankcase heater. He disconnected it, the breaker stayed "on", and it's been working fine ever since.
He's telling me that I don't have to have the crankcase heater replaced. This is a residential application, and I won't be running the A/C when the outside temperature is below 50 degrees F. He's also concerned that there's some risk to the other components when opening up a 14-year-old unit to replace the heater. I'll add that the outside unit is on the southeast side of the house, and gets both direct sunlight, and sunlight reflected from two stucco walls. It's an unusually warm location.
I'm looking for a second opinion. What am I risking without a working crankcase heater? I'd just as soon save the money, but not if it means I blow up the compressor in a couple of months...
Thoughts and opinions?
Anonymous2010-07-22T23:32:55Z
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If your compressor DOES NOT have an independent crankcase heater at all (belly band or bullet style in a well) and all you have is a single pole contactor - one contact and the other side barred - then it is incorrect to believe that the windings inside the compressor are energized at all times and heating the compressor. Single phase motors (1 line of power in 1 line out) can be safely stopped by breaking only one line of power. You can break both lines by using a two pole contactor; however, the minimum is one leg/line/pole. The Manufacturers use single pole contactors as a production/money saving feature (they cost less per unit than installing a 2 pole - less cost = more profit to them and still does the job). In this case, with no independent crank case heater, you gain/loose nothing by leaving the condensing unit on. There is no current flow through the motor windings as you have broken the circuit ( if there was current flow you then would have an unintentional circuit and a defective/grounded winding(s)). No current flow means no cost to you.
If you live someplace where it gets cold in the winter, You need to have a CCH. Its meant to prevent migration of oil from the compressor into the system during OFF periods in winter. I had a CCH fail in a 30 Ton Chiller at my work. I ended up having to replace an expansion valve because of it. A costly repair. You dont have to replace the heater with that exact one. They make heaters that wrap around the bottom of the compressor that do just fine. I have never replaced a cartrige type that you must have, but I'm pretty certain that changing one of these heaters is not a risk to other components.
RE: HVAC techs: Should I replace A/C crankcase heater? I have a Trane XL 1200 split system air conditioner (cooling only, no heat pump). It's 14 years old.
Earlier this week, it tripped the circuit breaker. The breaker would not stay reset, even with the thermostat set to "off". The HVAC technician immediately suspected a shorted...
what does he mean opening the system? it probably just had a band type heater that wrapped around the compressor. it probably wont hurt anything but you never know. a crankcase heater should not be that expensive. if he lead you to believe the newer residential units dont have crankcase heaters he is wrong. they are wired with 1 leg of the 240 going thru the compressor motor winding all the time to keep the comp warm