Originally Posted by jackmo
I am curious why some AC units require hard start kits & some don't.
I have a 200 amp service. The only large electrical item is the electric dryer the rest is lights,TV's & computer.
Its not the fact that some units require them. Some compressors are tighter than others. But past that is the fact that if you live in a warm area, your system might ask for cooling before your pressures equalize. Single phase compressors are VERY tempermental. Most compressors can start with some pressure difference between the high and the low side.
By this I mean, than when your system is running, your low side pressure could be around 70 PSIG while your high side pressure might run between 250 and 350 PSIG.
Alot of compressor will lock up if there is not a equalization of pressure from the high side and the low side. A single phase 208/240 compressor will start with an imbalance of pressure at about 80 PSIG. That means, if your low side is about 100, your high side better be around 180. New T-stats have a 5 minute time delay to allow the system to equalize.
So, as far as houses that require it, if you have an AC, I would require it. BUT, the common home owner looks short term and not long term. If you were to have an AC guy come put a hard start kit on, it might cost you $150 to $200. BUT, the compressor will last much longer and you'll be lowering the cost of electricity...a little, but every penny helps.
When any motor starts, its what we call locked rotor amps or LRA. If you can get any motor up to speed faster, you lower the LRA of that motor, thus saving you money in the long run. It's not alot, but it is something.
Bottom line is that every AC unit in all homes should have a hard start kit. I know people are going to argue, but do your homework. If a company can save $20 every time they build something, they will. But EVERY compressor manufacture recommends a hard start kit. Look it up and let the argument begin