DIYbanter - View Single Post - American Standard 5 ton unit and Hardstart Device on generator

wrote:
On Fri, 26 May 2006 11:35:05 GMT, Robert Gammon
wrote:

wrote:

I have an American Standard Allegiance 12 5 ton Air Conditioner. The
model number is 2A7A2060A1000AA and the date of manufacture is 01/2003.

I am trying to determine if it has a hardstart kit on it or not. Some
people have told me that all ACs newer than 5 years come pre-installed
with a hard start device.

Hard start kits are NEVER installed on a new AC. The purpose of such a
kit is to give extra energy to a compressor that is aging, has more
internal friction.

A service call by a reputable HVAC contractor will install such a
capacitor ONLY when it is needed, ie. an old unit that fails to start
sometimes, particularly when the unit is hot and you attempt a restart
within an hour after it shuts down.

Actually this is not correct. hard starts are installed on the better
models and especially heat pumps due to their high pressure starts in
winter.

We're talking again, about TWO very different problems.

1. Pressure differentials across the compressor that make a difficult
start. This can occur on units of any size, of any age. We can agree
that some mfg's on some models do provide for a hard start condition
related to pressure differentials across the compressor.

2. Older compressors will have higher internal friction due to wear.
Pressures in the system are nominal, exactly what they should be. These
compressors may not be scroll compressors although scroll is currently a
leading compressor design. A HOT start, i.e. a restart of the
compressor after an extended run time, before the compressor has time to
cool down, may result in a failed compressor start. Adding an extra
start capacitor ONLY, will be a stop gap measure that will allow the
system to run for a few more years before replacement is required. It
is arguable that this is also a hard start due to a pressure
differential, however the solution is far simpler and less expensive
than the hard start kit that some are discussing here.