Re: Why two fuses for a 5 ton residential AC?
- From: Bruce L. Bergman <bruceNOSPAMbergman@xxxxxxxxx>
- Date: Tue, 14 Jul 2009 11:50:37 -0700
On Tue, 14 Jul 2009 08:20:08 -0700, nomail@xxxxxxxxxxx wrote:
The entire plate on the compressor:
RHEEM MFG CO
MODEL RAFD-060 JBS MFD 1-90
SERIAL NO xxxxxxx OUTDOOR USE
Volt 208/230 1ph, 60 hertz
COMPRESSOR, R.L.A. 30. 8/30. 8 L.R.A. 178 <--not sure what this means?
OUTDOOR FAN MOTOR FLA 2.0
MIN SUPPLY CIRCUIT CAPACITY 40 AMP
MAX FUSE OR HACR TYPE CKT BKR SIZE 60/60 AMP
MIN FUSE OR HACR TYPE CKT BKR SIZE 50/50 AMP
FACTORY TEST PRESSURE HIGH 300 PSIG
FACTORY TEST PRESSURE LOW 150 PSIG
OUTDOOR CIRCUIT FACTORY CHARGE 118 OZ R22
TOTAL SYSTEM CHARGE <BLANK>
RLA - Running Load Amps - How much it draws at 208V /and 230V
LRA - Locked Rotor Amps - How much it draws on initital startup, or if
it can't start because there is still pressure in the system (short
cycling) or the compressor goes bad mechanically and jams.
You need to know these amp ratings to design the power feed circuit
and (if you are making your own electricity) to size the transformer
or generator plant feeding the unit.
Note that generators meant for Recreational Vehicle use often say
things like "Will start a 7,200 or 13,000 BTU Air Conditioner" in the
paperwork.
I currently have 6 ga wire 50ft, 50 amp breaker at a 200 amp service panel
and the 60 AMP SLO-LAG fuses at the shutoff box at the compressor.
Lights do not dim when it starts.
Are the 60 amp fuses needed or not?
THIS IS NOT 100% CLEAR TO ME in spite of your excellent discussion.
It says "Fuse or HACR Rated circuit breaker" so the fuses aren't
absolutely necessary. Either will do. Get out a magnifying glass to
read the breaker label for the HACR rating, which won't be on
old-stock breakers.
But I would still leave the fuses in, because circuit breakers DO
fail to trip occasionally - or they do trip, but after far too long of
a time delay that allows compressor damage.
It's cheap insurance, so big deal if you have to replace the fuses
every 10 years or so.
Regarding service:
The last fuse lasted 9 years - before that I had nothing but problems -
every week etc. Cleaned all surfaces an no real problem since <knock on
wood!>
No technician has checked the unit in more than 10 years and I see NO
problem and I am EXTREMELY cautious about tampering with something that
works. <GRIN>
May this be doing damage to the unit - to not have (annual?) service?
So don't let it crap out!
When it's running, check that the big suction line headed out to the
condensing unit is still frosty cold - that's the quick and dirty test
that there's enough refrigerant in the system. The "leftover" cold in
the system is how the compressor motor gets cooled - the incoming cold
gas goes through the windings. If the refrigerant charge is too low,
you start slowly cooking the compressor motor to an earlier failure.
If it's low on refrigerant you WILL need to call someone to fill it
up, because you need a Refrigerant Technician License to buy the
refrigerant (Multiple Guess Test, simple once you grasp the
principles) and $1500 to $2500 worth of gear on hand to do it legally.
(Must have a refrigerant recovery machine and an empty recovery tank
on hand if a big leak starts, so it doesn't leak into the environment.
Silly, but I didn't write the laws I just try to follow them. And
when the EPA can fine you from $10,000 up to a Half-Million Bucks for
each violation, you have an incentive to follow the rules...)
Everything else, you can do.
Get some Non Acid condenser coil cleaner and a pressure washer, and
clean out the bugs and dirt from the condenser core outside. Let the
soap soak then pressure wash out the crud.
Get a can of self-rinsing evaporator core cleaner and get the gunk
off the inside coils. You can't use a pressure washer, so it rinses
off with the normal condensation.
Get a case of good High Efficiency air filters, and change them
every couple of months, or as they get filthy.
And make sure the condensate drains are clear, and the secondary drip
pan is under the unit if it's a horizontal in the attic, and a general
once-over.
Oil the fan motor bearings with non detergent 10W Turbine Oil, and
change the belt if the blower is belt drive. Same thing with the
condensing unit fan if it's oilable - look for the little black plugs
and OIL markings on the oil holes, and plug them again when finished
to keep the rain out.
Spin the fan and feel the bearings, if they are getting lumpy buy a
new motor. Not too hard to change, not worth the trouble to fix.
My current plan is to buy 4 windows units when/if this unit craps out and
requires $500+ repairs.
No you don't - window units are far less efficient, and give more
trouble. And depending on where you are, natural gas heat is a LOT
less expensive than electric or heat pump. Propane and Oil heat are
more, but still cheaper than electric. That old furnace and central
air is still worth keeping.
--<< Bruce >>--
.
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- Re: Why two fuses for a 5 ton residential AC?
- From: Bruce L . Bergman
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