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HVAC capacitor questions

T

Tim Williams

Jan 1, 1970
0
Also, if the thermostat doesn't do it already, a similar "remain on for 5
minutes" relay is a great idea for the ventilation fan itself.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms


They replace the start capacitor. Your problem is the excessive heat down
there making that compressor start up against 500 psi internal pressures.
This explains why the caps blow during the heat waves. The compressor is
probably tripping out on overload until the condenser fan air can bring the
pressure down.I would go one step further and add a time delay relay between
the thermostat and the contactor. The time delay relay delays powering the
contactor for a full 5 minutes. Then an aux relay takes the t-stat voltage
and turns on the condenser fan immediately. This is a common technique used
in extreme conditions like rooftop units and trailer a/c's. When you do the
rewire use their 10000V HV wire or whatever it is.

Please view in a fixed-width font such as Courier.

..
..
..
..
..
..
..
.. +---------+ +---------+
.. | | | cndnsr |
.. Tstat>--+-----| aux rly |------+ fan |
.. | | | | |
.. | +---------+ +---------+
.. |
.. |
.. | +----------+
.. | | 5 min | +-----------+ +----------+
.. | | | | | | |
.. -----+ delay +----| contactor |-----| cmprssr |
.. | | | | | |
.. | on make | +-----------+ +----------+
.. | |
.. +----------+
..
..
..
 
N

NM5K

Jan 1, 1970
0
Do that hard start caps replace the 60uF compressor run cap or go in
parallel with it until the compressor starts then drops out?

I've heard some negative pres about kickstart caps causing more problems
than they fix. Do you have experience with these lasting long term?

Myself, I do not recommend using a hard start kit unless you
actually need a hard start kit.
IE: expansion valve instead of flow rater, has trouble starting, etc.
If it doesn't need one, I don't use them. I've got many condensing
units I've installed around town that have been in service for 15-25
years.
I was just on a call the other day to change a combo run cap on a unit I
installed 19 years ago.
It's never had a hard start kit and still runs like a champ.
 
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