HVAC for Dummies

For those who haven’t had to put up with me in person over the last 3 weeks or so, my air conditioner has been on the blink.  That makes me cranky.

No, I didn’t call a repairman; I already know that I need a new system (this one’s 15 years old).  I’m just not prepared to spend the $8k-$10k it would cost to replace it right now.  We had it recharged in June and it worked for several weeks, so I’m fairly sure there’s a leak.  That, and the last serviceman who took it apart did a sloppy job of putting it back together, so the insulation was all torn up and not sealing the unit, such that it was sucking in hot outside air and mixing it with the cooled air to blow in the house.

Over the weekend, HWTFM borrowed a recharge kit (some gauges and a tank of R-22 refrigerant) from a friend, and taught himself a little something about HVAC systems.  [Reason #457 why it’s good to be married to a farm boy/engineer

We now know, for example, that the vapor point of freon is about 100 degrees, so putting the tank in a bucket of hot water greatly assists in getting the last bit of freon out of a less than fully-pressurized tank.  We know that the coils are probably a little dirty and less than fully efficient, because the pressure differential between the "low side" and the "high side" was off just four or five pounds — not enough to call for a $$$ triple-digit repair, knowing that we’re going to replace it anyway next spring.

We’ve also figured out that it would probably be a good idea to put in an auxiliary duct fan on the west side of the house, because the HVAC system is on the east side, but the kitchen is always too hot in the summer with those west-facing windows.

My family’s gotten tired of the "if you can’t take the heat, get out of the kitchen" philosophy, since I’ve refused to cook on a good number of these recent nights.  A gas stove is a lovely thing in January, but not when it’s 95 degrees inside.

Do-it-yourself home repair isn’t for everyone, but for us, there’s significant satisfaction in learning how stuff works.

5 Responses to “HVAC for Dummies”

  1. on 19 Aug 2007 at 9:31 pm girlfriend

    Stay cool. It helps to keep tempers down. Great job HWTFM.

  2. on 20 Aug 2007 at 8:33 am Jacket

    Just had a 3 ton unit replaced (gas pack not a split unit) for $3500.00 installed. Might get some more estimates.

  3. on 20 Aug 2007 at 1:17 pm daco

    I agree. Sounds like Jacket got a good deal. Ours is a 3.5 ton, gas pack, replaced it back in Feb. for $4700.00.

  4. on 08 Nov 2007 at 5:39 pm victor

    vapor point of freon? what are you talking about. i fix your system for 1500 and it will run for ever!

  5. on 08 Sep 2008 at 5:24 pm Brien Hollis

    In our state you must be licensed and CFC certified to work on your A/C.
    HWTFM, Shame on you for breaking federal section 608 laws at a minimum. And Victor, evaporation is necessary for heat to be absorbed. I would not want you to charge my system because it WONT last for ever.

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