Fed up with central air, wondering if window or wall units would be best?

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  #81  
Old 04-28-12, 10:34 PM
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Two stage units run at 50-70% capacity on low which reduces temperature swings, improves dehumidification, and reduces total energy consumption. (it takes a few minutes of operation for a system to reach maximum efficiency and capacity)

If your system is far larger than it needs to be, setting it up as a single stage unit isn't a good idea in the long run.
 
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  #82  
Old 04-28-12, 11:31 PM
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Then it's gonna cost us for a new board on top of everything else.
 
  #83  
Old 04-29-12, 08:42 AM
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Couldn't the A/C unit be controlled by a two stage cool thermostat rather then replacing the $300 board? Of the multi-stage units I have seen they have two compressors so you would still have to do some rewireing.
 
  #84  
Old 04-29-12, 10:03 AM
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The board is $375 wholesale, and I don't know about that thermostat. It may cost as much as the board.

This is all kinda beating a dead horse. The bottom line is that this guy, who seems highly competent, and teaches this stuff, has looked at the system. He says that even if he rewires it single stage, there's no guarantee it will work, because with all those years of low freon every year ( possibly sabotaged by the original installers ) it may have even damaged the condenser unit itself by now. So we now have spent $120 from the first tech this spring and a bill so far of $300 from this second tech ( for freon and diagnosis ) and the choice of whether to sink another $100-$200 into rewiring it and trying to save this condenser unit, or spending another $2000 we can ill afford ( As in, we will be paying for it for a few years on the credit card. ) on a new 3.5 ton condenser to replace this one, and maybe being able to sell the old unit for $400 on Craig's List.

Those are the choices. From what I'm hearing of window units and wall units, they would compromise us in the winter and don't sound like such a good idea.
 
  #85  
Old 04-29-12, 11:29 AM
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Did you see my post about portable A/C units? They might be a good option.
 
  #86  
Old 04-29-12, 11:35 AM
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But they drain in the room, too. I heard you have to empty the water pan.
 
  #87  
Old 04-29-12, 12:42 PM
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Some do, but the newer ones evaporate the water in the discharge to the outside. I believe they mist it into the out going air. It is called "Self Evaporating" I see they have 3 at Lowes but you can find them at other places like Walmart, and Sears. Just make sure they say on the package or online Self Evaporating or something like that. Amazon has 97 models that are Self Evaporating
 
  #88  
Old 04-29-12, 12:49 PM
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We're gonna just get the teacher tech over here Wednesday and hopefully fix the central.

Thanks! You guys are great!
 
  #89  
Old 04-29-12, 01:54 PM
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Couldn't the A/C unit be controlled by a two stage cool thermostat rather then replacing the $300 board? Of the multi-stage units I have seen they have two compressors so you would still have to do some rewireing.

Read more: http://www.doityourself.com/forum/ai...#ixzz1tSrYLqE6

The OP's unit uses a bristol recip twin single compressor which runs backwards on low to enable one cylinder, forwards on high to enable both cylinders.

Low and high cooling don't utilize the same contactor and the compressor has to shut off for a minute or so when switching between stages.

Some very creative wiring with time delays would be required to stage that system without a board.

I think carrier abandoned that design recently and went for two-stage scrolls.
 
  #90  
Old 04-30-12, 01:10 PM
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The OP's unit uses a bristol recip twin single compressor which runs backwards on low to enable one cylinder, forwards on high to enable both cylinders.
Ok, along that line, couldn't you just wire it so that it will only run in the forward direction, single stage? Sure, it would not be the ideal/most efficient setting, but I think we are WAY past that.
 
  #91  
Old 04-30-12, 01:33 PM
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The "most efficient" setting, though, is using the control board and doing two stages, right?

But that means at LEAST an additional $375 on top of the $450 we've already spent, plus his time this week, and for what? We use the AC six months a year, more intensely between June and August. Would we save $50 over that time, by putting in a new control board?
 
  #92  
Old 04-30-12, 02:22 PM
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We use the AC six months a year, more intensely between June and August.Would we save $50 over that time, by putting in a new control board?
That is my feeling too, save $50 a year, so your payback would be about 7+ years. You might save the same amount getting one of those saver switches from the power company.
I would wait for the HVAC guys to reply on that one.
 
  #93  
Old 04-30-12, 02:33 PM
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Oh HECK no! ( another word came to mind! ) We will not let the government control our electricity too, they're already WAY out of control!
 
  #94  
Old 04-30-12, 02:37 PM
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Actually, it is the power company.

But really my point was: I doubt you will save that much with the 2 stages.
 
  #95  
Old 04-30-12, 03:47 PM
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It's the power company now, but the government is trying to set up a "Smart Grid", which of course this sets the stage for, and will be tied into, so the government will control our entire lives. I will not comply.

They've been bombarding us with offers for this, though, and that's why. Sell our souls for $25.
 
  #96  
Old 04-30-12, 04:24 PM
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Staging is more for comfort than saving energy.

Wiring it as a single stage system is a good temporary solution. (in the long run, it's better to fix it properly)

Low cooling at the air handler will have to be disabled, otherwise the blower speed will be too low when the t-stat doesn't call for high.
 
  #97  
Old 04-30-12, 04:53 PM
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The AC is tied into the gas forced air system, and it only has one speed, high. We had a tech look at it last year, thinking it could run at lower speed, but no.

And speaking of Big Brother. Xcel is upping the ante. We JUST got an offer today for a $25 Starbucks card AND $40 off our October bill, if we succumb to Skynet - er, I mean Big Brother's shut off switch.

I'm not at all tempted by Starbucks, since I took the time and learned to make the best coffee I've ever had, right here at home.
 
  #98  
Old 04-30-12, 05:39 PM
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If your furnace does not have 2 speed cooling capability then it is doing you NO good to have a 2 stage a/c.
 
  #99  
Old 04-30-12, 05:53 PM
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Installing a 2 stage condenser on a furnace which wasn't designed for it is beyond stupid. I wonder what else they screwed up.

The blower in the furnace and ductwork may not even be large enough for the 4 ton a/c you've got - many models have 3 ton drives.
 
  #100  
Old 04-30-12, 10:06 PM
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If your furnace does not have 2 speed cooling capability then it is doing you NO good to have a 2 stage a/c.
Oh, ok, well that settles it then. I guess part of the energy savings must also come from the lower fan speed on stage 1?

Oh well...
 
  #101  
Old 04-30-12, 10:33 PM
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Installing a 2 stage condenser on a furnace which wasn't designed for it is beyond stupid. I wonder what else they screwed up.
Well this IS a UBC modular home and we couldn't afford separate duct work for the AC, so they used the ducts for the gas-forced-air furnace.

The blower in the furnace and ductwork may not even be large enough for the 4 ton a/c you've got - many models have 3 ton drives.

( Shrug ) No idea.

Oh, by the way: The Wrong Automation - YouTube
 
  #102  
Old 05-01-12, 05:21 AM
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Well this IS a UBC modular home and we couldn't afford separate duct work for the AC, so they used the ducts for the gas-forced-air furnace.
This is how it is done in all houses that have a forced air furnaces in these parts. You only have separate duct-work for A/C if you have hot water heat, or something along those lines.
 
  #103  
Old 05-14-12, 03:13 PM
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Just as a follow-up on this thread: We wound up getting the teacher guy to just put in a new 3.5 ton condenser unit out there, and it works great. Trying to sell the old one on Craig's but getting nothing but scammers - the ones who tell you they want to send a money order, will even pay you MORE than you wanted, and will have their "moving company" pick it up. yeah right. When my ad says CASH ONLY. Good way to invite thieves...

But thanks for all your help guys, you're great here!
 
  #104  
Old 05-14-12, 03:20 PM
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Glad it worked out. Thanks for letting us know.
 
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