Carrier 2Speed Furnace Upgrade to Variable?

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Old 07-30-03, 05:31 PM
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Amy36
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Carrier 2Speed Furnace Upgrade to Variable?

I had a Carrier Weathermaker 8000 2-Speed gas furnace installed in my attic 5 years ago. I let the contractor talk me out of going with the variable speed model and am disappointed with the result. I have friends that have since gone w/ variable and realized much more even heating/cooling and much quieter operation, humidity control, etc. My home faces South w/ large windows and in the winter and summer I cook on the South side and freeze on the North.

I am now at the point where both outside units (we have 2 systems) are going and I'm looking at definite replacement of both outside units and the basement furnace (15 years old).

I might also replace the 5 year old Weathermaker 8000 2-speed just to go with a variable model in the attic at the same time, but am wondering if there is a way to convert it to variable speed (maybe a different fan and/or control module?) before I send it packing...

Thanks!
 
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Old 08-06-03, 11:23 PM
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lynn comstock
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[QUOTE]Originally posted by Amy36
My home faces South w/ large windows and in the winter and summer I cook on the South side and freeze on the North.
This is an air distribution or duct design issue. The south side needs more cool air to deal with the heat. The north side is getting too much. Balancing dampers to reduce the excess air on the north side MAY shift enough air to the south side to help a lot. It is a cheap thing to try. Test by closing the north side grilles as much as possible and see if much more air comes out the south (hot) side. If not, the duct design is flawed and the fix will require reinstalling ductwork of a better design. A popular option is to sell your problem house to another person (sucker?) and find one that works better before you buy it.

...but am wondering if there is a way to convert it to variable speed (maybe a different fan and/or control module?) before I send it packing
Not that I know of. I don't think that it will solve the problem that you describe.
 
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Old 08-07-03, 11:32 AM
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Im hot and cold

Like lynn said: Can you try balancing the dampers or closeing down the registers some. In the north side in the summer and I would try and turn the blower to fan on not auto at the tstat and see if this will move the air around for you all the time with the AC going on and off.
Or a good hvac tech could put a make break relay on the fan and another switch. This way it could run on low all the time and on high when it calls for cool. Are you sure that attic unit is only 2 speed most are 3 or more? You dont say how it is from up and down on the cooling and heat ED
 
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Old 08-09-03, 07:24 AM
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Other issues

you have other options....Plant hardwwod trees on the south side to block sunlight during the summer and the leaves drop off in winter to provide heat when you want it with the low sun angle. Also Awnings help a great deal in reducing the UV from heating up the house during the day, Every day, when I leave I close the blinds on the south, east,and west side of the house to reduce the solar gain...It works great. The plants still do good enough with the reflected leakage that gets by. A light colored roof like white keeps the heat down too if you get near that time, keep it in mind. Some people use insulated blinds..these passive ideas are cheap and not a lot of moving parts. Run the fan in the on position unless you have an outside air damper bringing in fresh air because this would also bring in the humidity....a NO-No these last few weeks...Lennox I know makes a variable speed fan for a package unit, not sure if Carrier does. these are usually a multitap 3 speed. If comfort is the goal...theres no question that radiant floor heating is what you need to check out...
Although it doesnt address the cooling problem! Zone damper control does however... Each room has it's own damper control thermostat, so that only the rooms that need cooling get it.
 
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Old 08-11-03, 06:09 PM
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Amy36
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Thanks for the responses, I appreciate the advise.

I tried adjusting the vents and that helped, but even better, when I ran the fan full time, it seemed to even everything out. The outside unit ran whenever the thermostat called for cool, but I kept the fan on.

I also read the installation manual on the Carrier 2 speed furnace - it actually has 5 fan speeds, but only 2 (low speed and high speed) are called for at any given time. You change jumper wires in the furnace to tell it which speed is low and which is high).

According to the manual, if I run the fan all the time, it runs on the low setting and then kicks to high when the thermostat calls for cool. It then goes back to low when the outside unit cuts off. In the winter, it runs on low most of the time and only switches to high for stage 2 heat (more gas consumption or something)...

What I found is that there's only a very small difference in the high and low fan speeds as it's currently configured (both seem to run high - I'd guess maybe low is set to 4 and high is set to 5). I'm wondering if the installer might have set it up that way when he put it in for some reason. The factory defaults specified in the manual would imply that there should be a difference in low and high speed operation and at this point there really isn't. It's definitely working, b/c when it changes you can hear it - just isn't much of a difference.

Would changing the low to fan speed low-1 make any sense? I wouldn't mind the fan on all the time if it were slower - it's kind of loud now. Also, my thermostat can program the fan on/off so that I could set it up to run the fan full-time only when we're home.

Thanks for the help!
 
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Old 08-12-03, 08:01 AM
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A/C fan

You found the manual and looked at it good for you. You are there im not and sounds like you have the know how to play with it so why not. Turn the power off and change the blower around. Turn it back on and try different settings for a day or so at a time. You will get it right I though you should have more fan speeds than you said . Sounds like that tech for the company should go back to school. Fan on low all the time willl also help in the winter for an open up and down stairs, we find ED
 
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Old 08-12-03, 04:07 PM
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you can't change the fan speeds around willy nilly!

The fan speed is set in accordance with the temperature rise of the furnace. Too slow and the heat exchanger will overheat and shut off, provided the safety works; too fast and the air will come out too cool, and may cause condensation to form. In the cooling mode, use high speed to load up the coil...
 
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