Do i need a new furnace?

Old 12-20-06, 09:26 PM
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Cool Do i need a new furnace?

Hello All

I just moved in to a new house. Here is what I know

The house was built in 82, and had an electric furnace. 5 years ago, the furnace was replaced with a brand new high efficency furnace. The new furnace is an Arcoaire DC90. The home inspector said that the furnace is in excellent shape and I believe him. But the problem is that the house is either too hot or too cold.

I thought that the problem may be caused by the thermostat given that it is the cheapest one available on the market and I thought I could get a programable one anyway. Now it should be noted that I took appart my thermostat and my furnace is only a 2 wire system.

So off i go to HomeDepot, and I could not find one because according to the homedepot man, only the cheap 10$ honeywell thermostat works with a 2 wire system. He then went on about how if i wanted to get a better thermostat. I apparently need to go to a 4 or 5 wire system. This apparently depends on if the fan,vsingle step vs multi step cycle. Apparently if the fan is a single step, then I am stuck in this mode until i replace the furnace. Is this true????

The House also has no A/C, I had planned on adding the A/C this summer, but according to the home depot man, there is no point installing one, because the fan will not kick in.

So what are my options, can i go to a 4 or 5 wire?
Can the fan be replaced without replacing the furnace?
How do i figure out this 1 or multi step fan thing
If i want A/C I am doomed to gettng another furnace?
What are my options?

Old 12-20-06, 11:04 PM
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Id say first . Dont talk to him again. He dont know a D** thing about heat and cool. For now you can get any tstat to run just the heat or furnace. Heat just needs 2 wires is all.
But the problem is that the house is either too hot or too cold.
First is the filter clean then on the tstat you have look and see if you dont have a anticipator a small dial like. this is what tells the furnace how long or short to run. It will make the furnace run a shorter time and hold the temp more even. Or get a cheap new one that will say how to set the anticipator for the gas furnace you have. The tstat in a good place? No heat blows right on it?
Old 12-21-06, 05:50 AM
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Like Ed says you can use just about any stat. If it needs a common you'll have to run the new stat wire now. As for future a/c I would say your furnace is probably ok. sounds more like a problem with the location of your current stat or the anticipator setting.
Old 12-21-06, 06:53 PM
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I agree with Ed and mattison. If you are planning on getting a digital stat, pick anyone you like. You will only be using the R and W wires but you will find them on every stat in the store. The more expensive stats give you more choices on how to control the furnace. I like the Honeywell 5000 series for simplicity. The older set like the large display model. Then there is the 8000 series with many configuration options. I think you should try that first. It could be a furnace sizing issue or airflow problem too. Either one is correctible but you might be better off to find someone who knows HVAC to dig into that stuff. Go for the stat first and see how that works.

Old 12-22-06, 04:46 PM
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if your house was built without a/c you will need to have someone do a heat gain to determine how much a/c you will need. your also going to most likely need some duct renovation considering that heating duct systems are typicall designed for low airflow. sounds like a zoning system would do you good

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