I'm replacing my oil furnace and I'm deciding between a single stage or a 2 stage furnace w/ variable speed fan. I was just wondering since my house is so old, will it make any difference to get a 2 stage furnace w/ variable speed fan? it's about a $1000 dollar difference. Thanks
While it would be good, I'd put that money toward increasing insulation. Better payback.
If you have the money, do both.
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Yup , insulation will get you more bang for your buck .
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All a two stage furnace does is fire at a high output or low output. The higher output is good because it will get the temp up faster from being setback, when you come home and turn it on, when you've been away on vacation and turn it on, etc. There are also wifi thermostats now where you can turn it on from your phone, so that can also get the temp up on the way home.
The low output is good when it's not very cold out and/or it's just maintaining temperature. The lower firing allows the furnace to run longer, move more air, distribute it more evenly through the whole house. If you get a two stage, make sure you get a two stage thermostat to go with it. A two stage thermostat, the thermostat makes the call on which stage to use. If it knows the temp has to go up a lot, it will call for high, otherwise it will use low. With a regular thermostat a two stage will make the decision, based on how long it's been running. After it's run like ~7 mins, if it's still running, then it will kick up to high.
Variable speed blower, IMO, may be far less desirable. I don't think fully variable speed adds much. I have an ECM, which like variable speed, is an ECM motor. The big advantage to either is they use substantially less electric than a conventional blower. How much that saves depends on how much you use it and the elec rate. The downside is that the motors have electronics in them, are more failure prone and if they fail, instead of looking at a $150 motor, you're probably looking at $600. I also had an ECM fan motor on the AC condenser outside. It failed after just a few years. New one was like ~$350. I found a conventional motor that would replace it for $90. IDK how many years it would take to make up that difference in electric, but I suspect it's a very long time, given the usage here. For a furnace blower in a colder climate, the payback could be sooner, but I still suspect it's many years. Say it's ten, is it worth it, given that if the motor fails in six, you have to pay 4x more for a new one?
THIS is a very good point.
There is something to be said for simplicity and ease of repair.
mark
And also factor in that for my condenser fan, the $350 price was the lowest price I could find online. If you can't do the repair yourself, have to call an HVAC guy, that motor could be $500 plus labor and the replacement would have the same crappy electronics in it. IDK if an HVAC guy would put in a split phase motor instead or not. It takes a bit of smarts for one thing, to look up the specs on the two and find the equivalent one.
The furnace ECM I think is paying back faster, the electric bills in winter are lower, but I've also put in LEDs, etc that could be part of it. But the biggest savings were in the gas bill for the furnace and elec bill in summer with AC. Gas bill went down by ~40%, elec bill probably about the same.
"pchalas" wrote in message news:K7a6D.1982097$ snipped-for-privacy@fx10.am...
How much money will you save each year?
I wouldn't spend an extra $1000 for a more complicated furnance.
The $1000 difference he was quoted sounds way high too. The two stage is essentially a gas valve that opens part way or full. The variable speed blower, if it's being compared to a regular, non-ECM blower, there is some more substantial difference there, but you can buy those furnaces retail with maybe a $300 delta.
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