We're replacing an older (1987) Rheem/Ruud Deluxe 90, and are wondering if a two-stage condensing furnace with multiple speed blower makes sense vs. a single stage 90+? Looking at Am. Std. Freedom 90's, and may well not own the home more than another two to three years.
As a percentage of total hardware cost, does the two-stage with four-speed blower payoff either in terms of $ savings on electricity, or a noticeable difference in improved comfort over a single stage?
The primary benefit of a two stage system is comfort. The energy savings are there, but should not be a factor in your decision. The smaller first stage gives you a longer run time, which evens out the temp in the home.
Your existing furnace has a multiple speed blower- just like the new one you are looking at. A standard AC blower will only use one speed each for cooling and heating. Multiple taps (speeds) allows some fine tuning of the airflow.
You will not save money on the electric portion unless you get a variable speed DC drive motor.
If the existing furnace is oversized, you will save some money on operating costs, but the cost of replacing the equipment and the short time you plan to be there is a factor.
If your intent is to replace it anyway, get the two stage variable speed drive.
If the current system works, and you are replacing it in an attempt to increase the value of your home, better talk to a real estate agent about that.
Proper Prior Planning Prevents Piss Poor Performance
"There is hardly anything in the world that some man cannot make a little worse and sell a little cheaper, and the people who consider price only are this man's lawful prey. It's unwise to pay too little.
When you pay too much, you lose a little money -- that is all. When you pay too little, you may lose everything, because the thing you bought was incapable of doing the thing it was bought to do.
The common law of business balance prohibits paying a little and getting a lot -- it can't be done. If you deal with the lowest bidder, it is well to add something for the risk you run. And if you do that, you will have enough to pay for something better."
N.S., thanks for the advice. I'm a professional inspector, and have an innate distrust of some Agents. Besides, I'm confident that the average buyer would be far more interested in the nifty kitchen counters than the furnace particulars. I was more concerned about comfort and potential $ savings (if any), rather than resale $.
Had the furnace inspected a couple days ago by a pro; when he pulled the burner set out, it was visibly deteriorated. I figured, "O.K., it's 18 years old, no big deal replacing the burners." Then, we looked up into the exchanger. Looked like someone had buck-shotted it. Best guess, leaking condensate pan. So this hardware move is one of necessity, rather than proper prior planning. Thanks again for the opinion.