We found out yesterday that the heat exchanger in our 18+ year old furnace is cracked. If it were me I would not do anything as we have a new CO2 detector, but GF wants a new furnace. Our decision is down to a Westinghouse 60k two stage one fan speed 95.1% efficient unit vs. the same model with a variable speed blower. In a 1300 sq. ft. home, is the variable speed blower going to be appreciably better than the fixed speed blower regarding comfort, or economy? The variable speed unit is about $315 more than the fixed speed unit. We are located in Dayton Ohio area. The brick home has excellent newer windows and updated attic insulation. Cheers,Steve/OHIO
GF is right to want to replace the furnace. A bad heat exchanger is a killer. I myself would have condemned the furnace and disabled it so you would not be able to use it. And I can do it by law. If you have any concern that the exchanger is bad have them prove it to you when they get it out. You can see if so ask. Now my take on all the high efficiency units out there in the world. Scam. Ask them what the replacement cost for a variable speed motor is installed. It may shock you and will this company be there when it goes out. The controls in that motor alone are sensitive and do have problems. They will come back.
By computer board. I am not familiar with the Goodman but I have studied a carrier to try to understand it. I think that one simply used the temperature of the heat exchanger to adjust the fan speed. Aside from that it always started the fan off slow with little delay. That improves efficiency two ways. One it loses less heat immediately without blowing air too cold as with a single speed fan heat setting which if it came on immediately can cause condensation. And the fan delay of most furnaces put more heat up the stack before the fan kicks in. Also a motor draws a lot of power getting up to speed so bringing it more slowly saves power. While that might sound like it won't do much the other half of the savings comes from the board in the thermostat. They have two or three stage heat or with a variable speed heat pump or dual compressor the levels of heat are many. The thermostat uses temperature and time to determine how much to heat. If the difference between the room temp and setting are great it increases the level of heat like a two stage electric would. But it also senses the time it takes to heat. If it is a longer run and the delta T is still high the thermostat increases the heat input and then at the furnace end it adjusts the blower speed to match based on temp to get the desired heat rise depending on the heat input determined by the thermostat. This means the thermostat is unique to the furnace and proprietary. The two boards work together. A generic thermostat won't work right or well for it. You would lose some of the function. I hope that helps.
I would go with the variable blower. It's much more comfortable, quiet and economical. I don't know about other brands, but I have never had one go bad. I install Arcoaire and Comfortmaker, which is the same as Bryant/Carrier (same factory) and it comes with a 10 year parts warranty, and a 10 year no hassle warranty (free furnace replacement if the heat exchanger cracks). Also if the blower motor did go bad the furnace circuit board is configured so a standard blower motor can be used if the tech didn't have one on his truck. I'm not so sure about the brand you chose. I installed one westinghouse a few years ago and didn't like it. By the way, it's CO that's the dangerous one, not CO2 Be sure the furnace is at least 95% efficient so you can get the 30% tax credit off your taxes. I'm a contractor.
westinghouse by nordyne is a fine product made by hand in o'fallon mo. it has a quality pledge warranty and the variable speed blower is 100 times nicer and more comfortable than fixed speed,tell them to throw in a 5 inch filter media for free and leave your fan run for ever ($14)dollars a year for electric,your home will feel awesome summer and winter by the way the co2 might just kill you before the detector goes off it will get you sick before warning you
Definitely get the variable speed blower. Not sure about Westinghouse since I've put in mostly Carrier/Bryant but Westinghouse may have the same control available. I use a thermidistat, a combination thermostst and humidity control that controls fan speed for optimum comfort and efficiency. In the summer if the humidity is higher than setpoint, the fan will slow down, making the evaporator even colder, which in turn wrings more moisture from the air. In the winter, the fan will vary according to load, outside temperature, and humidity (if you have a humidifier). These fan/control combinations work great. See if your dealer has this type of control. The only downfall to a variable speed fan is when the motor eventually fails, they are about $400 dealer cost. I've put in tons of them though and haven't had any failures. Also, make sure they have a 5 year warranty on all the furnace parts (except for heat exchanger, which will have a 15-20 year warranty)
