When I bought the new furnace I decided on the deluxe model from Carrier; the Infinity 80. It has many nice bells and whistles, all of which as far as I can tell are actually useful. It’s a well thought out product. It wasn’t the most energy efficient model (which was the Infinity 96), but that one would have cost me thousands more all told, for all the other modifications to the house I’d have had to make and I couldn’t justify it. But the one I bought was supposed to be able to monitor both the inside and outside temperature over a period of time, and set its burn rate and fan speed to the most efficient (and hopefully less costly) way to heat and cool the house. So I bought the furnace that burned a bit more efficiently then the one I had, with extra features that hopefully make it even more efficient in use. BGE Home installed it Tuesday after New Year. Hopefully the technician they sent over yesterday finally got it working.

Swear to God, every time I catch myself thinking Things are different then when I was a kid I just want to smack myself. I’m Not That Old! But I traded a simple Honeywell round thermostat for a device that looks a bit like an iPod attached to my wall, only with a bigger LCD display and lots more buttons. It tells me what the temperature is inside. It tells me what the temperature is outside. It tells me what temperature I’ve set the heat to. I can program it to different heat settings for various times of the day, for each individual day of the week, or for every day during the weekday and every day during the weekend. I can keep the heat low when I’m asleep, or at work. I can create a completely separate set of heating points for vacation. It’s actually quite simple to program. It tells me when the furnace is on. It tells me if the fan is going, and at what speed. It tells me what the humidity is. It’ll tell me when the media in my electronic air filter needs cleaning. And ever since they installed it, it’s been telling me to call for a service technician to fix it.

System malfunction - Call for service.

I can press a combination of buttons and get a more precise diagnosis, or I can go into the basement and read the error code directly off the furnace. And no…I don’t have all this memorized. Lately I’ve had to keep the instruction manual near my…uh, thermostat device thing. What’s it called again? Ah…right…it’s the Carrier Infinity Control So I have a control unit now, instead of just a plain old thermostat. And it not only came with an instruction booklet…inside the instruction booklet is a quick start guide. Dig it. My new furnace has a quick start guide.

The error code it was throwing, 33, meant that at the low heat/low fan setting the heat exchanger was going over temperature. That threw the furnace into a mode where it would only operate at high heat and high fan speed…exactly like the old furnace did. Efficiency was out the window, but at least I had heat. The probable causes were maddeningly all over the map. Something could be impeding air flow into the furnace, or air flow out of it. Something could be impeding the draw up the chimney. The dual setting burner valve could be malfunctioning. Gas pressure could be set just a tad wrong. Over the past couple weeks the technicians from BGE Home have tried everything. Making matters worse was that the problem could take hours to develop. A technician would leave my house thinking they’d finally fixed it, only to have the error code pop out again four or five hours later.

Finally, yesterday, BGE Home brought out a big gun…a high ranking technician who knew this particular model. He spent about four hours with it yesterday afternoon carefully monitoring the temperature rise in the heat exchanger and tweaking this and that, until finally deciding that it was a combination of improper settings on the PC board, and too much bypass air going through the humidifier. As I watched him turning on and off the furnace to reset the PC board in it so he could test it some more, a thought occurred to me and I had to go sit down.

He’s rebooting my furnace. I have a furnace that boots. I don’t just switch on the furnace, I boot it up… And sure enough, as the furnace was switched on my Control Unit displayed various messages while polling the…uhm…peripherals, of entire system…the compressor, the humidifier, the air filter. You could watch it booting up. My mom used to tell me stories about how she and her brothers shoveled coal into their parent’s coal fired furnace, and cleaned out the ash trap. In point of fact, many of the old row houses over in Hampden, just a short walk from my neighborhood, still have their coal door. I have a furnace with a computer in it that’s probably more powerful then the one that calculated the descent of two astronauts to the surface of the moon back in 1969. And all it does is figure out how to maintain temperature inside my little rowhouse.

My humidifier, a Honeywell Enviracaire (somebody please smack the marketer who invented that word…), uses a fibrous pad that is fed water when the furnace comes on. Air is blown through the pad and into the return air duct, just above where it goes into the furnace. It’s a good system in that it uses no water reservoir where mold and germs can get growing, and there is no water spray from it that can cause corrosion in the furnace itself. But the air going through the media has to come from somewhere and it needs to be somewhat forceful. You can use a fan to push air through it and into the return flow, but it would have to be a big one. A better way is to tap the some of the air coming out of the furnace and route it back through the humidifier. But that air is hot. So you’re basically adding heat to the return air. You can tweak the system to account for that, but it’s a rather fine adjustment of a valve on the humidifier air intake, and switches that control how the furnace ramps itself up to running temperature. Apparently this was all off by just enough to make the heat exchanger run too hot at the low burner/low fan setting. At least, that’s the current theory.

A furnace, even one of the old ones, needs to be recognized as a part of a system that includes your duct work and how big the house is and how it gains or looses heat. You can’t just throw something in and expect it to be as efficient as possible, and if things are grossly mismatched it might not even work at all. And the more efficiency you want to wring out of the system, the more deftly you have to tweak the various parts of it. And that means the whole thing becomes a bit touchy. One of the reasons I’m not blowing a fuse over how long it’s taken to get everything to work is that I kinda saw this coming. I figured there would be a period of adjustment, I was just hoping it wouldn’t be as long as this. This new furnace is a lot more touchy then I’d reckoned on.

My old habits of opening and closing various vents throughout the house will make this furnace throw that same error code. I just can’t disturb the air flow. I have to keep everything open now, and let the furnace do its work if I want it to run at that super efficient low burner/low fan setting. Which is fine, it’s just a habit I need to change. It actually makes the house nice and comfortable when it can run in that mode most of the time. You can’t even hear it running it’s so low. Yet the house is nice and cozy now. And with the humidifier running, I can keep the temperature setting down about five degrees and still feel very warm and snug. And I’m not shooting sparks off whenever I touch something that’s metal now. Thanks to the humidifier the static electricity I usually get when the furnace is on is gone completely. When I switch from AC to heat again next winter, I’ll have to remember to set the humidifier airflow valve correctly (it needs to be turned off completely in the summer). Mom would tell me it beats cleaning out an ash trap.