Relay Computing, Redux

On Saturday, November 26, 2011, I posted about my nearly-twenty-year-old furnace and its relay computer control systems, and installing An AprilAire humidifier. Two days ago, instead of cool air, to combat the ghastly late July heat, we were treated to the smell of burning insulation. At first, we assumed it was my jumkbox PC (see Separating Work from Play, along with Update 1 and Update 2). I'm loading its very cheap Chinese power supply fairly heavily and it has been very warm. Alas, sniffing the heating duct proved this not to be the case.

Diagnosis: the fan motor had burned out. Our technicians who serviced the thing had been saying, virtually unanimously, "It's working ok now, but it's (19,20,22) years old, and it's not worth spending a dime on parts for it." We took their advice.

So new furnace, one of these Lennox modulating furnaces. Instead of waiting for the house to drop to a low enough temperature to make firing up the big guns worthwhile, it has a range of low power settings down to 35 percent, and will use them when the house is only a degree or two low. It's rated at 97.5 efficient. We also got one of these air conditioners with it. It's a midrange model (whereas the furnace is top of the line) since we cool sporadically 3-4 months a year and heat continuously nearly 8, and the furnace's uber-blower serves both systems.

Expensive? Yes. Does it come with a lot of cool bells and whistles? Yes. The control system on this furnace is impressive. It can control the humidifier. It has an outdoor temperature sensor built into the air conditioning unit. It runs diagnostics on itself It has, I'm told, a Carbon Monoxide sensor built in. It has a directly connected air intake. Its exhaust flue is PVC and plumbed out through the side of the house. The system is nearly silent. It can download its own firmware. Did I have surge suppressors put in on both the AC unit and the furnace? You betcha.

It's not quite to the point of saying "Hal, turn up the air conditioner, please." But it's close.

Naturally the weather broke just as they started testing the air conditioner. Now it's lovely and temperate, after a small rain storm. We have the windows open, and we're enjoying the fresh air. And the amazing, impressive, digitally controlled HVAC system that looks as though they've installed warp drive in our basement... is turned off.

Go figure.

-JRS