Ending and Beginning

I’ve surrounded our cast iron wood stove with some thermal mass: about 9 gallons of water and a couple hundred pounds of brick and concrete. This has:

• slowed the rate at which the stove warms the room & house after lighting a fire.
• extended by 6 hours or so the time during which the heat from the fire heats the house after the fire goes out

That’s all fine and good, but what has it really gained us? There’s not enough thermal mass to allow us to treat it like a Russian stove and build just one or two fires a day. From a time and effort standpoint, considering the extra labor involved in splitting kindling and building a new fire, it doesn’t make sense to let the fire go out and relight it every few hours.

So as I see it, we don’t yet have enough thermal mass to have just a couple of fires a day, and it might be hard to get enough around the stove. And if you’re not at that point, the only real benefit is that the stove/mass keeps heating the house for six hours or so after you let the fire go out. More thermal mass will further slow the rate at which the  stove warms the house, but will extend further the stove/mass heating of the house after the fire goes out, and eventually you would arrive at the ideal of just one or two fires a day…probably.

There is the possibility that a cast iron or steel stove lets too much heat escape up the chimney to ever be able to adequately heat whatever thermal mass surrounds it to get down to the 1 or 2 fires/day ideal. One of the advantages of a Russian stove is that exhaust gases from the fire are channeled through masonry, capturing more of the total heat output of the fire. Surrounding a conventional iron or steel stove with thermal mass would be like building a Russian stove that had thermal mass only around the firebox — obviously much worse at capturing heat.

And so it’s still a question in my mind as to whether conventional stove with thermal mass can ever get even close to the Russian stove performance ideal.

So, I was on the fence about whether we should get a new furnace this year or not.

Pros for getting a new one:

• It’s 14 years old.
• There’s a worthwhile tax credit that expires on 12/31/2010.
• How much longer are we going to stay in this house? (Having newer mechanicals is a good selling point.)
• The new one would be more efficient (95% efficiency required to qualify for the tax credit). Efficiency could be very important if the price of LP goes up in the coming years.

Cons against getting a new one:

• Even with the tax credit, it’s a lot of money.
• How much longer are we going to stay in this house? (Why put money into a place when you’re going to leave?)
• We’ve been burning lots of wood for the last several winters, so our furnace has been used less than average and probably has more life left in it than the same furnace in a comparable house where it was the only source of heat.

Like I said, I was on the fence.

We attempted to turn the furnace on for the first time this year on 11/19/2010. It wouldn’t run. I went down and pulled off the air intake pipe, then it ran. A plugged air intake pipe has been the problem several times before.

But during that night, I woke up and  I could hear the furnace trying to start but never coming on. I shut it off from the thermostat since I didn’t feel like messing with it in the middle of the night. I thought the air intake might have slipped back into the opening.

The next day, I went down there and the air intake had not slipped back in the opening. Since I am not comfortable pulling a gas furnace apart, I called our local furnace repair service on Monday, and they came out and looked at it. They gave me an estimate of over $400 to repair the old one, and that tilted me over to getting a new furnace. By that afternoon, the new one was installed and we were $3,375 poorer.

$3,375   Invoice Amount
$-150   State Rebate Program
-$1,020 Federal Tax Credit
$2,205   Final Cost

It’s still a lot of money, but I’m glad we did it.