Making sense of heating systems
Published on October 18, 2022 at 3:37pm EDT | Author: Chad Koenen0
The Prairie Spy
Alan “Lindy” Linda
I serviced and installed heating, air conditioning, and refrigeration products while doing business as Lindy’s Hardware in New York Mills. Then I designed an HVAC (heating, ventilating, air conditioning) program for the tech school at Wadena, which I taught for fifteen years, up to retirement a couple of years ago.
That’s my background, and that’s also why I get calls from folks puzzled about what they should do with their heating situations. Mostly around here we do not have “cooling” situations, at least when it comes to comfort cooling, or air conditioning. Mostly we have “heating” problems, and that’s where money can theoretically be saved. (Theoretically, anyway.)
I say that because while payback on money you invest in very expensive heating equipment can somewhat be calculated, what is not so readily predictable is the money that will be taken from you to repair this very complex “saving” machinery. If you ignore this part of the “savings” equation, you do so at your bank account’s risk. KISS is my approach. Keep It Simple, Stupid.
First, let’s compare fuel costs. LP (propane) is varying quite a bit, depending upon whether you summer fill, own your own tank, lease, etc. I figure this at pennies per gallon cost. (I use pennies; it breaks down more understandably.) Let’s do the price at $1.55 per gallon, or155 pennies. (This is about what I just paid.) You get 92,500 Btus per gallon. 92,500 divided by 155 gives you 597 Btus for your penny. If you have a reasonably modern gas furnace, it’s probably 90-plus efficient. 597 at 90 percent efficiency gives you a final 537 Btus for your penny.
Number 2 fuel oil is around $4.00 a gallon. It has 140,000 Btus in a gallon. Number 2 at 400 pennies per gallon is 140,000 divided by 400 gives 350 Btus per penny. At a normal 80 percent, you end up at 280 Btus for your penny. Out in the country, propane wins.
Natural gas is still the king. In NY Mills, it’s around $8.00, or 800 pennies, for a thousand (Mcf) cubic feet, which is down from last year. A thousand cubic feet of natural gas is a million Btus. Divide that by 800 pennies is 1,250 Btus, which, if burned in a 90 percent efficient furnace, gives you 1,125 Btus for your penny. WE HAVE A WINNER!
(Trying to figure out some natural gas bills is almost impossible. NY Mills? Simple. One line has amount; next has tax, and there you have it. In Waterloo, Iowa, just for another example, it’s more complicated. Their bills would take an MBA to figure out. Their bill: Pipeline transport charge, gas supply charge, basic service charge, capital investment charge–and three or four more line charges! Really, really impossible to figure out! It’s almost like they don’t want people to know. Hmmmm.)
Near as I can figure it, in Waterloo you’re paying $8.47 for a thousand cubic feet (Mcf). That calculates out to 1,180 Btus per penny. Burn it in a 90 percent furnace, you get 1,062 Btus for your penny.
But only if you live in town. Those of us outside town have to wrestle a very slippery bit of arithmetic to find a winner. First, my opinion: Keep it simple. Avoid too many moving parts and electronic controls. Gas furnace. Oil furnace. Air conditioning. Simple. And lowest cost going in. Yes. I admit. I’m not in the business of selling HVAC stuff to make a living. That’s my disclosure statement. But it also means that I do not have a horse in this race, not even an inexpensive one. Any heating solution involving an air source heat pump, in my opinion, must also be accompanied by wiring your house for off peak usage.
Should you choose to wrestle this arithmetic, and choose off-peak electricity (I’ll use REA figures, which by the time you add in fees and tax and stuff, is about 6 pennies per kilowatt (Or more, depending upon some pretty fuzzy multipliers that they have control of.), or 3413 Btus, so if you’re using straight resistance heating on off-peak, like electric baseboard (good because no moving parts) or an electric plenum heater (not quite so good because control issues can cause headaches), you get 3413 divided by 6, or 569 Btus per penny.
Yes, off-peak resistance heat compares well, but remember, you have a significant up-front electrical wiring investment to recover, likely in the thousands of dollars, and you still need a back-up unit. (There is yet another situation whereby you do not need a backup unit. It’s called storage. In my opinion, the up-front costs and complexity outweigh the savings.) Finally, you get those favorable off-peak rates because they can shut you off when it’s very cold. But what I really hate is them shutting me off when it’s also very hot! You can bring in your back-up unit when it’s cold, but there isn’t one for hot.)
Finally, most HVAC personnel will recommend an air source heat pump, and it will sound good because “it’s only a little more money” than straight air conditioning. (IF it is off-peak!) Here’s where things get complicated. You can only get the really high efficiencies with air source stuff by combining it with very high efficiency back-up furnaces, and this is where the KISS rule (keep it simple, stupid) is broken. These heat pump, plenum heater, furnace combinations can completely ruin any savings at the drop of a hat. I know. I’ve been on both ends of this. I’ve had it happen to me. And I’ve had to repair it for others. I still do enough of that to know.
FYI, here’s where my opinions come from: I’m not making my living by selling the equipment discussed above. If I were? I might like selling you more expensive and complicated stuff. I might. As I look back to when I actually sold HVAC equipment, I still liked KISS. I hated telling my customers that it was going to cost $2000.00 to fix their stuff. (And I had to tell some folks that.)
What do I use? Since I did all my wiring for off-peak by myself, I got by for less than a thousand dollars by installing my own 200-amp main, a 100-amp sub to off-peak; another to on-peak; and another meter base. I use a single-stage air-source heat pump, set to not come on below thirty degrees. Anyone who tells you you can run these down to zero or below is neglecting to tell you that you’re not getting much out of them when it’s that cold.
You’re confused? Well, this is confusing stuff.