If one had a large-scale home retrofit program with the goal of saving energy, what would be the pros and cons of a policy to replace all standing pilot light furnaces?  Health and safety improvements count, as do energy savings.

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1st - safety, IMHO a trump card
Can now tighten & indoor ventilate as possible, rather than as limited to by CAZ req's. Though obvious, a Program may place E savings at the head of the list, increasing the oppt'y for travail & unfortunate headlines.

Well a standing pilot light / naturual draft piece of equipment is at best a .78 whereas a direct vent is around .95 - right there is a 17% increase in fuel efficiency. You pretty much eliminate the CAZ & associated problems with that

Cons - their are only two and the main one is cost but most of those units are probably coming close to retirement & they are probably looking at repair costs that will keep escalating until it is replaced

The second one, at least for water heaters is if the power goes out & there is no backup source or means of lighting it - you are quickly going to run out of hot water - most ovens (at least the burners) can still be lit with a match & your furnace, well it won't work without power (no matter what type you have)

With furnaces that old, cracked/rusted heat exchangers become a safety issue. You're dealing with furnaces at least 20 years old, many are much older. If the A-coil for the AC unit (if they have AC) is the same age as the furnace it is often clogged with dirt limiting airflow. Low airflow causes furnaces to "ride the limit switch" cycling the burners on and off as they overheat. Since most installed furnaces are twice the size needed the homeowner has no idea the furnace has a problem.

If the old furnace happens to be operating properly (there are a few of them) then upgrading to a 90% would have a LONG payback time strictly from an energy savings prospective. 10% of an annual gas bill might be $200, a new installed furnace is about $2,000. A 10yr payback... In warm climates payback time is longer, cold climates shorter.

We guessed that standing pilot light furnaces are not generally sold anymore.  If true, that means that they are on their way out, so a policy of converting them simply speeds up a natural technology evolution process.  Still, it might be worth doing to get energy savings now rather than later.

In a program that already replaces furnaces for "health and safety" reasons and to save energy, many standing pilot furnaces are already being replaced.  But using the standing pilot itself as a criteria for replacement might result in a few additional furnaces being replaced.

So, one of the pros might be fuel savings.  A standing pilot might account for about 1% of the fuel usage, representing waste.  However, the standby heat from the pilot is not all waste.  It heats the house in winter, and dehumidifies the basement in summer (since furnaces are often in the basement in our cold climate).  

We thought the economics might look different for natural draft vs. fan assist models; and LP vs. natural gas.

I hate to break this to you, but there not dead, not by a long shot though it should hopefully be tougher in your area

Fuel savings though is more than 1% (depending on usage of course - see above for numbers) & while it may add "heat..." most of that will be lost & a byproduct of combustion is water vapor

LP vs Nat - yes the numbers differ some but it all comes down to what is available

Nat draft vs fan assist vs direct - direct wins hand down from a safety & efficiency stand point


The last of pilot light furnaces rolled off the assembly line about 20 years ago. Any you find in the field are at least that old, many much older. Saw one yesterday that was made in 1975. Most manufacturers went from standing pilot to induced draft during the late 80's. There was only a few years where induced draft furnaces didn't have in-shot burners. These are rare to find still in use and were made during the transition from pilot to induced draft. Haven't seen one less than 20 years old. Any modern furnace will have in-shot burners. Better quality/high efficiency furnaces will be sealed combustion condensing models. Payback time isn't worth it for southern climates, but they make sense up north. The big opportunity to reduce energy bills comes from downsizing the furnace. The old beasts from the 70's/80's were typically twice the size needed to heat the house.

Technology has it's place, but legislating the adoption of new(or in this case not so new) technologies is not the way to reduce energy use. Last week I repaired a 100 year old NG converted coal burner for a client who has spent his money on weatherization instead of new furnace technology. His current NG use is $280/year, if he saved 20% of this with a new furnace that cost $3000 installed then his simple payback is around 55 years. Enforcing this kind of change, though beneficial to some would be impractical for others.

A more typical annual household natural gas heating bill here in WI would be more like $873, so that's what makes furnace upgrades more economical here.

Yes, a typical annual household heating bill here is about the same, but my client has spent his money on weatherization, so he is saving $600/year. There is no heating appliance that can make that kind of difference. We need to use our common sense to temper the advice of those who stand to gain by implementing their product.

Bill, nailed it again.  Exaggeration of benefits to "make the sale" is distressing.  Ecobee advertises 24% savings!  I love their thermostats (seeing how and when equipment operates is EYE OPENING, but the credibility loss of such absurd claims is distressing) 

Accurate modeling with tracking would fix this.  It would show the $280 starting, and the (maybe) $200 ending, and the homeowner would see the energy value and be able to factor that into his decision.  



It seems unfortunate energy transparency isn't seen as a necessary consumer protection, it would make widespread tracking of promises to actual savings possible:

An advantage is these furnaces have long passed useful life and will need replacement soon anyway, so "payback" is irrelevant.

By incentivizing replacement you can control quality of DESIGN and implementation.

I've been to houses where big old sp furnaces were replaced with grossly oversized "90%" furnaces that are so choked by undersized duct and short cycling/high limit that the homeowners not only realized NO savings, they suffer control and imbalance issues greater than when they had their old unit.

On the other hand, when done right I've seen TOTAL savings as high as 30% simply replacing 84% induced with 95% communicating modulating.

So, encouraging replacement of a thing needing replacement anyway, and insuring its done RIGHT can mean 15-20 years of significant savings instead of missed opportunity. Also, you'll be able to check envelope opportunities and show HVAC contractors a better path.

We recently did an audit for a client with this MASSIVE old, asbestos-wrapped boiler.  The client was complaining of $60 and $70 gas bills IN THE SUMMER.  When we got to his house, we figured it out.

The boiler had this huge pilot light with a 4 - 5-inch flame, and you could hear the thing crackle.  It was running all year long, even in summer, though he had a separate hot water heater.  "Typical" pilot lights burn 7.3 therms of gas a month, and the flame on his was easily four times what I'd call normal.

An HVAC contractor told him, "Yup, this thing could run for 50 more years."  And he's probably right.  But I asked my client if he wanted to be paying so much money for something that was 60 percent efficient when it was installed (in the 1920s) and optimistically, is 60 percent of that 60 percent. 

He's getting bids now, and they're pricey, to be sure.  But if he chooses to replace that old behemoth, his gas bills will be a lot less, AND his home will be safer.


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