Monday, January 18, 2010
How I Reduced My Natural Gas Use 75 Percent for Less Than $1,400
(Photo credit VA5LF via the Flickr Creative Commons license).
[Update 5/04/2010] We had a record warm winter this year so I could not tell what the impact of the new furnace was. However, I just got a gas bill for a month where the average temperature was just one degree warmer than last year and my gas bill was considerably higher. Not cool. It is possible to use more gas with a 95% efficient furnace than an old 80% one. My guess is that the more powerful blower has been pressurizing my leaky ducts and forcing a lot of hot air out into my unheated basement. Sure enough, when I inspected the new duct installed on top of the new furnace I found a 1/4 inch wide by 2 foot long gap in the back. That leak alone is almost like having an extra furnace register to nowhere! I am now in the process of sealing all joints and will let you know what happens.
[Update 4/11/2010] A 2 inch diameter plastic plug fell out of the furnace today allowing the exhaust to dump strait into my basement. The technicians forgot to apply any PVC glue to it. This is a situation that could very easily be fatal to a sleeping family.
This is an update to a post I did last winter titled:
Weatherization Nation--How I reduced my natural gas use 60 percent for less than $400
In that post I speculated that getting the next 20 percent reduction (for my goal of 80 percent total) was going to cost more than the first 60 percent, which was the result of picking all of the low hanging fruit (weatherizing). It has cost me an additional $1,000 to date to get that last 15 percent by replacing my worn out 80 percent efficient furnace with a 95 percent efficient one. The price difference between an 80 and a 95 percent furnace is about $1,000, which I added to $400 to come up with $1,400, which I admit is creative book keeping because my new furnace cost a lot more than a $1,000.
My hot water solar panels are on hold until better weather. I've concluded that a heat pump hot water tank would not be cost effective for my application. I found a study where this concept was tested in different cities. The test done in Seattle showed very little gain for two main reasons. The tank was in an unheated basement (as mine would be) and the winter air temperature was too low to provide much energy. In addition, the winter temperature of tap water in Seattle tends to be quite cold because it is coming from snow melt.
If one of these is located in, say, a hall closet, it will act just like an air conditioner, cooling your house to heat your water causing your furnace to use more energy to heat your house back up for a net energy loss.
Putting one in an attic would work because a lot of hot air ends up there that you can't use. On the other hand, a hot water heater in an attic is asking for real trouble when it eventually springs a leak.
In short, if you can't find a warm place outside of your home's insulated and heated envelope for one of these, they probably won't do much for you during the heating season.
One day it dawned on me that my 80 percent efficient gas furnace is 20 years old. This is old for any appliance, especially a gas furnace. This led me to discover that my gas utility is offering a $350 rebate to anyone upgrading to a 90 percent efficient furnace. And to ice the cake, the stimulus package offers a 30 percent tax credit, up to $1,500, for the entire cost of upgrading to a 95 percent efficient gas furnace. The rebate and credit knocked $1,400 off the $3,600 cost.
This credit is analogous to the cash for clunkers program for cars in that it will use a lot of tax money to accomplish next to nothing environmentally. It's mostly an excuse to pump money into the sagging economy, and only a fool turns down a government handout.
One drawback to government meddling like this is that businesses tend to jack prices to capitalize on the credits, nullifying some of the benefits to the consumer to grab some for themselves. This happened to the Prius when the hybrid credit went into effect. Every contractor was trying to use the rebate and credit to make their bids appear lower. I asked them not to mention either in their bids so I could get a clear apples to apples price comparison.
With sales tax, I will end up paying $2,500 for a 77,000 BTU Lennox furnace with a variable speed motor and two stage burner.
This furnace should in theory account for another 15 percent decrease in gas use, thus my estimate of a 75 percent reduction from our normal gas bills. That makes me only 5 percent away from my 80 percent goal.
I chose this furnace design for two main reasons. The variable speed motor uses half the power of my old furnace (when on low), saving about 300 watt-hours for every hour it runs (on low). This will help with my efforts to reduce electricity use 80 percent, which I have not yet written about.
I wanted a two stage burner because my home's heating needs are modest by today's McMansion standards and the furnace should run most of the time with the blower at lower speeds and with only half of the burners ignited. The higher blower speeds and extra burners will come in handy on especially cold days but will for the most part remain on standby.
Let me share some things I learned so you don't have to climb up the same learning curve.
To achieve this kind of efficiency, today's higher end, 95 percent furnaces have reached ridiculous levels of complexity. All things being equal, complexity equates to higher cost and lower reliability in general. For this reason I registered with Lennox for their extended warranty, which is free at this time as a promotion, which is another reason I chose Lennox ...although more than one salesman told me that most of the major parts inside most furnaces are made by the same companies.
Thermostats have also reached ridiculous levels of complexity, especially if you have central air and heat combined, which I don't, thank God. There is little need for cooling in Seattle. Today's higher end thermostats communicate with the programmable circuit board in the furnace to do all kinds of worthless things, much like the never ending new and improved versions of Microsoft Word.
I refused to be talked into a fancy thermostat. I liked my bullet proof, but not very accurate, round mercury switch version that is about half a century old. I didn't want the technicians to even touch it. They touched it anyway and I'll get to that part in a minute.
The last thing you want is to wait for your furnace to fail in the middle of winter when you can't take the time to get multiple bids and are at the mercy of the sharks.
January is a good time of year to get bids from contractors because business tends to be a little slack, in part because nobody is in the mood to spend money after seeing their Christmas Visa bills, especially in this economy. I got seven bids and coincidentally chose the one right smack in the middle of the price ranges.
I threw out two of lowest bids because (after checking on the Internet) the model numbers listed were not for a variable speed two-stage furnace, as I requested.
The next lowest bid was only $170 less than what I accepted but was for a furnace that I was not sure would really qualify for the tax credit. The website claimed it was "up to" 95 percent efficient. The tax form says "at least" 95 percent efficient. Some companies have compromised on the efficiency percentage points to keep the price a little lower than competitors. They got caught by the hard and fast cutoff of 95 percent by the federal tax credit and have been scrambling to modify their furnaces so they can pass independent tests certifying that their furnaces are 95 percent efficient. The furnace contractor certainly would not be liable if the furnace ends up not qualifying a year after installation, so just because he says it will qualify does not mean it will.
The three bids that were higher were significantly higher, up to $1,500 higher for the same furnace I had installed.
The lowest bids were done by the business owners themselves. The higher bids were, not surprisingly, done by salesmen working on commission.
Green being the latest shtick, two of the highest bidders, although from different companies, arrived in Priuses with the words "hybrid heating and cooling" painted on their sides. One was a 2010 model with a solar panel built into the roof. Thanks to the Prius, the word "hybrid" has a lot of marketing appeal. I drive one myself, when my wife isn't using it ...
One salesman confided that they had tried to market solar panels but gave them up after several bad outcomes.
Another whipped out a laptop with a printer and started to do an energy audit of my house in order to pick the appropriate sized furnace. I told him not to bother because it would be meaningless in a home that incorporates night insulation window plugs, and passive solar heat gain. We also close the heating vents to the upstairs. In addition, I suggested that a two stage furnace may stay on the lower settings most of the time making the whole analysis of dubious value. Not to mention, the furnace sizes come in a few large increments so you are likely to be slightly over-sized or under-sized no matter what you do. I buried them with common sense and now I just have to hope I didn't screw myself somehow.
This salesman said I would have to sign a paper that I would not sue if the heating system is sized wrong. I called his bluff, didn't sign a paper, and they didn't get the job (this was the highest bid with the guy driving the 2010 Prius).
My new furnace arrived on a Monday morning, 1.5 hours after it was supposed to. The first thing I did was check the part number to make sure they were not going to try to install a similar but cheaper model. The only difference in the model part numbers was the letter "V" which stood for variable speed motor and the furnace laying in my garage floor did not have a "V" in the part number. I pointed this out to the technician (who was late because he had gotten lost) so he called his boss who insisted that this was the right furnace, even though the part number on the bid clearly had a "V" in it. He finally capitulated and said he would send another one out.
This was supposed to be a simple swap out. All they had to do was replace a short piece of ducting to transition from the new furnace, rearrange the gas pipe, and install the PVC exhaust ducts, all in a wide-open unfinished basement.
They kept trying to talk me into a new thermostat, I suspect because they had managed to break the thermostat wire off in the wall. They could not get a new wire up to my thermostat because of blocking in the wall. The technician had to remove my old thermostat and I had a feeling it would never be the same again. I finally got a hammer and chisel and cut a notch in my sheet rock around the blocking and dropped a chain to the poor technician who was at his wits end by now.
After all this they could not get the furnace to work because it had a bad inductor motor and we had to spend the night without heat.
After they left I inspected their work. The technicians had twisted and cocked the existing gas pipes rather than install proper lengths of pipe, giving the installation a Dr. Seuss look, with one pipe sitting on a switch that could not now be turned. The new duct didn't fit and had two one-inch wide gaps that they covered in tape. I could see that the furnace was not level from ten feet away and they ran the condensate line down my siding rather than into my mop sink as requested. Oh,and the filter was leaning up against the furnace at about a 30 degree angle with no way to secure it to the duct opening.
I called the boss and complained. The next morning I was not pleased to see a very pissed off technician at my door who informed me that he was there to rearrange the gas pipes "on his own time," that the furnace was supposed to lean in that direction, and one inch gaps were perfectly acceptable. I'm just hoping he did not run a screwdriver though the circuit board before he left, but at least the furnace now works.
I decided to replace my thermostat after all this because, oddly enough, it was no longer working properly. I wanted a simple, non-programmable unit and as usual turned to the internet for advice. I found one commenter who, after taking the advice of another commenter on how to hook up his thermostat, found that it had melted over night. Later I found the comment that had misled him on another thread. I wonder how many houses that jackass has burned down.
I also learned that you have to take what the contractors tell you with a big grain of salt. Trust but verify. They just want to sell you a furnace. It's a jungle out there. Good luck!
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