Tuesday, September 11, 2018

heat 4 - the new furnace

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The new furnace has been operating here for the last two days taking the chill off cooler night temperatures.

Very quiet! Should use much less electricity. I intend to show how much less.


The installation techs had two visits ripping out the old oil burner/tank and installing the new propane furnace. Another visit tomorrow to correct some minor deficiencies identified at the "gas check".

I found it interesting that another company, in this case, my propane supplier who this summer installed my propane service, inspected the work of the furnace installer and did a leak down test. A gas pressure meter with high resolution is attached temporarily to a port at the tank regulator, the system filled to recommended pressure then the tank valve closed off. The pressure is watched for 15 minutes to note any drop. They did find one very minor leak outside, at the fitting to the regulator. It wasn't dangerous but it would have wasted gas. It was fixed with a bit more torque on the fitting.

This series is about my home electric energy use. My former heat source, a 1994 vintage Brock oil furnace burned fuel oil for heat but used up to 700 watts of electricity while it was running to power two motors and the spark igniter. One motor pumped oil and air into the burner, the other pushed air through the house. The igniter ran all the time there was flame, even after ignition.

The old furnace ran up to 35% of the time when the outside temperature was -15C. See the previous article Heat 3. My metrics to compare are the duty cycle at a given outside temperature and the energy drawn. Once I know these for the new Lennox EL296E 96 AFUE furnace monthly over the winter, I should be able to compare new to old to see how much of an improvement has been gained.

[click any pic to enlarge]

The burner motor in the Lennox is a conventional capacitor start motor but it is tiny - 1/20 HP! The diameter of the body of the motor is about three inches. A sewing machine might have a motor of this capacity. This motor supplies combustion air from outside to the gas burner.

In the oil burner, the corresponding motor also pumped oil as well as air to the flame. I believe it was 1/2 HP single speed. Because propane is pressurized in the tank, there is no need to pump.

As promised by my supplier, it has two speeds. Unlike the single speed oil burner and most gas units, this Lennox has two operating levels for the burner - High and Low. So I will have to watch the usage to identify the two, they may have different current draws. Supposed to provide efficiencies when little heat is required. Most of the time in winter Canada, a LOT of heat is required! It will run on high most of the time I think.

I will have to find the motor start capacitor that is attached to the two brown leads (shown on the lable). A failed motor start capacitor is an old time problem that could happen to this new motor after a few years. And an easy fix if you have a replacement capacitor, a few dollar part.

The house air mover motor is the bigger of the two at 1/2 HP. It is deep inside the bottom of the furnace but I can see it if I take out the air filter and look in the opening. I am actually taking this picture with my hand in the air duct!

This Endura Pro motor is from Genteq. It is indeed an ECM "Electronically Commutated Motor" which is supposed to save energy. It is also variable speed.

More on ECM later...this is an introductory tour.

The new furnace does not have a pilot light! When it is OFF, no gas is used.

I also have a new thermostat, a Honeywell T6 Pro which I am getting used to. Mine is not wifi connected but is a high end conventional programmable with the latest Honeywell baseplate and new multi-condutor wire to the furnace where previously there were only 2 wires. I now have a C-wire (or common wire). I believe I can upgrade just by plugging in a Honeywell Lyric T6 Pro but haven't decided to do that yet. I am most interested in verifying energy usage rather than control and I am not convinced that Lyric (or any of the others?) will help me do this.

The Lennox control board is about six inches square, located behind two covers. The thermostat connections are at the bottom. The micro computer is the small black rectangle near the center. I was not able to read any markings on it. The single 7 segment LED readout and the one single button are just up and to the left of the micro. This is a real mixed media board with surface mount and high power connections, spade lugs, Molex type connectors and some conventional size capacitors and a relay or two. Probably typical for a high power consumer appliance. It is marked Lenox under the wires at the top right so is a proprietary board.

This board is about 18 inches off the floor so to study or work on it means a very low stool to sit on or crouching on your knees.

I was joking about the error codes and a friend had asked me if there was a computer interface, like a USB port. I didn't see one. But there are about 25 status/error codes that show on the LED if required. I think you have to push the button to display.

I did my first mods!

The door that covers the big new filter didn't have a handle and was very difficult to open with fingernails so I added a solid brass handle!

Once the door is off the filter is in the opening and very difficult to remove since it fills the opening almost completely. Again, fingernails don't really work.
So I added a folded tab of packing tape which makes the filter easy to pull out to inspect. The tab folds flat against the filter when the outer metal cover goes on so it is out of the way.

Both work great!

The filter is supposed to last six months but you are supposed to look at it once in a while. Mine already had a few big dead bugs in it.

If they made it easier to look at, people might look more often!

More on the guts of the new furnace later...

I have lost my ability to see my overall electricity usage. The McMaster University program has ended. My Blueline Energy sensor no longer works. That will be another story. So I cannot yet see the electrical usage of my new furnace.

Thanks for your interest

George Plhak
Lions Head, Ontario, Canada

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