Getting To Know My Janitrol FEC 120-84


Old 11-09-10, 04:17 PM
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Getting To Know My Janitrol FEC 120-84

This is a Janitrol FEC 120-84
I live in Ohio, where my average Jan Temp is 18.8/32.6.
My house is uninsulated baloon style wood frame with wood siding.

I have an old furnace (some might say ancient) and when it quit making heat last winter the repairman told me I should replace it as a matter or both safety and efficiency. One of the things he told me was that most likely the efficiency of that furnace is only about 60%. I don't really understand that. The nameplate says:

Input: 120,000
Output: 96,000

That looks like 80% to me. So why is it that people tell me I'm only getting 60% efficiency? Does it decline with time? Is there anything I can do to bring it back up to 80%?
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Old 11-09-10, 05:59 PM
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The 80% figure is a steady state measure while the furnace is on, at it's most efficient.

The 60% figure is basically BS, but efficiencies are lower in standby modes when only the pilot burner is operating and while the furnace is warming up and cooling down.

Also, old furnaces tend to lose more heat up the flue.

So newer furnaces are more efficient. Figure a more realistic efficiency level for an olde pilot light furnace of about 75% and a newer mid efficiency furnace of 80%. Condensing furnaces get opwards of 90-95% efficient.

If you have a pilot light system, they can be converted to a pilot that is lit only when the furnace is heating, avoiding standby losses of the pilot burning all the time.

Or you can gain some of that back by turning the pilot off at the end of the heating season and relighting it in the fall.
Old 11-09-10, 09:14 PM
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@SeattlePioneer: Thanks. I would be interested in knowing more about upgrading the pilot, where might I find more info? If I decide to keep the old beast, what should I do to keep it working?

Just a side note, I keep running into this 60% efficiency thing everywhere I turn:

"as far as efficiency,,your old one is probably in the 60% -65% range" (Should I replace a 30+ year old furnace? ? - Yahoo! Answers)

"50 year-old furnace is more than likely < 70% efficient." (keep or get new - HVAC-Talk: Heating, Air & Refrigeration Discussion)

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