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Old 10-04-2013, 10:53 PM   #1
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Question About An Electric Furnace...


I have an Intertherm electric forced air furnace, model # FEH-020-HA-C. Over the past few years I've had to replace a couple of elements, a sequencer and a few of the furnace's internal wires that had burned off. This furnace has four 5000 watt elements.
According to the schematic it has a single speed blower motor, that's what it says anyway. The motor is a 240 volt motor and has two wires coming out of it. It also has a ground wire. Both wires go into the Molex connector. From there one wire goes to one of the 60 amp fuses and the other wire goes to one of the sequencers and connects to the same terminal as the upper element. The sequencer is wired to the other 60 amp fuse, or in other words, the other side of the 240 volt supply.
I've been noticing lately that the motor seems to only be running at half speed, although sometimes it will suddenly increase to full speed. I seem to remember it doing this occasionally in the past too. I am wondering if this is normal. Is this furnace supposed to run the blower at half speed some of the time?

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Old 10-04-2013, 11:27 PM   #2
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Question About An Electric Furnace...


what kind of thermostat do you have? What kind of system do you have?
Intertherm is a mobile home manufacturer specific.

Can you check amp draw through the blower motor wire? Do you have only one stage cool or two? Variable or two stage thermostat?

On average, no, no such thing as a single stage blower "ramping up" so what we need to know is is the system single stage, amp draw of blower motor during initial start up and subsequent "ramp up" and what kind of overall system you have including thermostat, condenser and air handler.

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Old 10-05-2013, 08:37 AM   #3
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Question About An Electric Furnace...


No it is not normal. does the motor have a capacitor attached to it or 2 extra wires from it to a capacitor? if so the cap may be weak. sounds like one of the motor windings is dying from old age and running slow is why you are blowing so many elements. looks like it needs a new motor 2 me. I have run into that same problem and it is the motor failing. U may have to get the motor from Intertherm as some of them have an extra small diameter/special size/mounting to fit in the small fan of those units. Universal/generics don't fit.
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Last edited by yuri; 10-05-2013 at 11:12 AM.
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Old 10-23-2013, 11:04 PM   #4
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Question About An Electric Furnace...


Thank you for your replies. The thermostat is just an old style Honeywell mechanical type, not programmable or electronic. I do not have central air. The furnace is used for heat only.
Anyway, since it is getting cold here now, the furnace has been running for the past three weeks or so. I've been doing some work inside of it, mainly replacing burnt wires and connectors for the elements. I had to push a few wires out of the way to get at some connections while I was working. Strange thing is, except for the first few times the furnace came on after I started it for the season, the blower has been running at full (normal) speed ever since. I'm still checking to see if it may have just been a bad connection, a break inside one of the wires, a loose push-on connector, etc.

All of my problems with this furnace started when I had to replace a burned out element. I bought a 5 kw re-string kit, or at least that's what it said on the package. After I installed the new element the power wires to the element began burning off. Out of curiosity, I compared the new re-string element with the three existing elements. Using my ohmmeter, I found that the new element read 10.4 ohms while the original elements all read 11.7 ohms. According to the label on the furnace, all of the elements are 5 kw. To my way of thinking, there must be at least a 700 watt difference between the original elements and the replacement element based on the readings from my ohmmeter. The new element pulls too much power. Which helps explain why the wires keep burning off. I am replacing the wires with a heavier, high temperature type of wire.

A couple of years after replacing the first element I had to replace another one. I used a re-string kit again and it too is rated at 5 kw, but it also reads 10.4 ohms and therefore draws more current than the original. Shortly after that I had to replace the sequencer that controls those two (upper) elements. Now the limit switch that controls those elements looks like it is getting too hot, so I fully expect that I'll have to replace it soon. I have been trying to locate some lower wattage ( 3.5 kw or 4 kw ) elements, but so far haven't had any luck.

Last edited by Koldhammer; 10-23-2013 at 11:12 PM.
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Old 10-24-2013, 04:50 AM   #5
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Question About An Electric Furnace...


At 230 volts, a 11.7 ohm strip heater is 4.52KW
At 230 volts, a 10.4 ohm strip heater is 5.08KW

At 240 volts, a 11.7 ohm strip heater is 4.92KW
At 240 volts, a 10.4 ohm strip heater is 5.53KW
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Old 10-24-2013, 09:53 AM   #6
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Question About An Electric Furnace...


Why not just buy and install a new furnace? In my experience those restring kits don't last that long as they never are the exact same length as the OEM springs and overheat and burnout due to the irregular spacing when you stretch them etc. Lots of my colleagues agree. I always buy a new element kit. With all the parts you are and will be putting in to it you can buy most of a new furnace and yours is never going to be very reliable IMO. Not very safe to keep having wires burning off. I have seen LOTS of burnt out and roasted electric furnaces pretty much catch on fire. Safety comes first IMO especially if you have a family. BY the time the main 60 amp breakers trip most of the wiring has overheated and burnt up and basically works like a fuse. A LONG time ago they put fuses on each element circuit but that is gone now.

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Last edited by yuri; 10-24-2013 at 10:01 AM.
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