Question about fuses on a
Coleman Evcon electric furnace
Question sent as the result of the feedback form.
It was submitted on Tuesday, December 26, 2000 at 20:18:07
By Robert Stewart of Austin, tx.
Brand: Coleman Evcon
The problem that I keep having, is
the buss fuses keep blowing out. We had it repaired, or we thought so.
They replaced a transformer and said it was fixed. Now the heater just
went out again this time the fuses caught on fire, and burned a couple
of wires. I do know that it can be rewired, but my question to you is why
does the fuses keep blowing out, not only do they blow but they are also
really hot to the touch.
From: Scott Meenen n3sjh: It sounds
like you have the wrong size fuses or a problem with dirty or crummy connections
on the fuses and holders causing both to over heat and fortunatly the fuses
will blow to protect the equipment from fire (you hope). Loose connections
cause as much if not more problems than short circuits.
I would suggest buying or borrowing
a clamp on ammeter (shown above) and checking the current draw on the heaters.
Unless the heaters are shorting to the case of the cabinet they should
draw the same or less of their rated current. The rule of thumb for fuses,
circuit breakers and wiring is to load within 80% of the rating of the
wiring and the fuses should blow when over loaded to 125% (the reciprocal
of 80) of the circuit capacity. A 5kw heat strip will draw 21 amps at 240
volts and 18 amps at 208 volts. Following the rule you need a 30 amp circuit
for the 21 amp load.
Example a 12 gauge wire normally can
handle 20 amps that means you should have no more than 18 amp flowing through
it and when you get to 25 amps the 20 amp fuses or circuit breakers should
blow. This does not mean that you should run 20 amps even though the wire
can handle it and the fuses or breakers may not blow. This margin is to
allow surges for motors and other starting currents.
pump defrost cycle.
blower and fan controls work.
heat pump contactor images.
This page will be updated soon
Blower: usually a squirrel cage centrifugal air moving device. Will move
large volumes of air relatively quiet. Will use less energy with more back
Fan: a paddle type air moving device used where noise is not a major consideration.
Will use more energy with more back pressure.
Combustion blower: A blower used on high
efficiency furnaces or oil burners to move combustion air. usually 1/20
to 1/6 horsepower.
OEM: Original equipment manufacturer.
Horsepower: 746 watts
KW Kilowatt (1000 watts) or 3400 BTUs per hour
RPM: revolutions per minute.
Service factor: the extent to which a motor can be safely overloaded beyond
its name plate ratting without over heating.
Air over horsepower: The rating of a motor assuming air flow through the
windings usually as a result of the air moving device.
SAE: Society of Automotive Engineers.
Ton 12,000 BTUs per hour of heating or cooling.
Short circuit: an unwanted low resistance electrical path.
Short: (slang) any electrical malfunction. Please avoid using this term
in this manner.
Good Luck Scott
If your heat pump forms
ice outside in the heat mode click
If your air conditioner or heat pump ices
in the cooling mode click
If you have
water leaking problems with your air conditioner
click here to solve it.
For other heat pump problems click
For other heating system problems click
Any other questions feel free to contact us by
any of the means below. good luck Scott.
We service and repair the following brands:
American Standard, Amana, Arco, Arco-Air, Bryant, Carrier,
Coleman Evcon, Comfortmaker, Day/Night/Payne, Dunham-Bush, Fedders, Fredrich,
Goodman, General Electric, Hotpoint, Heil, Intertherm, Janitrol, Kenmore,
Lennox (Armstrong, Johnson Air-Ease), Miller, Modine, Nordyne, Rheem/Ruud,
Sears, Stewart Warner, Trane, Williams, White-Westinghouse, Whirlpool,
Weil Mclain, York, (Frasier Johnson/Borg Warner) and others.
Written By: Scott
Meenen N3SJH of:
This text written by: Scott Meenen * G & S Mechanical
G&S MECHANICAL SERVICES.
Specializing in Mechanical, Controls
and Electrical Modifications Of
Heating, Air-conditioning, Refrigeration,
Ice Production and Food preservation.
Anything having to do with Heat
Serving MD, DC, and Northern
Contact us http://toad.net/~jsmeenen/contact.html/font>
us at: email@example.com
Go to or return to
the G&S Mechanical home page
list of all the file on this site visit the site map