I upgraded the supply on a friend's shop to 200 amp service. While I
was there he asked me if I could install an electric furnace. I
calculated the heat load at 17,500 BTU/ hour.
I installed a new air handler rated at 22mw.I ran six gauge supply
lines on 60 amp breakers. I made sure that the air intake size was
adequate.
Here comes the problem, the heating unit has four rolls of coils only
two get red hot. I checked the voltage on both sides of all four coils
and get 110 v. The unit does not put out hot air, just luke warm. It
runs constantly and barely gets the place up to 60 degrees.
Any sugestions on where to go from here?

Ozark

22mw? Do you mean 22KW? Normally 10 KW requires 240 volts and a 60
amp breaker and #6 wire. Figure about 4.1 amps per KW at 240 volts.
An 11 KW heater would would work using the circuit provided. For 22 KW
you would need another 60 amp circuit. (2-x11 KW; 2x 60 amps @240
volts).

Note that 5KW would provide 17,065 BTUs/Hr. Therefore, your load
calculation must be wrong. A 5 KW heater should be enough to heat the
shop if your load was correct.

Note also that your heater elements should not glow. That indicates
low air flow. The heating coil in an electric furnace should have a
dull red glow or no glow at all if there is enough air flowing over the
heat coils. (The heat coils are also refered to as strip heat.)

Hope this helps

Stretch

"Stretch" wrote in message
oups.com...
22mw? Do you mean 22KW? Normally 10 KW requires 240 volts and a 60
amp breaker and #6 wire. Figure about 4.1 amps per KW at 240 volts.
An 11 KW heater would would work using the circuit provided. For 22 KW
you would need another 60 amp circuit. (2-x11 KW; 2x 60 amps @240
volts).

Note that 5KW would provide 17,065 BTUs/Hr. Therefore, your load
calculation must be wrong. A 5 KW heater should be enough to heat the
shop if your load was correct.

Note also that your heater elements should not glow. That indicates
low air flow. The heating coil in an electric furnace should have a
dull red glow or no glow at all if there is enough air flowing over the
heat coils. (The heat coils are also refered to as strip heat.)

Hope this helps

Stretch


AGree with all that and add this...

If you have a 25kW heater, its prob staged, meaning that the sequencers are
going to be delayed in bringing the strips online.

Your reading of 110V per side, really means nothing other than you have
110VAC to the strips, but they do require 220.
You should be reading 220VAC across them, assuming you have wired the
furnace correctly.

You don't say what area of the country you're in, but in my area, 17MBH
isn't much, especially if the shop isn't insulated well, and has loose
overhead doors. With the same air flow going across each coil, you should
have about the same color, but not bright red. What's your incoming voltage?
What's the voltage at each coil? What are your inlet and outlet air temps?

wrote in message
oups.com...
I upgraded the supply on a friend's shop to 200 amp service. While I
was there he asked me if I could install an electric furnace. I
calculated the heat load at 17,500 BTU/ hour.
I installed a new air handler rated at 22mw.I ran six gauge supply
lines on 60 amp breakers. I made sure that the air intake size was
adequate.
Here comes the problem, the heating unit has four rolls of coils only
two get red hot. I checked the voltage on both sides of all four coils
and get 110 v. The unit does not put out hot air, just luke warm. It
runs constantly and barely gets the place up to 60 degrees.
Any sugestions on where to go from here?

Ozark

This is Turtle

Bob , write out the number of BTU's need to heat the shop , but i think
your saying 17,000 btu of heat per hour to heast the shop.

Now you say there is 4 rows of heating elements in the furnace and only
2 is getting hot or turning red. I think you have a 20 KW electrtic
heat package and only wiring up 10 KW of the 20 KW of heat.

Now if your running 10 KW to heat a shop that only needs 17,000 btus is
or sounds find to do this job so, when you say it will never get up to
60 degree F in the shop with the two elements are running.

Now with all this said. i think you have your antisipator set wrong and
causing the a short cycle condition in the electric element running
time and not let the heat electric elements keep up by going on and off
too much.

You need to find your heat intisipator in the thermostat and set it
high as it will go on 1.2 or 1.1 or 1.0 . The scale goes fron .15 to
1.2 and setting it on the highest number you can will make it do fine.

e-mail me if you like to discuss it.

now we have some control freaks CBHVAC and Paul milligan that like to
confuse home owners that come through here and just beware who you
speak to.

TURTLE

since a little 110 volt 1500 watt plug in heater is about 5000 btu's,
your calculation says that you can heat his garage with four of these.
turn off your equipment and show me this at about $15-25 per heater or
borrow them times four. that will prove your heat load calculations.

see also:
"Convert is an easy to use unit conversion program that will convert
the most popular units of distance, temperature, volume, time, speed,
mass, power, density, pressure, energy and many others, including the
ability to create custom conversions!
see freeware download at:
http://joshmadison.net/software/convert/

Turtle, he says it never cycles off, --therefore the heat anticipator is
not preheating the bi-metal, etc., causing short cycling.
You are correct in which direction he should go for longer cycles,
usually there is an arrow on the older THs pointing the direction to
move it to get longer cycles.
- udarrell


TURTLE wrote:

This is Turtle

Bob , write out the number of BTU's need to heat the shop , but i think
your saying 17,000 btu of heat per hour to heast the shop.

Now you say there is 4 rows of heating elements in the furnace and only
2 is getting hot or turning red. I think you have a 20 KW electrtic
heat package and only wiring up 10 KW of the 20 KW of heat.

Now if your running 10 KW to heat a shop that only needs 17,000 btus is
or sounds find to do this job so, when you say it will never get up to
60 degree F in the shop with the two elements are running.

Now with all this said. i think you have your antisipator set wrong and
causing the a short cycle condition in the electric element running
time and not let the heat electric elements keep up by going on and off
too much.

You need to find your heat intisipator in the thermostat and set it
high as it will go on 1.2 or 1.1 or 1.0 . The scale goes fron .15 to
1.2 and setting it on the highest number you can will make it do fine.

e-mail me if you like to discuss it.

now we have some control freaks CBHVAC and Paul milligan that like to
confuse home owners that come through here and just beware who you
speak to. TURTLE


--
PROPER A/C UNIT & DUCT SIZING ESSENTIAL for EFFICIENCY & BTUH PERFORMANCE
http://www.udarrell.com/proper_cfm_b...syste ms.html