# A question for the HVAC guys

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
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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
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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.
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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?

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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
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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:

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PROPER A/C UNIT & DUCT SIZING ESSENTIAL for EFFICIENCY & BTUH PERFORMANCE
http://www.udarrell.com/proper_cfm_btuh_duct_sizing_air_conditioning_systems.html
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On 29 Dec 2005 16:29:10 -0800, snipped-for-privacy@hotmail.com wrote:

Call a real heating company like you should have done in the first place. You've already saved the guy some money now have a real tech check it out and get it right. Bubba
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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.
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