Any HVAC people on here?

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tom4018

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I was thinking that I remembered someone was a HVAC tech on here. Had a question if any one is. Thanks.
 

ddd75

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i fix furnaces and install new ones all the time.

not an expert but whats the problem>?
 

jltrent

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What's your question? I am pretty good at working on old worn out farm equipment. :lol:
 
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tom4018

tom4018

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Had a guy give me a take out electric furnace that I wanted to use temporarily in my shop. Was trying to hook it up to test it before mounting it. Was just planning on having it have a short piece of duct blowing out single pipe.

Wired it up just to test last night and it runs a few minutes and trips the 60 amp breaker on it. Will the lack of duct work on it cause that? Was just using a single pole switch on it for testing as I didn't have thermostat yet.
 

greybeard

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If anything, I would think the lack of a somewhat restrictive duct would cause it to pull fewer amps..not more.
I assume it's rated 240 volts due to the heater strips. 60A should be plenty good.
 

CottageFarm

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No, the lack of duct wouldnt be an issue. Whats the rating on the single pole switch?
Picture of the switch would be helpful...
 
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tom4018

tom4018

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CottageFarm":xog3bhn6 said:
No, the lack of duct wouldnt be an issue. Whats the rating on the single pole switch?
Picture of the switch would be helpful...
I got the switch on the 24 volt control side, the thermostat wires. It is a 15 or 20 amp switch. Was using it to test before sinking a lot of money into it. I was told by the guy that gave it to me to wire a 2 wire thermostat into the red and white wires. It also has a couple more, gray and brown. Maybe I did something wrong using this just to test it.


 

ddd75

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what size heat strip? If its 15kw you'll need 2 breakers.

10kw and less it shouldn't blow a 60.
 

greybeard

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tom4018":34dt0ydb said:
CottageFarm":34dt0ydb said:
No, the lack of duct wouldnt be an issue. Whats the rating on the single pole switch?
Picture of the switch would be helpful...
I got the switch on the 24 volt control side, the thermostat wires. It is a 15 or 20 amp switch. Was using it to test before sinking a lot of money into it. I was told by the guy that gave it to me to wire a 2 wire thermostat into the red and white wires. It also has a couple more, gray and brown. Maybe I did something wrong using this just to test it.


Pretty big wires for a thermostat. You sure you aren't bypassing a relay instead?
 

CottageFarm

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White and red on the thermo wires are correct for turning it on.
So the Heat strips (2-or 3?) all come on? Does the fan run?
Assuming your incoming 220 wires are all connected correctly, my first thought might be a bad high limit switch on one of the elements tripping the breaker. Also verify all connections are tight and secure. Look for any scorched wires around the high limit and relays as well. Also may need to test the transformer for proper function
 
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tom4018

tom4018

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greybeard":15261x6h said:
tom4018":15261x6h said:
CottageFarm":15261x6h said:
No, the lack of duct wouldnt be an issue. Whats the rating on the single pole switch?
Picture of the switch would be helpful...
I got the switch on the 24 volt control side, the thermostat wires. It is a 15 or 20 amp switch. Was using it to test before sinking a lot of money into it. I was told by the guy that gave it to me to wire a 2 wire thermostat into the red and white wires. It also has a couple more, gray and brown. Maybe I did something wrong using this just to test it.


Pretty big wires for a thermostat. You sure you aren't bypassing a relay instead?

He said they were the thermostat wires.
 
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tom4018

tom4018

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CottageFarm":33wcbowx said:
White and red on the thermo wires are correct for turning it on.
So the Heat strips (2-or 3?) all come on? Does the fan run?
Assuming your incoming 220 wires are all connected correctly, my first thought might be a bad high limit switch on one of the elements tripping the breaker. Also verify all connections are tight and secure. Look for any scorched wires around the high limit and relays as well. Also may need to test the transformer for proper function
It comes on and runs a few minutes. Don't see anything that's looks like has been hot. Pretty sure I wired the 220 right.


 

jltrent

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Mine did simular and it was the motor. It was not an easy job to get the fan off the motor shaft. I also replaced the Capacitor while I was at it. That has been a couple years ago and worked great ever since. I think it cost around $175 for the parts and my labor.
 

backhoeboogie

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greybeard":qvaexu3f said:
If anything, I would think the lack of a somewhat restrictive duct would cause it to pull fewer amps..not more.
I assume it's rated 240 volts due to the heater strips. 60A should be plenty good.

More amps GB "with current goes the flow" Pumps are the same way. High flow, high amps.
 

CottageFarm

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There are, unfortunately, several things that could be at fault. Need to eliminate one at a time.

1.Inspect all wiring carefully. Especially hot wires. Look for any nicks or anything that could be grounding out.
Verify all connections are tight and free of corrosion.
2.You didn't mention whether the fan comes on? I don't want to assume anything...
3.Try connecting a thermostat instead of the switch.
4.Its not common, but breakers do go bad, especially if they've been tripped many times.
5.Next step is testing or replacing parts. I would start with the transformer, limit switches, and contactors/sequencers in that order.

Lots of good videos on youtube to walk you thru different diagnostic tests for different parts.

The upside is this is likely an inexpensive, but frustrating process.
 
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tom4018

tom4018

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CottageFarm":okzre70b said:
There are, unfortunately, several things that could be at fault. Need to eliminate one at a time.

1.Inspect all wiring carefully. Especially hot wires. Look for any nicks or anything that could be grounding out.
Verify all connections are tight and free of corrosion.
2.You didn't mention whether the fan comes on? I don't want to assume anything...
3.Try connecting a thermostat instead of the switch.
4.Its not common, but breakers do go bad, especially if they've been tripped many times.
5.Next step is testing or replacing parts. I would start with the transformer, limit switches, and contactors/sequencers in that order.

Lots of good videos on youtube to walk you thru different diagnostic tests for different parts.

The upside is this is likely an inexpensive, but frustrating process.

Fan runs and actually the whole unit seems function normally for the few minutes it runs before the breaker trips. I thought this type furnace would've been better a couple of the 5000 watt garage heaters since it has a stronger blower. Going to try to troubleshoot it more this weekend but I just don't want to put more in it than what the other heaters would cost me.
 

CottageFarm

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The solution should cost substantially less than buying 2 5k units

Do we know why the unit was originally replaced? Just looking for potential starting points....

Any chance you have a clamp style multi-meter to test the voltage running thru wires both upstream and downstream of the circuit breaker on the unit?

If not....If it were mine, I think the first thing I would test is the circuit breaker in the unit. Either swap it with another one or bypass it to see if it trips the breaker in the panel.
 
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