Heat Pump not performing like it should

[Roy D. Cooke, Sr]

Originally Posted by sshockley

Well here is the culprit...bad wiring job. I'm going to order a whole new Electric Heat Kit in the morning. One of the Limit switches was open and it cost $82 to replace by itself. I can get the whole kit for $211 and have it delivered to my house by Saturday morning. Any ideas why the circuit fried like it did without tripping a breaker?

Yes breakers trip on over load, a loose wire can cause heat with out over loading the circuit .
You will find this some times in the panel and the breaker can be destroyed .
You see a switch that has burn markes on the wall usually from a loose wire and this frequently can cause a fire ... Roy

[Stephen P. Shockley]

I'm planning on swapping out the supplementary heater on this thing in the morning, but have one question. The supply coming to the Air Handler disconnect is #6-2 AWG Aluminum SE cable. Then the same type and size is used from the disconnect to power the Air Handler. Is there any reason why I can't replace the leg from the disconnect to the Air Handler with #6-2 AWG Copper wire? The breaker in the Main Panel for the Heat Pump is a 50 AMP, so I wasn't sure if I could get away with #8-2 copper.

Forgot to mention that the new supplementary heater comes with a built in circuit breaker that is a 60 AMP.

[Bruce A. King]

Originally Posted by sshockley

I'm planning on swapping out the supplementary heater on this thing in the morning, but have one question. The supply coming to the Air Handler disconnect is #6-2 AWG Aluminum SE cable. Then the same type and size is used from the disconnect to power the Air Handler. Is there any reason why I can't replace the leg from the disconnect to the Air Handler with #6-2 AWG Copper wire? The breaker in the Main Panel for the Heat Pump is a 50 AMP, so I wasn't sure if I could get away with #8-2 copper.

Forgot to mention that the new supplementary heater comes with a built in circuit breaker that is a 60 AMP.

Check your post for typo's, you mentioned 6-2 copper and then 8-2 copper.

The strips need to be wired for 125 percent of the load since they are considered continous loads by the code.

You need #6 copper for one 10kw strip. The #6 copper cable sold in many stores is a lower temperature rating and would be rated for 55 amps but this would still work for most 10kw strips and most blower motor loads added in.

#8 copper might work for one 7.5kw strip but the blower amps added in could bring the total over the limit.

A 5kw strip can use #10 copper.

These sizes all assume the wire lengths are within limits too.

I'm not an electrician, just have lots of experience and google by my side.

[Stephen P. Shockley]

Sorry for the confusion, you may have to dumb it down just a bit more for me. I'm attaching an image of my Air Handler's load ratings. My heater strip has two 5kW strips in it. In the image, my model is the third one down on the list. The original installer never marked it off. I guess I'm still not clear on which of the numbers to use to calculate the load rating, because they provide a min value at 208V and a max value at 240V.

From what I can tell, the #6-2 AWG Aluminum SE cable is of the Type XHHW-2 it is rated at 60 AMPS under the 90 deg C column, (http://www.armstrongssupply.com/wire_chart.htm). If they used the minumum 46 Amp for the 208V supply to calculate this, then they would have come up with 57.5 + 2.1 for the Fan for a total of 59.6. The breaker at the panel is a 50 Amp.

Just still not clear on how to come up with the right number for the changeover to copper that I want to make from the disconnect over to the Air Handler itself based on the data in the image. Do I multiply 1.25 x the 46 Amps for the 240V supply rating and then add the Fan's 2.1 Amps and use the same 59.6 result to calculate the correct Amperage for the copper?

[David A. Andersen]

Seeing that you have had a burn out the way it was with Alu, why don't you stick with #8 but go to copper? Your not running it back to the main panel are you?

It shouldn't cost too much more.

[Bruce A. King]

Originally Posted by sshockley

Sorry for the confusion, you may have to dumb it down just a bit more for me. I'm attaching an image of my Air Handler's load ratings. My heater strip has two 5kW strips in it. In the image, my model is the third one down on the list. The original installer never marked it off. I guess I'm still not clear on which of the numbers to use to calculate the load rating, because they provide a min value at 208V and a max value at 240V.

From what I can tell, the #6-2 AWG Aluminum SE cable is of the Type XHHW-2 it is rated at 60 AMPS under the 90 deg C column, (http://www.armstrongssupply.com/wire_chart.htm). If they used the minumum 46 Amp for the 208V supply to calculate this, then they would have come up with 57.5 + 2.1 for the Fan for a total of 59.6. The breaker at the panel is a 50 Amp.

Just still not clear on how to come up with the right number for the changeover to copper that I want to make from the disconnect over to the Air Handler itself based on the data in the image. Do I multiply 1.25 x the 46 Amps for the 240V supply rating and then add the Fan's 2.1 Amps and use the same 59.6 result to calculate the correct Amperage for the copper?

You should be using the 240V numbers for regular residential power.
The data plate says copper only.
You should use #6 copper.
If you end up splicing copper to the exisiting AL I would get a box that has terminals instead of just using big wire nuts.

The problem with heat pump strips is that some people end up not getting the compressor repaired and use the heat strips all the time.

[Stephen P. Shockley]

Ok, I have it all installed and did end up replacing the leg from the disconnect to the Air-Handler with #6 copper wire. Turned it on and could smell a burning smell coming from the registors. I turned if off immediately, because I didn't read anything that said this was normal when first fired up. Didn't smell like wires burning, DSS or smoke. I have heard of a burning smell you get when turning it on for the first time in the heating system, but nothing with regards to first turning it on after a heater strip replacement. Anybody know if this is to be expected?

[Wayne B. Wilson]

Stephen
As you said the coil was dirty, That would me think the heating coils are too, most likey dust burning off the heat strips , try it and monitor. It should disappear fairly quick

[Stephen P. Shockley]

Thanks Wayne. I had actually read that the factory sprays some sort of oil coating on the coils before packaging to prevent rust and that is the smell off of a new one, so I decided to be brave...lol.... Just after posting and finding that information I went ahead and tried again. Didn't smell anything the second time I restored power and turned it on. Hopefully, I've got it this time.

[Wayne B. Wilson]

Keep us posted. lol so you replaced the heat coil too?

[Stephen P. Shockley]

Ended up buying the whole heater coil assembly with breaker. The cost ended up being $139. Trane wanted $72 a piece for the limit switches if I were to get them through a local HVAC guy I know (they won't sell to me...lol). Dave A. walked me through testing the limit switches and one of them was bad and I didn't want to take a chance at buying one only to find out the other might be welded shut from the heat it had when it fried. Anyhow, I do have a few spare parts.

I'm re-wiring the second floor unit next weekend before anything happens with it.

[Doug Edwards]

gotta give you credit, it was a ballsy move. Never saw anyone do HVAC work by Braille before.