Breaker feeding Disconnect for HVAC

[Paulski]

I'm getting a new heat pump system, and the air handler in the attic wants 240v 15amps. Space is at a premium in my main panel so I need to use a triplex breaker, but I'm having trouble finding a 20-15/15-20 Siemens breaker. I can find a 20-20/20-20 triplex breaker no problem.
A 30 amp (two 15 amp fuses) quick disconnect is required at the air handler, can i use the 20 2 pole breaker to feed the 15/15 amp disconnect since the air handler is protected by the fuses?

My other thought is (let me know if this is crazy in some way! Just seems like a lot parts to go from 20 to 15 amps?!?) put a sub panel in the attic next to the quick disconnect, fed it off of the 20a 2 pole triplex breaker in the main panel. Than i can put a 15a 2 pole in the sub panel to feed the quick disconnect. This also has a benefit of i can also put a single pole breaker in the sub panel to power to the attic lights

Little background on current system-
20 amp 1 pole breaker feeding air handler/lights in attic
40 amp double pole breaker feeding condenser unit outside (breaker is a triplex 20-40/40-20). I plan to reuse this circuit for heat pump mounted outside

 

[wyliesdiesels]

Which breaker model line? QT?

According to this it doesnt exist

https://cache.industry.siemens.com/dl/files/576/109793576/att_1054656/v1/SIE_BR_QT.pdf

but i did find it on amazon, third party seller. Im guessing its BS

SIEMENS Q22015CT 20/15A 240V 4P 10K NEW QUAD - Amazon.com

SIEMENS Q22015CT 20/15A 240V 4P 10K NEW QUAD - Amazon.com

www.amazon.com

 

[wyliesdiesels]

I'm getting a new heat pump system, and the air handler in the attic wants 240v 15amps. Space is at a premium in my main panel so I need to use a triplex breaker, but I'm having trouble finding a 20-15/15-20 Siemens breaker. I can find a 20-20/20-20 triplex breaker no problem.
A 30 amp (two 15 amp fuses) quick disconnect is required at the air handler, can i use the 20 2 pole breaker to feed the 15/15 amp disconnect since the air handler is protected by the fuses?

you dont add up the poles to get 30a. 240v 15a is a 15a circuit.

As far as using a 30a disco fed by a 20a 240v breaker, it depends on the wire size and MCA listed on the air handler. Have a screenshot?

My other thought is (let me know if this is crazy in some way! Just seems like a lot parts to go from 20 to 15 amps?!?) put a sub panel in the attic next to the quick disconnect, fed it off of the 20a 2 pole triplex breaker in the main panel. Than i can put a 15a 2 pole in the sub panel to feed the quick disconnect. This also has a benefit of i can also put a single pole breaker in the sub panel to power to the attic lights

you dont want a subpanel in an attic.

Little background on current system-
20 amp 1 pole breaker feeding air handler/lights in attic
40 amp double pole breaker feeding condenser unit outside (breaker is a triplex 20-40/40-20). I plan to reuse this circuit for heat pump mounted outside

I wouldnt want the air handler on the same circuit as the lights but to each their own. Regardless, you wont be able to keep feeding the lights when you convert this air handler circuit to 240v unless they ran 3-wire (2 hots neutral and ground). So you will have to run a new circuit for the AH...

 

[Paulski]

Here is the spec sheet. I guess the quick discount would be two 15 amp fuses, not 30. I can keep the lights on a different circuit, the attic lights are only two 24" Leds

 

[wyliesdiesels]

#14 wire and 15 breaker or fuse. i dont see where it requires fuses.

 

[theoldwizard1]

A 30 amp (two 15 amp fuses) quick disconnect is required at the air handler, can i use the 20 2 pole breaker to feed the 15/15 amp disconnect since the air handler is protected by the fuses?

Yes. You can always install a smaller breaker/fuse "downstream". The feed to the disconnect will still have to be 12/2.

Around here, a NEMA 5-15R "convivence" outlet is also required near the compressor.

 

[Paulski]

Thanks everyone. The system plan has been changed up to a Diakin DFVE60, which is 120v, wanting a 20 amp breaker.
Any suggestions on what to use for disconnect in the attic? Is it as simple as using a single pole light switch mounted by the unit? Or use a cord to a receptacle?

 

[mikedodge]

You can get motor rated switches for stuff like that. It looks like a light switch but more heavy duty. Usually see them near furnaces or on small under counter hot water tank.

 

[PCustoms]

Thanks everyone. The system plan has been changed up to a Diakin DFVE60, which is 120v, wanting a 20 amp breaker.
Any suggestions on what to use for disconnect in the attic? Is it as simple as using a single pole light switch mounted by the unit? Or use a cord to a receptacle?

Get a non-fused AC disconnect

 

[Paulski]

I think i like the non fused disconnect over the switch since I can see the actual air gap, or not accidentally bump the switch on without realizing it. I found this one on HD:

Halex 60 Amp Non-Fusible Metallic AC Disconnect HNF60R - The Home Depot

Offer the best and ultimate addition to your electronic application by selecting this Halex NonFusible Metallic AC Disconnect.

www.homedepot.com

Since it's 120v, do I only connect the load supply to the disconnect and wire nut the neutrals? Or connect the load and neutral to each leg of the disconnect so they both get disconnected when the lever is pulled out?

 

[JunkBonds]

Stick with a 240v system. Do it right

 

[wyliesdiesels]

I think i like the non fused disconnect over the switch since I can see the actual air gap, or not accidentally bump the switch on without realizing it. I found this one on HD:

Halex 60 Amp Non-Fusible Metallic AC Disconnect HNF60R - The Home Depot

Offer the best and ultimate addition to your electronic application by selecting this Halex NonFusible Metallic AC Disconnect.

www.homedepot.com

Since it's 120v, do I only connect the load supply to the disconnect and wire nut the neutrals? Or connect the load and neutral to each leg of the disconnect so they both get disconnected when the lever is pulled out?

dont need to disconnect the neutral. just wire nut them

 

[wyliesdiesels]

Stick with a 240v system. Do it right

so 120v systems arent right?

 

[dscheidt]

Around here, a NEMA 5-15R "convivence" outlet is also required near the compressor.

Code is 25’ and at the same level. (So in the attic)

 

[yatg]

I think i like the non fused disconnect over the switch since I can see the actual air gap, or not accidentally bump the switch on without realizing it. I found this one on HD:

Halex 60 Amp Non-Fusible Metallic AC Disconnect HNF60R - The Home Depot

Offer the best and ultimate addition to your electronic application by selecting this Halex NonFusible Metallic AC Disconnect.

www.homedepot.com

I like the Square D disconnects. QOTR200TRCP
simple switch, no pullout to fumble with.
About $21 at Home Depot.

 

[Codyboy]

Stick with a 240v system. Do it right

They do make a 230/208 in that same model op Posted
Diakin DFVE60
I too would go with a 240 volt model. Not sure if that makes it right but I like 240 to keep loads balanced on each leg easier.

 

[nadogail]

240 volt systems allow you to use the more economical thinner wire.