40amp heat pump on 100amp panel?

[bzinsky]

Doing my first house flip, I usually do commercial projects. I’m not sure what to do.

This is an 1800sq ft twin in an upscale neighborhood with victorian homes. I have an existing 100amp panel. I have a 60amp subpanel right next to it as well. The 100amp panel is full.

I’m installing hvac now, and the hvac guy decided to use one zone as a gas heater and one as a heat pump, both have AC. The electrical requirements for these systems are
Unit 1 -50amp breaker for heat pump strip heat
Unit 1 -20amp breaker for its normal duties of blower/ac/heatpump
Unit 2 -20amp breaker for normal duties of blower/ac

That actual heat in the heat pump strip is a 8kw, which has an actual load of 33amps (i think).

I’m trying to get away with not upgrading the main panel. Because then I have to upgrade the service feed, and it’s pretty expensive. Is this going to be ok?

My plan was use that 60amp subpanel for all the hvac. Or maybe upgrade that to an 80amp. Which is easy because it’s right next to the main panel.

Thanks in advance for taking the time to read!

Edit:stove is gas, dryer is gas, water heater is gas

 

[wyliesdiesels]

Have you done load calcs?

Without those and without telling us all loads, its hard to say over the internet.

Best bet is do a load calc.

But if everything is gas, my WAG is youll be fine.

 

[Jim greengo]

Do you have a gas water heater and stove?

 

[alfredeneuman]

I've done an absolute minimum load calc on your existing service.
1800 sq ft X 3va per = 5400va (EDIT: General lighting & Recps)
2 small appliance @ 1500va = 3000va
1 laundry circuit @ 1500va = 1500va
It comes to a minimum of 41.25A
It doesn't take into account any other loads on the service.

 

[walta]

It seems to me you are forgetting 2 240V 30 amp breakers one for each outdoor units.

The air handler for unit 2 is likely to 120V 20A

Generally the 240V 50 amp strip heat breaker will power that air handler unit 1. So you can scratch one breaker off your list.

1 50 amp breaker might be enough heat if you are in AZ or FL but most other places and homes will need 2 or 3 50 amp breakers.

If no one has done a manual J every one is just guessing if you have the correct size of equipment for this house.

Walta

 

[sberry]

There is a couple ways to view this. Now or later and this is a flip. I have seen a lot o0f homes run major electric appliances on 100, Wouldn't concern me a lot to look at it 85% loaded in the calc, a little would depend on the condition of the equipment and would depend on if I thought I could recoup the cost, I can do an upgrade at cost so that's another part of the equation.

 

[alfredeneuman]

TWouldn't concern me a lot to look at it 85% loaded in the calc,

Unless it's a continuous load you could use up to the full 100 amps

 

[sberry]

Yes, agree, was making a point that its not overloaded. If it was in good shape, the wire and connections good might not be in a rush to upgrade it unless it was a sales asset in this case.

 

[bzinsky]

Thanks for the advice guys, I think I’ll try to keep the 100amp service.

I haven’t done load calcs, but aren’t they pretty standard for a house? I’ve done them for commercial. I mean most normal houses all have the same appliances so I thought it’d be a standard thing and just based on sq footage and whether said appliances are gas or electric.

 

[Aceman]

Excel load calc:

https://www.mikeholt.com/documents/calculations/formulas/ResidentialLoadCalculations.xls