Gas furnace blower motor rating?

Question

I have a 16-year old Trane XL80, single-stage gas furnace. I am replacing is with a new Trane XL90, dual-stage gas furnace. I'm rewiring my garage, and I'd like to put the garbage disposal (1/2 hp) on the same 15A circuit as the furnace, since I'm just powering the blower. Problem is I can't figure out what the blower draws. Does anyone have any ideas or any ballparks? I've asked Trane and gotten no response. I've asked the contractor who's going to install the new furnace, but he's decided to stop returning my phone calls (a common problem with Bay Area contractors). Thanks for any help.

Answers to some questions.

The existing circuits are
- dedicated 15A for disposal (1/2 hp = 7A, roughly)
- furnace shares 15A circuit with upstairs master bedroom and some general lighting

Sq. footage, panel rating, main breaker rating, etc. are not relevant, since I'm not asking for total guidance.

The reason I want to share these two appliances is that I've run out of space in my panels to bring the kitchen up to code, I don't want to rip out an entire panel to add 1/2 slot, although I may do that anyway, and I don't want to put motors on the same circuits as lighting.

Per CA code, furnace blower should be on a dedicated circuit. Disposal must be. I'm cheating, because the probability of starting the disposal *and* having a 2-stage furnace kick into high (from a dead stop) at the exact same time is about as close to zero as it gets.

Answer 1

I install and service heaters and it is possible to do what your trying to do however its against code in most municipalities. The amp draw on those type of motors is maybe 3 or 4 amps however the max amp possible could be as high as 10amps. When you size a breaker it goes by full load amps not running amps so if you have both come on at the same time it is possible it will trip the breaker. I would add it onto another breaker or add a new breaker for it just to be safe.

Answer 2

Large appliances like a furnace should be on their own circuit, and 15 amp sounds fine based on the limited information shown in the question.
The garbage disposal should be on the kitchen's small appliance circuit (not with the electric oven cook-top, or refer!!)
A couple of important missing facts are: What is the Sq Ft of the home; what is the main breaker size at the distribution panel-board; what size circuit breaker served the old Trane XL80?
If the home was built 16 years ago, you probably have a dedicated circuit for the furnace and a separate one for the kitchen small appliances.

Answer 3

The motor should have wattage listed in it.
watts divided by volts should be amps, amps times volts should be watts
I'm not familiar with new Trane furnaces but usually they are 15 amp (1875 watts) if 112volt system. the 1/2 hp disposal (off hand)should be about 8 amp.
I would put the disposal on the wall circuit or it's own circuit with GFI or GFCI.

There are double breakers available, that is that they take the space of one breaker and compound it into two.

Answer 4

Why don't you get an amp probe, or ask an electrician to borrow one from? you can get the reading while it runs.

I'd bet it's no more than 6 amps, but I would surely take the advice of the first answerer and put the disposer on a seperate circuit, and maybe even drop it down to a 1/3 HP.

I think furnaces in houses HAVE to be on seperate circuits, not sure about a garage, though.

Answer 5

there is a amp rating on tag on furnace dont reccomend using same circuit share with dish washer or have electrician twin circuits in panel depending on brand of panel and age size wire etc