Hi guys. How difficult is it to rewire a furnace cable that is hardwired to a box, to a plug instead? Just looking to run it off generator temporarily if needed. I could cut the end of an extension cord to use. I don't have caps/butt ends to properly join the furnace cable to the extension cord wires, but would electric tape work just for a day or two?
Change Furnace from Hardwired to Plug
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Hedges
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That could be done. Could tap at the breaker panel, removing hot wire from breaker and connecting to plug (neutral and ground from extension cord would go to busbars in panel.) Or could tap all the wires at a junction box, maybe at furnace.
Wire nuts would be the usual connection. Tape works.
If you're planning for (power) failure, could open that junction box and splice an extension cord outlet to line from breaker panel, plug to wires of furnace. Then plug them together for normal on-grid use.
Wire nuts would be the usual connection. Tape works.
If you're planning for (power) failure, could open that junction box and splice an extension cord outlet to line from breaker panel, plug to wires of furnace. Then plug them together for normal on-grid use.
Thanks. I’m looking at doing something like this now. I don’t have wire nuts unfortunately.
If you want something more permanent that gives you the ability to power just one thing via generator try one of these.
ezgeneratorswitch.com
Manual Generator Transfer Switch - EZ Generator Switch
EZ Generator Switch is the most affordable and efficient generator connecting manual transfer switch on the market. The switch gives you a simple way to connect any generator to power essential circuits. We are the only company in both the United States & Canada building switches compatible with...
ezgeneratorswitch.com
Hedges
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Solid wire is not as secure when twisted and taped as would be stranded wire.
Wire nuts are the way to go.
If switch was replaced with a 2-way (SPDT), that could let one of two sources power the furnace.
Wire nuts are the way to go.
If switch was replaced with a 2-way (SPDT), that could let one of two sources power the furnace.
Leviton 15 Amp 3-Way Toggle Switch, White R62-01453-02W - The Home Depot
Leviton offers a comprehensive line of UL Listed products for every electrical need. Leviton's wiring devices and accessories are backed by state-of-the-art research, design, engineering, manufacturing,
www.homedepot.com
John Frum
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Thanks @smoothJoey, we are having an interlock and inlet, or a manual transfer switch installed finally next month. Still undecided.
One of our furnaces didn't make it through the arctic storm, now we have 2 new furnaces
How do I audit a furnace's power usage? Will an amp clamp at the breaker do it?
John Frum
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I not sure if an amp clamp will give your current over time but you can get an instantaneous reading and then estimate the duty cycle.Thanks @smoothJoey, we are having an interlock and inlet, or a manual transfer switch installed finally next month. Still undecided.
One of our furnaces didn't make it through the arctic storm, now we have 2 new furnaces
Or you can get one of these and figure out each branch circuit and the mains.
Hedges
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I not sure if an amp clamp will give your current over time but you can get an instantaneous reading and then estimate the duty cycle.
Or you can get one of these and figure out each branch circuit and the mains.
One reading with an ammeter to find instantaneous current & power.
Wire an outlet to something switched in the furnace (fan motor) and plug a mechanical timer into it.
Watts x hours = Wh
(Estimating duty cycle as Joey says would be simplest. Couple of cycles daytime and couple at night.)
But obviously a logging gizmo would be easiest. So long as furnace runs on 120V, feed it through a power cord and use Kill-a-watt.
That’s beyond my capabilities. The furnace is hardwired to a junction box.
I was planning on getting the Sense installed also, but it would be beneficial to know what the furnace uses if we go with a manual transfer switch so I know whether to have it connected or not. Might have to get the electrician out twice.I not sure if an amp clamp will give your current over time but you can get an instantaneous reading and then estimate the duty cycle.
Or you can get one of these and figure out each branch circuit and the mains.
John Frum
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The sense supposedly has ai that identifies individual loads.
Hedges
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Since Sense has clamp-on ammeter, that does make it easy.
It would be nice to just have a clamp-on AC amp-hour meter. Something with a reset button, then read accumulated Ah after a day of operation. No need to simultaneously measure voltage; we know that is fairly constant. But I don't find that, just more complicated gizmos with wired or wireless communication to a computer.
Furnace specs will tell you peak voltage and current. BTU tells you output per hour, and how much heat is lost by your house determines how long it has to run per day. Try to calculate/estimate.
Any measurement you take will give results based on current weather.
You're going to want to run the furnace during power outages so you want a transfer switch. If your alternative energy electric system can't keep up you won't run it as many hours and the house will be colder.
Hedges
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!!??
KISS!
When my range hood lights dim I know the electric duct heater came on.
But a gizmo keeping track of all loads in the house? GIGI? Do you train it by manually enabling various appliances and keying in what you just did?
What I saw was multiple current clamps, so it directly measures several circuits.
The furnace with the lower energy requirements is 115V, 10A (minimum supply circuit conductor ampacity), 15A (max overcurrent protection device). Looks like 80,000 BTU/hour? See photo.
Yes, that is the goal. With the transfer switch, or interlock and inlet.
I'm not sure our 2200W, more like 1600W on natural gas, generator will be able to do this. But I'd like to see what the furnace uses at startup and to keep the blower motor running. No way the 1200W inverter and 100AH battery will pull it off.
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Hedges
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If the blower motor is 1200W, might need 6kW surge for a fraction of a second to start.
But that was 10A "conductor ampacity", not motor rating, which is probably less.
With a clamp ammeter you can find actual running current.
From my measurements, surge current could be 10x running current and 5x nameplate rating.
1200W continuous would keep it running once started. But even if 2400W surge, won't start more than a 500W motor.
If that's 100 Ah 48V lithium, 5kWh, it would run a 500W blower or even a 1200W blower up to 3 hours, so on 25% of the time though a night.
What you want is an inverter than can start the blower, and an auto-start generator which only needs to run when battery low.
Probably an inverter upgrade would be the way to go.
But that was 10A "conductor ampacity", not motor rating, which is probably less.
With a clamp ammeter you can find actual running current.
From my measurements, surge current could be 10x running current and 5x nameplate rating.
1200W continuous would keep it running once started. But even if 2400W surge, won't start more than a 500W motor.
If that's 100 Ah 48V lithium, 5kWh, it would run a 500W blower or even a 1200W blower up to 3 hours, so on 25% of the time though a night.
What you want is an inverter than can start the blower, and an auto-start generator which only needs to run when battery low.
Probably an inverter upgrade would be the way to go.
I don't have a meter yet, how does this one look?
Sadly, no. It's only a 12V lithium battery. And no auto start, the generator is a (modified tri-fuel) Honda EU2200i.
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I have the cl-390 at the clamp works great.
The voltage is .2 off which is horrendous considering it ~$200.00CAD.
Hedges
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What that AC or DC?
I've read you should flip the clamp over and see if you get same reading. If not, supposed to be some way to zero.
My only experience with clamp meters so far is 100A 0.300V AC current transformers with resistor, and some AC and DC current probes for scopes.
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