About a 25 year old forced air gas furnace, the kind with an inducer
blower. No fancy electronics; just whatever kind of time delay they have
for the blower and an updated inducer control board also has a delay
circuit. So it's more a matter of wondering if the motors, gas valve, and
transformer will object to the perverted waveform of a "simulated sine
wave" inverter. I have a real generator so the inverter is more of a
backup to a backup. Thought I'd ask first.

I'm going to guess that the 24V transformer will have an output that's
closer to a real sine wave which lessens any unhappiness of the gas valve
and electronics so I suppose the transformer itself and the motors are the
items of concern.

On Nov 10, 1:39*pm, Chet Kincaid wrote:
About a 25 year old forced air gas furnace, the kind with an inducer
blower. *No fancy electronics; just whatever kind of time delay they have
for the blower and an updated inducer control board also has a delay
circuit. *So it's more a matter of wondering if the motors, gas valve, and
transformer will object to the perverted waveform of a "simulated sine
wave" inverter. *I have a real generator so the inverter is more of a
backup to a backup. *Thought I'd ask first.

I'm going to guess that the 24V transformer will have an output that's
closer to a real sine wave which lessens any unhappiness of the gas valve
and electronics so I suppose the transformer itself and the motors are the
items of concern.

It will be fine as long as the voltage is reasonably close.

And you'd be surprised how a waveform will remanin intact through a
transformer.

On Nov 10, 4:20*pm, jamesgangnc wrote:
On Nov 10, 1:39*pm, Chet Kincaid wrote:

About a 25 year old forced air gas furnace, the kind with an inducer
blower. *No fancy electronics; just whatever kind of time delay they have
for the blower and an updated inducer control board also has a delay
circuit. *So it's more a matter of wondering if the motors, gas valve, and
transformer will object to the perverted waveform of a "simulated sine
wave" inverter. *I have a real generator so the inverter is more of a
backup to a backup. *Thought I'd ask first.

I'm going to guess that the 24V transformer will have an output that's
closer to a real sine wave which lessens any unhappiness of the gas valve
and electronics so I suppose the transformer itself and the motors are the
items of concern.

It will be fine as long as the voltage is reasonably close.

And you'd be surprised how a waveform will remanin intact through a
transformer.

I guess it would depend on whether or not the inverter can handle the
load.

I've got a cheap inverter that I keep in my van for charging drill
batteries, running a laptop or portable TV on long trips, etc.

I always know when I overload it because it squeals like a pig.

Chet Kincaid wrote:

About a 25 year old forced air gas furnace, the kind with an inducer
blower. No fancy electronics; just whatever kind of time delay they have
for the blower and an updated inducer control board also has a delay
circuit. So it's more a matter of wondering if the motors, gas valve, and
transformer will object to the perverted waveform of a "simulated sine
wave" inverter. I have a real generator so the inverter is more of a
backup to a backup. Thought I'd ask first.

I'm going to guess that the 24V transformer will have an output that's
closer to a real sine wave which lessens any unhappiness of the gas valve
and electronics so I suppose the transformer itself and the motors are the
items of concern.

Motors and solenoid valves are the least likely components to care about
the AC waveform. Both motors and solenoid valves are routinely operated
with PWM type drivers which produce waveforms much further from a sine
wave than a "MSW" stepped square wave inverter. As long as the inverter
is appropriately sized it should be fine.

On Nov 10, 12:39*pm, Chet Kincaid wrote:
About a 25 year old forced air gas furnace, the kind with an inducer
blower. *No fancy electronics; just whatever kind of time delay they have
for the blower and an updated inducer control board also has a delay
circuit. *So it's more a matter of wondering if the motors, gas valve, and
transformer will object to the perverted waveform of a "simulated sine
wave" inverter. *I have a real generator so the inverter is more of a
backup to a backup. *Thought I'd ask first.

I'm going to guess that the 24V transformer will have an output that's
closer to a real sine wave which lessens any unhappiness of the gas valve
and electronics so I suppose the transformer itself and the motors are the
items of concern.

Can the inverter handle a 900 w surge load, im guessing on this but my
furnace pulls about 350w continous and common surge for a motor
pulling 350w is about 900w. Use a clamp on amp meter to test yours and
compare it to the inverters spec. What is your inverters specs, what
model, you didnt say. If it cant handle startup it might just shut
down since it wasnt designed to start motors.

Should work. I tried to run my old Miller on inverter, but didn't have
enough power to run the blower fan.

My new furnace has a circuit board. I wrote the company (York) to ask
if I could run modified sine. They wrote back and said I should ask
the distributor. You mean, I should ask the guys who are paid to say
"You want 70,000 or 90,000 and do you want fries with that?" and they
would know? York sure came back with a stupid reply on that one.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Chet Kincaid" wrote in message
...
About a 25 year old forced air gas furnace, the kind with an inducer
blower. No fancy electronics; just whatever kind of time delay they
have
for the blower and an updated inducer control board also has a delay
circuit. So it's more a matter of wondering if the motors, gas valve,
and
transformer will object to the perverted waveform of a "simulated sine
wave" inverter. I have a real generator so the inverter is more of a
backup to a backup. Thought I'd ask first.

I'm going to guess that the 24V transformer will have an output that's
closer to a real sine wave which lessens any unhappiness of the gas
valve
and electronics so I suppose the transformer itself and the motors are
the
items of concern.

I used the DC cables that came with the inverter. I probably ought
have used much fatter and shorter cables. The DC power feed into the
inverter runs a LOT of amps.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Pete C." wrote in message
ster.com...

Motors and solenoid valves are the least likely components to care
about
the AC waveform. Both motors and solenoid valves are routinely
operated
with PWM type drivers which produce waveforms much further from a sine
wave than a "MSW" stepped square wave inverter. As long as the
inverter
is appropriately sized it should be fine.

Chet Kincaid wrote:
About a 25 year old forced air gas furnace, the kind with an inducer
blower. No fancy electronics; just whatever kind of time delay they have
for the blower and an updated inducer control board also has a delay
circuit. So it's more a matter of wondering if the motors, gas valve, and
transformer will object to the perverted waveform of a "simulated sine
wave" inverter. I have a real generator so the inverter is more of a
backup to a backup. Thought I'd ask first.

I'm going to guess that the 24V transformer will have an output that's
closer to a real sine wave which lessens any unhappiness of the gas valve
and electronics so I suppose the transformer itself and the motors are the
items of concern.

Depends on the inverter. Some do not put out a sign wave and can harm
transformers and inductors which provide power to sensitive electronics.

--
LSMFT

Simple job, assist the assistant of the physicist.

Pete C. wrote:
Motors and solenoid valves are the least likely components to care
about the AC waveform. Both motors and solenoid valves are routinely
operated with PWM type drivers which produce waveforms much further
from a sine wave than a "MSW" stepped square wave inverter.

Routinely? On a simple furnace that's 25 years old? Rest assured the
motors run directly on line power and the electronics such as there are on
24 V from a transformer.

As long as the inverter is appropriately sized it should be fine.

2500 continuous, 5kW surge.

Chet Kincaid wrote:

Pete C. wrote:
Motors and solenoid valves are the least likely components to care
about the AC waveform. Both motors and solenoid valves are routinely
operated with PWM type drivers which produce waveforms much further
from a sine wave than a "MSW" stepped square wave inverter.

Routinely? On a simple furnace that's 25 years old? Rest assured the
motors run directly on line power and the electronics such as there are on
24 V from a transformer.

You missed my point. I didn't say the motors or solenoid valves in your
furnace ran on PWM drives, I noted that motors and solenoid valves in
general are routinely operated on PWM drives. The motors and solenoid
valves in your furnace should be quite happy on MSW power.


As long as the inverter is appropriately sized it should be fine.

2500 continuous, 5kW surge.

That should be plenty for a residential sized furnace. You of course
need a hefty DC supply to power that inverter, presumably a vehicle
alternator. That will likely draw around 100A DC running the furnace.

On Nov 10, 7:08*pm, Chet Kincaid wrote:
Pete C. wrote:
Motors and solenoid valves are the least likely components to care
about the AC waveform. Both motors and solenoid valves are routinely
operated with PWM type drivers which produce waveforms much further
from a sine wave than a "MSW" stepped square wave inverter.

Routinely? *On a simple furnace that's 25 years old? *Rest assured the
motors run directly on line power and the electronics such as there are on
24 V from a transformer.

As long as the inverter is appropriately sized it should be fine.

2500 continuous, 5kW surge.

Do you mean inverter that runs from a dc source and generates ac, or
do you mean a generator that runs from a gasoline-driven motor? A
2500 watt inverter would require humongous sized feeder cables if it
runs on 12V dc.

On Nov 10, 10:51*pm, "hr(bob) "
wrote:
On Nov 10, 7:08*pm, Chet Kincaid wrote:

Pete C. wrote:
Motors and solenoid valves are the least likely components to care
about the AC waveform. Both motors and solenoid valves are routinely
operated with PWM type drivers which produce waveforms much further
from a sine wave than a "MSW" stepped square wave inverter.

Routinely? *On a simple furnace that's 25 years old? *Rest assured the
motors run directly on line power and the electronics such as there are on
24 V from a transformer.

As long as the inverter is appropriately sized it should be fine.

2500 continuous, 5kW surge.

Do you mean inverter that runs from a dc source and generates ac, or
do you mean a generator that runs from a gasoline-driven motor? *A
2500 watt inverter would require humongous sized feeder cables if it
runs on 12V dc.

Not only big cables, but I saw reviews of several 12v cheapy
inverters, none could supply the rated watts, they were 10-15% off. So
if you have a 1000w inverter unit it may shut down as a 350w motor
pushes through its 850w needed startup surge. A 25 yr old furnace, its
motor is worn and could take well over 1200 startup surge, so a 2000w
inverter might work.

That's got to take large batteries, and very thick, short DC cables.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Chet Kincaid" wrote in message
news
2500 continuous, 5kW surge.

It's been a while since I checked the run amps of my furnace. Between
5 and 7, from memory. In any case, say 700 watts. At 12 volts, that
draws about 58 amps of DC.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Pete C." wrote in message
ster.com...


2500 continuous, 5kW surge.

That should be plenty for a residential sized furnace. You of course
need a hefty DC supply to power that inverter, presumably a vehicle
alternator. That will likely draw around 100A DC running the furnace.

Pete C. wrote:
You missed my point. I didn't say the motors or solenoid valves in
your furnace ran on PWM drives, I noted that motors and solenoid
valves in general are routinely operated on PWM drives. The motors and
solenoid valves in your furnace should be quite happy on MSW power.

Ah, I see what you mean. Thanks.

ransley wrote:
Not only big cables, but I saw reviews of several 12v cheapy
inverters, none could supply the rated watts, they were 10-15% off. So
if you have a 1000w inverter unit it may shut down as a 350w motor
pushes through its 850w needed startup surge. A 25 yr old furnace, its
motor is worn and could take well over 1200 startup surge, so a 2000w
inverter might work.

It's a Cobra CPI-2550 rated at 2500 W / 5000 W surge. (In the manual they
admit that 2500 is a one hour rating). I've tested it to about 1900 W with
resistive loads and some smaller inductive loads. (Meaning I plugged in an
air compressor because it was handy. It ran okay.)

I will likely never use it for the furnace since I have a generator but
it's good to have options.