Furnace advice

[Jerry Wilson]

I bought a P 40 suburban[110 volt model 40,000 btu] furnace at a to good to pass  up price.I had intended to run it off of the inverter, it runs awhile ,then the inverter shuts down.The inverter is a 2000 watt coleman .I know its not a high quality inverter, but i thought it would be able to run this furnace.The furnace runs great on shore power.Do i need a pure sine wave inverter or would a higher quality modified sine wave inverter do the job.The type of windings in the motor  must be making it hard for the inverter to run the furnace,because when it runs it make more noise than when it run on shore power  Thanks everyone       Jerry Wilson 4107

[gumpy]

I don't understand what you said about the inverter shuts down. Does it trip a circuit breaker? Does it set an error?  What do you mean "shuts down"?

How many amps does the furnace require?

What is the continuous load rating on the inverter?

My guess is that the furnace requires more current than the inverter can provide on a continuous load and overheats it.

Is there plenty of air circulation around the inverter or is it blocked in where it can't get cool air to it?  Try putting a fan on the inverter while the furnace is running to see if it will go longer.

[pvcces]

Jerry, many motors make quite a bit more noise when run on modified sine wave power, which your Coleman produces. I can't think of any reason why a propane furnace would draw enough power to overload your inverter.

So, what's the rest of the story?

Tom Caffrey

[jjrbus]

It runs awhile, how long is awhile?  How big is your battery bank? How long and what size are the wires from the battery to the inverter? Electric motors make a little more noise on modified sine wave, no reason to run out and buy a true sine wave. A 2000 watt inverter should run a fan motor with no problem.

[JackConrad]

How big is the battery bank your inverter is connected to?   Jack

[larryh]

So many of the low end inverters give a false rating it says 2000 watt but if you read the small print it also states for 10 min etc. But any inverter should run your furnace motor how many watts? or amps? and what is the voltage when starting it? please not just a 12 volt but the actual battery voltage measured. How many battery?

Give us more to go on

LarryH

[Jerry Wilson]

Well the 'whole ' story is that I bought the furnace (uses less than 2 amps) to use in the bus even though it's a 110 volt unit.  I thought the only place we'd use it would be in a campground situation using shore power.  So I thought that a 110 unit would be sufficient.  In the meantime, I removed the original bus heat, and came up with the idea of using a water coil in front of the furnace. Using the fan from the furnace (through a relay) to blow heat into the bus with the coil being heated by the bus coolant lines, the whole system would be controlled by an in-line thermostat.  I had intended to power the furnace with the inverter being fed from two house batteries, and also through a solenoid connected to the bus batteries charged by the big alternator.  I figured I had plenty of power to the inverter.  The inverter powers the microwave, TV, & refrigerator, and handles that load just fine.  I assumed the furnace shouldn't give it any trouble. However, with just the furnace on, it runs for 5 - 10 minutes, and then the inverter goes off as if it was overloaded.  I know a 12-volt furnace would be better suited to this application, but I don't want to pay $500 + for a new furnace.  That's the story! Thanks, Jerry