With heat doubled than that the 240 v appliance can carry, the appliance will overheat, melt, or explode, or burn.
If you are using a 220V-240V appliance at 110V, you will need a transformer. If you are using a 110V appliance at 220V-240V, you can also use a transformer but may be able to get away with a (cheaper) converter though not with all appliances.
Some motors will not start or will run slowly. Motor damage is a definite risk. If it has a fan and heat, heat will be about 25% BUT if fan does not start fire may happen.
IF the outlet is the ONLY outlet on the circuit, it's perfectly fine to change it to a 240V outlet (or disconnect, given it's for a heat pump) and change the breaker to a two-pole 240V 15A breaker - all your 120V wiring is already rated for 250V if not 600V.
If it is some AC drive, it most likely will burn out very quickly. If it is a universal drive, (or DC), it may spin up to twice its intended speed, and wear out quickly. If you plug a 220V device into 110V outlet, it will normally last a little longer before it dies.
In the United States and neighboring countries, however, household outlets run at 110 or 120 volts. This can pose a serious problem for travelers. Connecting a 220 volt appliance to a 110 volt outlet can damage or destroy the appliance.
Do not plug a 120V device directly into a 220V wall socket, even if the plug shape and size are identical. Although goods sold in the U.S. but available around the world sometimes accommodate 220V voltages -- iPods, for example -- other devices can be destroyed by such high voltages. When in doubt, use a converter.
Installing a 240-volt heater on a 120-volt circuit is not as big a safety risk, but you will notice that your heater will fail to work most times. When it does run, it will end up giving out much less heat than what you needed for your room and below what you expected.
You MUST make changes at the breaker box, do not simply change the outlet itself to a standard 120v outlet without changing from the current double pole breaker to a single pole breaker... you will burn out the entire electrical system/electronics of the new gas range!
The differences between 110 and 120v are too small to matter. If your power supply has a rating of 120v, it actually has a range of 110 to 125v. Any appliance whose rating falls within that range can work on both 110v and 120v outlets.
Further, you might find yourself bringing an air conditioner, refrigerator, or clothes dryer from overseas—designed to operate on 220-240 volts—over to the US and Canada, where the line voltage is 110-120 volts. In both instances, an ACUPWR step up voltage transformer/converter will allow this to happen.
For the dryer, you'll need to carefully go through each internal circuit and figure out how to make it accept 120V. The heating element is the easiest; simply connect the endpoints to 120V instead of 240V. This will mean the element will see half the voltage, and (thanks to Ohm's Law) 1/4 the power.
220v to 110v Step-Down converter or transformer reduces the incoming 220v or 240 Volt electricity found in most parts of the world to 110 Volt USA power. These voltage transformers enable the use of 110v USA electrical products in foreign countries where the voltage ranges from 220 Volt.
At 240V the amperage is 50% of what it is at 120V. So, by using 240V you are able to take up less space in your electrical panel, and allow more room to make any future modifications which involve electricity. It also requires less wiring and you can fit more heaters on a 240V circuit than you can on a 120V circuit.
So while the 240V sounds like it has twice the power, it generates the same amount of heat (watts) per square foot as the 120V system, heats up at the same rate, and would cost about the same amount per square foot to heat the floor.
A standard 120V outlet contains a 120 volt wire and a neutral wire, and preferably a grounding wire. A 240V outlet has two 120 volt wires and a neutral wire. Older homes often have three prong 240 volt outlets, but modern outlets have a ground wire and four prongs.
If the input voltage is higher than the normal, it will lead to electrical burned and may cause serious consequences such as fire. If the input voltage is below rated, the electrical appliance can't work normally or simply failed to work, and it may also cause damage to the motor.
Remember that you will have to know and understand how to make the correct splices in the motor junction box so that you don't put 240V on a motor wired for 120V (likely damaging the motor), or 120V on a motor wired for 240V (may not start, or be very sluggish).
Converting a 110-volt outlet to a 220-volt outlet requires extensive rewiring and most building codes would require inspection. There is an alternative available: Use a voltage step-up converter.
While a 220V to 110V situation results in Undervoltage, a 110V to 220V situation will lead to overvoltage. The appliance will work but it may draw up to four times as much power as it needs. This could cause the appliance to burn out.
You can convert a receptacle from 220 volts to 110 volts in one of two ways. The first is to use a 220 to 110 adapter. The other is to rewire the receptacle or install a new receptacle next to the old one and connect it to the 220-volt wiring.
It's not safe. Even if you used the right-size wire for 50 amps, it's a code violation (and dangerous) to supply a 20-amp lighting or receptacle circuit with a 50-amp breaker. The breaker supplying the circuit must match the receptacle rating.
The answer is no in all likelihood. Most dryers use a 240 volt circuit, while the common domestic containers are 120 volts. If plugged into this outlet, the dryer does not work.
Dryers are typically 240V, but can be 120V. It's not safe to run a 240V dryer on a 120V circuit. You can run a 120V dryer from a standard household outlet.
A 120 Volt Compact Dryer offers all of the modern features you could expect from a premium dryer, but with some additional benefits. First, instead of needing a special 220 volt outlet or adapter as you do with many dryers, a 120 volt dryer simply plugs into a normal electrical wall socket.