That's no particular feat, you can heat a forge to 1200C with enough insulation and just 600W. Also, this is just considering a limited referential, ie. the one

That's no particular feat, you can heat a forge to 1200C with enough insulation and just 600W. Also, this is just considering a limited referential, ie. the one impacting the most your wallet. If you consider a bigger referential, your efficiency will drop below 1 for sure. Not to mention that your system will leak refrigerant (it's really not a matter of "if" but "when"), which is likely to have greenhouse effects.