There’s no such thing as a 100% efficient “engine”. But in this case, since the waste heat is put to use (heating the house), OP thinks there’s a loophole.
But, house would also need to be soundproof. Any noise leaking to the outside is lost energy.
Sorry everyone for posting this out of order. Somehow I got my dates screwed up on the last few starting on the 14th, but with this one we’ll be back on track.
I've invented a 100% efficient combustion engine
I use it to heat my house.
KeepassXC and KeepassDX Guide (purplerabbit.gitlab.io)
14 December 1980 (sh.itjust.works)
Sorry everyone for posting this out of order. Somehow I got my dates screwed up on the last few starting on the 14th, but with this one we’ll be back on track.