Heat output is a factor of resistance and that exists even without adding work. The energy to do the hashing is actually tiny but the efficiency of the electricity on the silicon amplifies the thermal cost.

So, yes, it will be about equal to running electric heaters. Which means it could also do your hot water as well, while mining, with no loss of hash from catching all the heat. And if you sucked the heat out of it even harder, you can probably increase its hash output.

All currently electric heating systems could be replaced with miners. Waste heat could be captured to push a gravity battery upwards too.