domestic hot water also providing heat?

This is new to me: Found hot and cold water lines from basement (tapped in area of oil-fired water heater) run to 2nd story bathroom with PEX tubing. The two lines were connected together “temporarily,” with the intention of using them to feed and return from a baseboard heater for the bathroom(heater not present). No circulator present, or allowed for. The real question for me- is it appropriate to use domestic hot water for space heat? This is not an isolated loop, the water used for heat is the same water that would be used bathing, dish washing etc. I know it can’t work without a circulator, but the whole idea doesn’t seem right to me. All opinions are welcome.

How big (gallons) is the water heater?

If it’s just one baseboard, there would need to be some sort of zone control installed on this particular supply line in order to circulate the heated water.

I don’t see an issue with this as long as it is only one baseboard supply. An electric baseboard would have worked just as well.

Im by no means an expert on this, but I wouldnt recommend it. I dont see it as a health hazard, as long as there is no openings in the system. Have the pipes EVER been used for anything other than potable water? Circulation will happen as long as there is an up and down pipe, and it will distribute some heat, inefficiently.

David beat me…

That almost looks like PB instead of PEX. Where were these stubbed out in the bathroom? I have a similar set up but it is just a loop for heated towel rods and not a baseboard unit.

PB? oh oh…

u sure u wernt looking at a domestic hw recirc loop? Any body runs pex for heating loop is off.