The heater for the pool/spa is broken. It appears to have been broken for some time. The spa is in the corner, and overflows into the pool, which I'm sure looks very nice when it's all up and going.
Questions are - is it pointless to even run water to the spa, if the heater doesn't work? If there was water in it, it would just be the same temp as the rest of the pool water, right? Would BadThings™ happen if we didn't put any water in the spa, and left it empty?