So here's the situation:
My furnace is in the attic of my split-level for some god-awful reason. I've insulated around it as much as the furnace specs allow, but the heat it gives off and the opening for the ladder below (also insulated and sealed as much as practicable) still means I have snow melt and ice dams in winter. I've done a lot of work to insulate and vent the attic this year so it has adequate air flow to move heat out; but as long as its up there, I'm going to have a warmer attic than I'd like.
The way my ducting is arranged, I can move it down to the space next to my water heater fairly easily, but there isn't space unless I put in a tankless water heater. I'm looking for recommendations on indoor, tankless, gas water heaters and what information should I be paying attention to among all the numbers and terms that get thrown out by the different manufacturers. I'm not expecting the promised savings or unicorns to bow in my presence that is promised by manufacturers, this is more about fixing a different problem.