Put it against a wall and if you have the ability to determine which way the joists are running you want them to be running perpendicular with the wall. If you put it out in the middle of the floor you’d want to think about beefing things up and if your joists run parallel to the wall you’ll still probably be okay but if it were me I’d beef it up or find a place with perpendicular joists. If you don’t have visible access to the joists underneath then it’s a general rule of thumb that they are ran the shorter span of of the room.
Tank would sit between living room and dining room in corner that has 2 walls on each side
joists are perpendicular and metal beam that runs entire length of basement looks to sit directly behind where tank sits on floors above, cant move tank back due to wall
looking at supporting underneath but looks like 1/2 of tank sits over finished portion of basement and based on ductwork/furnace, water heater no area to put floor jacks up
my lfs who is doing all work while not engineers but have been working woth them last 10yrs for all my needs and doing install was not concerned about floor
So what is below the wall that the back of the tank sits against? The beam or is there a wall that matches the wall above? Or is it a partial wall and the rest braced with the beam?
I think you are ok. The 180 will weigh more than the 120, but will have more floor joists spreading out the load. I did the same thing a few years ago and spoke with my friend, who was a civil design engineer at the company I worked for then.
And basically since the 180 will be spreading across the 6ft and spread to entire ground, they felt my 120g now is probably worse on the floor because it only has the 4 touch points to where it is transferring all the weight