Horizontal or Vertical

[Chubby Johnson]

Does it matter at all if a motor/pump is mounted vertically or horizontally in a hot tub?

I assume that eventually all pump seals leak so is it a big deal if a pump is mounted vertically?

[In Canada eh]

Chubby,

  It doesn't make any difference on how the motor is mounted.  We have a couple dozen sample and chemical feed pumps at work that have the motor mounted vertical.  The seals will not wear out any faster or slower with a vertical motor

[Chubby Johnson]

So you are saying that the pump bearings would not be damaged at all if water leaked into them on a vertical mount?

[In Canada eh]

That's not what I'm saying at all.  I have never seen a motor mounted below the pump in a vertical position, only above the pump.  Mounting the motor below the pump would make no sense at all for the exact reason you stated, the risk of water leaking into the motor.  It's not so much about the bearings causing you concern it's more about the motor windings and a dead short.  What hot tub has a pump with a motor mounted below the pump?

[Vinny]

If a therapy motor is mounted vertically in a tub - what is supporting it? Motor flanges are on the bottom and bolted to the floor.

I would imagine that it would be very noisy since a tub is a free standing device with flimsy walls. I would also think that the motor will eventually fall out of the flimsy walls due to the weight and torque of the spinning motor.

If I got the picture in my mind wrong - please post a picture of what you're talking about.

[Pathfinder]

what kind of tub are you planning to do this to???  I would think you will have priming & flow issues as well. Remember spa pumps are fed by gravity not self priming like pool pumps. You would have to be sure that the weight of the water in the vessel is enough to push the water up into the pump or you would have to install a check valve at the base of the filter canister.       I might be wrong on this but Im sure these issues need to be addressed first.