I just got my hands on a huge hot tub (just the tub and pipes) and I want to build it up from scratch. I dont know anything about hot tub's innards, but I'm going to learn. From what I have read, it looks like I need a blower, heater, 2 speed pump and filter. Now this tub is 7' x 7' so I figure I should probably use 240V instead of 120V. I also figure that I should probably get at least 2 horsepower blower and pump. And I'm probably going to go with a 100,000 BTU Natural Gas heater. Anyone with some knowledge have any advice?

a 2hp blower would be fine, but I've always had no problems with a 1HP blower. For sizing your pump, count the number of jets. Each large jet (3" or larger) add 1/4HP. For each pair of smaller jets (under 2") use 1/4Hp. So if your tub has 8 large jets and 14 small jets, use a 4hp motor/pump. it's better to err on the larger side. Using 240V will save you on electricity. If you have a lot more jets than that, often you will find tubs that will have two pumps, one two speed, and a second, high speed, booster pump. If you go that route, be sure to include a check valve on the outlet side of the booster pump so when your main pump is running only, it doesn't back feed through the booster.

Thanks for your advice.

The tub is pretty old, so it only has 4 big jets. It has 3 rows of tiny holes in the bottom of the seats, but I guess those don't classify as jets. I may consider adding more smaller jets. I believe that would only mean drilling holes for them and having enough HP to use them, correct?

What I am still confused about is what I need exactly overall.
Is the blower/pump/circulating pump/motor all the same thing?
Do I need to hook everything up to a control system?

Do you have any schematics that may help for the plumbing?
Also, would you recommend a ozonator?

Thanks for any help. I can't wait to get this thing going!!

the little holes in the seats are for air only, and that is where your blower comes in. Your blower and pump are two separate entities. If you do drill more jets, be absolutely sure you have a single wall (the seats are double walled for the air channel to provide for the air holes in the seats) and on as flat of a surface as possible.

When installing new jets, drill your holes with a hole saw from the INSIDE of the tub, and then remove the insulation on the back side of the shell with the same hole saw, from the back side, using the bit in the hole saw to follow the hole and the teeth of the saw to carve out the insulation. Use silicone on the back side of the shell for the jet housing, and just lightly lubricate the gasket with a water based lubricant (believe it or not, KY jelly works very well for this) and assemble the jet before running any pvc.

A control pack will be necessary to run the equipment. You can either get a digital pack with topside control or you can build a mechanical (if you are going for cost) yourself. I have the information SOMEWHERE and if I can locate it I will post it here.

The plumbing is rather simple, generaly you will have two lines going to each jet, one for induction air, and one for water. You will have no less than two drains (one may be a skimmer) and those are connected together, then to your pump. The outlet of the pump goes to your filter. The filter outlet goes to your heater, and from your heater to the jets. Just connect all the jets from one to the other. The air induction is usually a hose (or pipe) that goes from each jet (usually the smaller of the two openings in the jet housing, usually on top of the other water opening) to an air control knob on the spa shell. I do have a diagram for that somewhere also, but agian I will have to see if I can find that.

You probably won't need to use a circulation pump. The idea behind this is to use a small pump solely to circulate the water through the heater when the tub is not in use, to save on energy. Your design can be as simple as using a 2 speed pump, using the low speed to heat and filter. Most older spas use this design.

Ozonators are optional. They are to help sanitize, and allow the use of less chemicals for sanitization. In your design, I would install a small "ozone jet" which would hook up to your water line going to the jets. This jet is small, about 1" in diameter, and has a second hookup for your ozone generator. When your spa is running, it will draw air from the ozonator and into the water. These jets are often placed about midway up in the footwell.

Hope that all helps, and I will try to locate those diagrams.

Wow, thanks so much for all of your advice!!

So all I really need (without adding extra jets for now) is a 1HP 2 speed pump, a 2HP blower, a heater, a control panel and an ozonator (optional).

The 'double wall' where the little blower holes are have their own channel running beneath the seats. It seems that if I wanted to cut into the seat where I would install jets for a back massage, it would not affect this area at all.

So to be clear about the oxonator jets - I need to actually cut out holes for new jets in order to add the ozonator?

Thanks again for all of your help!

You could probably get by just fine with a 1HP or a 1.5HP blower, I have a 1HP blower on my 8 seater, and it has no troubles keeping up. If you want to add an ozonator, I would install the single ozone jet in the footwell and have it tied into one of the main jet supply lines via a "TEE" connection. The seat backs should be clear of the channel under the seat for the blower holes. At least, I've never ran across a tub yet that had air channels in the backrests.

Thanks again for your help!

I am going to be confident in buying the folowing to get my spa going:

1HP 2 speed pump
1HP blower
heater
control panel

If you happen to find those specs you mentioned for plumbing that would be very helpful.

Sorry for the delay. Hopfully these diagrams will help you figure out your plumbing.

Thanks, I appreciate it.
You have been very helpful!