Spa Pump and Twirlybyrd jets

[bsjeep]

I'm currently planning a new pool build. A couple PBs offered upgrades to use these twirlybyrd jets.
I'm currently thinking 7 ft circle spa with 6 jets. (seems pretty standard)

http://twirlybyrd.net

Anyway they spec 20-30 GPM for best performance. So if I take the most GPM scenario I would need 30*6=180 GPM
Assuming ample sizing of the runs to the jets, say a 2.5" pipe or 3" pipe

Q1: 2.5" return would be 120 GPM at 8in/sec as stated in TFP piping chart I found. I'm assuming if I go over 8in/sec the Head Loss is increasing and thus the max GPM of the pump is going down.

Q2: The PBs both spec'd a 2HP Pentair VS pump, but it seems like I can't really make the 180GPM number with it? perhaps the Pentair IntelliFloXF VS 3HP would do it if I could get the head loss down. I found a curve chart for the pentair pumps on their website that I'm going off.

Q3: Then I looked at the spa drain, just looked up some standard pool drains, looks like you usually do a set of 2 (which seem to have 2" connections) connected to maybe 3 inch piping to the pump. The 3" pipe gets me over 180 GPM at 8in/sec so that seems fine, but the drains are rated at 74GPM per grate, so like 140-150GPM, so does that mean my kid will stick to the drain? Do I actually need 4 drains in my spa?

Q4: One PB said if I add a 2nd pump we can do 8 or 10 or more twirlybyrd jets, makes sense but also makes me wonder back to the Q3, the drain scenario? And also, this is assuming I'm not keeping the water warm and have any heating going on, which could be a different pump etc, lower flow rate, etc, but still the same drain intake?

Thanks for any insights or thoughts, it's been a lot of fun reading the TFP board in my research so far.

 

[Bama Rambler]

I can't comment on the jets, but adding a third floor drain in the spa would solve the flow problem. Plumb them in a triangular pattern. They need to be 3' apart so you'd need a circle of about 4' diameter for them to fit in. I'd plumb between them with large (2½" or 3") piping.

 

[mas985]

Q1: 2.5" return would be 120 GPM at 8in/sec as stated in TFP piping chart I found. I'm assuming if I go over 8in/sec the Head Loss is increasing and thus the max GPM of the pump is going down.

Normally for a spa, you will want to stay below 6 ft/sec to avoid entrapment issues and keep head loss in the plumbing to a minimum so I would recommend two loops of 2.5" pipe. This might also work better for the pump because no residential pool pump can produce 180 GPM.

Q2: The PBs both spec'd a 2HP Pentair VS pump, but it seems like I can't really make the 180GPM number with it? perhaps the Pentair IntelliFloXF VS 3HP would do it if I could get the head loss down. I found a curve chart for the pentair pumps on their website that I'm going off.

Both would be under powered for 180 GPM. Two pumps on two loops would be a better solution.

Q3: Then I looked at the spa drain, just looked up some standard pool drains, looks like you usually do a set of 2 (which seem to have 2" connections) connected to maybe 3 inch piping to the pump. The 3" pipe gets me over 180 GPM at 8in/sec so that seems fine, but the drains are rated at 74GPM per grate, so like 140-150GPM, so does that mean my kid will stick to the drain? Do I actually need 4 drains in my spa?

Again, for the suction, you want to be under 6 ft/sec so two loops of 2.5" pipe should do the trick and you should be able to plumb each drain into one of the loops but it depends on local codes.

Q4: One PB said if I add a 2nd pump we can do 8 or 10 or more twirlybyrd jets, makes sense but also makes me wonder back to the Q3, the drain scenario? And also, this is assuming I'm not keeping the water warm and have any heating going on, which could be a different pump etc, lower flow rate, etc, but still the same drain intake?

I think you need the second pump with just 6 jets.

 

[Twirlybyrd]

Hi bsjeep,
I just saw your thread on our product. I agree with Mark's recommendations and applaud your knowledge of pool hydraulics. However, I want to give an important update:

Our flow rates stated on our site are 15-20 gpm. Shortly after we launched Twirlybyrd, we developed a helpful tips sheet for builders based off feedback we had been getting that was also downloadable from our site. On that sheet we recommended flow rates of 20-30 gpm. That sheet has been pulled from our site as it is not correct. At 15 gpm, our Twirlybyrd massage fittings will have a soft effect and at the other end, 20 gpm will be very strong. We have noticed in occasional applications, that flow rates beyond 20 gpm may cause too much force and create a slight noise in the fitting because of the excess force.

We apologize for the error and appreciate your interest in Twirlybyrd!