Ideal plumbing for spa jets and jet pump?

[BlueWave8]

Hello everyone, its been awhile but I'm finally about to start dig/rebar next week so I needed to finalize my spa jet plans. I need some help brainstorming this one!

In regards to powering my spa jets-- my original plan was to use four JetArray Inline spa jets which require 20 gpm each. I thought I could reach this pretty well with my single pump plumbing set up (original plan).

The JetArray Inlines have been on backorder for three months, and I've already pushed my build out once because I wanted to try to wait for them, I don't think I want to push it out again, since my subcontractor quotes are increasing by the month (as the economy is weird right now). I did find JetArray Clusters in stock somewhere, so I am thinking about using two JetArray Clusters (70gpm each!), and two to four "standard" spa jets. I want at least two seats to have a really fantastic spa experience, hence the crazy jets.

I'm pretty sure that I'll need to add some kind of jet pump to achieve that. So I'd like to ask for a spa jet pump recommendation and what the ideal plumbing set up for this system will be.

This is a new pool and spillover spa build. Pool/spa heat will be heat pump only. The pool will have no main drains, the only pool water suction will be the skimmer. The spa will have a 32" channel drain that supports three 2.5" plumbing connections. I do not plan to use an air blower, but I will have a large 3" air intake pipe. All plumbing to and from the spa will be 3", and the spa is roughly 20-25 feet from the equipment pad.

I'm not sure if I should have a standalone loop for the two JetArray Clusters, (still not sure I'd be able to achieve 140gpm with one pump on that) or if I should do more of a "booster" setup with both pumps and a loop with all of the jets. Or have a separate loop for the "standard" jets and a separate loop for the Clusters? What's the best way to accomplish this?

JetArray Cluster:

https://www.c-m-p.com/wp-content/uploads/2014/08/23308-900910-Jet-Array-Cluster-Instructions.pdf

This is the cartridge filter I have, however I haven't been able to find head loss information for it. In their specs they claim the "maximum pressure drop" is 2.9 psi and state a max flow rate of 134gpm.

CJ-2750 Cartridge Filter-CJ2750

www.circupool.com

This cyclonic pre-filter came with my equipment kit, and I plan to use it, but am wondering if I should install a check valve bypass around it for spa mode? As the head loss increases quite a bit at high flow.

CircuPool® TJ-16 Typhoon Cyclonic Pre-Filter for Swimming Pools. No Cartridge, No Sand, No DE media

www.circupool.com

CircuPool SmartFlo 3hp variable speed pump (already purchased this for main pool/spa pump):


Head loss curve for the AquaCal heat pump I plan to use. This will have an external bypass plumbed. I believe the AquaCal external bypass kit has a ~5psi check valve:

 

[ajw22]

You should use a dedicated water loop for the two JetArray Clusters that has suction intakes in the spa floor direct to the pump and then the pump return direct to the JetArray Clusters. No filter or heater in the water loop to allow maximum GPM flow.

Your main pump should have its own suction intakes in the spa floor that circulate water through your filter and heater and then return it to the spa and the standard spa jets..

 

[mas985]

With all those jets, you will likely need two jet pumps in addition to your main circulation pump (assumes 2x70 GPM + 4x15 GPM = 200 GPM). For jets, it is best to avoid running the high flow rate through filters and heaters which can add a lot of head loss not to mention poor filtering. So I would plan on three loops for the spa. 2 loops for the spa jets, half on each pump, and 1 loop for general circulation, filtering and heating which will have it's own return eyeballs (2). Of course, that means you will need a MD pair for each loop.

Note too that with current DOE regulations, you may not find large single speed pumps anymore and if you, they will likely be close to the cost of a VS.

 

[BlueWave8]

Thank you both for the responses.

I forgot about the DOE changes...hmm..

How about this for a jet pump for the two JetArrays:

(Curve D on the graph)

Sta-Rite Max-E-ProXF | XPE-8 | 2HP Energy Efficient Pool Pump | 023009

Pool Supply Unlimited has some of the best prices when shopping for Sta-Rite Max-E-ProXF | XPE-8 | 2HP Energy Efficient Pool Pump | 023009

www.poolsupplyunlimited.com

Any idea how much head loss the JetArray Clusters would have?

I was thinking I might be okay with the main pump in high speed for the four 15GPM jets. 11.5' for the heater, about 13' for the cyclone, another 7' maybe for the cartridge filter adds up to 31.5', plus another 10ish for the plumbing (all 3", 20-25 feet). About 45-50' of head loss total, the Circupool 3hp should do 100gpm at that which should be fine for the four 15gpm jets. What do you guys think?

 

[mas985]

Those jets are 7/16" nozzle orifice and to get a strong jet, the PSI loss of the jet should be around 20 PSI. This requires 25 GPM per jet or 100 GPM for each cluster. 70 GPM per cluster is a minimum and will produce very weak jets (10 PSI). You really want to plan for more flow rate.

However, those jets also have inserts that allow you to reduce the orifice size to 3/8" jets. To get the same 20 PSI, a 3/8" nozzle requires only 20 GPM per jet or 160 GPM total for 2 sets of 4 jets.

As for the pump, there are several on that sell sheet. Have you checked to see which are available. None are DOE compliant. Only the VS version of the XF is DOE compliant.

But it you chose the Intelliflo XF VS, then the likely operating points are the following for each type of jet:

8 x 7/16" Jets: 166 GPM @ 56' of head and 13 PSI per jet (weak jets)
8 x 3/8" Jets: 139 GPM @ 69' of head and 17 PSI per jet (moderate jets)

The 3/8" jets will feel much stronger than the 7/16" jet even though the flow rate per jet is less. The reason for this is the jet velocity of the 3/8" is 50 ft/sec and the 7/16" jet is 44 ft/sec.

Note too that with the 7/16" jets, the flow rate through the 3" pipe exceeds 7 ft/sec. The cross pipe between the MD pair would need to be upsized to 4" to remain compliant with current entrapment regulations. The 3/8" jets are close enough to the 6 ft/sec to be ok with 3".

If you want to go with a single pump for all 8 jets, then I would stick with the 3/8" jets. But you could try both sets to see what you like best.

 

[BlueWave8]

I missed that information about the reducers. I will get those on order. I called around about the Max-E-Pro, but as you stated, I didn't find any available. I'll likely have to go with the Intelliflo XF VS, it feels a bit excessive having two variable speed pumps. And the Intelliflo is nicer than my main pump! Oh well....

Thank you for the help, great information!

 

[BlueWave8]

Thanks again @mas985 , one more quick question....

The drain in the spa will be a single 32" channel drain with three 3" ports (they all share a common manifold, making it anti-entrapment compliant in my locale).

https://www.poolsupplyunlimited.com/Products/Manuals/5887_202081120406.pdf

One port will feed a 3" line to the main circulation pump that will have the heater, filter, and 2-4 standard spa jets. Should I tie the other two drain ports together for this additional high-flow loop? If so, what is the best way?

Run two separate lines from the drain and tee them together at the pump's intake, tee together at the drain and run one line to the pump's intake, or something I haven't thought of?

 

[mas985]

The manual you posted indicates 2" ports, not 3". For a MD port, for safety reasons, you want to stay below 6 ft/sec. For 2". that is 63 GPM. But with 3 ports, maximum target flow rate would be about 190 GPM so that would still be ok as long as you use all three ports. You can combine them into a single 3" or take them all the way to the pad. It doesn't really matter that much since 3x2" pipes has a slightly lower head loss than a 3" pipe.

 

[BlueWave8]

You're correct, I thought it was 3". It says 2-1/2" OD so I could put a 2.5" to 3" adapter on each one and run three 3" lines back to the pad (I can't even buy 2.5" pvc pipe locally). Then I suppose I could tee two together into the high flow loop, and have the one for the main circulation loop.

 

[mas985]

3x2" pipes will work just as well as a single 3" pipe.

 

[BlueWave8]

Yes but three 3" must be better, right?

 

[wireform]

I'm not sure the spa will benefit much from the heat pump and may take very long to bring up temps to the desired setting. You may need a LP or NG heater for that.

 

[mas985]

Yes but three 3" must be better, right?

Not really. 3x2" has slightly less head loss. It really won't matter that much so just go with whatever is available.

Also, I agree with @wireform about the HP. NG comes in much higher BTU ratings so will heat the spa faster.

 

[BlueWave8]

Are we sure we are talking about the same thing? I was referring to putting a 2.5" to 3" adapter on each of the outlets of the main drain, to have a total of three, three inch lines running from the drain to the pad. Then combining two of the three inch lines into the 3" union on the XF, and the remaining 3" line going to the main circulation pump. I'm not comparing three 2" vs one 3", I'm comparing three 2" vs three 3".

I do agree with you both about natural gas. If I had NG in my neighborhood, I'd absolutely have that for spa heat. I had an LP heated spa at my last house, I did love the quick heat up times. If I get LP I am required to bury my tank, a buried tank plus an LP heater is the same cost as a really high performance variable speed heat pump, and the heat pump also gets me dirt cheap pool heat (I don't want to heat the pool with LP! $$) If you plug in the numbers for the SQ150VS heat pump into mas985's heater spreadsheet, and do worst case, lets say March, (I'm in FL, so the other thing I have going for me is crazy high humidity most of the year). It might take around 2 hours to get my spa up to 104. But its really only Feb-March that it would take that long, most of the year it should take 30-45 minutes to get to 104. If it bothers me, I can pick up one of the new RayPak electric resistance heaters (that can be used with salt pools) for about $900-1200 and plumb that in to do double duty with the heat pump for a much quicker heat time in spa mode in the winter. I'm going to leave room for it on the pad and in initial plumbing, I'm pretty sure I'll get one.

My electric in FL is quite cheap as well, about 11 to 13 cents per kwh, and I plan to install solar photovoltaic in a couple years. So I'd rather use electric vs continue to pay to fill up a propane tank. You have to really shop around to not get gouged on delivered propane in my area, its one thing I'd rather not have to do. When you consider that adding the $1000 Raypak is about the same cost as filling up a propane tank 2.3 times it starts to sound better!

 

[mas985]

Sorry, I misread that.

3x3" is overkill (i.e. diminishing returns). 3x2" already has very low head loss so 3x3" won't improve that much. Won't hurt anything either other than $$ but I wouldn't bother.


Also, it isn't about the cost of LP vs HP, it is more about the time to heat as HP don't generally have very high output BTU. Of course, you could go with more than one HP.

 

[BlueWave8]

Right, I understand for time to heat, I know its a huge difference. For me, its that the acquisition cost of the two are equal, and the ~$5000 LP setup (buried tank, anode bags, heater, gas line) only gets me quick spa heat, not really pool heat. The $5000 VS heat pump gets me pool heat (almost free) and spa heat, except in Jan-March where it will take a couple hours. It would be different if I had NG and could use that to heat my pool as well, but propane is too expensive to heat the pool with.

Then factor in the ongoing cost. Running the new variable speed heat pumps in FL climate is more or less negligible in cost, whereas spa only LP is like $400 every 3-4 months. And it takes work on my part to get it refilled every 3-4 months. I'd rather the two hour wait times a couple months out of the year, and never worry about refilling or shopping around for the best propane deal. It's no fun to go out to use your spa only to find that your tank is empty!

Its true I could get a cheaper heat pump and double up, I might think about that a little more. But I really like how efficiently the variable speed one can run in a humid climate. Or the Raypak E3Ts give you 37k or 62k BTU at the flip of a switch...seems perfect to supplement a heat pump for a spa, no?