spa plumbing / pump question

[garykli]

Hi, this is my first post, so hopefully its in the correct forum.

I'm about to sign a contract to build a pool. The PB is insisting on using a 2hp variable speed pump + 2hp air blower for the 8 jet spa as well as the rest of the pool (~26k gallons). The other pump is going to be dedicated to the three sheer descents.

Is one pump enough for pool + spa? Should I be getting a dedicated spa pump to power the jets? PB intends to plumb the spa so that the water going into jets will pass through filter/heater. Is that going to cause problems? He claims Jandy's ok with this configuration and he's been doing this for years w/o issues. Is the water coming out of the jets going to be too hot when the heater is on?

Thanks!

 

[mas985]

There are a couple of red flags for me.

1) The PB is using a blower. That is usually a crutch for a poor spa design. Either pipe that is too small or the lack of a Hartford loop in the air vent. If designed properly, a spa should not require a blower. With 8 jets, I would not use less than 3" water lines to and from the spa and make sure the PB uses a Hartford loop at the spa.

2) Depending on the jets, 8 jets could require up to 200 GPM which a 2 HP pump would not be able to handle.

3) You may be able get by with a single pump BUT the filter MUST be over sized to handle the excess flow rate. Also, sand and DE filters have the disadvantage of backwash valves which causes excess head loss. I would go with a large 400-500 sq-ft cartridge filter. You may want to build in a bypass for the heater so it doesn't add to much head loss although some heaters already have a built in bypass.

A couple of questions:

What is the pump model#?

What is the distance between the spa and the pump?

What is the flow rate requirement per jet?

 

[garykli]

The mumps is going to be Jandy ePump 2HP. The distance between the spa & equipment should be about 15ft. I'm not sure what the flowrate req for the jets is, but based on what I was reading it should be about 15GPM. The piping to be used is 2.5". And the filter is 585sf.

I'll ask the PB about the Hartford loop.

Thank you for the suggestions / feedback! Much appreciated!

 

[mas985]

8 jets @ 15 GPM is 120 GPM. The ePump can't produce that much flow rate on spa plumbing with the filter and heater included. Also, at 120 GPM, you would need 3" pipe to keep the velocity below 6 ft/sec which is now a requirement in many cities.

 

[garykli]

Thanks Mark for the feedback!

What would be a good pump to use as a dedicated spa pump? Per recommendations above, I'm going to go w/ 3" pipe and probably a 3hp pump (just for the jets) and run the filter/heating for spa/pool as well as the decorative sheers on the 2HP Jandy ePump.. Do I want it to be a variable flow pump or is single speed sufficient? Would VF/VS pump give me control over how strong the jets are?

 

[mas985]

Most full rated 2 HP pumps (e.g. Stealth) would be able to deliver 120 GPM on 3" plumbing without the heater and filter. A VS would allow you to take some pressure off the jets if that is something you think you might want but for me, I like them at full force all the time.