Identifying Spa Pump & Motor Replacements



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Identifying Spa Pump & Motor Replacements

Identifying a correct motor or pump replacement for a spa can be a tricky business: motors come in various sizes, pumps can have non-standard (up-rated/brake horsepower) ratings, sometimes the horsepower rating will be blank. Correct identification can make the difference between a profitable parts sale/service call and an expensive mess.

Let’s cover some of these terms:

• Up-rating – The practice of labeling a motor at higher than its traditional horsepower rating. For example changing a 2 HP pump into a 3 HP pump by only changing some of the ratings on the sticker.(See Brake/SPL ‘Special” Horsepower)
  
• Frame Size – Motors come in different sizes, we define these standard sizes by motor frame numbers. Unfortunately these motor manufactures do not agree on the terms they use for these frame sizes. For simplicity we refer to standard spa motors as 48Y and 56Y, but motor manufacturers call them all sorts of things. Some motor manufacturers even call the 48 frame motors 56 and vice versa.
  
• Brake/SPL “Special” Horsepower – These are commonly used for even bigger “up-ratings” a 2 HP pump can change to 4.5 HP or higher merely by changing the sticker on the motor. This rating is primarily based on the HP the motor attains less any load. True HP is the rating of the motor under load, this is the most important rating we as techs look for.
• 
  With horsepower ratings you cannot trust and frame sizes called all sorts of different things – what are you to do? The best weapon in our quest to identify a correct replacement is careful observation. We can identify frame size with a ruler and noting where the bolts are, we can get an idea for the horsepower by observing the amperage & voltage and find out one speed or two speed with the RPM rating. Everything we need to know is at hand you just need to know what to look for.
  
• Below is a checklist of things we use when identifying a pump. We don't always them all, but the more you know the more likely it is you will get it right.
  

• Pump ID checklist:

  • Amperage
  • Voltage
  • RPM rating
  • Pump brand
  • Pump model
  • Motor diameter
  • Impeller part number
  • Pump casing part numbers
  • Number of screws that hold the pump wet end together
  • Shape of the pump faceplate
  • Distance between motor thru-bolts and the head size.
  • Position of motor thru-bolts
  • Pump discharge location
  • Pump suction location
  • Outside thread diameter of suction and discharge

What do we do with all that?

Amperage and voltage – Normally the correct replacement will be the same voltage and near the same amperage.
RPM Rating – A 3450/1725 rating means you have a 2 speed motor, a single 3450 rating means you have a standard 1 speed motor, a single 1725 rating means you have circ pump motor, ratings of 2850 or 1425 mean you have a 50 hertz overseas motor.
Motor diameter – 48 frame motors are around 5-1/2” in diameter, 56 frame motors are around 6-3/8” diameter.
Distance between motor thru-bolts – 48 frame motors have thru-bolts about 3-5/8” apart, 56 frame motors have thru-bolts about 4-1/8” apart.
Thru-bolt head sizes – 48 frame motors usually have 1/4” heads on the thru-bolts, 56 frame motors usually have 5/16” heads.
Mounting Bolt Pattern – The distance between the bolts on the 48 frame bolt pattern = 3.65". The ditance between the bolts on the 56 frame = 4.1".
Pump brand/model – Replacing a pump with exactly the same pump will ensure a good fit. With most pump models only one motor size fits, eliminating a lot of the frame questions.
Pump case/impeller part numbers - These will usually lead to a particular pump model, and the impeller numbers to a model and horsepower. If there are no part numbers we can use basic shape and number of screws to try and narrow down to a pump model.
Outside thread diameters (where the plumbing hooks up) - The common thread sizes are 1.5” Buttress = 2-7/16” diameter, 2” Buttress = 3-1/16”diameter and 2.5” Buttress = 3-11/16” diameter.
Thru-bolt locations – most motor bolts that attach pump and motor are located at 11:00, 1:00, 5:00 and 7:00 O’clock. If yours are located elsewhere, ask before ordering a motor.
Pump discharge location – some pump discharges are located directly in-line with the motor shaft (they may be straight up or point left or right) we call these “center discharge” pumps, some pump discharges are set off to the right side of the wet end we call these “side discharge” pumps.
Pump suction location – most pumps have the suction is in the center of the wet end, 100% Drain pumps have them lowered to the bottom.
As you can see there are a number of things to consider when selecting spa pumps and their parts, if you follow the guidelines above you will find it is not hard to get it right.

This Article Supplied by Spa Parts Plus.

Until Next Time...