Pentair Mastertemp unions

JimMarshall

Gold Supporter
TFP Guide
Jun 5, 2017
1,003
Oil City PA
Heater unions

I’m upgrading my pump and plumbing to 2”. Does anyone know the proper part number I’ll need for connection to my Pentair mastertemp 125?

Or can I re-use my old unions?
 

tspenard

Active member
Nov 10, 2016
27
St. Louis, MO
I don't know the answer, and there is no confirmation on this when searching the OEM coupler kit:

https://www.poolsupplyunlimited.com/pentair-98960311-bulkhead-union-kit-black/153913p1

But you could measure the outer diameter of your existing couplers to see if it just so happens to be a perfect slip fit for a 2" coupler. IOW if it has the same OD as 2" PVC pipe then you should be able to glue it. I would suggest using the red label glue (and primer) on these couplers because they often don't tell you what material they are made of. The red label general purpose glue is suitable for PVC, CPVC, and ABS.

Amazon.com: Oatey 30821 Cement 8-Ounce Milky-clear: Home Improvement

Another idea would be to see if other Pentair coupler kits, designed for larger pools such as pumps and larger heaters, would have the same threads and O-ring sealing surface diameter. The MasterTemp 125K is fairly small so they probably don't expect it to be installed on 2" pipe. Some of these use the 1.5" ID / 2.0" OD method of optional pipe size connection.
 
Last edited:

JimMarshall

Gold Supporter
TFP Guide
Jun 5, 2017
1,003
Oil City PA
I don't know the answer, and there is no confirmation on this when searching the OEM coupler kit:

https://www.poolsupplyunlimited.com/pentair-98960311-bulkhead-union-kit-black/153913p1

But you could measure the outer diameter of your existing couplers to see if it just so happens to be a perfect slip fit for a 2" coupler. IOW if it has the same OD as 2" PVC pipe then you should be able to glue it. I would suggest using the red label glue (and primer) on these couplers because they often don't tell you what material they are made of. The red label general purpose glue is suitable for PVC, CPVC, and ABS.

Amazon.com: Oatey 30821 Cement 8-Ounce Milky-clear: Home Improvement

Another idea would be to see if other Pentair coupler kits, designed for larger pools such as pumps and larger heaters, would have the same threads and O-ring sealing surface diameter. The MasterTemp 125K is fairly small so they probably don't expect it to be installed on 2" pipe. Some of these use the 1.5" ID / 2.0" OD method of optional pipe size connection.
I’ll have to get out my calipers and see