pump flange compatibility - unions

Users who are viewing this thread

jameswing

New Member
Messages
2
Reaction score
0
Points
1
Location
Colorado
I believe the regular pump flanges are interchangeable between Taco and Grundfos pumps, for example (and presumably others too,) thus allowing us to swap out different brands of pumps without changing flanges. But it is unclear whether the pumps with 1-1/4" unions can also be swapped out with different brands. Here is an example:
Taco pump with 1-1/4" union connection
Grundfos pump with 1-1/4" union connection

Here is Grudfos' half-union.
Here are specs on the Taco half-union, which is very hard to find anywhere, and (& perhaps BECAUSE) it costs twice the cost as the Grundfos version.

I've seen contradictory specs on them. Some sites say the Taco half-union is a 1-1/4" DIN thread. Some say it is NPT (which is certainly wrong for the mating threads in the union). Yet a third brand (Armstrong) is purportedly NPSM threads in the union. I don't have confidence in ANY of the specs, as I've found plenty of them that contradict each other.

Typically, one brand of union is not compatible with another, as the mating threads are not standardized. But it's unusual to even be able to buy a half-union (likely for this very reason). I kindof *suspect* these are indeed standardized, but I'd sure like to get confirmation from someone with a lot of experience swapping out pumps with 1-1/4" union connections of different brands. It seems like it would be odd for these manufacturers to go out of their way to make the other flanges the same, but then make the sortof-standard 1-1/4" union NOT the same.

Can anyone confirm or deny compatibility of the 1-1/4" half-unions for Taco vs. Grundfos?
 

Fitter30

Well-Known Member
Messages
4,477
Reaction score
831
Points
113
Location
Peace valley missouri
No i can't but I've never tried another brand because i can't afford a problem. No different than replacing a pump or a cartridge. Labor cost to much. What advantage would another company have
 

jameswing

New Member
Messages
2
Reaction score
0
Points
1
Location
Colorado
Advantage: 1) One brand of half-union is in stock while the other brand (that matches your pump) is back-ordered; 2) you have a Taco pump with identical specs in stock, and need to replace a Grundfos pump -- even if you had the Taco 1-1/4" half-union "Freedom Flange" from Taco on hand, removing the identical flange from Grundfos to sweat in the Taco part seems like a waste of time. You don't swap out other flanges to be the same brand as the pump your installing as a matter of course, right? 3) Grundfos half-unions are half the price of Taco's half-unions, and WAY more available. Is the availability difference BECAUSE of the price difference and known interchangeability?
 

Fitter30

Well-Known Member
Messages
4,477
Reaction score
831
Points
113
Location
Peace valley missouri
Advantage: 1) One brand of half-union is in stock while the other brand (that matches your pump) is back-ordered; 2) you have a Taco pump with identical specs in stock, and need to replace a Grundfos pump -- even if you had the Taco 1-1/4" half-union "Freedom Flange" from Taco on hand, removing the identical flange from Grundfos to sweat in the Taco part seems like a waste of time. You don't swap out other flanges to be the same brand as the pump your installing as a matter of course, right? 3) Grundfos half-unions are half the price of Taco's half-unions, and WAY more available. Is the availability difference BECAUSE of the price difference and known interchangeability?
If you have the room could just buy the flanges 2- 1.250" screwed ball valves and 2 nipples that's if you need the valves
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks