Circulators - Flange Compatibility

peterb01

Hi,

I am trying to replace a (failed) Grundfos UPS15-58 circulator with a Taco 0018e, but cannot get the top flange to stop leaking.

The existing top flange uses a flat gasket, the existing bottom flange uses an O-ring gasket.

The Taco manual says that only O-ring gaskets can be used, and that use of flat gaskets will void warranty. However, the O-ring gasket that comes with the Taco does not seem to be compatible with the existing swivel flange (leaks). I've tried the flat gasket as well, but this also leaks.

I am trying to avoid having to replace the existing top flange as this would need the entire system to be drained down.

Pictures below - am I doing something wrong?

Thanks!


Bottom Flange:


Top Flange

EBEBRATT-Ed

Try the "O" ring on the pump and the gasket on the flange.

peterb01

I tried that as well, but it also leaked (and got worse as I tightened it down further)

EBEBRATT-Ed

I don't understand. Your flange alignment looks perfect. How is the other pump flange liquid tight??

There has to be a defect in one of the flanges or the gasket or O ring.

I would suspect the steel top flange is bent or warped .

peterb01

There are no leaks with the original Grundfos - it's when I switch to the Taco that the leak occurs at the top (swivel) flange. The pictures of the flanges are with the Grundfos installed - I put it back to get the boiler back online.

The Taco install instructions say to use O-ring gaskets only, which leak with the top swivel flange (I don't think they are compatible). The flat gasket leaks also, which I think is down to differences in the pump where it mates to the flange - the Grundfos seems to have a much wider ring to compress the gasket and form a seal.

Hope this helps explain things.

Thanks!

hot_rod

Those swivel Grundfos flanges are a PITA, a very small sealing surface. They will not work with a ring only gasket.
Did you flip that chrome flange? It only seals one way. A flat gasket should work. I think they shipped with flat gaskets.
Could be the hole is too large in the gasket?

kcopp

Raven makes a nice black rubber flat gasket. They will not become brittle over time like the red rubber type..

Lyle {pheloa} Carter

I've used the flat gasket and the O-ring in the same situation. Are you using the flat gasket that came with that flange? Substituting a different flat flange gasket won't work the hole in the center is too large.

peterb01

An update on this one - I ended up replacing the swivel flange with a cast iron fixed flange, using the O-ring supplied with the pump.

After a bit more research I found the post below,

https://forum.heatinghelp.com/discussion/170615/taco-255-2-flanges-not-compatible-with-0015e-circulators

In particular the following from Taco:

Generally speaking the current 00 series casings have had excess material removed from the flange sealing area for weight and cost reduction. Engineering determined it was not necessary to seal against our companion flanges. However, it created less sealing surface area for the old 254-256 series bronze , swivel style shut-off flanges, as well as the current Grundfos swivel style shut-off flanges, etc.
The ID of our gasket area is larger than the OD of the companion flange surface, so there’s not enough surface area to seal against. During my 15 + years in Tech support I have seen the o-ring and flat gasket used to seal the flange but its never a good idea to mate two compressible gaskets together; chances of leaks are fairly high. Do not recommend.

Thanks all for your thoughts and suggestions.

EBEBRATT-Ed

@peterb01

Thanks for the info good job now we all know.

Intplm.

Maybe this with some gasket seal next time?

Dave H_2

Those swivel flanges made by Grundfos where only designed with Grundfos circs, the inside sealing surface "fell" into the cavity of a Taco circ.

The only fix is to replace the swivel flange (as you did) or use a a newer 00e circ with a stainless casting (or use another Grundfos).

Dave H.