Y-Pipe strainers

michaelmiracle · April 22

This is a hydronic boiler system in a school in Denver. The system is from the 1960's, the boiler and near boiler piping was replaced in 2015.

There is a Y-pipe strainer before the circulator and another after the circulator both 2" pipe. The one before (china) closes down to about 1 1/2" size strainer, the one above (Italy) does not. Just cleaned them out and the strainer above the circulator is without a strainer. The one below was fairly clogged with sludge after a year.

Question; should I do something different about this setup? Change the strainer to the larger one above the circulator, add a strainer to the one above, or leave it alone?

Screenshot 2026-04-22 at 12.27.09 PM.png

Screenshot 2026-04-22 at 12.27.57 PM.png

hot_rod · April 22

the ones above the pumps look like Y pattern swing check valves

ChrisJ · April 22

https://forum.heatinghelp.com/discussion/comment/1894892#Comment_1894892

Are these pins / shoulder bolts what gives it away?

Jamie Hall · April 22

The ones above the pumps aren't strainers — they are check valves. Or werent'. I hope the innards of the check valves are still there???

michaelmiracle · April 22

Ok. I see.

Thanks for the help.

Nothing inside them that I could see easily, But I will check again.

edit: I read up a little and the cap is for 'easy maintenance'. What maintenance do these need?

109A_5 · April 22

Larger strainer(s) may give you a longer service interval.

I think I would clean out the original strainer more often and see how it goes.

At least the strainers are doing something, IMO they are installed wrong.

hot_rod · April 22

You may need to do a system flush, add clean water and a hydronic chemical if you have chronic sludge issues. A Y strainer that plugs will starve the pump of flow and can cause a pump failure.

More and more systems are getting dirt separators instead of strainers. More capacity, better performance and easy to blow down.

Typically one at the boiler return.

pumpcontrolguy · April 22

On Y strainers it's quite handy to put a blow down valve on them so you or building staff can blast out the shmutz more frequently, but like @109A_5 mentioned, they shouldn't really be installed upwards like that since they wont work properly that way

EBEBRATT-Ed · April 22

The ones above the pumps are check valves for sure.

hot_rod · April 23

some things to avoid with circulator piping.

No flow restricting devices on the inlet side

A section of straight pipe upstream and downstream

Pump away from an expansion tank

A blow down valve is a good idea for occasionally serviced.

If the system has sludge or magnetite you usually need to remove the strainer and scrub it clean. To fine of mesh can cause more problems than it solves.

michaelmiracle · April 23

Looks like my setup has several of those incorrect items.

EBEBRATT-Ed · April 23

I don't know why they don't want a check valve on the discharge.

hot_rod · April 24

two purposes tor the check, to prevent ghost flow when one pump is off , and to prevent reverse flow when one pump is off

The piping has a bit to do with it also, primary secondary assures no pump interference when both are running

That is not an ideal check for Hydronics, as it requires a pressure difference to seal tightly, and the long travel length can cause a hammer noise

Other than that, it looks fine

Intplm. · April 28

https://forum.heatinghelp.com/discussion/comment/1894990#Comment_1894990

A very good point. As shown in the above pictures, there is no flo-check. Ghost flow is surely occurring without flo-checks, not to mention water hammer.

Y-Pipe strainers

Comments

Categories