Best Of

Putting a control on a tee is questionable. Should be in the boiler.

A few thoughts. The most common, on the shelf HW 8043 is a 8 Cv, 8 psi shut off. In some cases with high head circs, they can push through a bit. Lower Cv of any ZV will always have a higher shut-off rating.

Also check to see if one spring have been disconnected, this is a common hack on HW if they experience water hammer noise. But it lowers the shut off pressure, so they may leak through.

The ball on the shaft rotates, so it closes off in a different location every time. Over a period of time you get a lot of criss cross imprints and can get small leakage. Same thing with the higher head circs allowing some flow to leak through.

Aggressive fluid can cause the ball to deteriorate also. Allegedly these valves were two years old! Perhaps an agressive acid cleaner was put into the system??

Best practice is to use a pressure bypass valve if you have 3 or more zone valves on a fixed speed circ. You want a flat curve circ on zone valve systems. As the valves close you run up the pump curve. Or better yet a delta P circulator

Fig 6-3 shows the difference between steep and flat curve circs and the ∆P difference as valves close off. On the vertical axis these two circs are about the same gpm, but the head is quite different.

All these factors were considered when the Caleffi Z-One was developed. It has a peroxide cured EPDM flapper. A coils spring that is torqued on every valve. Thicker gears with lost motion disconnect.

We have had an ocassional water hammer so the close-off torque has been reduced, dropping our 20 psi close off down around 15 psi, but slowing down close off a few seconds.

That is the trade off with spring return valves. Enough torque to hold 12- 15 psi, but slow close off to avoid water hammer potential.

Neither SSA1099 nor W2 states what you actually did to earn those $$ ? A million years installing new fixtures doesn't make me a MasterPlumber or even a Journeyman. New construction work doesn't teach me much about repairing old stuff. There's probably licensed folks in every vocation who aren't really qualified.

The ball of that zone valve is rubber.

I have actually is a couple cases witnessed the stem its is attached to snap off.

It is w/in the realm of possibility that the rubbed could wear down…especially if the water quality is poor.

Yes by all means get a mix valve on that radiant.

The AquaSmart and HydroStat can use extension cables too. Just have to order them.

TThe valve is only rated for a certain differential, if you exceed that it can leak through. If the radiant loops are very long you could have enough drop over the loop to exceed that differential. Or the valve could just be bad.