Taco to the Rescue

FB

When our Brand X Differential Bypass Valve started leaking, its flawed design necessitated replacement with a different device. After more time and effort than I care to reveal, a Taco 3196 and two isolation valves were shoehorned into the limited space. Retained by unions, it should be easy to replace without having to drain the system.

Joe Mattiello

Apparently, the Taco 3196 worked well. Thanks for taking the time to share your positive experience on the wall.

Zman

With the great variety of ECM circs out there, I am surprised that people are still installing and servicing bipass valves.
That kind of configuration is like driving your car around with the gas peddle floored and then using the brake to adjust your speed.
The bipass on my own system is working just fine. I am going to take it out and save about $40 a year in electricity.

hot_rod

There was, and still is a place for a bypass valve in fixed speed, zoned systems. Since it is not possible to build a completely flat curve centrifugal circ pump, the bypass merely attempts to "flatten" the curve.

Agreed a VS pump is a more elegant way to adjust the circ to the system, the DBV has been a very important device to allow multi zoned, fixed speed systems behave and operate quietly and to design conditions.

Perhaps in your lifetime all circs will be switched to VS technology, in the meantime don't ignore the simplicity and functionality of the bypass valve, or discourage it's use .

It is a super simple valve by design and very easy to understand and set properly

There are plenty of multi, especially micro, zoned systems out there that could benefit from this valve. They are often built into radiant manifolds and some of the pump mixing blocks used in radiant.

Even the flattest curve, fixed speed circa can over pump micro zones and even cause ZV hammer, the DBV was designed to solve those issues before the industry evolved to VS.

Here is a well detailed tech sheet, written in plain English on how to install and adjust the bypass valve, for those un-familiar with DBVs.

Rich_49

Rod I don't completely disagree . But the industry has evolved to VS and ECM . Not to mention energy efficiency and the Green movement . So why use one or not remove it from candidate upgrade systems . Or should we keep using 80 watts when 9 - 55 will do ?

hot_rod

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For me and my customers I am perfectly comfortable with ECM pump technology.

Some, maybe many contractors are fine with fixed speed, and prefer to wait some years for ECM to prove. Some glitches are still possible with new technology.

Some installers still prefer cast iron scoop vents.

Wholesalers I visit keep on the shelf and sell sell many 3 piece B&G series 100 style pumps.

So maybe a good, better best pump selection analogy, in terms of energy efficiency?

My post was to make sure installers understand the function, installation and operation of a bypass valve, and don't discard the need for this device.

RobG

And to add to HR's perspective, manufacturers still ship many boilers with fixed speed pumps. The customer is lucky if the low bidder even uses a DBV. Sad but true.

hot_rod

Isn't a DBV basically a balance valve. Set one alongside a PIBV pressure independent balance valve, take a close look of the exploded view. They are doing the exact same function

All the PIBV has is a characterized function to exactly regulate the flow, that differs it from a DBV

Savy designers and engineers realize the vital importance of balance valves in hydronics. Which is why millions are sold and installed. They assure the efficiency of the device they connect to. Even systems with VS pumping benefit from the use of balancing devices

Would you install a mod con and not adjust the gas valve to get it to manufacturers spec? The adjustment you make is a balancing function. That is what balancing does, assures the best possible efficiency.

For fixed speed circs the bypass valve is a simple balance device, not a band aid, in my mind

Remember not all zoned systems need them, look at the pump, it's curve and the gpm requirements of the connected zones.