Hot water bypass valve

[cmcd1]

I have a jacketed tank application requiring 120 degF water to maintain temp of the product.

I am matching existing applications, where there is hot water supply and return headers. The supply side drop includes a small inline centrifugal pump, with a 3-way bypass valve that ties back into the return riser.

What is the purpose of this? How does it operate? I am
assuming it requires a signal from an RTD???

 

[gmorin]

I've seen that arrangement in a greenhouse application before. It is good for heating applications where you don't want to have on-off swings in your heater temperature.

Basically, if your temperature is at set point, the water is recirculated through your jacket and you don't consume any hot water.

If you drop below your set point, the valves will open a little and let some hot water into the loop. A corresponding volume of colder water returning from the jacket is let out and returned to the boiler / heat source.

I'm guessing here.....

If there is not an RTD or thermocouple in the line, the valve could be operating on a capillary. Basically, the capillary has a working fluid that expands with heat and moves the valve operator against a spring.

A capillary would be shown on a diagram as a process line (with x's on it in our company standard) going from a pipe or tank connection to the valve operator

Good Luck

Greg