Flo-Control Q & A
A Flo-Control Q&A
Q: What does a B&G Flo-Control valve do?
A: It has two jobs. First the Flo-Control valve acts as a check valve, keeping the system flow from short-circuiting into places where it doesn’t belong. Second, and just as important, the Flo-Control valve stops hot water from migrating into a zone that’s not calling for heat.
Q: Can’t I just use a swing check valve to do this?
A: A swing check valve will do the first job (preventing flow from short-circuiting), but it usually can’t do the second. The Flo- Control valve has a weighted check. When the water in the boiler is hot, it tries to rise into the system piping. We call this gravity circulation. The Flo-Control valve’s weighted check stops gravity circulation before it can create a problem with your customer.
Q: Should I use a B&G Flo-Control valve only on the supply line?
A: If you’re using circulators, you need a Flo- Control valve on each supply line, but you might need one on each return line as well. Gravity circulation doesn’t need a complete circuit; it can happen in a single pipe. The hot water rises up the pipe as the cold water falls. If a radiator on the return side of your zone overheats, install a B&G Flo-Control valve on the return. That solves the problem just about every time.
Q: Why does a B&G Flo-Control valve have two inlets?
A: So you can use it in a horizontal line, or as an elbow. The Flo-Control valve’s model designation, “SA,” stands for “straight” and “angle.” We make them this way for your piping convenience.
Q: Can I use the “extra” inlet for anything?
A: You can use it as a place to install a boiler-bypass line. You’ll need a bypass if you’re putting a low-volume boiler in a high- volume system (such as an old gravity hot water system).
The bypass gives you a way of raising the temperature of the returning water; and that helps to keep the flue gasses from condensing. Run the bypass only from the bottom tapping of the Flo-Control valve to the boiler return. If your circulator is on the return, pipe the bypass into the circulator’s inlet side.
Use a B&G Circuit Setter valve in the bypass line to balance the flow between the system and the bypass line.
Q: Do I need B&G Flo-Control valves if I have a primary/secondary system?
A: If the secondary circuit is above the primary circuit, it’s a good idea to install a Flo-Control valve on both the supply and return lines of the secondary circuit. If the primary circuit is higher than the secondary, you probably won’t need the FloControl valves unless the secondary circuit contains a boiler.
Q: If I use zone valves, do I still need B&G Flo-Control valves?
A: Not on the side of the system that has the zone valves, but you may need them on the other side. It all depends on how you run your piping, and how close your boiler is to a radiator that might overheat from gravity circulation. Sometimes you can have gravity circulation and not even notice it! It all depends on where the radiators are.
Q: What is the purpose of the knob on the top of the B&G Flo-Control valve?
A: If you turn the knob counter-clockwise, you’ll lift the weighted check off its seat. This will give you gravity circulation, which you may want if the circulator should fail. Once you’ve repaired the circulator, turn the knob clockwise to reseat the weighted check.
Q: Is there much of a pressure drop across B&G Flo-Control valves?
A: There’s just enough to make the Flo- Control valve work effectively. For instance, with three gpm flowing through a three-quarter-inch Flo-Control valve, the pressure drop will be about 2-1/2 feet. For six gpm flowing through a one-inch Flo- Control, the pressure drop will be about 11/2 feet. We have charts available that show the pressure drops for all our valves. If you need to know, just call!
Q: What size B&G Flo-Control valve should I use?
A: Usually line size, but you might want to use a larger Flo-Control valve on a volume boiler that comes up to temperature very quickly. Quick-start boilers sometimes produce enough thermal lift to raise the weight of a line-size Flo-Control valve.
Q: Do B&G Flo-Control valves make noise?
A: B&G Flo-Control valves have a patented design that eliminates noise. When the flow from the circulator lifts the weighted check, it also tilts it a bit to the side (that’s the idea we patented!). This slight tilt of the weighted check on its stem keeps it from “chattering” as the water flows by. It’s a small detail, but it’s one of the things that makes the B&G Flo-Control valve so reliable.
(If you have a question about B&G Flo- Control valves, and you didn’t find your answer here, call your ITT Bell&Gossett representative. They’re the people with the answers to all your hydronic heating needs!)
Reprinted from CounterPoint July 1996, Vol. 3, Issue 1