Designing Domestic Hot Water Recirculation Systems: Part 3 Pump Control
In the last R. L. Deppmann Monday Morning Minute we selected a B&G Pump after determining flow rate and pump head. This week we look at the various means of pump control.
(Photo credit: Wikipedia)
Domestic hot water recirculation pumps could simply run continuously. This satisfies the requirement to have hot water available at the last fixture. It also satisfies any concern about stagnant flow conditions if the system is properly designed and balanced. Running a pump 24/7 will waste energy. What options are available?
Domestic Hot Water Recirculation Pump Timers and Aquastats
(Photo credit: B&G TC-1 Timer)
A timer simply turns the pump on and off at certain times of the day. Think lamp timer! The engineer may want the pump off at night in an office but running during the day. The Bell & Gossett TC-1 timer designed for the NBF pump series is an example of this type of control.
(Photo credit: B&G AQ-3/4 Aquastat)
An Aquastat similar to the Bell & Gossett AQ-3/4 shown above turns the pump on at 100°F and off at 120°F. Obviously, there are other control brands with more options for temperature. The simple controls mentioned above may be combined. The B&G NBF pump could employ both the TC-1 and AQ. The pump will control the temperature, but only during the times set by the timer control.
ECM Smart Circulator Pump Control
Once again, I mention the B&G Ecocirc®-XL Smart ECM Pump. This pump has a built-in temperature sensor which will ramp the pump speed up and down to maintain a set temperature. This pump will remove the overheating and react to supply hot water usage to save energy. No other controls needed. The screenshot below shows the simple laptop or iPad interface to set up the internal temperature program and to set the temperature and the sampling time.
Check out the rest of the Designing Domestic Hot Water Recirculation Systems Series:
- Part 1: Determining the Flow Rate
- Part 2: Determining the Pumping Pressure Drop
- Part 3: Pump Control