The HeatManager™ is the new microprocessor-based energy saving control from Beckett for use with new or existing boiler systems. This technical bulletin is intended to familiarize you with the HeatManager™, and to help you understand exactly how it works to save energy.
Theory Behind The HeatManager™
- The HeatManager™ adjusts the burner firing pattern to accurately match the boiler output to the home’s heat load (also referred to as heat loss) at that moment.
- Heat Load: The number of BTU’s per hour (BTUH) needed to maintain the home at a comfortable temperature (i.e. 70° F). The heat load is affected by many factors, including: local temperature, wind, and sun; insulation levels, window orientation, home occupancy, etc. On a very cold day, the heat load will be heavy; on a milder day, the heat load will be much lighter.
- A boiler is sized to insure comfort at temperatures well below the worst anticipated. At any temperature warmer than the most extreme, the boiler is able to provide more BTUH than the home needs. The result is that the burner cycles on and off many times an hour to keep the home from overheating. This repeated on/off cycling is a very inefficient way for the boiler system to operate.
- Most of today’s boiler systems don’t adjust to the home’s heat load. They usually turn on both the burner and circulator every time there is a call for heat. This result is that the burner will fire even though there is still plenty of usable heat in the boiler.
- The HeatManager™ adds intelligence to the system, and ensures that the burner fires only after all of the usable BTU’s have been extracted from the boiler.
DETERMINING HEAT LOAD
- The HeatManager™ uses a single, easily installed strap-on temperature sensor attached to the boiler supply (out-flow) pipe to measure both heat load and boiler water temperature. See Figure 1
- Every time the burner shuts off – either due to high limit or end of heat call – the sensor begins taking temperature readings of the boiler water. The sensor takes 3 readings per second and transmits them back to the HeatManager™.
- The HeatManager™ then determines the heat load by analyzing the temperature drop off rate of the boiler water during the burner off cycle.
- On cold days the water temperature will drop more quickly than on mild days. Whether or not the circulator is running during the burner off cycle also has an affect on the rate of temperature drop.
- Therefore, a fast temperature drop of the boiler water corresponds to a heavy heat load, and a slow temperature drop corresponds to a light heat load. See the graphs in Figure 2
- The HeatManager™ is installed in series between the boiler control and the burner. This wiring configuration gives the HeatManager™ the ability to interrupt the call to the burner, and to hold off burner firing when appropriate. See Figure 3
- After determining the heat load, the HeatManager™ uses a patented algorithm to calculate the minimum boiler water temperature needed to maintain comfort at the measured heat load. This is the ideal burner cut-in temperature.
- If there is a call for the burner to fire while the boiler water temperature is above the ideal cut-in temperature, the HeatManager™ will delay burner firing. The preheated water already in the boiler will circulate to provide heat. Below are two examples of how the HeatManager™ would operate to conserve fuel in two different scenarios: