Boiler System: HVAC Series Part V

Posted on Wednesday Jun 24, 2020 at 02:30PM  


This Boiler blog is the fifth in a series of blogs that explores how Veris Industries products can be used to monitor and regulate heating, ventilation, and air conditioning (HVAC) applications.

How a Boiler Works

A boiler uses a combination of heat and pressure to increase the temperature of water. Like the chiller provides cooled water to the air handlers to condition the air, the boiler provides heated water to the air handlers to heat the air. Depending on the type of boiler and the application needs, the boiler can produce either hot water or steam. For our example, we will focus on a hot water producing system.

The boiler system is comprised of a: feed water system, hot water distribution system, and fuel system. The feed water system provides water to the boiler and regulates it automatically to meet the hot water demand.  The hot water distribution system collects and controls the hot water produced in the boiler. The hot water is routed to the heating coils in the air handler. The fuel system regulates the burners that heat the water.

Inside the boiler, burners produce flames that heat metal tubes filled with water. Temperature and pressure are closely monitored and controlled to ensure safe operation of the boiler. 

Diagram of a Boiler System

Diagram of a Boiler System

How a Boiler System Works with Veris Products

Product Family Why it is used on a Boiler
Power Meters Monitors the power used by the boiler. May assist with load shedding agreements. Excessive power usage may indicate a mechanical problem in the boiler pump motor(s).

Wet DP used to monitor the differential pressure between water supply and return. Controls bypass valve to regulate flow based on demand. Provides a secondary proof of flow by monitoring the differential between supply and return air.

Gauge pressure is used to monitor pressure on the line. Using a gauge pressure on both the supply and return will provide the data needed for the BMS to calculate the differential pressure.

Low or high pressure readings may be an indicator of a mechanical failure in the system like a leak, pump failure, a clog, etc.

Current Sensors Monitors run status on all pump motors. Can be used to detect on / off status, locked rotor, and overall pump status for proof of function / water flow. If the pump is drawing current, it is also pumping water.
Temperature Used to monitor temp for heated water loop, helps to control the valve that determines water recirculation speed. Helps to determine pump speed, how much water needs to be returned, and is a main control point for the system. The value from this temp sensor can also be used for BTU calculations.
Flow Meters

Flow Meter monitors water flow in the supply and return lines of the heated water loop.

BTU Meter is a flow meter combined with temperature sensors and can be used for energy measurements. The output is BTUs not a flow rate - its output is a measurement of the energy consumed by the boiler. It is also used to check the efficiency of the boiler. Clogs, malfunctioning pump, humidity changes, compressor cycling issues, can all be the causes of boiler inefficiency. 

Gas Flow Meter monitors the amount of natural gas or propane supplied to the boiler.

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