HVAC Heater Sizing Calculation Guide

Sizing heaters is one of those HVAC tasks that appears very complicated from the outside, but after you understand the logic, the whole process becomes crystal clear. Each heater, be it electric, hot water, or gas-fired, has to be appropriately sized in order to maintain comfort inside the space. If the heater is too small, the room never warms up. If the heater is too big, the system cycles too often and wastes energy.

In this post, I will simplify heater sizing into easy steps and simple engineering logic. This is actually how we do the calculations on actual MEP projects whenever we are calculating heating requirements for rooms, offices, workshops, and all other conditioned spaces.