Fenestration is a fancy architectural term that means “openings in the outside of the building.” You will see this word a lot when you read ACCA manual J or when you are doing a manual J load calculation. Fenestration loads include heat losses and gain through windows, doors, skylights, etc., and they can make up […]

I am consistently surprised by how much false information still circulates out in the field, and one of the ones I hear often is the idea that you cannot or should not “top-off” or recharge R410a systems on top of an existing charge of R410a when the system is low. So, to be clear, before […]

Every gas furnace data plate/tag has a specification for the temperature rise through that furnace. It is shown in a range like 50-80° or 45-75°. Those two numbers are the lowest recommended temperature rise; the highest allowed temperature rise through the furnace is usually a 30° difference. When possible, we want to get the rise toward […]