Originally Posted by
54regcab
.You can buy a 50k furnace with a 1200CFM blower, but a 75K with a 1200CFM blower may get installed instead because that's what the supply house has in stock/on sale at that time. Doesn't matter that the house only needs 40K of heat according to a load calculation. Doesn't matter that the ductwork can only deliver 800CFM of air and the furnace will cycle on limit come winter.
Here's what doesn't matter, the load calc doesn't matter if they are not addressing the duct work. Why waste your time with a load calc if your not going to correct the duct design? your just wasting your time and the customers time. If you have some dummy installing a system that the duct is so insufficient that the furnace goes off on high limit, you don't address it with a smaller cfm furnace, because airflow is also important to the cooling performance, low airflow= low performance. You folks must have a great job security up yonder, with all the HX warranties. This is why we call them A/C and Heating "systems" the duct work is part of the system.
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