Arrived to remedy a system that is creating carbon monoxide in the home. Performed diagnostic and found that the system is backdrafting down the water heater flue because of the negative pressure in the utility room. The negative pressure in this room is from the system operating with high static pressure. Recommend modifying duct work to decrease the static pressure and installing vents for the room so the furnace has enough combustion air. Spoke with homeowner about speaking with a design specialist to receive estimates for repairs. With homeowners approval reached out and got a design specialist in route. Furnace and water heater have been labeled unsafe to operate and has been shut off.