Carbon Monoxide Venting

Our gas furnace (right side pipe) and our gas water heater vent through the side of the garage, and the vent pipes go up through the plastic rain roof so all the exhaust gases (especially any possible carbon monoxide) don't get trapped under the rain roof to go in the house when the door is open... we have a plug in carbon monoxide detector near the gas cooktop in the kitchen, but the two vent pipes from the garage are just common sense to eliminate any problems
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To hide the pipes I built a red painted 2x4 frame that will, after the weather is warm enough to put a fresh coat of paint on the garage wall, have SMALL hole lattice cut and mounted