Pls. bear with me cuz I'm new at this. My home is in N.W.Oregon. (rainy) During winter I'm trying to find out if it is OK to plug the foundation vents to save heat. The furnace and hot water heater(blanketed) are very high efficiency units and are gas fired. I believe they are both vented internally with P.V.C. exhausts. They are both located in this space. All heating ducts are wrapped along with hot water pipes. The space has plastic vapor barrier covering all exposed dirt. There is a small(10'x10')concrete pad there also. We store things there like yard furniture and other things we don't feel will be harmed by a damp environment. I have heard both yes and no regarding plugging the foundation vents with the foam plugs available in home improvement stores. stores.