Insulate those pipes, and take one for the marital team

Q: We have a fairly new gas furnace, maybe 6 or 8 years old. The pipes that return air to the furnace (cold air returns?) are located in the attic and crawlspace. They are round pipes made of sheet metal and are not insulated. The house was built in the 1950s.

My spouse and I are having an ongoing "discussion" about whether it is important to have insulation on these pipes.

Since I know you will pick on the losing person, I am not going to identify which person feels which way. In any event, one member of the marital team feels that since the cold air is being heated in the furnace, what is the point of the insulation? One or the other partner has already insulated the actual hot air pipes in the crawlspace in our ongoing effort to save energy.

We anonymously thank you for your reply.

A: "Cold air" is a relative term. That air is the temperature of the room, say 70 degrees. When it is exposed to those cold-soaked pipes in the attic and crawlspace that may be 40 degrees, it obviously cools it. For purposes of discussion, let's say that 70-degree air is cooled 15 degrees to 55. Air entering the furnace is now 15 degrees cooler than it would otherwise be.

Forced-air furnaces work on what is called "heat rise." A typical newer furnace may produce a heat rise of 70 degrees. Seventy-degree cold air would come out the hot side at 140, while 55-degree air would come out at a corresponding 125.

The difference in heat production relates to the amount of time the furnace must run to heat your house to your desired temperature, which has a direct impact on that dreaded gas bill.

Excuse me, but exactly how long ago do you think I fell off the turnip truck? I'm married. I know the dynamic of the situation here; I see the manipulation, subtle like a Mack truck. Let's just get this piece of business out of the way first: You are absolutely right, you win. The pipes need insulating if you want to continue to improve the energy efficiency of the house.

However, since it was Hubby who spent all that time on his back in the mud and hot attic rolling around in fiberglass insulation as a devoted member of the "marital team," it is now your turn to be a team player and insulate the cold-air side of the system.

Take heart, for there are far fewer pipes, and it shouldn't take you nearly as long. Meanwhile, he will lend you all the support you need, get you drinks, insulation, tape, whatever is needed to get the job done — just so long as it is in between innings.

Darrell Hay is a local home inspector and manages several rental properties. Send home-maintenance questions to dhay@seattletimes.com. Sorry, no personal replies.