I recently purchased an old house. I have had the wiring redone (There was still knob-and-tube in some rooms) and am having the gas furnace replaced (It is 24 years old and 140,000 BTUs. Being replaced with a 75,000-80,000 BTU model, depending on which contractor I go with.)
The house only has a vented crawl space, about 2 feet between floor and ground. The only ductwork is in this space, none to the 2nd floor, unless one of the contractors comes up with a reasonably priced method to add it in (Not too likely.)
The question is, should I insulate the metal ducts in the crawlspace? While it has been a warm winter here so far, only a few days in the freezing range, we do have some very cold winters. Would insulating the ducts help with heating and cooling costs? Could it cause problems of some kind?
Owning a house is so educational. And far too expensive.
I wouldn’t imagine that it would even be an acceptable option to leave them uninsulated. We’re talking a crawlspace that’s vented to the outside air, any uninsulated heating ducts are going to leak crazy amounts of heat when the temperatures drop.
One thing comes to mind, though. If you insulate those ducts, the crawlspace will get a lot colder, so you may get a water pipe freezing problem that you didn’t have before.
I would find a way to insulate them (wrap them with fibergalss batts, and support with plastic sheeting) and then make sure critters can’t get in there to shred it for nesting materials.
You may consider electric heating in the upper rooms. It’s much easier to fish wires up to the attic than ducting.
Another option is to install ceiling grills in the lower floor ceiling so the heat can pass through to the upper floor. I don’t know if those are legal now (fire and smoke issues).
Look into running ducts through the back corners of first floor closets and up to the second floor. You can often find ways to make this work, and without the expense and mess of breaking into your walls. You only lose a minor amount of space in your closets, usually back in the corner which you don’t use much anyway.
People have done a lot of that in this area of South Minneapolis, where older hot water heat houses have had to have air conditioning added as part of a airplane noise settlement with the airport and Northwest Airlines. (They cheated out of the deal anyway, but that’s another story.)
Definitely insulate the ducts under your house. It will pay for itself in reduced energy costs alone.
When considering adding ductwork to the 2nd floor, if this is for heat only, you really don’t need very much. A big problem with heating a 2-story house with a single furnace is in trying to keep the downstairs warm without roasting the upstairs. If it’s not too terribly cold now, I’d forego the expense. If the upstairs really needs some extra heat, be conservative. It would suck to pay for ductwork that you found you had to close off 90% of the time.
First off, yes insulate the ducts. The contractor will probably do that as part of the job, to meet code.
Secondly, you could do a split system. Put a gas pack (self contained heating unit) on the roof for the second floor. Ducts go through the roof run through the attic, and the return also runs though the attic and out through the roof.
No wall cutting, no lost closet.
I am already planning on heat tape for the plumbing in the crawlspace. I don’t know if there have been problems with freezing before, since I have only had the house since November.
Unfortunately, the only closet down stairs is under the stairway, no access to the upstairs from there. They can put a vent from the furnace up into the main bedroom closet, but the house design pretty much prevents getting it any farther. That still leaves 2 bedrooms and the hallway with nothing but heat rising up the stairs. If I decide I really need to, I will probably spring for the electric baseboard.
Frankly, the central air not reaching upstairs is a bigger concern for me. The prior owners had a window unit upstairs. Still waiting for a quote from one contractor, will see if he comes up with anything.
