"Moving Heat" : Convection Air Currents in Your House

[SmokeyTheBear]

Thank you, Bruins4877, but be careful about lurking ME- I'm learning as I go along! I hope I'm getting this stuff done correctly and safely; that's one reason why I keep coming back here, reporting in and asking additional questions. I imagine that working with *any* house is challenging in this regard, but it's especially interesting in a 54 year old house.

At least we aren't dealing with the really old type of electrical service wiring... that would be really sporty!

If I were to see knob and tube, out it would come then and there, been there done that to a big two family. The place was stripped of all wiring within two days of getting the keys. Bad stuff no want to see, likewise mixed aluminum and copper.

 

[SmokeyTheBear]

I've got to bow out, Time Warner seems to be playing games with its system this evening for some reason. Both my eMTA and Cable Modem have been reprogrammed several times and it is frustrating trying to surf.

 

[Harvey Schneider]

Nothing should be introduced into the volume of the electrical box that can support combustion. That is so that, if a connection in the box were to overheat, it cannot ignite any combustible materials.
Where you are placing the gasket, if I understand, is where the fixture trim meets the ceiling surface. That is outside of the electrical box and below it. It does not in my opinion, therefore, pose a risk.

 

[becasunshine]

Poor connections inside that box can cause resistance heating to take place. If the joints are properly done then the insulation is very likely blocking some of the heat loss that was there if there is a bit of a temperature rise. Again it is a matter of the exact temperatures over time and the materials involved at that location.

90 isn't a problem.

If you are worried about the insulation you are using I'd get some Roxul at a big box it is fireproof.

The splicing connections were done properly on all of the ceiling fans. I am quite confident about that because The Hubs installed every one of these fans, and he's been installing ceiling fans for over 30 years now. We were Early Adopters when residential ceiling fans became popular.

I'm not particularly worried about the insulation cording catching fire, per se- the actual cord of insulation is a few inches away from the electrical wires going through the center of the fan fixture to the motor and the light below. I would say that I'm using an abundance of caution, referring back to cautions about insulating inset lights- although nothing about these fixtures is "inset light" like. I'm referring back to cautions about trapping heat in fixtures- but I can't see how there would be any heat generated in the interior of that base to get trapped. All of the things that are generating heat in the process of operating are hanging down below, into the room.

Or- should we think of it like insulating the electrical outlets and switches? Those inserts are UL approved, fireproof- but why, exactly? I'm not being snarky. I'm trying to understand "why" so I can understand "how" in terms of insulating these ceiling fans safely.

I remember about 25 or so years ago, when people started insulating their outlets with left over styrofoam meat trays... and there were house fires.

So I'm wondering if we have inadvertently wandered into that territory with putting the foam insulation cording around the perimeter of the base, in between the base and the ceiling...

 

[becasunshine]

Nothing should be introduced into the volume of the electrical box that can support combustion. That is so that, if a connection in the box were to overheat, it cannot ignite any combustible materials.
Where you are placing the gasket, if I understand, is where the fixture trim meets the ceiling surface. That is outside of the electrical box and below it. It does not in my opinion, therefore, pose a risk.

Harvey Schneider, what you describe is exactly what Hubs did: the electrical box itself is above the plane (plain? plane) of the ceiling, in the unconditioned attic space. On three of these ceiling fans and four of the closet light fixtures, those boxes are under 54 year old wood plank floors that are nailed to joists. We cannot reach them from above, in the attic, to caulk/spray foam around them.

What you describe in terms of the relationship between the ceiling fan base, the ceiling surface and the foam cord ("pool noodle-like") insulation is exactly right. The electrical box, containing the spliced wires with their caps, is in the attic above the plane of the ceiling. Then comes the bracket to which the base will be attached with screws. The bracket is also above the plane of the ceiling; it is attached to joists. The base of the ceiling fan has holes through it which correspond to holes in this bracket; screws go through the holes in the base and into the holes in the bracket and this is how the ceiling fan is suspended and held aloft. The perimeter of this base has a wider diameter than the position of these screws. The perimeter of the base abuts the living space surface of the ceiling. Hubs installed the foam cord insulation in between the perimeter of the base and the surface of the ceiling. The foam resides below the electrical box, some inches horizontal distance from the electrical box, and separated from the electrical box by the bracket and the actual ceiling.

 

[becasunshine]

If I were to see knob and tube, out it would come then and there, been there done that to a big two family. The place was stripped of all wiring within two days of getting the keys. Bad stuff no want to see, likewise mixed aluminum and copper.

We were sitting here trying ot remember that term, Smokey- knob and tube!

Nope, no knob and tube, and no aluminum wire. We are really, really lucky in that regard. We have a favorite Big Box Home Improvement Store nearby because that location hires some super knowledgeable staff. Many are retired skilled craftsmen/women- electricians, plumbers, contractors, etc. who no longer needed/wanted to run their own business but still wanted to keep their hands in the trade. Some are young people who are graduates of local trade schools, or working part time in addition to their regular jobs in the trades, in order to earn extra money. They know their stuff! Some of the staff are renovating older homes with knob and tube wiring, and like you- out it came!

 

[Harvey Schneider]

Some of the staff are renovating older homes with knob and tube wiring, and like you- out it came!

I was considering buying an antique house that had knob and tube. Opened a wall cabinet and saw the bare wires, knife switches and cartridge fuses. I turned around and headed for the nearest door.

 

[Madcodger]

Becca, we can't say for certain without seeing it, but I'm not immediately seeing a problem with what you're doing if it's not in the box. And when in doubt, there's always a local electrician for a professional opinion.

 

[Jeff Lawson]

The pool-noodle stuff is called backer rod. It's used mainly for taking up space when caulking big joints in concrete, with say Sika products.

If you are simply stuffing it around the electrical box to compensate for an imperfect cut in the drywall or plaster, there shouldn't be any problem there. In a perfect world the cut would be perfect and there wouldn't be any gap. It's not like you are closing a vent that was intended to be there.

I would think you would even be able to stuff a little piece of that backer rod slightly into the box knock-out that has the wiring going into the box, just to seal it. But like was said previously, you wouldn't want to fill the whole box with a bunch of cellulose or something combustible.

Those boxes don't have a need to be vented...there is nothing about them that is meant to do that. They are simply there to protect the wiring and provide and attachment for something else. I think generally, if an appliance was meant to be vented, there would be a vent. If there were a relay or something else that would make heat, it would likely require a different housing.

Not a pro...so take it for what it's worth. Thanks for the TP advice, that was very handy in understanding our home's convection currents.

 

[becasunshine]

Becca, we can't say for certain without seeing it, but I'm not immediately seeing a problem with what you're doing if it's not in the box. And when in doubt, there's always a local electrician for a professional opinion.

Joe, thank you. No, no where near the box. Technically, the "pool noodle" is in a completely different room than the box. The box is in the attic. The "pool noodle" is on the other side of the ceiling, in the conditioned living space.

Good point on the local electrician. We have a good relationship with the electricians who helped us when we tore out (as in, TORE OUT) and renovated the laundry room and kitchen. I can call them and ask about local code to make sure.

 

[Madcodger]

Also, for those wondering what to use to seal areas such as the top plate in the attic, acoustic sealant works well because it does not harden and stays flexible (so it will still be useful the following season, after the wood has expanded and contracted. Much better than caulk but not for areas that will be seen as it's not a finish product (aesthetically). Big box stores won't have it but a well-stocked contractor's warehouse will.

 

[becasunshine]

The pool-noodle stuff is called backer rod. It's used mainly for taking up space when caulking big joints in concrete, with say Sika products.

If you are simply stuffing it around the electrical box to compensate for an imperfect cut in the drywall or plaster, there shouldn't be any problem there. In a perfect world the cut would be perfect and there wouldn't be any gap. It's not like you are closing a vent that was intended to be there.

I would think you would even be able to stuff a little piece of that backer rod slightly into the box knock-out that has the wiring going into the box, just to seal it. But like was said previously, you wouldn't want to fill the whole box with a bunch of cellulose or something combustible.

Those boxes don't have a need to be vented...there is nothing about them that is meant to do that. They are simply there to protect the wiring and provide and attachment for something else. I think generally, if an appliance was meant to be vented, there would be a vent. If there were a relay or something else that would make heat, it would likely require a different housing.

Not a pro...so take it for what it's worth. Thanks for the TP advice, that was very handy in understanding our home's convection currents.

All over the northern hemisphere tonight, people are hanging toilet paper from doorways with little swatches of tape, to watch the convection currents from their wood burning appliances move through the house, so that they may understand how to most effectively use their fans to heat their houses during this Arctic Train Event. Kinda warms your heart to think about, doesn't it? Little strips of toilet paper, wafting in the convection currents, all over the world... while people figure out how best to use renewable resources... OK SHOW OF HANDS HERE- HOW MANY PEOPLE RECYCLED THOSE TOILET PAPER STRIPS BACK INTO THE BATHROOM FOR FURTHER USE?

No wait, TMI- we don't want to know!

Jeff, thank you- so THAT'S what the Pool Noodle Insulation is really called! "Backer rod." You know, I think The Hubs knows the proper terminology, because I think I've heard him use that term before- "backer rod." He had to use it when he was replacing the old thresholds in this house. There were gaps. I wasn't hands on involved in that project, so I don't know where those gaps were, but The Hubs was pretty pleased with the outcome, and I remember he said that the backer rod worked out really well for him in that application. I just never put two and two together about Backer Rod re: Pool Noodle Insulation.

(I am over-tired and getting silly- sorry!)

Jeff, per above, we aren't even putting the backer rod around the box. We put it in between the base of the ceiling fan, that part that snugs up against the living space side of the ceiling, and the ceiling itself. Two screws go through this base and into the bracket that is attached above, spanning two ceiling joists. These two screws go through the base into the bracket to hold the ceiling fan aloft. The screws are located well inside the perimeter of this base, and they go through the hole cut into the ceiling through which one threads the electrical service wires from the fan up into the box, which is located above the brace, in the attic. This hole is larger than is necessary for the wires to transect the ceiling, because one must also work through this hole, to access the box in the attic, to splice the wires, cap them and stow them in the box, to hang the brace in between two joists, and then finally to attach the base to the brace with two screws. The brace is on the attic side of the ceiling; the base is on the living area side of the ceiling. The box is above the brace. Per above, the perimeter of this base is wider than the hole that is cut through the ceiling; it has to be wider, because it abuts the ceiling and gives the fan some lateral stability.

The Hubs put the backer rod in between the perimeter of this base and the surface of the ceiling that faces downward in the living area of the house- so it's a good distance away from the electrical box in the attic, and separated from it by the ceiling.

About the venting- Yeah, that was our thinking too- if the box for a ceiling fan contained something that would produce heat, then it would come with precautions similar to those for recessed lights.

 

[becasunshine]

Interesting update:

While Hubs was working in the attic, putting spray foam insulation and/or caulk around the outside of the boxes that he could access, I was working downstairs in anticipation of the coming Arctic blast and ice event. When we opened up the shades this morning there was excess condensation on the windows. Whoops- too much humidity in the house.

It was rather temperate here this afternoon, highs in the upper 40's. Since Hubs was in and out of the attic anyway, and we needed to blow some moisture out of the house, and I wanted to vacuum the house thoroughly in case we lose power later today, I figured it was as good a time as any to air out the house, to do a complete air exchange. We shut down the stove, made sure that the furnace was off, opened all of the windows in the house, ALL OF THEM, and turned on both the whole house fan in the laundry room window, set to exhaust, and the exhaust fan in the bathroom.

When we shut the stove down and opened up the house, the HVAC thermostat showed 70'F.

In addition to actively exhausting the house, we had a pretty stiff breeze going on here ahead of the cold front. I could feel the wind blowing through the house as I vacuumed. The house dropped into the upper 50's in about an hour, maybe an hour and a half.

After the attic work was done, and the vacuuming was done, we closed up the house, fired up the pellet stove, got the pellet stove set on cruise, and went out to grab some dinner and run some errands. We were gone for a couple of hours.

When we got back home (REPLETE WITH POOL NOODLE INSULATION AND FURNACE CEMENT) the HVAC thermostat reported the temp in the middle of the house at 66'F. The pellet stove had gained at least 8' on its own- no help from the gas furnace- in a couple of hours. This as the outside temperature was dropping significantly.

Hubs set to work, caulking around the perimeter of the light fixtures in four closets, caulking up a few more random places that we'd noticed, and stuffing backer rod around the perimeter of the bases on the ceiling fans and a pendant light fixture (again, lights hanging far below the base, into the conditioned living space.)

The house temp immediately went from 66'F to 67'F.

Since completing the last phase of this project, insulating the ceiling fans and closet light fixtures that we couldn't access in the attic, from the conditioned side of the ceiling, the outside temperatures continue to fall, and the temperature in the house has risen yet another degree to 68'F.

I thought that paying attention to these details would have at least an incremental impact, probably a cumulative impact, but I didn't expect it to have an immediate and measurable impact.

 

[Jeff Lawson]

All over the northern hemisphere tonight, people are hanging toilet paper from doorways with little swatches of tape, to watch the convection currents from their wood burning appliances move through the house, so that they may understand how to most effectively use their fans to heat their houses during this Arctic Train Event. Kinda warms your heart to think about, doesn't it? Little strips of toilet paper, wafting in the convection currents, all over the world... while people figure out how best to use renewable resources... OK SHOW OF HANDS HERE- HOW MANY PEOPLE RECYCLED THOSE TOILET PAPER STRIPS BACK INTO THE BATHROOM FOR FURTHER USE?

No wait, TMI- we don't want to know!

Jeff, thank you- so THAT'S what the Pool Noodle Insulation is really called! "Backer rod." You know, I think The Hubs knows the proper terminology, because I think I've heard him use that term before- "backer rod." He had to use it when he was replacing the old thresholds in this house. There were gaps. I wasn't hands on involved in that project, so I don't know where those gaps were, but The Hubs was pretty pleased with the outcome, and I remember he said that the backer rod worked out really well for him in that application. I just never put two and two together about Backer Rod re: Pool Noodle Insulation.

(I am over-tired and getting silly- sorry!)

Jeff, per above, we aren't even putting the backer rod around the box. We put it in between the base of the ceiling fan, that part that snugs up against the living space side of the ceiling. Two screws go through this base and into the bracket that is attached above, spanning two ceiling joists. These two screws go through the base into the bracket to hold the ceiling fan aloft. The screws are located well inside the perimeter of this base, and they go through the hole cut into the ceiling through which one threads the electrical service wires from the fan up into the box, which is located above the brace, in the attic. This hole is larger than is necessary for the wires to transect the ceiling, because one must also work through this hole, to access the box in the attic, to splice the wires, cap them and stow them in the box, to hang the brace in between two joists, and then finally to attach the base to the brace with two screws. The brace is on the attic side of the ceiling; the base is on the living area side of the ceiling. The box is above the brace. Per above, the perimeter of this base is wider than the hole that is cut through the ceiling; it has to be wider, because it abuts the ceiling and gives the fan some lateral stability.

The Hubs put the backer rod in between the perimeter of this base and the surface of the ceiling that faces downward in the living area of the house- so it's a good distance away from the electrical box in the attic, and separated from it by the ceiling.

About the venting- Yeah, that was our thinking too- if the box for a ceiling fan contained something that would produce heat, then it would come with precautions similar to those for recessed lights.

Okay...I get what you are doing. You are way okay. Except for I should now do the same with my ceiling fans!

Such a great thread.

This cold front got here in Colorado on Wednesday and boy, it has been cold. I had trouble with my "new" pellet stove for the first 36 hours or so. But it is now doing a pretty good job keeping up as our only heat source for 2200 sf tri-level home.

Pellet heat along with conservation tips like in this thread is really good stuff!

 

[SmokeyTheBear]

I was considering buying an antique house that had knob and tube. Opened a wall cabinet and saw the bare wires, knife switches and cartridge fuses. I turned around and headed for the nearest door.

Gee, you mean you didn't just buy the place and rewire. Damn no sense of adventure. We had a pile of old gas light lines in that house as well along with a copper hot water tank that used to be heated by a coil in a cook stove, the stove was gone and the tank was walled around instead of being removed. Oh well, one can learn a lot from an old house.

 

[Lake Girl]

Since buying the house 4 years ago I have been tearing down walls to replace insulation (R-7 insulation in the walls...DOH) and windows. I have used R-13 in the walls, then putting rigid foam up before sheet rocking.

I hope when you are installing vapour barrier you put a section around the electrical boxes to be pulled through the full vapour barrier sheet that covers the wall floor to ceiling. Tuck tape to full wall vapour barrier or rigid foam. This avoids air infiltration through the electrical box.

When replacing windows, seal with waterproofing tape similar to this if at all possible http://www.mfmbp.com/doc/WindowWrap Brochure 10-12.pdf
Purchased a different brand from menard's but the brand name is only on the exterior wrapping of the roll... Stops air and water infiltration around windows and doors.

 

[becasunshine]

God bless my husband, who HATES to caulk with a white hot passion (because he tends to be a perfectionist about it, and CAULK SIMPLY WILL NOT DO WHAT HE TELLS IT TO DO! NO! BAD CAULK! BAD!) My husband has spent three weekends straight with a caulk gun in his hand. The house is noticeably less drafty, more comfortable.

Right now I have all of windows completely unswaddled, cell shades up, Butt Ugly Thermal Curtain Panels pulled back, trying to dry out some condensation on the inside surface of the windows before it's time to swaddle the windows again for the night. It's gray outside with intervals of freezing rain and sleet, temps are hovering at freezing. The gas furnace is off and has not been on for days, since it was on briefly (very briefly) when the HVAC tech was here testing the gas water heater vent for back draft (no back draft, so that's good.)

The pellet stove is finally, comfortably, truly carrying this house on a cold, gray day with no thermal gain.

Hubs is behind the furnace right now, with furnace cement, resealing that furnace vent where it goes into the wall. It's a bigger job than it first appeared. The old sealant was shot. He pulled most of it out and he's re-sealing the whole thing.

God bless that man- he's had the patience of Job for the past three weekends.

Before we started this particular phase of Adventures With Old Houses, I would not have imagined that caulk and similar incremental steps would have such an immediate, noticeable return. I'm a believer. Even my husband, who hates caulk, is a believer.

Take home message: if you think you *might* need to caulk, you probably do. =/

 

[Madcodger]

Thanks for sharing effects of your efforts, Beca. Great work!

I am slightly (and only slightly) concerned about the moisture buildup. If you can purchase an inexpensive hygrometer (humidity meter) or two and place in a couple of rooms (perhaps one on each floor) it would be good to monitor that. Now, don't be too concerned as it may simply be normal humidity levels, a rapid drop in temps outside with the approaching storm, and windows with somewhat lower R-value (not much to worry about in that case as long as it doesn't occur often enough to harm the window area with moisture). And it's rare to "overseal" an older home - almost impossible in most cases without some heavy duty sealing efforts. But it's not expensive to monitor humidity, and it's better for your health to keep it at 40 - 60% anyway, so not a bad thing to monitor with inexpensive devices.

And I still advocate that blower door test by a certified auditor, but enough preaching...

Joe

 

[becasunshine]

Joe, I do understand your concern about humidity. I remember that, as a child, it was considered OK for condensation to be on the storm windows, but not on the inside surface of the interior windows. Houses were much more drafty and the heating plant was typically a big honkin' oil burner or boiler. We blasted cold out of the house! I remember that while oil furnaces could last forever, they were sort of like the old work horse Mercedes- they needed their pampering at least once a season. When the oil furnace was down for a repair or for service, my parents would turn on the electric oven and leave the door opened. The things we remember!

Anyway, we have cell shades on all of the windows except over the kitchen sink and in the laundry room. Our cells aren't on tracks but we have the Butt Ugly Thermal Panels over some of them- and those are consistently the windows that collect condensation on the inside. The other windows in the house that don't have the thermal curtains over the cell shades don't accumulate the condensation, so I think it's a matter of trapping moisture behind those curtain panels.

When the a/c is typically on in the summer, of course we don't have this problem.

I do not object to a blower door test- but I was afraid to have it done before now.

We have owned two pop up campers and we have a small travel trailer now. Especially with the pop ups, we had to find that sweet spot between holding in heat and allowing the tenting to breathe, so that we didn't accumulate mold and mildew. It was especially essential for that tenting to be dry, dry, dry before the pop ups were put away.

We made window panels out of Reflectix and aluminum tape that we stored under the matresses when not in use. At either temperature extreme we'd pop them in the windows and zip the window flaps up around them. This essentially made somewhat of a "hard sided" camper out of a pop up.

We have camped in a pop up at the northern most tip of the Chesapeake Bay with friends in the middle of winter in sub-freezing weather. That pop up didn't even have a furnace- we were using an electric space heater, the Reflectix panels and a heated mattress pad at night. (Yes, nuts. We were all nuts- but we had a good time!)

I've stood in our second pop up at high noon in Charleston, South Carolina in August and registered a temp of 70'F with the a/c running and the Reflectix panels in place- so it does work. In that case, the condensation happened on the OUTSIDE and got the outside of the tenting wet.

That's what finally drove us out of pop ups- the various and myriad ways in which we had to make sure that the tenting was dry before we left the pop up folded up at home. We didn't have an optimum situation for leaving a pop up opened at home to dry out- so we just went to a small travel trailer.

Even in the travel trailer we often keep a window cracked to avoid moisture build up, or "inside rain" during cold weather.

So yeah, I do know what you are saying about humidity- but also, like you said, it would be difficult to seal this house up to air tight without some professional intervention, and even then I'm not sure it's possible.

I think it's the rapid temperature decline and OK but not triple pane replacement windows coupled with Butt Ugly Thermal Panels.

I'll bet you that if I fired up the gas furnace right now, with its big blower, fired up that big old combustion in the laundry room and sucked air in through every remaining crack in this house, that the condensation would dry up in a heart beat.

BTW, we just got a good roll of thunder through here- gonna be an interesting weather day!