I have a north facing bedroom on the "hit list" with 3 exterior walls and a cathedral ceiling. The room also has 30 or so sq ft of North glass. Room is 12x14 and I've already bumped the supply duct from a 6" to and 8". This helped a lot but hasn't entirely fixed the room being colder/hotter than the rest of the house.
Hi Bob, whats under and over that peninsula? I'm sure you're just testing us, but the description is so common. A long run to and from a highly exposed area of a home and crash, down goes the comfort level. Obviously, more heat helps, but windows and exterior walls are probably sucking the heat out at a rapid rate. Being the the north side, exposed windows are losing radiant energy and gaining very little. Even if they are a bit high tech, they need help. Floors are next, but I don't know what is down there. If it's a low heat/no heat area, then either the floor needs massive amounts of insulation or the crawl/basement needs its own insulation and a heat source. Having a warm space under a floor makes a big difference. More details and we can play more.
Floor is concrete slab covered with carpet, so not much can be done with it. The run is about 25' from the furnace, the original design was an 8" duct split to 2 6's (the other feeds another bedroom). New design got the 8" bumped to a 10" and the 6" going to the cold room bumped to an 8", the 6" going to the other bedroom left as-is. Think 8x6x6 wye converted to a 10x8x6 wye.
Here are some photos to help you visualize the room, house was built in 2000, brick exterior walls. Other than increasing size of duct, replacing the 4 way register with a commercial grade, and adding a fan, the room is how it was when we bought the house.
Is that the return or supply grill at the top of the interior wall?
Supply, there is not return grill for the room. I've considered adding a "jumper grill" as a "return" over the door, but the door is rarely closed so I haven't messed with it.
What's your climate zone Bob? The slab was probably built with no insulation under or around. Some in the ground insulation that slopes away from the slab and extends up to cover the edge would make a difference, all-be-it a major project. Even just some edge protection would help. I have found the IR on both the inside and outside to point to the exposed edges of a slab.
What does the IR tell you in the rest of the room? When it is cold, the IR shines. If the ceilings are a big issue, a couple of inches of rigid on the inside with a new layer of drywall isn't that bad of an upgrade. The exterior walls can be done as well if those are 2x4. If 2x6 they should be fairly good.
Your audit numbers should be telling you if this is a heat loss issue or a heat supply one. Are the ducts losing much heat from source to room?
I have no IR camera to check the room with, but that would answer a lot of questions. I would LOVE to have one, but at $1,000+ I just can't afford one. I do have one of those $30 hand held IR temperature guns from Harbor Freight tools but that's it. Duct supply temperature is within a few degrees of all of the other registers in the house. It's when the HVAC has cycled off off that the room is has the biggest temperature difference vs. the rest of the house. A complete air sealing is next on the list before any major project like adding rigid insulation are done. The ceiling box above the fan is my biggest challenge, foam, caulk, or drywall mud is the question...
If you know someone who wears glasses and can't find their front door without them, well IMO, that's an auditor without an IR camera. I know a lot of auditors try to get by without one, but $1,000 is extremely low. My camera was $8,000 when I started and one 10X better would now be about $3,000. You need a demo to play with and SEE for yourself. Don't short change your business, ask a contractor what his tools/truck/toys cost.
Have you run your heat loss calculations yet?
If I was doing this for a living the $1,000+ camera could be easily justified, I do feel somewhat "blind" on knowing where the leaks really are. This is my own house and I'm just trying to make it a bit warmer for my kid in the winter w/o having to use an electric heater. He's 5yr so old enough to know not to mess with it, but we have to unplug it in the daytime so my 2yr old won't touch it.
I've done preliminary heat loss calculations, but as others have stated the accuracy is questionable. I do know my heat never runs more than 1/2 the time even on coldest days and the A/C never runs full blast even when we hit record temperatures last summer.
A couple of things...home depot sells the insulated floor panels (2'x2') that you could add to the floor if you have the space to allow it. Also, what kind of venting do you have outside? If you have soffit and ridge vents, most likely they are done incorrectly and you have wind washing through the ceiling insulation. I have in the past air sealed the soffit venting and closed up the ridge vent and have had great results.
Interesting point about the venting. The sides are standard soffits, but I have no idea if they are blocked off by insulation underneath. The flat spot at the top forms a small "attic" above the room which is open to the rest of the attic in the house. There is no roof venting for the room. Blocking the soffits sounds like a great idea especially since hot air typically flows OUT of them in the summer (southern wind blows air into the other side of the attic, exits out of the north vents).
I feel as if most of the issue is the HUGE window in the room. Are Tinting or Thermal Curtains effective or just marketing hype? I have no problem with taking down the vertical blind and replacing it with thermal curtains if they really do work. The vertical blind stays closed most of the time, I just opened it for the photos.
Here's what the room looks like from the outside to give a better idea of what we're dealing with:
From looking at the pictures (inside and out) the likelihood is that this ceiling assembly is too shallow and has less (possibly R-19) while the rest of the building has R-30 or more. Add to that the probability that the soffit venting is allowing air movement through the insulation and compromising the effectiveness. Converting it to an unvented assembly is an option, you would need to look through the details carefully and see if it can be done as a retrofit with your circumstances. I assume this is a double glazed window. There is a possibility that the window openings were not sealed well. You could pull the inner trim off - seal it correctly with foam and re-install them. This might help some. Getting some infrared images would really help you with the best course of action, especially since you say this room has greater heat loss/gain the rest of the house, which is really the root cause of the comfort issues. Not knowing exactly why this is happening means you are just guessing at probable fixes. Since this is a tract home, do other owners with similar floor plans have the same issues?
I'll have to ask some North facing neighbors how well their "oddball" room is doing. I suspect this is a 'tract issue" and our house isn't the only one with this issue. My dad's house is a similar age and design but faces South. He made his own "insulated panel" our of a piece of 2" Styrofoam covered in cloth. Takes it out in winter for the extra warmth. Helps, but room is still too warm in summer, winter it's so bad because house faces south. Room is currently an occasionally used guest room and he's not too worried about it now.