I need some input on an HVAC balancing question --- I have a raised ranch home with a finished basement and an open stairwell connecting the two floors. It's an early '90's build originally equipped with a heat pump. All registers for the basement are along the ceiling and it was equipped with an electric space heating wall unit in the finished front half of the basement and electric baseboard units in the laundry room and half bath down there. The heat has never balanced properly (probably the reason for the electric space heaters in the basement which we don't use because of the cost). The difference between the upper floor and the basement is 10-20 degrees or so lower in the winter. Since purchase we have installed a sealed combustion gas furnace along side and tied it into the ductwork for the heat pump (which has saved a lot of money). In the past 5 years I have audited the home and sealed bypasses in the kitchen soffit, plumbing chases, cantilevered front facade, sealed most of the wiring penetrations in the attic, dealt with 5 panned returns (one of them which was connected to the back of the bathtub space) and insulated the small space under the front entry. All this got the BD from 2,500 CFM@50 down to around 1800 CFM@50 (which made it less drafty on the top floor but not warmer in the basement). Closing registers either partially or all together still doesn't seem to help much either and creates moisture on the upstairs windows(double pane) now that the house is tighter. I'm at a loss as to what to try next.
Sounds like you need to re-work the ductwork and obtain the ability to control that environment as its own zone. Is the ductwork accessible for re-working? Might just need to plan a sheetrock removal/replacement stage of the project to really achieve the comfort you're looking for from that system.
I was thinking that might be the next thing --- when we moved in the back half of the basement was not finished but we've finished a room in the back corner with drywall for extra living area. When we did that we ran a supply duct off the very end of the main trunk that runs to the end of the home down to floor level ( it helps a little but not enough). One register for the small room and one double that size to the family room so there would be warm air at floor level in that room from the heat pump. Most of the ductwork is behind drywall now. What kind of zoning could I do with an open stairwell? There is only one T-stat at this point -- on the main level.
Running a supply off the end of a trunkline is generally a bad idea. Makes it very hard to balance the system, as it has difficulty building back-pressure. The open stairwell is fine. Generally, the supply-side of a system is the only part that is zoned (turned off/on with use of modulating dampers). An HVAC contractor should be able to design a solution for you that includes a separate line of ducts for the basement and along with a t-stat for that level.
I was thinking the end of the line was not a good place for a bigger register but it was the most convenient place at the time =( I'm not sure there's room for a separate line of ducts but I will keep that in mind. Do you have any info on which certifications an HVAC contractor who could do that work would have?
You've spent time air sealing and doing good work. You seem to have the equipment in line. What about the rest of the thermal enclosure. Do you know what insulation there is? Especially in the basement area.
I get calls from homeowners regularly with cold basement questions. Not insulating the basement walls is a large part of the problem. Some of it may be a stack pressure effect.
You don't say how big your home is. Are we looking at a 2500 sf conditioned area, 20K cubic feet or is there a nice vault? Or is your home closer to 4000 sf conditioned area?
It is a 28 x 44 ranch so top floor is 1200 sf with 2 x 4 construction. The basement is 27 x 44 with the front facade bricked and about 3' sitting above grade all the way around the home. So total heated sf is about 2400 sf. The entire front of the basement was finished w/ 2 x 4 studding and drywall when we bought it (I believe there is just f/g for 2 x 4 construction there with plastic against the block first). We insulated with fiberglass inso when we did the back corner. That leaves the middle back furnace room and the back wall of the laundry that are bare block with no finished ceiling (probably 30' linear feet of block which we have coated with drylock). The front is carpeted and back is just vinyl or painted floor. No vaulted ceilings. There are 4 double hungs across the front of the basement. Last year we took the trim off the inside and foamed where the builder had just stuffed f/g and then caulked the window frame to the brick on the outside facade. It is warmer since I took the vented soffit out of the 1' cantilevered first floor and installed blue board and foamed the edges. The front of the house gets the east/north wind so you can only imagine how air-cooled the basement ceiling was. Stack effect -- I didn't get to foam the top of the front wall in the attic yet. There is loose f/g installed up there. I got the kitchen soffit closed and as much penetrations as I could find for the main hall partitions but I haven't had time to get up there and do the very front wall yet. The outlets on the front basement wall do seem to pull air during the BD test but -- short of removing the whole wall, I'm not sure what else I can do! If you think that sealing in the attic on that wall would be worth the trouble I can schedule some more time to swim in my loose f/g up there!
Kari, Your air sealing has brought the home down from 7.6 ACH @ 50 to 5.5 ACH @ 50. Nice gain. Almost meets Energy Star. You can get it lower, gains from this point will be effective with more effort. Get some IR images during the blower door testing. That will give you lots of good clues to where to work.
Isaac has some good advice on the ducts. I wouldn't worry about a leakage test until you get a good mechanical contractor to run a Manual J and a Manual D on your home. Then you will know how the air is getting distributed. The MC can then plan with you to revise the ducts as needed. That would be the time to seal.
Stack Pressure will always be with you. Hot Air rises. You can work with that to plan your air distribution with the manual D.
Good Luck! Keep us posted.
After all that's been looked at and done my gut feeling was a Manual D to see what's delivered where and if it's right -- not a fun prospect for a home that's already drywalled. I asked Isaac too -- what certifications would I be looking for for someone who could do Manual D and J calcs? Sounds like a good project for the March Home Show. Most Contractors are in the same spot and I can just go from booth to booth and ask questions. Comparison shopping!
Check for Contractors certified by ACCA to do Energy Star V 3. That program requires Man J and D so you will not be told, "Oh! You don't need to do that! I've been doing this for 35 years!"
My experience with the ESV3 credentialed contractors is that they only go through the process (kicking and screaming) when they're required to. So you need to ask for their experience level, and choose one with good experience. As far as testing first, I would definitely recommend doing that; it may be that there is a hidden leak(s), or possibly a disconnected takeoff. I see that fairly often; poorly connected flex that pulls loose and isn't noticed. I saw it on new work a few weeks ago. Unless it's tested you don't know. It looks like you're in Montoursville, PA, I would look at the list of contractors/auditors in the Keystone HELP loan program, and the HERS raters in the area (go to the Energy Star site and do a search). I'm sure there are folks that can do a quick duct test for you. As a quick cursory test just use a facial tissue, or piece of notebook paper and realize the effect at each register.
I get the impression that there is only one return in the basement; that would be an issue for me.
I may have missed it, but is the upper level cooler in winter, or is it the lower level?
[ I may be going to Lewisburg for an audit; if I do I could make a quick visit for a duct test in conjunction with it if you still have the need.]
hmmm -- I love networking & have heard of the Keystone HELP loan program. There is a large return at the bottom of the wall in the family room which covers two stud bays. The den and a study down in the basement have doors (can be used for bedrooms) and they each have a maybe 6" x 8" return. The basement is always cooler than the upper floor whether summer or winter. The original registers for the basement family room are near ceiling level which works great when the central AC is on but when the heat is on it doesn't keep it warm.