I have a suspicion that I have a poorly placed HVAC register and thought I’d run it by the guys that know 🙂 before I start fooling around with possibly moving the thing. I’d ask at the DIY forum I frequent, but they appear to be down at the moment. Y’all are better anyway ;-).
Here’s the situation. A few years back we had a heat pump and all the ductwork retrofitted into our ca. 1955 ranch style house. The air handler is in the attic as this best fit our situation. I couldn’t be happier with the unit except that our master bedroom has never properly cooled and heated. It’s a small 12×14 corner room (heavily shaded by deciduous trees in the summer) with a window on each exterior wall. The ceiling register is located next to an interior wall and a couple feet in front of the door to the hall. It’s a good 5 degrees warmer in that room right now than the rest of the house (considering that it’s getting over 100* outside that’s probably not that bad.) This would partly be due I’m sure to the lack of insulation in the walls (which we’ll fix when we remodel the room sometime in the next year) but I also wonder if the aforementioned register is not in the proper location. Interestingly enough this is probably the shortest run of ductwork, and is the first one off the trunk. Flexible ductwork, unfortunately (if only I knew then what I know now.) The rest of the house is comfortable even though in my humble opinion the ducting is snaking around way more than it should.
I’ve attached a rough sketch, the red rectangle is the register location.
Replies
move it near the window that has the most sun load....
go one better and put one near each window...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
WOW!!! What a Ride!
Forget the primal scream, just ROAR!!!
Really hadn't thought about putting an extra register in. My thought was to move the one shown to in front of the window at the bottom of the graphic. That's south, although sun is relative. There's a whacking great ash tree out there that shades that side of the house. The other window is a western exposure but that one is shaded by a big pecan. Really though, by taking the unnecessary curves out of the ducting that's already up there even adding another branch and register would probably keep the total footage of ductwork the same!
straighten and shorten the runs if you can and do move the registers close to the windows...
the windows are the weak link in your BR walls insulation...
also you'd get better air treatment for that room...Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!Forget the primal scream, just ROAR!!!
"move it near the window that has the most sun load.... go one better and put one near each window..."
Curious about this. The builder is all of his subs built my home with the notion that nothing will be allowed to be changed, and certainly not personalized. :)
The floor registers that supply air are slammed right up against the kick molding in the family room. One supply register per window pair. If I had window treatment (I do) and allow the air to flow naturally out of the registers the drapes would be all over the place (flag waiving in the breeze). Instead, I am forced to either not use window treatment, or deflect the air using a plastic cowling.
I am using plastic cowlings to deflect the air coming out of the supply registers and allow the air to travel across the floor, into the room. If I remove the cowlings and also the drapes a large section of the carpeted floor will become heated, and in turn radiate heat into the room. Of course, this will allow the window jamb and glass to remain cool, but the room will heat up.
So, I have to now wonder if there is a standard, or a generally accepted rule-of-thumb that determines how far out from the wall the supply register should be. And like the supply registers in my home, so, too, are the doors and their jambs shoved right up against a wall so no upgrading or customization can be conducted by the homeowner.
So, I have to now wonder if there is a standard, or a generally accepted rule-of-thumb that determines how far out from the wall the supply register should be.
Mine:
Floor registers: Opening cut 5" from the rough framing.
Ceiling Registers: 12" from the rough framing, space permitting.
mind you I said near each window and hold the registers 6 to 8" from the wall plus don't skimp on the final size...
the last house I had that put forced air into I used a reverse flow unit...
heated in up direction and cooled in the down direction with returns in each room to complete cross room flow and had the air movement traveling the walls and across the ceiling.......
worked great...
sounds like yur registers are too close to the walls and yur air exchange needs improving...
the doors and their jambs shoved right up against a wall so no upgrading or customization can be conducted by the homeowner
can add some detail to this???Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!Forget the primal scream, just ROAR!!!
There's no question in my mind that your current registar location is wrong. You're "short cycling" the air flow right out that door and it never has a chance to heat/cool the room.
I would give serious thought to moving it to the corner farthest from the door - or splitting the supply duct and putting a registar near each window.
The choice would depending on which window gets the most summer sun, how well your walls are insulated, and whether you have low-e double pane windows.
You might see some amount of improved heating/cooling effeciency if you can straighten the flex ducts as much as possible. Whether it's flex or solid duct, bends really eat up flow rate.
Edited 8/8/2007 7:16 pm by Dave45
Thanks. I suspected as much. It's never really been an issue before, but with this 100+ degree heat we're having right now it's become really noticeable that that room is decidedly warmer than the rest of the house.Happy, happy, joy, joy. Something else to add to the project list!
You've got it. The register should be in the opposite corner of the room.
Yes, the register location is wrong.
Another problem could be that the duct takeoff is so close to the air handler off the trunkline. Good practice is no takeoffs within 3 duct diameters of an elbow or change fitting. If your trunkline is 8" deep duct, then that first takeoff should be no closer than 24" to the fitting/air handler. Supply takeoffs that are too close to directional changes can actually act as returns, or have no airflow at all.
This would partly be due I'm sure to the lack of insulation in the walls
You're not implying that the house is insulated except for the bedroom in question, are you?
Edited 8/9/2007 2:37 am ET by Ragnar17
Goodness y'all are active :-). As far as the insulation goes, we're getting there slowly. The drywall in most of the rooms was in poorish condition when we moved into the house (3/8" drywall) so that as we have time/money/inclination we've been replacing it with 1/2" and/or 5/8" (ceilings if necessary.) this means that as far as the walls go the house is about 3/4 insulated. When the 'rock comes down, the insulation goes in. As far as the ceiling, we're cleaning out old rock wool insulation that in many cases has compacted down to about an inch where it exists at all, and replacing it with fiberglass. The old rock wool stuff is nasty, in removing it we're also trying to get some of that muck out of the attic. I thought about blowing in cellulose but there's a couple rooms which are going to keep the old 3/8" stuff on the ceiling and I did not want the extra weight of cellulose on there. They're swoopy enough as it is.
Cindy,
The reason I was asking about the status of the insulation was that it will obviously affect temperature inside the house.
If the warm room is NOT insulated yet, but many of the other rooms are, that will go a long way in explaining why it's warm in that one room.
That should be obvious, but sometimes the most obvious things get overlooked.
Actually, I would just assume that that was the answer except that the room next to this bedroom, also on the south side of the house, and maybe 3/4 insulated (I'm in the process of remodeling that one so it will be fully insulated shortly) which also has about 8' of glass on it (french doors with sidelites) stays comfortable. That's what is confusing to me and is probably the main reason I started looking into this.I've never thought about it before since we'd had several wet, coolish summers and it's never been as noticeable as it has this year, which has been a very dry, hellish (ahaha) summer. That room (den) is about 250 square feet and has two branch runs to it. However there's no doubt there's better air flow as there's also an interior pair of french doors which usually stay open. But on the other hand I haven't noticed a whole lot of difference in temps even when those doors have to be closed for whatever reason.With the tips and info I've gotten in this thread, and with some additional poking around on the internet though I think I can make it better just with some tinkering with the length of the runs, register locations and jump ducts and stuff. Maybe not perfect, but better.
There is NOTHING WRONG with the location of that register. IF there is a RETURN in the oposite corner.
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
That's true Bill, but how many returns have you seen in a corner of a house? - lol
Where is the return in the room? If it's not in the far corner, or there isn't one at all, all your conditioned air is just moving right out the door to the nearest return.
Mike Hennessy
Pittsburgh, PA
Doh! I just saw Bill Hartman's post after I launched this. I guess we agree!
Edited 8/9/2007 8:54 am ET by MikeHennessy
Also If there is no or inadequate return...then when the door is shut there is no return path
True. The doors in the house are mostly kept open for that very reason. There is one large return in the ceiling of the hallway about 10 feet away. I've got about an inch space under the doors when they are closed which I realize is nowhere near enough but works somewhat. Or at least does when the dog doesn't plop herself in front of a closed door to take advantage of the cool breeze blowing through there!
Jump duct would help
I've never run across the phrase "jump duct." Could you explain? Admittedly, the HVAC is almost the only aspect of the house that I never really looked into much, preferring to leave it the, er, "professionals" in this case.They say a picture's worth a thousand words. Here's three thousands worth:
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It's a mess, isn't it? Also, my mistake, it's the second line that's going to the bedroom in question. The first goes to the hall bath. You're also looking toward the quarter of the attic that we haven't gotten to yet in terms of replacing the insulation. I firmly intend to finish with this this year (she says, hoping these aren't famous last words.)
A jump duct is a short duct between a room and a hallway (or path that returns to the air handler). There are also transfer grilles...sometimes above doors. It is hard to push air into a space if there is no place for it to go when the door is shut.
Thank you. That makes sense. I would suppose it's the pressurization aspect of it. Installing jump ducts sounds like a better option than putting grilles between rooms for instance, as I'd think there'd be less sound transfer.
Jump duct would be better for sound.
I took a quick look at your attic photos and you do have insulation issues. Unless you live in San Diego(mild climate) you could easily make some cost effective improvements. A local energy rating company could tell you how.
Central Alabama. We've got a mild climate for 9 months out of the year. And then there's summer . . .
A little off track, but that "whacking great ash" may have only a few years left. All the ash in the upper midwest are dying of another asian import disease.
If you close the register in the duct immediately preceeding your bedroom does it increase the airflow?
The ducts are one duct, one register. But I closed it anyway and no, it doesn't seem to affect it. There's actually a pretty good bit of air moving through there, and it is cold.I know. "Green Ash Borer." We're keeping an eye on it.This is the best photo I've got of it, and that photo's about four years old. The back doesn't look like that now as we've had to do extensive repair work to the back this year and just tried to upgrade while we were at it (like the french doors mentioned in another post.)
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Found another slightly more recent, early last summer:
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Okay, since you've got so much time to work on your house :) start now to look for a WoodMizer owner, and plan on using the ash for your own hardwood T&G floors as well as end table and a dresser made out of ash.
You can end up with ETKTM ( every tool known to man ). Think of the endless possibilities for arguement i.e. discussion, here on the merits of which planer, router, shaper, floor finish, parallel or perplendicular to floor joists, staples vs nails. wide vs strip floor....(like Larry the Cable Guy says...I can go on like this all day.
I've already got about ETKTM lol! I could probably go into business if I wanted to ;-). Somebody's going to score when I die. I'm very big on getting the proper tool(s) to do a project as I went too long "making do" with what I had and being severely frustrated by the time and effort it would take. Once I factor in buying particular tools vs. hiring a pro contractor vs. what I want and what I can do (I built that deck, BTW,) and what we can afford it becomes a no-brainer. Now I just have to find time to build some storage in my shop to store the tools.When the ash goes I'd already thought about having the stump cut off fairly high and taking a chainsaw with a carving chain to it. I have an art background although I haven't seriously followed it in years. But ash wood. Hmmmm . . . As far as time goes, I'm a "kept" woman (heh), the husband and I figure that it's cheaper for me to stay at home and work on the house rather than have the upkeep of another car, plus the gas, plus the clothes to dress "professionally" etc., etc. Data entry clerks don't exactly have salaries comparable to CEOs. But I'm really looking forward to when I can do woodworking and such for "fun" rather than necessity.
This is REALLY basic, but no one has mentioned it yet, unless my eye were glazed at that moment.Most registers have a balancing mechanism that is just a set of adjustable louvers inside that are set by a little lever on the outside.Is the adjuster open in that register?Is there a blockage in the duct? A really cheap airflow guage can be made by attaching a smooth working hinge to one end of a 2x8x1/8" piece of wood and a 6" piece of 1x2 making an Ell. Set the 1x2 horizontally on the top edge of the register flange with the 1/8" flap hanging down in the middle of the register. Extend your tape measure 12"-18", so your hand doesn't interfere with the airflow around the guage, and measure the distance from the blown out bottom edge of the flap and the face of the register. If your HVAC system has never been balanced; at night, or in the morning, before the AC turns on for the day, set all the registers balancers to half, and the thermostat to its' coldest. Check the airflow with your spiffy new guage and adjust the lowest ones up to the average, the the highest flowing ones down to average. If the register in the hot room won't come up to average, check the duct for blockage.When the cooling load is at max, open the register(s) in the hottest room or two a bit and close the one in the coldest room(s) the same bit. Wait 45 mins or so and repeat as needed until all the room temps are where you want, or the same cooler than you want.Set the thermostat where you want.SamT
My guess is that you'll get the most improvement by junking the central return and putting in proper room returns.
Mike HennessyPittsburgh, PA
Is the central return an idiosyncrasy of a heat pump? Every one of the people we got estimates from before we had the system installed were using the single return system. Although I suppose it could also just be regional. If I remember correctly, the long defunct forced air heating system that was originally in the house (which must have been quite innovative for 1955)had two returns.
The single, central return is an idosynchrisy of low budget, residential installation. In many smaller residences, with undercut doors (as was the standard pratice for ever), the central return was adequate. Barely. The residential HVAC market is tight, with little margin for profit and little consumer demand for better (until its too late and comfort has been compromised).
Moving air properly is independent of the manner in which the air is heated or cooled, be it a furnace or a heat pump or any air mover. My main FA system has 8 returns, but then I designed it and installed it myself. I have a secondary system that has "only" 2 returns.
I don't think a single return is appropriate for any type of heat/cooling. IME, most localized heating/cooling problems in forced air systems are due to badly designed return systems. Tempered air cannot enter a space unless existing air has some place to go. The tempered air will tend to flow from the register toward the return along the shortest path. The register and return should be sized and located to achieve a fairly uniform flow of conditioned air through the whole room.
Mike HennessyPittsburgh, PA
Am not a HVAC guy. Other, more qualified have responded to the return / supply locations.
However >>>the ducting is snaking around way more than it should.<<<
A very qualified installer which I have used on several occasions told me this is for noise control - he claims that in order for the system to move air quiety, ducts need at least three 90* turns in each one - sound will travel around 2 but not 3. His installations seem to support his statement.
Jim
Never underestimate the value of a sharp pencil or good light.