I would like to finally get some decent heating and cooling into the upstairs of our old (1911) stucco Arts & Crafts farmhouse. The upstairs consists of 3 bedrooms and a bath with a central open staircase and hallway (door at the bottom of the stair). There are 5 furnace vents feeding all this but only 1 (albiet large) 6″x20″ return placed at the bottom of the stairway. The new (2 years old) Amana high efficiency furnace has helped but the temperature differential between upstairs and downstairs is still large. I have been told by some that the existing return is OK but not great while others say it is completely inadequate.
So here is my question. The new furnace has left me with the old chimney that could provide a chase for return ducting and luckily a return duct runs right next to the chimney in the basement. The chimney would allow returns to be placed in two rooms and the central hallway. Am I on the right track? Somewhere in my discussions on this issue someone mentioned it might be easier to use 3 tubing runs (4″) in the chimney chase than to uncap the chimney and run ducting down from the top. If that would work what do you think of using dryer vent tubing to act as the return ducting? Unorthodox to be sure but it would allow me to DIY this project. As always thanks for all your input.
Replies
When you had the new furnace installed did you get it zoned?
I don't know what that means. It was put in by a reputable local HVAC company but we did not mention the upstairs issue at the time, thinking that the old furnace was the problem.
With a zoned system electric dampers are placed in the ductwork, so that individual zones can be turned on and off with separate thermostats. Adds $500-1000 to the price of a system, but well worth it for most multistory systems.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Or get two HVAC units. Ultimately, this seems to be the best in older two story houses.
Ahhh, the joys of the open staircase. Apparently, no one who designs a house like that actually lives in one. Otherwise they would realize how hard they are to keep uniformly warm or cool.
Right now, there is nothing keeping that wonderfully cool, but heavy, conditioned air upstairs. I bet you might even feel a breeze in the stairway as that cold air rushes downstairs.
You are on the right track that you need to get rid of that hot air upstairs. I think your idea of a return where you are thinking is a good idea too. I would have that HVAC installer decide how to do it though. You may need a different blower unit, motor, or controller AND you need the size of all returns to be proportionally correct. They will also have access to better duct at cheaper costs than you can get ahold of, and will be able to seal it better too.
Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Parenting has always been a mix of sage life advice and inexcusable laziness.
I'd be willing to bet the air's never getting up there in the first place. Longer ducts result in reduced airflow, especially when running the AC and the cold air must be pushed uphill.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
My last house was a 1700sq colonial. With the thermostat downstairs, it would be cozy in the whole house IF all the door to all the rooms were closed... and then only for awhile as the cold air seeped out anyway. Downstairs would feel like a meat locker, upstairs like a greenhouse. Plenty of cold air got upstairs, but it didn't stay up there long.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Parenting has always been a mix of sage life advice and inexcusable laziness.
That was because you were sending cold air everywhere, vs just upstairs.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Dat is true.I have 1600 sq ft house. 800 up and 800 down and separate systems.The only AC is on the upstairs. The only opening between the 2 is a a switch back stairs. No large open gallery design.And 95% of the time the lower level is cool enough..
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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.
Yeah, until we had our two furnaces replaced with one (and a zone system), we only had AC upstairs. We'd generally run the downstairs fan during cooling season, but that's all it took to keep downstairs cool.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
I don't know if I agree with your statements re: open staircases being a problem in themselves. Rather, it may be more appropriate to classify them as a feature that exposes other issues in a home. We have a three-storey staircase here with a 2'x8' light shaft. No issues with the top floor overheating in the summer or the bottom floor becoming frigid in the winter. The secret sauce is a well-insulated home. In the middle of winter, I can turn down the RFH system on the top floor and see a temp drop up there. So much for heat rising. Similarly, the top floor also does not run continuously all summer to keep the house cool. Honors for that goes to a ground-floor zone which has larger windows and a southern exposure (which equals a lot more heat gain). BTW, all rooms have either individual returns to the cooling system, or feature transfer grilles.So, I'd encourage the OP to consider putting in that return and making sure that the rooms up there do not rely on doors being undercut or similar nonsense when it comes to getting air back down to the air handler. Zoning the system will certainly help, but the first step is to ensure that the rooms upstairs get adequate air flow, whether the doors are open or not.Only when the entire AC system has a "balanced" air flow pattern (i.e. where the CFM delivered to each room match the heat gain on a room by room basis) will the house become truly stable, temperature-wise. My guess is that the house currently has awful balance between the shorter downstairs runs and the longer runs that feed the upstairs bedrooms. A big return via the old chimney duct may be just what the doctor ordered, just make sure that every room on the 2nd floor has some way to exhaust into it.
I'm not an HVAC expert by any means. But I had a similar situation as yours in my house. Like everything else done to this house the HVAC was performed by some hack that left one return air vent (8" x 24") for the entire house (1200 sq ft) on the main level. Needless to say the living room was the only cool spot in the entire house. In my case I ran insulated flex duct in the attic for the returns and used either 7" or 8" diameter for most rooms. In your case 4" duct sounds like it'd be inadequate but probably better than what you have now. I would think it'd be better to get as large a duct as possible into that chimney and branch off at the top into the individual rooms. I would definitely not use flexible dryer vent for returns because it really is an impediment to good air flow. If you can get rigid duct into the chimney it'd be ideal. My second choice would be lined and insulated flex duct pulled as tight and straight as possible for good airflow.
> I have been told by some that the existing return is OK but not
> great while others say it is completely inadequate.
Rank me in the "inadequate" group. Assuming the usual 4"x10" register, you have 200"sq of heating/AC but only 120"sq of return. Add in the fact that there are doors between most of the registers and the return, and you have a problem.
I would bet that fixing this still won't take care of your problem, though. I have a 2 story, and the downstairs stays cold in the Summer, even with all of the registers shut off. What I'm trying to figure out how to do is to place a heating return high up in the kitchen or living room and connect it to a heating register low down on the downstairs family room wall. Run a duct between the two with a fan on its own thermostat and things would even out a bit.
Last summer I had to punch a hole in a brick wall for a bathroom exhaust fan duct. Going through the side of that chimney will not be fun if it's masonry.
why use dryer vent when U can use actual 4" duct?
anyways ... yup ... from where I sit ... that's the problem and that's the fix.
no need for 2 AC units or zones if it's balanced ...
as in ... enough suck to match the blow.
years ago my FIL decided to buy us AC ... which was a fantastic gesture on his part ... 'cept he sent over the hvac guy he'd dealt with for years in his rentals.
I'd paid attention to my hvac guy over the years ... and had a bit of a clue.
the installer fought me about adding a return upstairs ... and was trying to get out of it till I got out my sawzaw and showed him a decent path where a return "could" run ...
and even left if in the bath room to make his life easier as opposed to one stud bay over and into the hall. I'd never do that in a customers house ... but in out house ... that door is open 99% of the time ... so I knew it'd work.
and it does.
one central or a couple branch returns should make a world of difference.
not ideal ... but with an older house ... better than nothing.
Jeff
Buck Construction
Artistry In Carpentry
Pittsburgh Pa
This is all great input. What I am hearing is to maximize the upstairs return, tap into as many rooms as possible, and possibly even placing the hallway return up high. I was thinking flexible ducting just to reduce the hassle of opening up the chimney for more standard "rigid" ducting. Guess I'll just have to buck up and deal with a larger mess. The attic insulation is pretty minimal and that will be upgraded also, after I replace the old knob and tube wiring. God, I love old houses.