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momto3 04-11-2013 09:53 AM

Issues with hot upstairs (long, sorry)
I have moved in with my fiance, into his house. He bought it several years ago intending to flip it, the market flipped instead and luckily it is big enough for us all so KISMET! We have 7 people living here now... good times. Bad times are how unpredictable the HVAC system is. I've spent the morning investigating ducting trying to figure out what the hell is going on. I've been coming around this house for almost three years now, and it's better with some changes, but not good enough.

1. it's an older house, built in '77 with a single multistage heat pump and blower unit in the basement. blower isn't that old, and neither is heat pump. Replaced the stat this fall, that was a treat since it was a 3/2 heat pump... I do not recommend ever doing that yourself. but I did it and it works a champ (honeywell professional model)

2. There seems to have been a damper at one point. I say this because there is writing on the ductwork in the basement that says "open summer closed winter" but there is no longer a damper. I'm not sure what it was dampering where it was so it might have been removed for just being stupid in the first place. My assumption was that it would have dampered off part of the downstairs to push air upstairs since all of our woes with this system are basically that... that in summer it's hot as hell upstairs and freezing in the basement and in winter it's cold upstairs and reasonable in the basement. i think the damper was removed when they added a humidifier because the flexible ductwork coming from the humidifier is right against where the damper handle was.

3. The main level is comfortable year round. The thermostat is central on the main level. Clearly the stat is working and the system works on one level.

4. there are two returns: ceiling level on main floor and ceiling level on upper floor. Today I decided to try blocking the main floor return and see if pulling the hot air from upstairs would help the problem. Good idea or bad idea?

5. Windows are an issue. There is a real need for new windows, but I have sealed up these to the absolute best so they are not leaking, but they are not energy efficient in any way shape or form. but they aren't leaking.

6. there are a bazillion vent in this house. A bazillion. Ten upstairs in a 5 bedroom/2 bathroom house, and nine on the main floor and two in the basement. AND i found one today in the crawl space that was OPEN AND BLOWING MY PRECIOUS COLD AIR INTO THE CRAWL SPACE!! WHICH WAS FREEZING SINCE IT IS A FOOT AWAY FROM THE FURNACE IN THE BASMENT. Can you tell I'm irritated at that one? It is finished for storage. It is mostly underground and is going to stay conditioned enough with the ductwork running through it for my Christmas ornaments to be safe, right?

7. the master bedroom is above an unheated garage. It is the worst. But it is also the furthest from the furnace in the basement. There is obviously not as much air moving from the vents up there as on the main floor.

8. I run the fan 24/7, which helps more in the winter than in the summer.

My questions are this: Would closing some vents help manage the air flow better? Closing vents downstairs to push air all the way upstairs? Should we look at a bigger blower fan? The heat pump is more than enough for the house, it's pretty big, but unsure about the fan itself. Is closing the return on the main floor the right choice, to pull more hot air from upstairs? We run ceiling fans upstairs much of the time to circulate the air around, which helps somewhat sometimes. Clearly this is a cheap design in cheap old construction. The two HVAC guys that came out to look at the system had differing opinions - one wanted to put in a bazillion baffles, one wanted to redo the system going upstairs and no baffles. i felt like neither was the right answer and they were looking to score a hefty fee.

If you made it through, thanks for reading and for ANY advice.


techpappy 04-11-2013 02:31 PM

I was going to suggest continuous fan but you are already doing need a pro with manometer to measure air flows across the furnace and at each supply and return, check for blockages, e.g., dirty AC Coil/filters etc. Check duct sizes and capacities..Check fan operatiion..make sure proper rotation...proper fan speed etc. Fan speed can vary a lot on some models. If belt driven can have wrong pulley or belt slipping....then make an informed decision.

taylorjm 04-11-2013 04:19 PM

Well, I'm no expert, but we have a 2 story house with a similar issue. Heat is fine, but a/c, it's very hard to get the second story cooled off. Furnace is in the basement, so it has to push air through about 50' of duct to get to the farthest room, and by that time, there's nothing left. We have a zoned system so every room has a thermostat and dampers, but when the a/c runs in the summer to keep the upstairs cool, it naturally flows down to the main floor. So the upstairs is comfortable, and the main floor is about 65 degrees! Everyone wears sweatshirts in summer! I finally put booster fans in all the upstairs runs, and the amount of airflow is amazing! I didn't go with the cheapo fans, I put in some centrifugal fans designed for hydroponics. They are on a dimmer so I can turn them down in winter. There is of course much more noise though. We can hear the blowers running on the main floor, and you can hear the additional airflow in each room. Hopefully, the a/c will run less this summer now, and prevent the main floor from getting as cold, we will have to wait and see!

BikerAggie 04-12-2013 08:27 AM


Originally Posted by techpappy (Post 1156995)
I was going to suggest continuous fan but you are already doing that..

I bought a house last year and have found I have a similar problem, a hot upstairs. You touched on one thing I have been contemplating. Are there thermostats that will just run the HVAC systems blower a few extra times an hour and not necessarily turn the furnace/AC on? I think my whole house could benefit from some additional forced airflow.

My 2000 sqft house had a new single unit (less than 5 years) so I am not wanting to toss it out and go with 2 separate units (upstairs/downstairs) like many do here in Houston. Currently I have one return at the 1st floor floor level, and one in the stairwell, also at the floor level of the 2nd floor. In the summer you can feel yourself walking into the heat boundary layer as you go up the stairs...

I am thinking of adding a return air line from the 2nd floor's ceiling, blowing in another ~foot of insulation into my attic (currently just have 6") and possibly adding a duct booster to the line supplying the 2nd floors air. Does this seem like a reasonable plan? Should I close off the existing 2nd floor return that is right at the floor level? It is a straight 5' shot into the plenum in the attic, so I worry that even with a new ceiling mounted return air line, the unit will preferentially draw from the existing floor level return.

bobinphx 04-12-2013 09:58 AM

well, I had the same issues with my house... I fixed them!!!! myself!!!!

first off, I removed all the flex duct as it was not installed correctly and was 25 years old and leaky. I also added a second return close to the original, as the original was too small and not allowing the right amount of air flow. My ducts run in the attic, so I sealed them and then wrapped them in two layers of r13 insulation and then wrapped them again in a radiant barrier. I sealed and sealed and sealed alll the ducts that I could get to. I changed out the very restrictive register grills also. We then figured out that the bedrooms with doors closed were stacking up air flow, so I added transfer ducts to the hallways. I also changed the air filters from standard size (1 inch thick) to 5 inch media filters... wow did that make a difference, both in air flow and in dust!!!!

all told, the upstairs is the same temp as the downstairs now and the electric bill dropped by 25 percent.

so my suggestion is to start by getting a feel for how much air is comming into each room. You can buy a cheap anemometers on ebay that will help you know what amount of air is comming into each room. once you get a feel for the air flow, pull off all the registers and check again. Then remove all the air filters and check again. This will tell you if you need to address ductwork issues or if its just a matter of restrictive grills and filters.

Since all the grills are off, I would suggest sealing around all duct to wall interfaces. use cheap caulk or air duct mastic. Then I would try and seal all the air ducts seams, as far into the ducts as you can reach!!!

if the air flow is great without registers and filters, start to research new registers and think about media filters (not the pleated kind at the hardware store, but jumbo sized ones from various online stores!!)

if your issue is duct work, I highly recomend getting rid of all flex duct and replace it with sheet metal!!!! doing this made all the difference for my house. note that I have metal in the walls, but the feeds to the walls were flex. I only removed about 20 feet of flex duct, but the increase in air flow was amazing. (the old flex, when pulled tight was over 40 feet long!!! so it was installed totally wrong!!!!!)

also research transfer or jump ducts for bedrooms or rooms with the doors closed all the time.

Of course this is all worthless if your house is not sealed well... so get after air sealing the house. you can find leaks by using what I call caveman tatics. close all doors and windows, turn on all bathroom fans, the fan over the stove and run the dryer if it is inside the house. This will cause a negative pressure in the house. now grab a cig or some incense and drag the smoke around all doors, windows and outside wall to floor interfaces...I bet you will see some leaks!!!!

good luck and feel free to pm me for pictures and more info if you have questions.

bob in phx

ps. I would also suggest a 3m wireless thermostat that can run just the fan on a percentage of time. this will help stir the air in the house too!!! I love mine!!!

momto3 04-12-2013 10:07 AM

there doesn't seem to be flex ducting, it's all sheet metal. From my little inspection yesterday there are a TON of obvious gaps and leaks, the connections aren't tapes or sealed at all. Bought some foil tape to work on that this weekend, see if that make a difference with air flow. Also thinking about putting the damper back in to see if that helps. It wasn't in when he bought the house four years ago, he didn't even notice it had been in at one point. Going to block off a few vents in the basement where it is always cold.

of course, this weekend the temps are dropping back to normal spring so we can't see a difference for a while. hopefully when it heats back up it will be better. There was a 6 degree difference, 73 downstairs, 79 upstairs yesterday. This is better than it was with the fan running 24/7.

going to do some more investigating and research, thanks for the tips.


taylorjm 04-12-2013 12:25 PM

The one thing you will have to watch out for is that if you close the dampers downstairs to force more air upstairs, there may not be enough airflow and your coil in the house could freeze up. All of our ducting is in the basement and walls, so replacing it or even sealing it isn't an option, that's why I went with the booster fans. That way I could increase the airflow without choking it off enough to ice up the coil. I know the hvac guys will say the system isn't right, and the ductwork isn't right, and shouldn't need blowers, etc, and I agree with all that, but reducting the house would mean tearing up all the floors and walls...which isn't an option. It's hard to get that cold air from the basement to the 2nd story! Before, to get the upstairs to 73, the main level would be 67, and the basement would get into the upper 50's!!! But the a/c would have to run a long time to get the air upstairs without the booster fans, so I'm hoping they will help this summer.

bobinphx 04-12-2013 01:10 PM

booster fans are a great option!! we didnt use them because the other changes make the difference. One thing i forgot to add was that we also changed the pleunum... it was a stupid design. a 2 foot square box with 18 inch flex on top and 16 inch flex on the sides... the air came in, hit the bottom of the plenum and then had to find a way out!!! an 18 inch pants WYE fixed that problem!!!

I guess we got luck as the trunks in our house were all sheet metal and fairly linear with sheet metal takeoffs to the rooms. I did add some homemade turning vanes for an odd feed to the dinning room (the duct went 270 degrees around the kitchen!!)

also we were lucky as we could see most of the linear duct from the room vents.. I was able to put a brush on a yard stick and with a strong light apply mastic in the ducts fairly well.

So, to the OP,,, sounds like you have lots of leaks to fix up. ALuminum tape is great. be sure it is ul listed (UL listed lasts longer) and be sure the surface is clean and be sure to rub on the tape. You can get a rubber tool to really stick down that tape. I personally did all my joints with mastic, mesh, more mastic and then tape over all of that. Yep overkill,, but as a Home owner I had the time... also dont forget that wall to duct joint.. that has saved my family and neighbors a bunch of money over the years...

jagans 04-12-2013 02:28 PM

Leaky Ducks, Need Duck Tape to seal up the Quacks. :laughing:

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