Hot Upstairs - Take 2

[Art Mulder]

Hello Folks,

Back in this thread : http://www.sawmillcreek.org/showthread.php?t=37358
I spoke about our issues with having a hot upstairs in a two story house with a vaulted entryway.

I have a science degree, so there is no excuse, but I did some really bad science and changed multiple things at once. (Bad science. In a good experiment, you change exactly one thing, and then measure again. Unfortunately, when you're talking your own house, changing just one thing and measuring involves waiting like 2-3 weeks to get enough hot days to get some average results.)

The main thing I did was install a roof-mounted thermostatically controlled attic vent. (more on that below)

But I also made a careful survey of all the ductwork in the house. In the basement I found two vents that were open, that I thought had been closed off long ago. So those were closed via dampers. On the main floor I also closed off the damper in the entry way. The goal here is just to close unnecessary vents, and hopefully direct more air pressure upstairs to the other vents.

On the return side, I blocked the basement return, leaving just under 1/4 open. On the main floor there are two returns, I left one alone (it is a basic 6x12" size). The other one was a large 6x18" size, and I sealed that one 3/4 closed (cut some cardboard to fit and placed it inside the cover). That leaves 3 returns on the 2nd floor, one in each bedroom, all three are 6x12" size. The goal here was to restrict some of the return flow from the lower levels, and try to force the furnance to draw more air down from the 2nd floor, and improve the overall circulation.

The attic fan was a bit of a pain in the neck to install. We have a 6x12 pitch roof, which I didn't think was that steep. I've been up there before to clear gutters and inspect things, etc. But I've never had to sit up there before and try and push a saw around, or lug a toolbox, or wrestle with a 24x24x12" dome-shaped fan. Suddenly I realized ... viscerally, just how steep and slippery my roof was...:eek:

But all things considered, the fan went in okay. We've had a few rainstorms since then, and I guess I did it right, as there are no drips or wet spots in the ceiling.

One thing I did before installing was to wire up the fan on the workbench to check it out. It ran very nice and quietly, and the thermostat appeared to be reasonably accurate. (I set it to about 95F.) Fortunately we had some fairly cool days in early June for the attic work, since I hate getting up there in the stifling heat. You don't want to do the roof work on a cold-day, though, as the hot sun helps makes the shingles more flexible for working with.

But does it help? At this point, all I can say is: I think so. We've had a few 31c days, and the A/C seems to do a better job of keeping the house balanced inside. We've also had a number of 28c days, when we didn't even need to turn on the A/C. We're glad we did it. However, I do recommend, if at all possible, just get this done at the same time as the shingling job, so you can let the roofing crew do it for you... :rolleyes:

Here's the photo evidence. Step one - have wife standing buy in the backyard with the camera, so she can collect evidence of your insanity, and also call the ambulance if you fall. Step two - rip out an old vent, and cut an 18" diameter hole. (When I checked the jigsaw blade a few days later, it was completely smooth. Do shingles really blunt saws? I couldn't believe it had completely worn back the teeth) Step three - check it out, adjust the fit, trim the shingles, remove nails so you can peel back surrounding shingles, slip it into place, goop on the roofing tar, lay the shingles back down, and nail it down. Step four - clean up, and promise to never do that again... :D

[Ken Fitzgerald]

Art.........Glad to hear everything went well and it appears to be helping! Yup....working on a roof....steep or not is not my definition of fun! Since I broke my back, I am REALLY scared of heights! I know that if I should fall again, I might not be walking without mechanical aide! Congrats.....let us know after the hot part of the summer passes how it worked out!

[Vaughn McMillan]

Nice job, Art. I had to laugh at your "bad science" reference, because the same adage is true chasing bugs in the software business.

...Since I broke my back, I am REALLY scared of heights! I know that if I should fall again, I might not be walking with mechanical aide! ...
Roger that. ;) I've always been afraid of heights, but now I have a good reason for it, like you do.

- Vaughn

[Stu Ablett in Tokyo Japan]

Art, I helped my Dad install one of those a long time ago, so I feel your pain!

We did it in the middle of summer and it was HOT in the attic, and I got that job, of course :rolleyes:

We really noticed a difference, and we could hear the darn thing come on during the day, so we knew it was working.

Next time on the roof (Ha!) get one of those roof anchor things, and tie a rope to your tool belt or something!

Roof Safety (http://www.rd.com/content/openContent.do?contentId=18126)

Cheers!

[Art Mulder]

We really noticed a difference, and we could hear the darn thing come on during the day, so we knew it was working.

Next time on the roof (Ha!) get one of those roof anchor things, and tie a rope to your tool belt or something!

This fan was pretty quiet. I can hear it from the back yard, if I try. In the house it is pretty silent. But I was pretty deliberate in putting the fan over the kids bedrooms, rather than ours... :D (in all seriousness, those bedrooms are on the west side, which gets cooked in the afternoon) I can hear a quiet hum in the kids bedrooms, if I put my ear against the wall to get bone conduction(?) through the building.

And yeah, you're right about safety harnesses... but I followed that link, and I have to say that it looks a bit like overkill. The problem for us as a homeowner is that it is always "just one small job" so we never justify the cost of renting or buying that stuff. It doesn't help that I have never, ever, seen a roofer using anything more than a few roof jacks in their work. (Our neighbourhood is 20 years old, so we see roofers in here all the time reshingling houses)

[Stu Ablett in Tokyo Japan]

Well, I think you are right, it was over kill, but then again, if you go over the edge of the roof, and say land on the drive way, that would be what...? (God forbid!)

The roof anchor that you put over the peak is a good thing to have, easy to install, and you leave it there. A decent harness is not expensive, and is cheap insurance against a nasty fall.

I had a buddy in high school who was working one summer as a helper on a roofing job. He slipped and fell, rolled off the roof, the house was a split level, so the side he fell off was 2 floors up. He landed on a stack of 1/2" plywood, lucky for him they had cut the straps on the stack to let if air as it has been rained on, the stack was expanded and he landed on his back, broke both arms, both legs, ribs, collar bones, and his pelvis, but, not his back. He was in a cast for most of a year, and missed grade 12, had to do it the next year. Oh yeah, he did not wear the harness provided, as it was too hot and would give him tan lines on his back (working shirtless to get that tan) Stupid mistake, and he paid for it, for a long time.

The roof anchor this is cheap and effective with a decent harness.

Just a suggestion.

Cheers!

Oh yeah, on the sound of the fan, we could only hear it when it started up, once up to speed, you could not hear it.

[Wes Bischel]

Art,
Glad to hear things are working out - sort of.:D I laughed at the "bad science" comment as well - LOML is a PhD scientist so I have learned a few things about designed experiments. Though being a Designer I still frustrate her by winging it every so often.:D :D

Stay cool!
Wes

[Chuck Beland]

If I was doing that type of job & It was a one time thing I would do what we used in the army tie a repelling harness alled a "swiss seat" no matter what you will not fall, all it takes is a rope twice your height & how you tie it around you waist & between your legs. then take another rope & tie it to the chimney. voila no fall:D

[Frank Fusco]

I am a big believer in the use of ceiling fans. Do you have one in the arched hallway? It should blow down in summer to break up that heat layer and maintain and even environment thoughout the house.

[Bob Aliano]

Art, we have a cathedral ceiling on the upper level of our tri-level and the thermostat is on the middle level. That configuration makes it cold on the loser level and hot on the upper level. It took me about 10 years to figure out the ventilation returns were at floor level but the heat spread from the ceiling down. Since the inter-stud space was being used as the return duct I simply installed a second return at ceiling level above each floor level return, lowered the temperature upstairs to a comfortable level.

[Lars Thomas]

Maybe an HVAC expert will stop by this thread. I was surprised to read you closed the basement Return Air. Since my basement is cold, I cut a return air in the basement this year. My thinking was to suck some of cold air out of the basement and blow it around the rest of the house. (I will close this Return air during the heating season) Was this the wrong thing to do? Some background, each of the bedrooms has a dedicated Return Air (RA). There is also one RA in the family room, one in the dining room and on in the upstairs hall. It is a two level home plus a finished basement (except for the shop, of course).

[Al Willits]

Just wondering why you blocked the basement returns if your trying to get cool air to the upper section of the house?

You'd think you want to pull that cool air out of the basement and blow it upstairs.

Al

[Stan Mijal]

Maybe an HVAC expert will stop by this thread. I was surprised to read you closed the basement Return Air. Since my basement is cold, I cut a return air in the basement this year. My thinking was to suck some of cold air out of the basement and blow it around the rest of the house. (I will close this Return air during the heating season) Was this the wrong thing to do? Some background, each of the bedrooms has a dedicated Return Air (RA). There is also one RA in the family room, one in the dining room and on in the upstairs hall. It is a two level home plus a finished basement (except for the shop, of course).


Lars,

A few years ago we replaced/upgraded our complete HVAC system. On the previous system I cut and put in a damper on the return air suide in the basement , thinking alog the same lines as you. When the new system was put in I asked if they forgot about a cold air return in the basement (at the junction of the cold air return and furnace) He explained they don't put them in because they actually make the system less effective. His reasoning was that a return at furnace would tend to much air and reduce the ability of the system to draw from the returns fartherst from the furnace. Having no basement return was to actually help the system circulate better throughout the house.

We have a colonial and suffered for amny years with trying to maintain somewhere near a constant temperature upstairs and downstairs. As most colonial owners we found this task to be frustrating and could never keep the upstairs warm enough/winter and cool enough/summer for a truely comfortable environment.

Working with the contractor we installed a dual zone system, but placing our upstairs vents on one main truck line and the first floor vents on a second truck. An electrically controlled damper directs the flow of sir through either or both sets of vents. A second thermostat was placed in the upstairs master bedroom ( finally I can controll my castle!) and an electronic control mounted near the furnace. It cost us and additional $2300 for the controls and ductwork/labor, but WOW , what a difference!
Instead of the upstairs being at best , withing 4 degrees (heating) and 8 degrees (cooling0 we can maintain a near constant temperature (withing 2 degrees) all year long!

Just thought I'd mention this in case anyone is planning a HVAC replacement--its the most cost-efictive time to go to a dual zone system.
I don't think I would EVER have another multi-level home without a zoned system.

[Al Willits]

Be aware that multi zones system are not just adding a damper if they're done right, frosting A coils and furnaces cycling off the limit are not uncommon when zones are installed improperly.


"""""""""""""""
When the new system was put in I asked if they forgot about a cold air return in the basement (at the junction of the cold air return and furnace) He explained they don't put them in because they actually make the system less effective. His reasoning was that a return at furnace would tend to much air and reduce the ability of the system to draw from the returns fartherst from the furnace. Having no basement return was to actually help the system circulate better throughout the house.
"""""""""""""""

Also the no register in the basement for their reason is bs...er...incorrect in my opinion.
Cold air will gravitate to the lower parts of the house, a return air vent in the basement will take that air and recirculate it though the rest of the house, sounds like they just wanted to save money/forgot to me.

I would put a damper on a vent in the basement though, it gives adjustability for changing seasons

Not always right, but 30+ years in HVAC says I'm probably pretty close on this one...:)

Al

[Stan Mijal]

Be aware that multi zones system are not just adding a damper if they're done right, frosting A coils and furnaces cycling off the limit are not uncommon when zones are installed improperly.


I didn't mean to give the impression we had not looked into the number and sizes of the ducting before going to such a system. our neighbor who is a mechanical engineer and designs commericial HVAC systems for many (20+) years, went over the system specs beforehand to ensure we would have a workable system.

"""""""""""""""
When the new system was put in I asked if they forgot about a cold air return in the basement (at the junction of the cold air return and furnace) He explained they don't put them in because they actually make the system less effective. His reasoning was that a return at furnace would tend to much air and reduce the ability of the system to draw from the returns fartherst from the furnace. Having no basement return was to actually help the system circulate better throughout the house.
"""""""""""""""

Also the no register in the basement for their reason is bs...er...incorrect in my opinion.
Cold air will gravitate to the lower parts of the house, a return air vent in the basement will take that air and recirculate it though the rest of the house, sounds like they just wanted to save money/forgot to me.

Thats the reasoning I always thought too, but faileed to take in account the number of sq feet of cold air return , if too large, will allow return air to be pulled preferentiall from the closest registers, leaving the farthese rooms getting an ineffective amount of circulation, hence conditioned air.

I would put a damper on a vent in the basement though, it gives adjustability for changing seasons


Seems like a reasonable compromise. If its too much return area, it can be closed down.


Not always right, but 30+ years in HVAC says I'm probably pretty close on this one...:)

Al




,,,,,,,,,,,,

[Al Willits]

What the engineers say works and what works in real life don't always agree, if your system works, that's what counts.


The main object of a furnace A/C unit is to cool/heat the air, if a room is to hot/cold, you need to modify the airflow, problem with "proper" sized ducts is heating and A/C is two different problems, both relating to heat rises.
Other than the kitchen and bathroom, each room needs at least one supply and one return to work properly, if during useage, one room gets to hot or cold, than air needs to be either removed or added.

That's where dampers on the registers come in, you may also have main trunk line dampers too.

I have put dampers on both return and supply registers where needed.

Here's a little experiment if ya get bored next time its cool out, run your furnace with both zones open, take a temp reading of what goes in and out of your furnace after maybe 5 mins of running, now shut one of the zones off and see what the temps are.

Should be a rating plate on the furnace that tells you what the differential should be, if your still with in that range, your probably doing ok.

Enjoy...:)

Al

[Todd Woodward]

Art, I had the same problem. My easy quick solution that has worked perfectly was to close all the downstairs air vents and open all the upstairs ones. Cold air falls. It will cool your entire house very well that way. It may take a bit longer on the initial start up of the season when it's really hot in the house, but it'll be cool upstairs (where most bedrooms are) quickly.