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Upstairs too warm, trying to sort out causes and find solution

Posted by neilw (My Page) on
Fri, Jun 27, 14 at 17:22

My 4 BR colonial was built in 1968, with single zone forced air and central AC. I've been in it for 8 years. The upstairs/downstairs temperature balance has fluctuated over the years, and now after our recent roof work (details below) we are finding the upstairs too hard too keep cool, while downstairs is fine. There seem to be a variety of factors at play here, and I'm trying to sort it all out (sorry for the long post). Any insight would be appreciated.

Relevant facts:
1) Our entire 4 BR 2 bath 2nd floor has a grand total of 2 returns, near the floor in the hallway. This seems to be a likely part of the problem, but the HVAC guys I've asked in the past have said that running new returns to the upstairs is very difficult (I'm going to ask again). There are plenty of supplies up there.

2) When I first moved in we discovered that the whole system had about 1/2 the necessary return air for the furnace size, causing the furnace to regularly overheat. This was fixed by adding a couple of very large returns downstairs (but doesn't help upstairs).

3) In the past, we added a bunch of additional insulation to our unfinished attic (blown cellulose). I think we're pretty well insulated up there, though I'm sure it could still be better.

4) With our recent roof job, we followed guidelines at green home advisor and removed the attic fan, while adding full soffit venting and a ridge vent. I do not know how the temperature in the attic compares to what it was before we got the job done, unfortunately (didn't measure attic temp last year, so I have nothing to compare to).

5) Typically, I'm finding the upstairs ceiling temperature tracks the indoor temperature, but on one hot day (a bit over 90F) it read about 5 degrees F above the room temp. I don't know if this is typical, very good, or very bad. I could always add the fan back if necessary, although it is not my first choice. More insulation is also a possibility. What should I expect here?

6) The problem is not isolated to very hot days, although I am not looking forward to seeing what happens when the mercury starts hitting the upper 90's in July and August.

7) We had our AC checked last year and it was working within spec. Haven't checked this year yet but I see no indications that it's working differently. I am told it is appropriately sized for our house.

Can anyone offer suggestions on how to diagnose the real source(s) of the problem and/or recommend ways to fix it?

Thanks,
Neil


Follow-Up Postings:

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RE: Upstairs too warm, trying to sort out causes and find solutio

Your situation sounds very typical of 4BR, 2 1/2 bath, two story Colonials as found thru the Middle-Atlantic and new England Regions.

I have lived in a few of them, including the one I am in now here in the Maryland Suburbs of DC. This is the first Colonial where I could keep the upstairs comfortable during the summer.

What I did here was in my 2000 Sq Ft colonial is invest in 1000 Sq Ft of attic insulation. (With hind sight, I should have also done air sealing also.) I tried adding booster fans to the ducts upstairs and I tried adding a Window A/C unit in the MBR upstairs and that prevented my wife from moving out, but I could typically get the upstairs thermostat temp no lower than 78 degrees.

BTW, my A/C unit was nearly 18 years old and properly maintained and serviced.

Three years ago, with lots of help from folks here, I repalced my A/C with a two stage Heat Pump with a variable speed inside air handler. No changes were made to my ducting other than to add an additional return in my basement to help a high humidity condition there. (That worked.)

Bottom line is that I now see more air flow supplied to my upper level and I am able to maintain a comfortable 75 degrees both upstairs and downstairs.

My HP runs for much of the day, almost always in the lower stage. Due to the significantly increased efficiency of operating this way, while my home is overall cooler and more comfortable, my electric operating costs have been greatly reduced.

Oh yes, I gave the Window A/C unit to my neighbor's daughter.

Best of luck. I'm sure you'll get great advice here.


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RE: Upstairs too warm, trying to sort out causes and find solutio

"now after our recent roof work (details below) we are finding the upstairs too hard too keep cool, "

" With our recent roof job, we followed guidelines at green home advisor and removed the attic fan, while adding full soffit venting and a ridge vent."

I installed an attic fan 22 years ago when I first moved into my two story colonial. I have a hip roof with a ridge vent and soffit vents.

There is a lot of debate about the pros and cons of attic fans. I feel in my house it helps lower the attic temperature. I think the real benefit comes in the evening when the outside temperature is in the 60s and the attic is cool by bed time.

My suggestion would be to replace the attic fan. I would install a kill switch so it can only turns on during the summer months. If you have adequate air intake into the attic, then the fan should not cause a negative pressure situation. One small fan is sufficient. Do not over do it as it will cause problems and wastes electricity.


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RE: Upstairs too warm, trying to sort out causes and find solutio

I had the same problem. I did the non-green thing and added an attic exhaust fan when the roof was done. It has been like a miracle for keeping the upstairs cooler. I also have blown cellulose in the attic. When the AC is on, I close all the downstairs vents (not returns). This forces more cold air upstairs. Seems like plenty still gets to the downstairs because it is comfy. I also have ceiling fans to help circulate the cold air in the bedrooms and that is a huge help.

The one thing I did not do and wish I had was have the ducts extended to ceiling height. There would be two vents for each duct upstairs -- one at ceiling to close in the winter for heat and the other at floor to close in the summer for AC. Perhaps you could still do that. Cold air falls, so you want it to start high, not at your ankles.


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RE: Upstairs too warm, trying to sort out causes and find solutio

Thanks for the responses so far.

mike_home wrote:
"There is a lot of debate about the pros and cons of attic fans. I feel in my house it helps lower the attic temperature. I think the real benefit comes in the evening when the outside temperature is in the 60s and the attic is cool by bed time."

I don't think there's debate that it cools the attic, the question is whether that is beneficial and at what cost. In my case, if I conclude it would create a net gain in upstairs comfort that I can't easily get any other way, I'd be willing to do it. I'm just not sure if that's really my root (roof?) cause though; it feels like I have a problem even when heat is apparently not coming into the upstairs through the ceiling.

It is true that I have pretty good venting up there now (way better than before), and maybe negative pressurization wouldn't be a big problem.

Somehow I need to determine for sure if attic heat is a problem that needs fixing.

dedtired wrote:
"When the AC is on, I close all the downstairs vents (not returns). This forces more cold air upstairs. Seems like plenty still gets to the downstairs because it is comfy."

I've been under the impression that it's not good to close too many vents, because you reduce the airflow of the system. Might be something to try for me, though.

The high vents upstairs for summer use are an interesting idea I hadn't heard before, might look into that one as well.


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RE: Upstairs too warm, trying to sort out causes and find solutio

neilw,

What is the age of your A/C system?


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RE: Upstairs too warm, trying to sort out causes and find solutio

saltidawg: I don't know the age exactly. It's a Carrier Tech2000ss, which probably puts it somewhere between, I dunno, maybe 12-20 years? It predates my ownership of the house (8 years), and was at least a few years old when I bought it. But I don't know exactly.


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RE: Upstairs too warm, trying to sort out causes and find solutio

Sounds as if it is similar in age to the one I had... I have to wonder if the roof work you had done is actually the cause of your problems.

Were you satisfied with your A/C prior to the roof work?


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RE: Upstairs too warm, trying to sort out causes and find solutio

It was never awesome but we seemed to have better temperature upstairs than we do now. I don't doubt that a new unit could do better, but I don't know if it's the weakest link right now.

I guess the three candidates are:
1) Air conditioner and blower
2) Ductwork
3) Attic temperature


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RE: Upstairs too warm, trying to sort out causes and find solutio

You close some of the vents on the first floor. Closing all of them may cause a high amount of static pressure.

How much of a temperature differential do you have between floors?

Did you change the roof shingles from a light color to a dark color? Dark colors absorb more heat.

Here is a monitor I use to track humidity. It also tracks temperature to 122 degrees. Measure the temperature in your attic. You don't want to go above 115-120 degrees on a hot sunny day. If it does then that is part of the problem.

Here is a link that might be useful: Accurite temp and humidity monitor


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RE: Upstairs too warm, trying to sort out causes and find solutio

I look at these issues from a slightly different pov.

do these upstairs rooms share walls with attic?
if so the problem could be heat gain from attic
into these upstairs rooms.

most of these shared walls are insulated, but
it gets much hotter in attic than it gets outside.
air sealing these walls & reflecting the heat back
into the attic and out of the walls is the solution.

below is a link to a very comprehensive air
sealing guide. page 5 has great detail for
sealing these walls. (walls shared with attic
space are called kneewalls) while their pics
are for smaller kneewalls, the whole of the shared
wall is to be treated in same method.

heat transfers from attic into walls, when central
system operates it draws air from attic into house
via air leakage sites.

the other option is to hire spray foam insulators to
foam seal walls. from top plate to between floors.
faster than using foam sheathing as shown in pdf,
but pricier. one is diy/the other hire out.

we use a foil faced foam sheathing on these walls.
the foil faces into attic space, reflecting heat out of walls.

pav's (powered attic ventilators) pull conditioned air
from the conditioned space via unsealed holes gaps etc.
if ductwork is in attic, the pav will pull air from leakage
sites in ducts.
there are quite a few lengthy discussions about pav's
here if you do a site search. its a hot topic...in more
ways than one.
if someone believes pav's work...there is little chance
of changing their minds, but lots of facts to back up
why they don't work. not a discussion I want to re-open.

my point is that often investing in fixing the house
(improving the buildings envelope) is a better choice
than buying bigger hvac system. taking time to determine
the actual cause of the upstairs being hotter is a good
use of resources.
air sealing is a good investment, as is duct sealing.
blower door testing & duct testing measure leakage, and
can be used to show you where leaks are located.

oh and salty...there is a lot of air sealing that can be
done from inside the conditioned space. air tight inserts
for recessed lights, sealing bath fan penetrations,
hvac supply box openings...caulking ceilings around fireplaces
etc. granted working from attic means you don't have
to be as neat...but sealing from inside is always an option.
I've done both in my house....a half dozen cases of caulk
later (caulk, mastic tape, backer rods etc) my house is
almost to the point of having to add make up air.

best of luck.

http://www.southface.org/default-interior/Documents/airsealingkeypoints.pdf


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RE: Upstairs too warm, trying to sort out causes and find solutio

That's an interesting document, thanks. I don't think that kneewalls are my core problem (they're not close to the rooms that are too warm), but they're almost certainly not sealed and/or insulated as well as they should be.

It is likely as well that my attic, while properly ventilated now, is probably not sealed well.

What kind of contractor would be able to do all the sealing work, given that I'd not be able to do it myself?


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RE: Upstairs too warm, trying to sort out causes and find solutio

An update for those still following along.

AC system was checked, all is well. 20 degree drop from return to output. Air out of furnace is 54 degrees, out of upstairs supplies is about 59 degrees. All agree that there are way too few returns upstairs, and probably too few supplies as well, and they're all at floor level is which is not helpful. Proposed HVAC solution: second AC unit in attic. Not too sanguine about the possibility of adding more returns high up in the walls.

Next I had an insulation/sealing company come in. They recommended I get the attic and kneewall sealed and raise the attic insulation to R49 with Ecofill (I'm probably around R20 right now they estimated). They pretty much guaranteed that I'd feel the difference, but hey that's their business. Estimate for the job was about $3000.

I am more sympathetic, in general, to the idea of insulating and sealing the attic, because that's beneficial in general, even if I don't know for sure it will solve this problem. I feel like my attic is probably pretty porous, so it has to help at least some. I'm thinking to do that and then evaluate next steps, if any are needed.

I have more guys coming to look at it, but that's where I stand right now. We've been super-lucky that it hasn't been a hot summer yet, so we haven't suffered much yet.

Feedback welcome.


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RE: Upstairs too warm, trying to sort out causes and find solutio

sorry I missed your post before this one.

if you get a blower door test performed on your home,
it will measure & find leakage areas,
they should also test ductwork for duct leakage,
measure & find leakage areas.

both Resnet & BPI energy raters/ auditors perform
these types of tests. although with BPI you may have
to request duct test.
the rater/auditor can recommend companies to do
air & duct sealing.

do all air & duct sealing prior to adding insulation in attic.

best of luck


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RE: Upstairs too warm, trying to sort out causes and find solutio

I know that my ducts are leaky in general, but I have no ducts in the attic. The plan would be to seal the attic and then add the insulation. Dealing with leaky ductwork would be a separate task.

I have not had a blower door test yet.


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RE: Upstairs too warm, trying to sort out causes and find solutio

The $3000 cost seems really high.


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RE: Upstairs too warm, trying to sort out causes and find solutio

Have you measured the temperature in your attic?


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RE: Upstairs too warm, trying to sort out causes and find solutio

3k for insulation & sealing kneewalls?
or does this include thermal bypasses..
recessed lights, attic access and all leakage
from attic into cond space?
without a blower door...how do they KNOW
where the leaks are?

I've been doing this testing for 15+ years &
always test before doing any work...and after
the work is done. every house is different.
although there are common leakage sites..there
are suprises, like open plumbing walls, dropped
ceilings over showers left open etc that have
a huge impact on effictiveness of sealing.
miss one thing...and it can reduce the effectiveness
of the 3k investment.
if they aren't testing...they are just hitting the high spots..
or low hanging fruit as some like to say.

the blower door test will teach you a lot
about your house.
while everyone sets their own prices in my
business, I'd charge you about $500-600
for blower door & duct testing.
this would include a written report..not a fill in
the blank report, but a report specific to your
home with leakage sites & sealing methods
for house & duct/return systems.
just for a ballpark idea of costs & scope
of services.

this info is the blueprint on improving your home's
efficiency. doesn't all have to be done at once...
but within the time frame of your chosing.

having diagnostic testing done would give you what
you need to go forward rather than spending
a lot of money with less than adequate results.

if second system is added in attic...then your
ductwork will be in attic...right?

will check back later...& as always
best of luck


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RE: Upstairs too warm, trying to sort out causes and find solutio

"3k for insulation & sealing kneewalls?
or does this include thermal bypasses..
recessed lights, attic access and all leakage
from attic into cond space?
without a blower door...how do they KNOW
where the leaks are?"

In theory the estimate included sealing all leakage between the attic and conditioned space in addition to the kneewall (presumably going after all the "standard" areas") plus insulating the attic hatch and putting an edge around the opening to contain the loose insulation. I don't know about other thermal bypasses.

Another guy came in this morning and his focus was the lousy state of my basement ductwork: leaky (despite the *many* patches I've applied), uninsulated, and undersized. No estimate yet. He felt that successfully getting more of the conditioned air to the upstairs was the #1 solution needed, and that insulating and sealing the attic would was not it (he also lightly recommended an attic fan, but I refrained from getting into that discussion).

As before, I agree that this is a good thing to do. I don't know if it is the #1 step needed to be taken.

I think it's pretty likely that if I got the attic insulated and sealed *and* got the ductwork fixed, I'd be in much better shape than I am now. But given that I don't want to immediately do both, I'm still uncertain how to proceed.

Am now working on getting a full audit with blower door test.


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RE: Upstairs too warm, trying to sort out causes and find solutio

I lived in a smiler house before. Upstairs always too hot, just as you describe. The real solution is of course an extra zone or unit just for upstairs. In my case I didn't want to spend the money.

Here is what I would recommend based on my experience:

Add the extra insulation up in the attic. I did this and it made quite a noticeable difference straight away, and of course it will lower your overall costs (R20 is nowhere near good enough). even if you later have to do more, the extra insulation will always make the upstairs more comfortable and save money and if you do it yourself (it's very easy to blow cellulose, just don't block the soffit vents).

I installed powered attic fans in one house on a thermostatic relay, they helped some, but that was a knee-wall insulated home with steep roof and poor overall venting. With a typical colonial you need to keep the heat OUT rather than focusing on lowering attic temps with fans, IMO.

As I said, I spent one long day installing insulation and the next noticed ah huge improvement in upstairs comfort. It was never as good as it is in my multi zoned home, but you can't expect it to be.


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RE: Upstairs too warm, trying to sort out causes and find solutio

Thanks for the feedback. I too am leaning towards sealing and insulating the attic as step 1, and then evaluating again. I will probably change my mind a few times before I'm through, though.

Need to decide between blown cellulose and blown fiberglass (spefically, EcoFill). Both seem to have pros and cons. The cellulose we have now seems fine but very messy and dusty, unpleasant to deal with.


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RE: Upstairs too warm, trying to sort out causes and find solutio

I would definitely put more cellulose up there. It is a messy job, but not bad and it will give you more ease of use if you need to move things around rather than a mixture of cellulose and loose fiberglass.


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RE: Upstairs too warm, trying to sort out causes and find solutio

How on earth do you work up there once you have 15" (or whatever) of cellulose? What if, god forbid, you need to run a wire or something? Seems like an impossible mess, but I guess that's the price you pay.


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RE: Upstairs too warm, trying to sort out causes and find solutio

easiest way is to create a walkway down the middle - I build a platform using 2x4s and then plywood cut to width. I make it about 2-3 inches above what I expect the top of the cellulose to be and install that before I put the cellulose in. That way I can judge depth as I spray it and also always have a safe way to get around in attic as I need.


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RE: Upstairs too warm, trying to sort out causes and find solutio

When I had my additional 2 feet of insulation blown into my attic, we used (removable) battens piled over the walkway down the middle.


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RE: Upstairs too warm, trying to sort out causes and find solutio

Follow-up:

I got a full audit with blower door test, which was awesome. Found a number of prominent leaks, some of which I'm plugging myself (supply registers, outlets, windowframes), some of which are for future consideration (basement), and some were plugged when I got my attic sealed and insulated yesterday.

It turned out that after my recent roofwork, there were some areas of the attic that really needed to be sealed and insulated, so I am I happy I got that done in any case. Now we will see how the house performs on a hot day, assuming we ever get another one around here.

Next on my todo list is probably my horrible supply ducts in the basement for the upstairs supplies (undersized, uninsulated and leaky). But we'll see how things go in the meantime.


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RE: Upstairs too warm, trying to sort out causes and find solutio

neilw,

Thanks for the follow up!

SaltiDawg


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RE: Upstairs too warm, trying to sort out causes and find solutio

What things in the attic needed to be sealed? Did you add insulation to the whole attic or just in some spots? How much insulation is now in the attic?


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RE: Upstairs too warm, trying to sort out causes and find solutio

They sealed everything, but said the top of the walls where the new soffit was created needed extra attention. The entire attic was insulated to R49 (actually a bit higher.)


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RE: Upstairs too warm, trying to sort out causes and find solutio

so now post pics of ducts & we will walk
you through the best (longest lasting)
way to seal them.

supply boxes need to be sealed where
they penetrate into living spaces.

paint on mastics & mastic tape
(I only use Hardcast 1402 mastic tape)
are the best products to use.

post pics & thanks for the follow up!


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