Climate control suggestions...

[John]

Howdy all. I'm fishing for some ideas on controlling the climate in my upstairs bedrooms. Here's the dealio...

It's a 2-story, Cape-Cod style house, 2 bedrooms and a bathroom. Bathroom is a big dormer on backside of house, and a dormer in each bedroom to the front. There is no attic, so to speak. The slope of the roof starts partway up the wall by the dormers up front, so ceiling follows that to a point, then flattens out and stays flat to the far wall. Behind wall, there is a crawl space opened up from the closet... same level as rest of room otherwise and roof slopes in there, as the oppposite end in bedroom. AC ductwork comes up through this space. Additionally... upstairs ceiling height is barely 7 feet. Currently, there is a ceiling fan in each bedroom. I installed a new one that has maximum possible clearance from ceiling without hitting my head. AC vents are one-per-room, in wall at floor level in bedrooms. If need be... I can take photos and post somewhere to help visualize this layout.

Now here's the deal... rooms are simply too uncomfortable during the day at this time of the year... quite muggy despite AC on and fans on. The AC system seems adequate enough... no problems downstairs. I suspect the upstairs is problematic in part because there is no attic to act as a buffer of sorts. I also suspect that the ceiling fans are nearly useless since they are possibly just circulating warm air off a warm ceiling. Cool air does come out of the vents, but being near floor, I suspect it just isn't getting circulated well enough.

Here's my thoughts...

a: I need to move AC vents from floor level up near ceiling. This will allow ceiling fan to circulate that air. OR... use floor fans instead if those will be more effective than a "hugger" ceiling fan to begin with. Getting rid of ceiling fans will let me have ceiling lights anyways. Moving ducts up, however, will let me have greater flexibility in furniture placement.

b: In the crawl space behind wall, get roof vents to exhaust stale, hot air. Passive vents, active vents, thermostat-controlled vents... any thoughts? Since ducts come up through this space, and space is hot, perhaps it's warming up the air in the ducts before it exhausts into bedrooms?

c: On the "front" side of the bedroom, where roof slopes and forms part of ceiling... I'm wondering if I should have vents there too? Sun is beating down directly on that and, with no attic as a barrier, is contributing to the heat in the room.

That's all I can think of for the moment. Thanks for any and all feedback.

[Art]

Put in a second ac system for the upstairs. Or install electronic dampeners to separate upstairs and downstairs zone if you think your ac is sized correctly for your house. Get estimates from pro's who can tell you what you need.

[m Ransley]

you need a pro to do a load calculation, is there a second floor return. When was your ac serviced last.

[HVAC fella]

You need additional supplemental cooling for your upstairs area because of the tremendous heat gain from having no attic. Rerouting the supply air up higher will not help. You need to consider a 'Mini Split' system if the upstairs is one open space . When you have a contractor come out..tell him to look into this possibility. Also, if you dont have a return in the upstairs..try setting a box fan at the top of the stairs and having it blow down the stairs -- it should make the upstairs a bit better but not corrected.

Dave

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Have you hugged your A/C Tech today ?

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[default]

If the existing AC unit isn't running all the time, then the current problem isn't the size of the AC unit, it's that the room that the thermostat is in is at a happy temperature before the bedrooms are. and moving the suppy and return vents so that there aren't any trapped air pockets might help. Ultimately, you want the ratio of heat-gain to air-exchange through the AC unit to be the same for every conditioned room. If one or more rooms is hotter than the others, then you need more of the air from that room to go through the AC. When you accomplish this, all of the rooms will be the same temperature. If this temperature is too hot, *THEN* you need either a bigger unit, or supplemental cooling.

--Goedjn

[m Ransley]

Dave says you need another AC upstairs. What about a Load Calc Dave , dont you do those ever ? We know you hack em in. But geeze. No return? put one in or it will never cool . Perhaps additional suplies, but a Pro will need to review you situation. A fan, thas a gooood haaacker boi davie, so thats what you tell unhappy campers. Is your unit running to capacity, a pro checked it out ! You may be able to reduce airflow downstairs but caution on freezing the coil, A thermometer in the A coil duct will show operating temp. A dirty filter, dirty blower cage, dirty A coil will restrict flow as will certain filters making reducing first floor air flow more risky, besides significantly reducing efficiency. Or you may be able to Zone your system another option after everything else has been reviewed.. First try running fan continuosly 24 hrs a day and slightly reducing

1st floor vents, ck filter, and get a pro out .

Dave is the local unlisenced Hack that sells new products other fixing them.

Shut Up Dave go clean your Ac, its time for your lunch

[SQLit]

Have you tried the on position for the fan? Let the a/c fan run all of the time. Might help a little. Check your unit's air handler, change the fan setting to the highest setting. Have you reversed the fans? Blow up Is it possible to get a return up there? Your thoughts on getting the air up are valid. Might be pretty ugly/expensive.

ideas above a just WAG's. you probably need a pro

[John]

I don't believe the system is zoned. There is no thermostat upstairs... just downstairs (across and down a bit from the intake). I do plan on having a pro come out soon... part of the reason for my inquiry here is to be prepared to ask the right questions when I do.

[John]

There is no second-floor return. I'm not sure when the AC was last serviced. I've owned the house less than a year, and AC system was installed new about a year or 2 before I bought it. How often should a system be routinely inspected? It was inspected prior to completing the sale of the house, though I suppose that may have been a pretty simplistic check?

[John]

The upstairs is not open. There's the 2 bedrooms with a short walkway between, and the bathroom between the 2 (bathroom does not connect directly to either bedroom). I will your suggestions in mind. Thanx.

Rather than a box fan, I have been running a window fan (two fans in one unit) in my bedroom window, set to exhaust out. It seems to help some, but by no means a cure.

[John]

Even the AC running nearly non-stop is of little help. One other suggestion I read about online is to install fans inside the ductwork to help force more of the cold air up... perhaps that would help accomplish what you are suggesting.

As for possibly needing a bigger unit... the existing system was installed new by the previous owners about 2 years or so ago. I've owned the place less than a year. I'm inclined to think the unit should be adequate for the house simply because of its age, but then I've inherited a lot of BS from these people already, so maybe they didn't spend the money on a suitable unit.

[John]

Even with AC on near-continuously, there's insufficient relief. As for=20 changing the fan setting to the highest setting (I assume you mean AC=20 fan?)... I don't see that option on my thermostat. It's a digital model=20 (Honeywell) that I installed myself this past winter. Ceiling fans are=20 on high. I haven't tried reversing them to blow up yet. Well I did=20 try, but the one in my room is remote-controlled and the remote isn't=20 working for some reason... will correct ASAP though. As for a return...=20 it should be possible and maybe not even particularly difficult. =20

I do plan to consult a pro soon. All the feedback I'm getting will help=20 me ask the right questions though. Thanks a bunch!

[m Ransley]

You dont want your upstairs windows open with fans blowing out, no wonder you run 24x7. An inspection is an inspection not a service-clean. Get a price and get a second floor return or forget it, you will not cool. Heating cycle works different.

[John]

Placing the window fans was an attempt to alleviate the problem upstairs. They do help some, but not nearly enough. Since the problem existed beforehand, they cannot be *the* problem or a part of it. I can see where they could be a problem once I address the root of the issues at hand though.

I'm pretty much sold on needing a second-floor return by now. Extending the ductwork for the existing return to the upstairs should be a relatively simple matter, but I'll be getting the final word from a pro at some point soon. Thanks for your time and feedback.

[TURTLE]

This is Turtle.

You give him too much Credit here. Dave is not in the HVAC business and just pretends he is. If you call him a Hack. You are giving him too much credit for it would say he has done atleast 1 hvac job in his life.

TURTLE

Shut Up Dave

[TURTLE]

This is Turtle.

Your speaking to a Fellow Who works at Burger King that fries French Fry and cleans up at nite. He is not in the HVAC business as he claims.

TURTLE

[geoffrey cohen]

John You have not said anything about the amount of insulation you have in or above the ceiling. Improving this may be all that's needed - if there is space. Use proper glass wool.

Geoffrey

[John]

There's that old pink fiberglass insulation along the inside of the wall, and in the small space between the ceiling and the roof. In the crawl space behind the wall, there is no insulation at all along the roof. I'm planning on installing a radiant barrier along those rafters, which was recommended by a number of websites I've visited, such as this one:

One other thing that I realized late yesterday that may be a problem is the filters I've been using. I started using the 3M Filtrete air filters in late spring, but started looking into reusable filters last night since these Filtrete's are gawdawful expensive to be replacing once a month. In the midst of looking into that, I read more details about MERV ratings as well as airflow resistance and how that affects AC function. It occurred to me that my AC may be underperforming because of these Filtrete filters... they have the highest MERV rating (best microparticle filtering ability), but as a consequence are likely creating MUCH more airflow resistance than the el cheap filters that were used previously. So this morning I got some el cheapos. It's too early to say if they have helped since it rained today and was pretty cool outside late this afternoon, but I'm keeping my fingers crossed.

[geoffrey cohen]

John You need to put some numbers on what you do. A good way of seeing what's going on is to use the Demo version of Manual J8 from Wrightsoft. As an example, in the model of my house an upstairs bedroom under a pitched roof with R28 insulation on the ceiling and a radiant barrier under the tiles needs 163cfm. If there is no radiant barrier the room needs 170cfm. However, if the insulation is removed and only the radiant barrier is used the room needs 338cfm !

Geoffrey

[John]

I may not have been clear. I'm not planning to do anything with the space immediately above the ceiling upstairs. I can see there is pink fiberglass insulation in place, though whether or not it completely covers the area is purely speculative. Doing anything up there would likely require tearing out the ceiling, something I'll consider only as a last resort since I may accomplish little more than find out there's nothing extra to do. The area I'm focusing on is behind the "far" wall... facing the rear of the house. Behind the bedroom wall is a fair-sized area that is essentially my attic. I can stand up in there up to a couple feet from the wall where the roof slope is too low to do so. The roof continues to slope on down to the floor. There is fiberglass insulation lining the walls in there. The ceiling is the roof, and there's nothing lining it. It's here that I plan to install the radiant barrier, and possibly a vent. Same goes for the bedroom on the opposite side of the dormer.

On the plus side, changing from the Filtrete air filters to the standard el cheapos seems to have made a huge difference. While there is still some room for improvement, the upstairs bedrooms are no longer exceedingly warm as they had been come noon. I'm hopeful that a combination of installing the radiant barrier and improving the air distribution in these rooms by moving the vents upwards (or just using a floor fan) will be all the extra that's needed. If not, then I have a lot of great advice from everyone here to fall back on. Thanks a bunch!