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View Full Version : O.T. A/C & Air Handling Experts....



Derek Arita
06-02-2006, 10:25 PM
My Orange County CA house is terribly set up when it comes to keeping cool in the summer. Normally I just crank up the A/C, but on really hot days, it will run continuously and never cool. I have had the system checked and it is doing it's job. Trouble is, the living room of this single story ranch has an open beam ceiling. Since there's no insulation up there, the heat really builds up in that room, then spreads down the hall.
Now for the question. I'd love to find a home air handling expert that could tell me where to put fans, which windows to open, where to insulate, etc. Does anyone know where I can look to find someone like that. I could ask my A/C service guy, but I feel like he'd just try to sell me up to a more powerful unit.

Frank Hagan
06-02-2006, 10:39 PM
I don't have a referral to a specific person, but you might check with both the Edison Company and Southern California Gas Company websites to see if they have a complimentary "Home Energy Audit" available. They often have grant money to do these.

Keep in mind that there are some tax rebates available for certain energy saving projects that might help you decide. This quote is describing the anticipated tax CREDIT on your 2006 taxes, as stated on http://www.aceee.org/energy/05finalnrg.htm, the website of the American Council for an Energy Efficient Economy:




Existing homes, with 10% of cost up to a $500 limit for:
Insulation and envelope improvements meeting IECC specifications
Windows meeting IECC specifications, with a cap of $200 per homeowner
Central air conditioners or heat pumps meeting 2006 Consortium for Energy Efficiency specifications (expected to be 15 SEER and 13 EER), capped at $300
Furnaces and boilers with Annual Fuel Utilization Efficiency of 95 or better, capped at $150
Water heaters with Energy Factor of .80 or better, capped at $300
Heat pump water heaters with an Energy Factor of 2.0 or better, capped at $300
Ground source heat pumps meeting specified performance levels, capped at $300

Remember that a tax credit comes off the taxes you owe, not your income, so you "get" every penny back (subject to AMT limitations, of course).

This may not work for a open beam ceiling, but one energy saver I used when I lived in Riverside was to install a whole house fan. They evacuate air from the house into the hotter attic, cooling it, and bringing in cooler air from outside. In Riverside, where night temps dropped 20 degrees from the daytime high, it was very effective to run the fan for a half hour to exhaust all the hot air out of the house and ease the load on the AC. This could work for you if you have attic space above the hallway, and can kick on the fan to move the air out.

Al Willits
06-02-2006, 11:03 PM
I'd try running the furnace fan continually, remember cool air goes down, so maybe shut down some of the lower feeds and make sure the upper ones are open and don't have objects in front of them, like curtains, dressers, etc.

Also make sure the condensing unit outside is clean and don't use the high efficiency filters in the furnace.

Gonna be hard to keep the upstairs cool with that type of house, maybe a ceiling fan or two blowing down might help.

Worst case maybe a small window unit upstairs to use when the main system won't keep up?
Some of the new mini split systems seem nice also, condensing unit still on ground, but evap is run though the wall or window., a bit quieter than a normally window unit.

Just a thought.

Al

Randy Denby
06-03-2006, 12:14 AM
If you dont insulate that open beam ceiling,and any non insulated walls/ceilings, the only alternative is upsizing the unit to handle the heat load. A ceiling is typically 60-70% of heat gain/loss in a dwelling. Higher percentages for dark roofs.Insulation is cheap compared to energy usage to compensate. It sounds as tho the existing unit was sized for the house based on normal insulating practices.....someone didnt follow thru with sufficient insulation.
Randy Denby
Air_Tech Service

Al Willits
06-03-2006, 9:45 AM
Problem with up sizing unit, other than major cost considering duct work will probable be to small, is that you may just end up with cold damp air in the none peak cooling loads, not good.
AC and Heating sizes are usually dictate by code fwiw
Also on really hot days your AC will run continually if sized right, not sure what you consider really hot though, but we see many units running continually in the mid 90's here in Minn, California's building codes may be different though.

You may want to decide how much money you want to spend on this, I gave you several fairly cheap suggestion, re-insulating and larger units are major expenses, you'd probably be better with a separate unit for the upstairs.


Al

Frank Hagan
06-03-2006, 1:28 PM
A lot of the open beam cielings did not have any dead space between the cieling and the roof on the outside of the home, so there's no opportunity to have insulation in there. The sun beating down on the shingles directly heats the cieling. I have an employee who had one of these, and he simply insulated between the open beams and drywalled the cieling. Not a good choice if you like the open beams, though.

Seems to me that air circulation is the key here. You're trapping the hot air up there. You might try cobbing together a temporary arrangement with a box fan just to see if continuous air movement from the highest area into the lowest will allow the AC unit to keep up with the demand. Or look into some kind of exhaust fan with a damper that would allow you to exhaust the hot air.

Ben Grunow
06-03-2006, 8:34 PM
If you have un-insulated surfaces the only real "solution" to the problem is to insulate whcih means losing your beams or upsize the unit to get a properly functioning system. Anything else is will have compromises at some point (and even the upsized unit will not be perfect on the hottest days). You have a house that was not built properly to be air conditioned.

HVAC equipment is sized according to the different loads placed on it by a house. Loads include windows and doors, roof surfaces and basements. All of these represent different levels of efficiency (better or worse at keeping the heat out in the summer and the cold out in the winter). THe designer measures a house and considers all of these items and using a complicated computer program he sizes equipment. Your beam ceiling seems like something that just creates way too much heat for any system or maybe the system is undersized or maybe there are not enough supply vents in that room (aiming up?). I suggest calling good HVAC contractor and ask him to go through this exercise on your home. See what size unit he suggest and compare that to what you have. Make sure you tell him that you have this problem. That should solve your problems. Good luck.

Andy Hoyt
06-03-2006, 8:41 PM
Open Beams/Rafters
Decking
Vapor Barrier
Rigid Foam Insulation
1x4 strapping 16" o/c eave to ridge
1/2" CDX
Shingles

Any else is a waste of money

Jim Andrew
06-03-2006, 9:06 PM
Is there a ridge vent? Wonder if the builder made any effort to make the
air circulate above the insulation in the ceiling? Surely it has something for insulation?
When I build with a sloped ceiling, I usually build the ceiling allowing for a
couple feet between that ceiling and the roof, so I still have an attic above. Eliminates all those problems associated with just finishing the
bottom of the rafters. Jim

Frank Hagan
06-03-2006, 9:36 PM
Is there a ridge vent? Wonder if the builder made any effort to make the
air circulate above the insulation in the ceiling? Surely it has something for insulation?
When I build with a sloped ceiling, I usually build the ceiling allowing for a
couple feet between that ceiling and the roof, so I still have an attic above. Eliminates all those problems associated with just finishing the
bottom of the rafters. Jim

Depends on the age of Derek's house. There are a lot of California open beam cielings with no "dead air" space between the cieling and the shingles. They literally used the beams to frame the roof, put 1x6 on them, paper and shingles. Then on the inside, they put sheetrock or, in some I have seen, real wood paneling (before the fake stuff came along). You can use rigid foam insulation between the beams and lose some "depth" to the beams.

Derek Arita
06-03-2006, 10:57 PM
I'm not in construction, so I can't tell you exactly what's up there, but I can tell you that there seems to be little or nothing between the tongue and groove boards on the interior and the shingles on the exterior. The house used to be covered with shake shingles, but now it's an asphalt roof. There may be 3/4" plywood up there...I don't know.
Some people have covered the T & G with insulation on the inside. Others have used rigid foam on the outside when the reroofed. My roof is still OK and I'd hate to have to cover all of that nice T & G. New insulation is a must, I know, but that won't take care of the open beam living room or as we like to call it, "The Broiler".

Randy Denby
06-04-2006, 8:01 AM
Problem with up sizing unit, other than major cost considering duct work will probable be to small, is that you may just end up with cold damp air in the none peak cooling loads, not good.
AC and Heating sizes are usually dictate by code fwiw
Also on really hot days your AC will run continually if sized right, not sure what you consider really hot though, but we see many units running continually in the mid 90's here in Minn, California's building codes may be different though.

You may want to decide how much money you want to spend on this, I gave you several fairly cheap suggestion, re-insulating and larger units are major expenses, you'd probably be better with a separate unit for the upstairs.


Al
I believe you have misread his question. He doesnt have a 2 story house. Size of a unit is dictated by the load on a building not by any"code". A properly sized unit will have a 60% duty cycle if calculated using ASHRAE mean load standards and parameters. Part of that design standard is balancing air flow to room load.Insulation is the cheapest way to achieve energy and comfort standards and levels
Randy Denby
Air-Tech Serviice
30 yrs experience
member American Society of Heating, Refrigeration ,Air Conditioning Mechanical Engineers

Randy Denby
06-04-2006, 8:32 AM
Also want to point out that the suggestion of "exhausting the hot air" will not be energy efficient either. What happens is, the exhausted air from the conditioned space (not talking attic here) will be re-supplied back into the space thru cracks in the windows, doors ,or anytime someone opens an outside door. An air conditioners biggest load (up to 70%)is removing humidity from the air. If you constantly are drawing fresh air in then you are putting even more load on the unit.
A unit is sized based on an areas "mean average temperature" and designed for 74 degrees inside versus outside "M.A.T." I live in Tyler Texas where the "M.A.T." is 99 deg F and 70% humidity. If that M.A.T. goes above, like up to 102 deg...then my unit will run longer than the 60% duty cycle .

Frank Hagan
06-04-2006, 1:35 PM
Randy, you are right that usually exhausting hot air doesn't benefit. I was taking a guess that Derek's area has a big difference between day and night temps (I have lived in both Orange County and Riverside County.) In Derek's area, he has low relative humidity year round, so the drop in outside air temp really makes a difference in the comfort level.

In Riverside, where it would be 100F in the daytime, the night time temps would drop to 70F. With 55% humidity, that 70F air felt chilly coming in the windows. And it sure did cool the structure down. The asphalt shingles would radiate heat for several hours in the evening; I was always amazed at how much hotter the shingles were than the air temp hours after the sun went down. Blowing the air into the attic just as the sun was going down helped a lot in that case.

I think Derek has an air stratification problem, and mixing the air might work. It would be the least expensive to set up and try ... just hang a box fan up in the peak and see if that helps even out the load.

Derek Arita
06-04-2006, 2:29 PM
When I use the A/C, most of the house gets fairly cool, however, that living room stays very hot. If I did use a ceiling fan in the room to circulate the hotter air at the peak of the ceiling, would that somehow cool down the room more efficiently?
Yesterday, I installed a whole house fan and an automatic attic fan. I quickly learned that if I don't insulate and somehow seal off all of the recessed lights, a lot of the hot air from the attic blows back into the house. This whole thing has become a real lesson in home air conditioning.

Al Willits
06-04-2006, 3:42 PM
""""""""""
I believe you have misread his question. He doesnt have a 2 story house. Size of a unit is dictated by the load on a building not by any"code". A properly sized unit will have a 60% duty cycle if calculated using ASHRAE mean load standards and parameters. Part of that design standard is balancing air flow to room load.Insulation is the cheapest way to achieve energy and comfort standards and levels
Randy Denby
Air-Tech Serviice
30 yrs experience
member American Society of Heating, Refrigeration ,Air Conditioning Mechanical Engineers

""""""""""

Ya, I might have missed the no two story thing, but not the code issue, leastwise in Minn, haven't a clue what Cailf does.
Minn code state a unit will keep a certain inside temp in both heating and cooling with a stated outside temp and wind.
Seems I mention checking vents and there distrubtion?
I did suggest several things that were cheap to try, I know that kills you people in the trades, but every customer doesn't want to spend a ton of money.
Whatever works for you.....

And as long as we're waving credentials..

Al Willits
Techicial Support Specialist
Centerpointenergy
Master Gasfitters card, Master AC, Journeymens Boilers card
37+ years exprience including running my own AC/Refrigeration business.
Not that it means anything.
<!-- / message --><!-- sig -->

Frank Hagan
06-04-2006, 4:09 PM
Al, I wouldn't be surprised if MN has a code requirement regarding the size of the units. MN has some of the strictest codes on the planet! ("MN Code" is a specific thing we have to build boilers for, although I understand the state has dropped the more restrictive code for compliance with CSD-1 code. Minneapolis is still requiring some of the extra safety devices, last time I checked.)

Derek, mixing the air will keep it from stratifying, and may help overall. A cieling fan, set so the air blows downward, will mix it well. It will certainly help in that room, although if your AC is undersized it could end up making the entire house too warm. You can test this with a box fan, just setting up a current of air that forces the air down. Cieling fans are pretty cheap, but getting the electrical up there if you don't already have a cieling light is troublesome with T&G cielings.

In your post, you mention that if your can lights are not sealed, you get the hot air from the attic ... is that with your whole house fan on? If it is, you may not have enough ventilation from the attic to the outside (although the powered attic ventilator should certainly help ... I don't know if you can use those in concert or not.)

Phil Maddox
06-04-2006, 8:03 PM
There is already some good information in this thread but I'll throw my 2c in the game anyway. Here is the plan of a attack that I would take.

1. If you use the whole house fan, you need more ventilation to the exterior if the hot air comes through your lights. You should seal the lights in any case - they make styrofoam baffolds for this.
2. I would install a ceiling fan in the area that is hot and leave it on most of the time. You could run wire molding exposed along one of the beams, it might not look too bad.
3. Are you using a programable thermostat? If so, make sure you are not allowing the house to get too hot before attempting to cool it down. Let the system cool in the morning BEFORE it gets too hot, most units can't keep up once it is too hot. Try setting the temp on "HOLD" all day and night on a temp that you can live with. If you have a standard T-stat, set it and forget it.
4. The attic exhaust fan should run when the whole house fan is running so you don't pressurize the attic. Many ways to get this done.
5. Balance your system. Can other areas be "turned down" to push more air to the trouble spot? This can be a tricky situation so if you try it, mark the position of the dampers so you can return them to their original position.
6. Make sure your fan is on high if it has multiple settings.
7. Run the fan all of the time, not just when the system is cooling. This may help balance things.
8. If nothing works, you may be able to upsize your air handler without changing your ductwork. You must enlist the help of someone who know about fan curves and static pressure. They make units now that can handle more static than in the past.

I'm not going to post credentials other than to say that I work with this sort of thing on a regular basis.

Good luck.

Phil

Ben Grunow
06-04-2006, 9:28 PM
Derek- are you saying that you have recessed lights in the broiler room ceiling? If so you have some space up there that could be insulated.

Al Willits
06-04-2006, 9:51 PM
All good points, not sure if California has it, but the power company here has what they call a Energy Saver Switch, we used to call it Off Peak.

Its where the power company cycles the AC unit during peak loads, here you can loose an easy 25% or more of your cooling power.

We're missing enough data here that I think we may be thinking of different situations and answering accordingly to what each of us thinks will work.

Al