Looking for answers to general questions


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Old 06-10-08, 08:56 PM
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Looking for answers to general questions

1. Why is it necessary for your unit to stay constantly running in the heat of the day instead of cycling on/off too much? I read this in several other posts.

2. Currently when my indoor temp reaches setpoint, the outside unit turns off but the inside fan stays on for maybe another 15-30 minutes. If I go to the thermostat and switch it from cool to off it still doesn't kick off. If i switch it from auto to on and back to auto it turns off. Any ideas? If i leave it alone it will eventually turn off on it's own.

3. I was wondering should the supply vents be pointed so that the air blows towards the walls/windows instead of the center of the room?

4. I have a room that runs about 8-10 degrees warmer than the rest of the house. That's after adjusting dampers. Is adding a return in that room the only solution, other than adding a window unit? I noticed that the supply vents in this room are right inside the door way. Could this be the reason the cool air isn't washing the room because the return is pulling the cool air down the hallway?

Any answers would be greatly appreciated.
 
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Old 06-11-08, 06:05 PM
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1. It is not a requirement for a system to run 100% of the time it all depends upon the heat load and capacity/condition of the unit. Keep in mind that longer run times help dehumidify th air which makes you feel more comfortable at higher indoor temps.
2.You probably have a bad TDR (Time Delay Relay) change it out or if you have a fan control board it is bad so change it out.
3. Does not make much difference
4. Run a extra supply line and place it further into the room preferably in front of the window and then run a return to this room for max comfort.
 
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Old 06-11-08, 06:26 PM
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Originally Posted by cheaptric
1. Why is it necessary for your unit to stay constantly running in the heat of the day instead of cycling on/off too much? I read this in several other posts.
A unit that cycles too often is a unit that is oversized. In HVAC oversizing is "never" a good thing. Saturns ellaborate explanation hits right on target

Originally Posted by cheaptric
2. Currently when my indoor temp reaches setpoint, the outside unit turns off but the inside fan stays on for maybe another 15-30 minutes. If I go to the thermostat and switch it from cool to off it still doesn't kick off. If i switch it from auto to on and back to auto it turns off. Any ideas? If i leave it alone it will eventually turn off on it's own.
Give the MFR name and full M/N of the furnace. Maybe the board was programmed to do so, and perhaps you can change the settings thru the switching of dip switches. Maybe you have a super duper modulating furnace with an ecm blower (ecm= electronically commutated motor) which ramps up and down its RPMs following specific board instructions. So, what do you have there in your house?

Originally Posted by cheaptric
3. I was wondering should the supply vents be pointed so that the air blows towards the walls/windows instead of the center of the room?
Towards "outside" walls and windows...doing so you blanket the hottest (summer) or coldest (winter) structural members in a room and reduce/eliminate the cascade or cold-wall effect (in the winter) and radiant heat effect (in the summer).

Originally Posted by cheaptric
4. I have a room that runs about 8-10 degrees warmer than the rest of the house. That's after adjusting dampers.
And how did you adjust those dampers????? You would need FIRST a good load calculation that tells you how many CFMs should be delivered to each room...then, SECOND, you need a balometer, a expensive airflow meter with which you go register after register measuring the CFMs and adjusting the dampers until you get the exact CFMs the load calc indicates you should have. This is called "balancing"

It is not a matter of just randomly flipping them open or closed.
 
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Old 06-11-08, 09:37 PM
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ThanKs Saturn and PFlor for the these explanations.

This is the type of unit i have. I don't believe it's anything special.
Outside unit---WeatherKing Model# 10PJA6001
Inside Unit----WeatherKing Model# 24AHJ21S04A01
T-stat--------Robertshaw Model #9520
This installed on a 2300 sq ft house with 10ft ceilings in north TX.


As far as adjusting the dampers, if i borrow a velometer from work, how can i figure out what kind of CFM i'm suppose to have for each room? The only dampers I adjusted was the duct work going to the warm masterbedroom. The trunk that feeds the masterbedroom also feeds the master bath and master walk-in closet. I closed the damper to the closet, throttled down the bath damper and made sure the room damper was wide open. I really didn't want to mess with the settings for the rest of the house that was comfortable.

I will try to see if i can get the Velometer from work.
 
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Old 06-11-08, 11:16 PM
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It is not unusual for heat pumps to run all the time during cold weather. During hot weather, this is usually indicative of a problem and the system needs to be serviced.

Fan usually runs after unit kicks off because it is on a delay timer.

Vents are usually placed in front of windows. A heat register placed in front of a cold window will block cold air and cause it to sink. If you go to a department store or other big store on a freezing cold day, you may find the doors open and a heat vent blowing fiercely up through a giant floor vent. The constant heat wave blocks the cold air from the open door.

The idea of placing vents under windows is to get of mix of cold and warm air in order to make the room feel more comfortable. This is the usual placement of vents in residences, but I have seen some very misplaced floor registers.

The worst was in front of the kitchen sink in one of my residences. Good thing I wear jeans or I would have looked like The Woman in Red.



Photo Credit: moviegoods
The Woman in Red

I once toured a new construction where all upstairs vents in bedrooms were in the middle of the floor where you knew they would be covered by beds. Hello?

Number of vents can be confusing. I have a bathroom in my rental with one floor vent. The tiny room is probably 60" by 60". It's a refrigerator room right now. I keep a basket of gardening and decorating magazines sitting over the vent to block the flow of heat and cold.

The 15' x 17' foot bedroom also has one vent in front of the window and was fine all winter because I like a cool bedroom. Now that warm weather is here and this being the first warm season for me, I find that the one vent (same as in bathroom) is not enough to cool the large bedroom. It is, however, placed beneath the window. That is all well and good, but one vent is not enough for the large area. I have opened the window a few inches and after tonight will seek a fan to circulate the air. I will also keep an eye on nighttime temps so that I can let some cool air in. Humidity level is also a major factor. If humidity level is high, you don't want that in your home. HVAC controls temperature and humidity. Open windows let in humidity.

I noticed that a unit across the parking lot installed a window unit this past week. They must be experiencing the same problems with the limited bedroom vents. While I think window units look tacky, if landlords allow them or if you own your own property and comfort is a priority, then a window unit can be installed.

I have a window unit at my mountain cabin. It's on the rear of the house where no one sees it or presents a decorating challenge to a anyone that's willing to drive that far into the mountains.

Back to your question, is your situation a matter of not enough vents or placement of vents and everything else is in order and HVAC unit proper sized for the structure, then a window unit might be advisable. Before socking a window unit into a window, I would consult with an HVAC pro.

Do not close off vents, especially to closets or other areas. You need humidity control in closets and other areas to prevent mold/mildew/odor issues.

Another note is that upstairs rooms tend not to be as cool as downstairs rooms because warm, humid air tends to rise. The warm bedroom of mine as described above sits above the downstairs livingroom. The entire downstairs is soooo much cooler than the upstairs. I cannot afford to crank down the AC to painfully expensively and excrutiatingly pay for the expensive cooling to accommodate the upstairs. I will simply install a fan near the cool air coming through the floor vent to circulate the cool air.

If you have a particularly warm room that is on the west, south, or south/west side of house, one important precaution against heat is to use insulated window treatments. These tend to lower temps easily 10 degrees. If living in a sunny environment, closing sun blocking draperies or blinds on side of house during day when sun predominates can lower heat in residence and need for cooling.
 
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Old 06-12-08, 05:11 AM
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Originally Posted by cheaptric
This is the type of unit i have. I don't believe it's anything special.
Outside unit---WeatherKing Model# 10PJA6001
Inside Unit----WeatherKing Model# 24AHJ21S04A01
T-stat--------Robertshaw Model #9520
This installed on a 2300 sq ft house with 10ft ceilings in north TX.
I'll check on the M/N's and if I come up with something meaningful will let you know in the course of the day.


Originally Posted by cheaptric
As far as adjusting the dampers, if i borrow a velometer from work, how can i figure out what kind of CFM i'm suppose to have for each room?
Keep in mind that a velometer measures the "velocity" (feet-per-minute: FPM) at which air is coming off the registers, not its volume (cubic feet -per-minute: CFM). Can a velometer do this job? hummm, yeeeah but not without you having to do some math. A way that would give you somewhat close readings would require that you measure Length and Width of the register (from the inside of its frame...in other words, from where its opening really begins), compute the area (A= L x W) and since the dimensions taken off the register will likely be taken in inches, divide the area by 144 to convert to square-feet. Then multiply this area in ft2 times the velocity your velometer showed in ft/min. The result is ft3/min (or CFM)

When you say adjusted the dampers, I hope you did NOT mean the vanes at the registers but rather the dampers themselves, which are located right off the trunk, where a branch starts its run towards the register. Adjusting the vanes at the registers does little (if anything) for you.
 
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Old 06-12-08, 09:09 PM
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Twelvepole,
Thanks for the response. First let me say that i have no floor registers, and my house is a single story house. All duct work is ran thru the attic The problem with my masterbedroom getting to hot appears to be cooling registers placement and the fact that the return is about 35 feet down the other end of the house. Guess i'll crack open the damper to the closet up a bit. thanks again.
 
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Old 06-12-08, 09:24 PM
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I'll check on the M/N's and if I come up with something meaningful will let you know in the course of the day.
Thanks I appreciate that.

Keep in mind that a velometer measures the "velocity" (feet-per-minute: FPM) at which air is coming off the registers, not its volume (cubic feet -per-minute: CFM).
I could have sworn we used our velometer for setting up the exhaust on our cleanroom tools. I could be totally wrong. I'll check Sunday.

Adjusting the vanes at the registers does little (if anything) for you.
No, I adjusted the dampers up in the attic. Found them because they had little flags tied to them.
 
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Old 06-12-08, 10:05 PM
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It's time to call a pro and DIY is not the answer. Hate to say so, but sometimes you have have to bite the bullet.
 
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Old 06-16-08, 04:30 PM
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New problem!!!!!!!!!

This morning I noticed that the outside unit was iced over completely. So i turned the unit off at the t-stat. Turned the disconnect off to the compressor and turned the air handler fan to on. I let it sit for several hours to defrost the compressor and the coil inside. At lunchtime I took the covers off the air handler to check the coils and then vacuumed all the water in the drip pan. Put it back together and turned it on. Let it run for awhile and checked the delta temp. I had 80 degree on the return and 70 degrees at the nearest supply vent. Temp on the t-stat showed 86 in the house. AFter it ran for 3 hours, t-stat reads 81 but now my supply is reading 64. (t-stat is located next to the return).

After reading on this forum, I checked the filter and it looked good, but replaced it anyway. Didn't see much on the coils. And since my delta t is only about 10 degrees is it that it's low on freon? I've been getting updates from my wife and she says that the lines are not frozen outside. Could it be something else? Getting ready to call someone out. Some help would be appreciated. Thanks in advance
 
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Old 06-16-08, 04:42 PM
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Maybe the family dog was laying against the return grille face and blocking it? just joking it sounds like a refrigerant level now if indeed your return filter and evap coils are clean. Just on the outside chance though you might want to keep a eye on your air handler blower if it is intermittent it will freeze everything up also.
 
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Old 06-17-08, 06:17 AM
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Well we don't have a dog but we do have a cat. Lucky for us the return is located in the ceiling.

I ran the A/C all last night and it maintained 78 degrees fine. No frozen line or compressor. I just have an issue with the delta T so i wanted to make sure that low freon would cause that problem.

Thanks for the reply Saturn.
 
 

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