[ByronAlpha]

Okay I would really like to get my HVAC taken care off. I will give a little background. I have a 1250sq ft house in Savannah, Ga. I have a 2 ton unit and a house that was built in 2005. I have no sort of shade and the house is in a starter neighborhood. My house quality in consider "average" according to my property sheet. I have vinyl siding and insulation on the attic floor.

In the summer my AC sucks and cost me a lot of money. My AC bill is on average of $250-$275 a month during the summer. I think that is crazy. I will admit I do like to keep the house on the colder side... or try to. In the summer I set the AC to 76 in the day. By sun set its 78 79 in the house. If I have people over or going in and out of the door its 80 or 81. At night time I do set the AC on 73 to cool the house overnight. In the morning it feels good in the house.

Okay Ive had two hvac guys out here to check things out. One I didn't trust and he just came out to top my freon off. My go to guy came out last year to replace a blower fan. He told my a lot of my issue is due to a spider duct work system? What the heck is that? Should I pay to get it replaced? Could I do that myself? I house is just one big box so the runs are very short.

What is a good plan to make my house more efficient? I think my windows are good. Does window film help out? I was thinking of going into the attic to fill any air leaks if find. I have a PAV and had no idea that they could be causing more bad than good. Ive been messing with mine for the past couple of day and I think its helping in my cause. Is there any sure fire test for this? As I sit here and listen to my air flow through my vents it sounds as the air coming through it not consistent. Is sounds like there are fluctuating amounts of cfm coming out of it. Normal? Last thing. It feels like I am getting less CFM in different rooms. What would cause this? And is there anyway to check this? Would wiring my blower fan higher help? I know I just asked a million and one questions. Any help would be great!!!!!

 

[CaptJ]

Larger A/C unit

I think you main trouble is the size of the A/C unit. in Ga the temps and humidity are high. A 2 ton unit isn't going to cut it, as you well know. A 3 ton unit would be more suited.
As for air flow in rooms being different, that might be OK if the room temps are ok. Try this; At night close all doors in the house. Keep them shut all day. Check from time to time in each room to see if any room is warmer than the others. If so, you may want to damper down the coolest rooms some. There are usually dampers near the air handler for this purpose. Alternatly you can do it at the registar, but this can lead to noise.
If you get a new A/C unit, look for a 14+ SEER. That will save you some cash on electric bills.
Good Luck

 

[garya505]

What is your indoor humidity? How long does the AC run each time it comes on?

You should probably have a pro check your airflow (CFM) and evaluate your ductwork.

 

[ByronAlpha]

I was thinking the same thing as well. Ive been told both stories. The one guy who I didn't care for suggested I buy a new unit as well. My AC guy now and good friend says yes I could benefit from a larger unit but doesn't suggest I go buy one. He suggest I fix the spider duct work this winter. He said probably around $700 for the job. Sound right? Whatcha think? :cheers:


Garya: Im unsure of my indoor humidity. Im sure its high. Its very humid where I live. My AC runs all day long. It does turn of at night. My AC guy has never taken any tests at my house. He has only been here to check freon 2 years ago and to replace a blower fan last year.

I checked ductwork last week as well to clean evaporator coil. It wasn't dirty to me at all.... Now I know me checking duct work was something I did very fast as I was very hot from the evap cleaning. LOL the more I think about it my "checking" was probably useless. I will check into more if needed though.

 

[mchild]

Okay I would really like to get my HVAC taken care off. I will give a little background. I have a 1250sq ft house in Savannah, Ga. I have a 2 ton unit and a house that was built in 2005. I have no sort of shade and the house is in a starter neighborhood. My house quality in consider "average" according to my property sheet. I have vinyl siding and insulation on the attic floor.

In the summer my AC sucks and cost me a lot of money. My AC bill is on average of $250-$275 a month during the summer. I think that is crazy. I will admit I do like to keep the house on the colder side... or try to. In the summer I set the AC to 76 in the day. By sun set its 78 79 in the house. If I have people over or going in and out of the door its 80 or 81. At night time I do set the AC on 73 to cool the house overnight. In the morning it feels good in the house.

Okay Ive had two hvac guys out here to check things out. One I didn't trust and he just came out to top my freon off. My go to guy came out last year to replace a blower fan. He told my a lot of my issue is due to a spider duct work system? What the heck is that? Should I pay to get it replaced? Could I do that myself? I house is just one big box so the runs are very short.

What is a good plan to make my house more efficient? I think my windows are good. Does window film help out? I was thinking of going into the attic to fill any air leaks if find. I have a PAV and had no idea that they could be causing more bad than good. Ive been messing with mine for the past couple of day and I think its helping in my cause. Is there any sure fire test for this? As I sit here and listen to my air flow through my vents it sounds as the air coming through it not consistent. Is sounds like there are fluctuating amounts of cfm coming out of it. Normal? Last thing. It feels like I am getting less CFM in different rooms. What would cause this? And is there anyway to check this? Would wiring my blower fan higher help? I know I just asked a million and one questions. Any help would be great!!!!!

Byron,

There are a number of things that could be the source of the discomfort you are experiencing. In fact, you should assume that the problem isn't just one problem but more than likely multiple problems.

The proper way to do HVAC is to do a load calc using the standards of Manual J, design the air distribution system (duct work) using the standards of Manual D, and select the proper equipment using Manual S. And then after it is all installed and operating take measurements and run some test to confirm that the total system is working the way it is supposed to by delivereing to each room the required BTUs to maintain comfort.

At this point there is no way to know if any of that was done but a fair guess would be that it wasn't. The most common issues that homeowners face is equipment that is oversized and duct work that is undersized AND improperly installed. Insulation and air leaks can be an issue and it would be a good idea to have some testing done to determine what you have for both to see if it can be improved.

Most contractors do not do load calcs, but rather, size systems based on local rules of thumb (thus the reason over sizing is common). Similar short cut methods are used in duct design and installation. If you are industrious you can call around to contractors in your area and ask if they size using Man J and design ducting using Man D and if you find one that does hire them to deterine the load on the home and whether the equipment can handle it. That same contractor would likely have the equipment and know how to use it to do a static pressure test on your duct work. This measures the resistence that the air flow has within the duct work. It would not be surprising that this test will show a high resistance and the system is not delivering the needed air flow to the home. Low air flow means low system performance and cause it to act like a smaller system than it is.

 

[Todd S 2]

Before I would enlarge the A/C I would make sure that the attic power fan isn't pulling the A/C out of the house. Like you mentioned, foam the cracks and gaps.

Regarding the spider duct, if it's rigid and insulated it would be okay. If it's flex, that could restrict the airflow.

Also, have the return air checked. Normally, the ductwork is the issue.

 

[mchild]

I was thinking the same thing as well. Ive been told both stories. The one guy who I didn't care for suggested I buy a new unit as well. My AC guy now and good friend says yes I could benefit from a larger unit but doesn't suggest I go buy one. He suggest I fix the spider duct work this winter. He said probably around $700 for the job. Sound right? Whatcha think? :cheers:


Garya: Im unsure of my indoor humidity. Im sure its high. Its very humid where I live. My AC runs all day long. It does turn of at night. My AC guy has never taken any tests at my house. He has only been here to check freon 2 years ago and to replace a blower fan last year.

I checked ductwork last week as well to clean evaporator coil. It wasn't dirty to me at all.... Now I know me checking duct work was something I did very fast as I was very hot from the evap cleaning. LOL the more I think about it my "checking" was probably useless. I will check into more if needed though.

So far everyone is giving you a guess as to what may be the issue. People from this board or any other forum can only do that. But, the locals you have spoken with are also guessing and they don't have to if they are true professional contractors.

Stop using using locals that are not professional enough to run the proper tests, measure performance and then develop a plan to resolve the problem(s). Only with good data can you make good decisions and guessing is not good data and no basis in which to make a decision.

 

[Stamas]

I'd focus on the airflow side 1st, then get the system diagnosed properly. It can't be done the other way around. Size of the system may very well be an issue, but get the airflow checked by someone who is qualified in air diagnostics.

 

[garya505]

As "just a homeowner", I think a larger unit might help but will cost you more in one-time and on-going costs, when it's really just masking the real problem. Kinda like this: your car tires are underflated, so put in a bigger engine?

Seems like 700 bucks to improve your ductwork would be money well spent.

 

[primecooler]

$700 sounds like a good buddy price or want a new girlfriend price. The materials alone can cost that. Unless you want another spider duct system. Proper design, installation and materials mean the price goes UP. Check with other contractors with references. Cookie cutter houses are usually using the cheapest contractors around, quality is never a issue with these guys...there is none. Also make sure the new ducting comes with balance supply dampers at the plenum, this helps after the system is in with adjusting your variance in room temperatures. good luck.

 

[ByronAlpha]

Wow! Im a member of quite a few forums ranging from one thing to the other. This forum seem to have some great members!

After poking around this forum, I do understand you guys can only guess. I am simply just giving some background and seeking general things I may do myself to improve my cooling efficiency.

To answer a few questions:

Yes I do have a flex spider ductwork system. My AC guys wants to redo the duckwork and install rigid. As far as a professional this guys is. Ive just never had him out to do any tests. I would assume his has all the meters and equipment needed to test my system.... I would hope. What would be some good questions to ask him? Also what size opening should I have in my vents? I only have a 4 inch opening.

 

[ByronAlpha]

About the $700. This guy has done my parents AC for the last 13 years. So naturally he has always given me great deals on anything I need. I also run a business now and Ive been helping him out on invoices if you know what I mean.

He said he would eliminate the spider system. Im unsure of what system he plans to run if I decide to do the work. All I know is it will be rigid.

 

[skippedover]

What are the answers?

1. Wht is the return air static pressure?
2. What is the supply air static pressure?
3. What is the system airflow in CFM?
4. What is the indoor dry bulb temperature?
5. What is the indoor wet bulb temperature?
6. What is the return air dry bulb temperature?
7. What is the supply air dry bulb temperature?
8. What is the outdoor amibent temperature?
9. What is the condenser discharge air temperature?
10. What is the indoor saturated evaporation pressure?
11. What is the indoor saturated evaporation temperature?
12. What is the system metering device?
13. What is the suction line temperature?
14. What is the super heat in degrees F?
15. What is the saturated condensing pressure?
16. What is the saturated condensing temperature?
17. What is the liquid line temperature?
18. What is the subcooling in degrees F?
19. Is the airflow correct for this size system?
20. Is the system properly charged with refrigerant.
Bonus Points for:
21. Indoor blower rating in HP.
22. Indoor blower rating in amps
23. Indoor blower motor actual operating amps
24. Outdoor unit rated total amps
25. Outdoor unit total actual operating amps
26. Outdoor unit fan operating amps
27. Compressor operating amps.

If he's a pro, he's already takek all the readings on at least 1-20.

 

[mchild]

Wow! Im a member of quite a few forums ranging from one thing to the other. This forum seem to have some great members!

After poking around this forum, I do understand you guys can only guess. I am simply just giving some background and seeking general things I may do myself to improve my cooling efficiency.

To answer a few questions:

Yes I do have a flex spider ductwork system. My AC guys wants to redo the duckwork and install rigid. As far as a professional this guys is. Ive just never had him out to do any tests. I would assume his has all the meters and equipment needed to test my system.... I would hope. What would be some good questions to ask him? Also what size opening should I have in my vents? I only have a 4 inch opening.

Even though it is a 'spider' duct system that in itself does not mean it needs to be junked. The typical poor install of these system allow the duct to not be pulled real tight (a must), allow the flex duct to make turns (a no-no and it can't be pulled tight if there are turns), allow the duct to not be properly supported causing it to sag (another no-no), not be sized correctly (improper design), no balancing dampers at the plenum, and more.

Your pro could possibly remediate the existing system and not have to replace the entire ducting and this should save you money.

In any event he should run static pressure tests of the return and supply side. He should design the duct using Man D (whether remediating the existing ducting or starting over) and target a reasonable total static pressure - this will vary on the equipment you have. After it is installed then he will need to balance the air flow to reach room (but he will need to have run a load calc to determine what the required CFM is for each room) and test the static pressure to make sure it is within the limits of the system and what the ducting was designed to.

 

[ByronAlpha]

About my ductwork. Can I take a picture and post it? Im sure I can capture it all in one pic. Also I keep reading about the ductwork hanging. Mine is just laying on the floor. Bad?

 

[Shophound]

As I sit here and listen to my air flow through my vents it sounds as the air coming through it not consistent. Is sounds like there are fluctuating amounts of cfm coming out of it. Normal?

If the airflow sounds "puffy" or "huffy" (that is it sounds like it comes out in bursts) that's a classic sign of flex duct not stretched tightly, or improperly curved (or both) and creating excessive turbulence inside the duct.

The tech who commented on the "spider" duct system may have been trying to tell you that your flex ducts are strung all over the place like flailing tenticles of an octopus vs. nice, straight shot runs. Yes, attics often don't allow super straight shots of flex to be run, but more often than not an installer will just use a whole box of flex duct to make one run, leaving a LOT of slack and compression in the run vs. cutting off the amount he needs and stretching it tightly to minimize airflow loss.

If you post pictures of your ducts in the attic, I know that will spur more comments to your thread. Pictures always do!

 

[mchild]

About my ductwork. Can I take a picture and post it? Im sure I can capture it all in one pic. Also I keep reading about the ductwork hanging. Mine is just laying on the floor. Bad?

Take pics and post. it will help a lot.

 

[Shophound]

About my ductwork. Can I take a picture and post it? Im sure I can capture it all in one pic. Also I keep reading about the ductwork hanging. Mine is just laying on the floor. Bad?

I prefer it to be suspended above the attic floor, supported with the proper strapping every six feet or so to minimize sagging between straps. 99% of the time when it's on the floor it just snakes everywhere, making unneccesary twists and turns to get where it needs to go. When it is hung it requires more thought and care from the installer (no guarantee, but it's more promising) on how to lay out the ducts and run them.

 

[ByronAlpha]

If the airflow sounds "puffy" or "huffy" (that is it sounds like it comes out in bursts) that's a classic sign of flex duct not stretched tightly, or improperly curved (or both) and creating excessive turbulence inside the duct.

That is exactly what my air sounds like. But is only in two rooms that it does this. My bedroom being the loudest. Which it also the hottest place in the house. The place I want cool more than anywhere else.

The tech who commented on the "spider" duct system may have been trying to tell you that your flex ducts are strung all over the place like flailing tenticles of an octopus vs. nice, straight shot runs. Yes, attics often don't allow super straight shots of flex to be run, but more often than not an installer will just use a whole box of flex duct to make one run, leaving a LOT of slack and compression in the run vs. cutting off the amount he needs and stretching it tightly to minimize airflow loss.

If you post pictures of your ducts in the attic, I know that will spur more comments to your thread. Pictures always do!

Its like deja vue. Those are pretty much his exact words.

 

[Todd S 2]

What are the answers?

1. Wht is the return air static pressure?
2. What is the supply air static pressure?
3. What is the system airflow in CFM?
4. What is the indoor dry bulb temperature?
5. What is the indoor wet bulb temperature?
6. What is the return air dry bulb temperature?
7. What is the supply air dry bulb temperature?
8. What is the outdoor amibent temperature?
9. What is the condenser discharge air temperature?
10. What is the indoor saturated evaporation pressure?
11. What is the indoor saturated evaporation temperature?
12. What is the system metering device?
13. What is the suction line temperature?
14. What is the super heat in degrees F?
15. What is the saturated condensing pressure?
16. What is the saturated condensing temperature?
17. What is the liquid line temperature?
18. What is the subcooling in degrees F?
19. Is the airflow correct for this size system?
20. Is the system properly charged with refrigerant.
Bonus Points for:
21. Indoor blower rating in HP.
22. Indoor blower rating in amps
23. Indoor blower motor actual operating amps
24. Outdoor unit rated total amps
25. Outdoor unit total actual operating amps
26. Outdoor unit fan operating amps
27. Compressor operating amps.

If he's a pro, he's already takek all the readings on at least 1-20.

There you go showing off again.

And I suppose they say you charge too much.