?? Residental Cooling Issues ???

[careybirdwell]

I'm looking for someone that can maybe lead me in the right direction. I have a 2300 sq ft 2 story home that was built new is 1999. We have 1 4 ton unit and the TStat is down stair. At first we had about a 3-4 degree temp difference between upstairs & downstairs. Over the last 19 years it has steadily gotten worst and this year we had a 10-12 deg. difference in the heat of the day. I assume it was our 19 year old A/C system, so when the evap coil went out, we replace the entire system ( not duct work) with a 4 ton 16 seer unit. Which help a little bit, but we are still at about 8-10 deg. difference in the heat of the day. The only other thing we did this year was paint the house, I thought maybe they had paint over the soffit vents which would make my attic hold more heat, but they look fine to me. I have also checked for leaking ducts and they seem fine. Does anyone else have any ideas on what I can check? THanks in advance

[Boss Buck]

What about radiant barrier / some new insulation?

[careybirdwell]

What about radiant barrier / some new insulation?

Does the old insulation lose it insulation factor?

[StrayDog]

Blown in insulation can become compacted/filled with dirt and be less effective.

Do you have hard ducts or flex ducts? Are there any dampers in your ducts/grills?

How old are your windows?

[careybirdwell]

Blown in insulation can become compacted/filled with dirt and be less effective.

Do you have hard ducts or flex ducts? Are there any dampers in your ducts/grills?

How old are your windows?

They are flex ducts, yes, we have dampers in the grills

and the windows are original (19 years)

[StrayDog]

They are flex ducts, yes, we have dampers in the grills

and the windows are original (19 years)

There are some HVAC guys on here who have real world experience- but I’m just a calculator jockey who dabbles in HVAC.

However, my opinion is one of the biggest shortcuts in HVAC is using flex duct. It has quite a bit of pressure loss - and most times I’ve seen it bent/crushed so your airflow is further choked.

If it were me I’d climb up in the attic an inspect the duct. Make sure it’s not kinked or crushed. Pull a few connections loose and see how dirty the duct looks with a flashlight. Clean duct, grills, and plenum.

Lastly, buy a cheap Anemometer (measures velocity of air). Measure velocity from all your ducts and systematically adjust your grills to try and balance the air to more evenly cool your home. If your HVAC installer calculated airflow to rooms and you have their report I’d try to balance to their numbers.

If you don’t get decent results from this I’d start by adding radiant barrier, new/more insulation in the attic, replace to hard duct, and replace windows in that order (mainly because that’s probably in order of increasing cost.

[careybirdwell]

There are some HVAC guys on here who have real world experience- but I’m just a calculator jockey who dabbles in HVAC.

However, my opinion is one of the biggest shortcuts in HVAC is using flex duct. It has quite a bit of pressure loss - and most times I’ve seen it bent/crushed so your airflow is further choked.

If it were me I’d climb up in the attic an inspect the duct. Make sure it’s not kinked or crushed. Pull a few connections loose and see how dirty the duct looks with a flashlight. Clean duct, grills, and plenum.

Lastly, buy a cheap Anemometer (measures velocity of air). Measure velocity from all your ducts and systematically adjust your grills to try and balance the air to more evenly cool your home. If your HVAC installer calculated airflow to rooms and you have their report I’d try to balance to their numbers.

If you don’t get decent results from this I’d start by adding radiant barrier, new/more insulation in the attic, replace to hard duct, and replace windows in that order (mainly because that’s probably in order of increasing cost.

Thanks, I have check the ducts for leaks and I don't see any bends or kinks that hasn't been there for 20 years

[JhuntsAlot]

I used to be an AC installation manager, about 15 years ago. For two story houses with a single unit we would often run an electric damper system. It would use two thermostats and when one are reached its goal temp, the dampe would automatically close for that area and force the full force of air to get the remaining area to goal temp.

But at a minimum, the thermostat should be upstairs, hopefully where your return air filter is. It is common place to have the t-stat upstairs on a two story, along with the return source. If both your t-stat and return air are downstairs, your original install might be questionable.



J

[Stuck]

To get a definite answer on your problem you need a rater to figure out what's causing your heat transfer or air exchange. Lots of things have changed in energy efficiency in home construction since '99. Although that does seem like a lot of home for a 1 ton unit.

[careybirdwell]

I used to be an AC installation manager, about 15 years ago. For two story houses with a single unit we would often run an electric damper system. It would use two thermostats and when one are reached its goal temp, the dampe would automatically close for that area and force the full force of air to get the remaining area to goal temp.

But at a minimum, the thermostat should be upstairs, hopefully where your return air filter is. It is common place to have the t-stat upstairs on a two story, along with the return source. If both your t-stat and return air are downstairs, your original install might be questionable.



J

The T-Stat is downstairs next to the return but I also have a return upstairs. If I moved the TStat upstairs wouldn't that just make my downstair about 10 degrees cooler than my Tstat setting

To get a definite answer on your problem you need a rater to figure out what's causing your heat transfer or air exchange. Lots of things have changed in energy efficiency in home construction since '99. Although that does seem like a lot of home for a 1 ton unit.

It is a 4 ton unit

[bowhntrmatt]

You may have to pay for some diagnostics to find your answer.

I’d probably start with a flow hood and a manual d/ manual j. This will ensure your system is properly sized, and will shed light on how much air each room is getting vs how much they should be getting.

As stated, simply adding attic insulation could make your problem get better.

Adding a zoning system is another alternative, but if you have single stage equipment it can be very difficult to retro in without causing damage to the system.

[JhuntsAlot]

The T-Stat is downstairs next to the return but I also have a return upstairs. If I moved the TStat upstairs wouldn't that just make my downstair about 10 degrees cooler than my Tstat setting

If you have a return downstairs, hopefully it is smaller than the one upstairs in an attempt to pull more of the hot air in the summer.

If they are the same size and both are smaller than the 20x30/20x20 sizes, that would not be ideal. Having two, it would probably be best to have a 20x30 upstairs (with the t-stat) and the one downstairs would be a 14x20 or something along those lines. Where we live, our biggest concern is the hotter months and moving the most of that hot air during hot months.

What are your return air filter sizes?


J

[JhuntsAlot]

You may have to pay for some diagnostics to find your answer.

I’d probably start with a flow hood and a manual d/ manual j. This will ensure your system is properly sized, and will shed light on how much air each room is getting vs how much they should be getting.

As stated, simply adding attic insulation could make your problem get better.

Adding a zoning system is another alternative, but if you have single stage equipment it can be very difficult to retro in without causing damage to the system.

As stated here and previously, attic insulation can play a big part.

Any chance of a pic of your attic insulation?


J

[careybirdwell]

If you have a return downstairs, hopefully it is smaller than the one upstairs in an attempt to pull more of the hot air in the summer.

If they are the same size and both are smaller than the 20x30/20x20 sizes, that would not be ideal. Having two, it would probably be best to have a 20x30 upstairs (with the t-stat) and the one downstairs would be a 14x20 or something along those lines. Where we live, our biggest concern is the hotter months and moving the most of that hot air during hot months.

What are your return air filter sizes?


J

As stated here and previously, attic insulation can play a big part.

Any chance of a pic of your attic insulation?


J

Downstairs is 12x24 and upstairs is 16x25. I will try to get up and take picture of insulation. I'm just trying to figure out what has changed in the last 20 years

[Quackerbox]

Does the old insulation lose it insulation factor?

Yes. I had ours re done 2 summers ago. Huge difference