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Message
Possible AC issue in house I am trying to purchase
Posted on 7/12/15 at 5:41 pm
Posted on 7/12/15 at 5:41 pm
First off house is 3058 Sq Ft living with 11 and 12ft ceilings and approximately 18 months old. It has 2 units a 4 ton XC14 Lennonx and 2.5ton XC14 Lennox. When I had the inspection done the thermostats were set at 78. Inspector turned down to 74. We were at the house for an hour and a half and never got any cooler than 77. This was last week in South La around 2pm where it was 92. Inspector said have an AC contractor check it out.
I have had 2 AC contractors come out and both have said basically the same thing. The units are too small for the house. They said should have been a 5 ton and 3 ton put in taking the ceiling heights into the load calculations. This is an open floor plan house but only 1 vent in the living room area. There likely should have been 3. The costs to switch out units is 13K. Seller told me today it took 7 hours yesterday to bring house from 78 to 73.
Is this normal for a house this big or should I be worried?
I have had 2 AC contractors come out and both have said basically the same thing. The units are too small for the house. They said should have been a 5 ton and 3 ton put in taking the ceiling heights into the load calculations. This is an open floor plan house but only 1 vent in the living room area. There likely should have been 3. The costs to switch out units is 13K. Seller told me today it took 7 hours yesterday to bring house from 78 to 73.
Is this normal for a house this big or should I be worried?
11
Posted on 7/12/15 at 6:14 pm to lsufan1971
Lower your offer by 13k...
Posted on 7/12/15 at 6:19 pm to lsufan1971
No this is not normal, 2 contractors have confirmed that , get it right now , or you will be miserable for years to come
Posted on 7/12/15 at 6:20 pm to lsufan1971
Not normal, definitely a problem if there are insufficient vents for the homes main living space. Lower your offer by more than $13k, as you will need additional ductwork in addition to the larger units. I'd also be looking closely at other systems....if an idiot built the place with insufficient AC ductwork, what in the hell else did he skimp on? I'd prob take a pass and look for a different house.
Posted on 7/12/15 at 7:19 pm to lsufan1971
Where did you measure the temp? You need to know what the temp is coming out of the vent registers from each system. You can't make any decisions without knowing that.
Obviously, you for sure need at least one more register in the living room.
I wouldn't be quick to trust the AC contractors. They want to sell you some new ones. They are all programmed to give the same answers. Even if those units aren't big enough, there are methods to make it satisfactory, but it would be nearly impossible to go into details without being in the house. Research it thoroughly online.
Obviously, you for sure need at least one more register in the living room.
I wouldn't be quick to trust the AC contractors. They want to sell you some new ones. They are all programmed to give the same answers. Even if those units aren't big enough, there are methods to make it satisfactory, but it would be nearly impossible to go into details without being in the house. Research it thoroughly online.
Posted on 7/12/15 at 7:20 pm to lsufan1971
I may be in the minority, but I don't think you have a for sure problem. I do contracting, and have had several AC repair men go to a home and say the unit is too small. This is when their companies designed the design and ran the load calcs. That concerns me a little, but not end all be all. They get paid to put in a/c, they say you need new a/c. The bottom line is this time of year it is hard to cool a home.
3100 sqft should be sufficiently serviced with 6.5 tons. Modern air, insulation, and codes have standard construction very tight and needing less ac than years past. People are often running 600 sqft on a ton when loads come back.
My opinion is that the seller is an idiot showinf the home with the ac set there. In the heat of the summer it will take that long to cool the house 5 degrees. You should be worried, but I would have someone run a load test for you. They are only a few hundred bucks and that will tell the tale.
Edit:
One register in the great room is not common, but I see it sometime. CFMS are what they go by. So if you have one 12" line that has two y's and one of the y's has another y that goes to two registers in the great room. Compare that to one register in the great room straight from the box. The one register would cool the room better. You can go by number of registers.
3100 sqft should be sufficiently serviced with 6.5 tons. Modern air, insulation, and codes have standard construction very tight and needing less ac than years past. People are often running 600 sqft on a ton when loads come back.
My opinion is that the seller is an idiot showinf the home with the ac set there. In the heat of the summer it will take that long to cool the house 5 degrees. You should be worried, but I would have someone run a load test for you. They are only a few hundred bucks and that will tell the tale.
Edit:
One register in the great room is not common, but I see it sometime. CFMS are what they go by. So if you have one 12" line that has two y's and one of the y's has another y that goes to two registers in the great room. Compare that to one register in the great room straight from the box. The one register would cool the room better. You can go by number of registers.
This post was edited on 7/12/15 at 10:32 pm
Posted on 7/12/15 at 11:41 pm to lsufan1971
For what it's worth I have a right at 3000 square foot house we just built. Equipment is Lennox. a 3 ton and a 5 ton at 13 SEER. Cools the house great. Ceilings aren't as high as what you're looking at.
Posted on 7/12/15 at 11:46 pm to hungryone
Pretty good point from hungryone. Since it's a fairly new house he probably can tell you who built the house. If it's his brother's-father in laws cousin who is now in the methadone clinic you probably will have waaaay bigger problems than the AC.
Posted on 7/12/15 at 11:47 pm to hungryone
quote:
take a pass and look for a different house.
Posted on 7/13/15 at 7:51 am to BeerMoney
I know who the builder is and he has built many houses in the sub. Since the house is under 2 years old the owner is looking to go back on the contractor. Apparently a new law in LA that protects homeowners with defects like this one. Homeowner is contacting his own HVAC person today. I have requested they do a Manual J calculation.
Posted on 7/13/15 at 9:16 am to lsufan1971
FWIW, our house has 2 units, and we had problems with our upstairs unit cooling during the day. 3 a/c companies said the unit was too small, so when it finally went out we replaced it with a bigger unit. We still have the same problem, though slightly improved. During the summer, it rarely gets below about 73 or 74 during the hottest part of the day. Priot to the new unit it hovered around 75.
So it may be normal. It also may depend on how the house it orientated, and where the windows are located. The west side of our house doesn't have much shade, and we have a large window(that is tinted) so we do get a lot of sunlight in the afternoon coming in the windows.
So it may be normal. It also may depend on how the house it orientated, and where the windows are located. The west side of our house doesn't have much shade, and we have a large window(that is tinted) so we do get a lot of sunlight in the afternoon coming in the windows.
Posted on 7/13/15 at 10:00 am to The Spleen
quote:
So it may be normal. It also may depend on how the house it orientated, and where the windows are located. The west side of our house doesn't have much shade, and we have a large window(that is tinted) so we do get a lot of sunlight in the afternoon coming in the windows.
This is a very good point: the unit isn't necessarily malfunctioning--the house can be poorly sited for energy efficiency. Large expanses of unshaded, west-facing walls, coupled with an unshaded driveway reflecting heat back onto the house...poorly placed windows that add to overall heat gain, etc.
So often, people completely ignore the realities of our climate & expect the AC to fix everything. I see so damn many new houses in LA that are unsuitable for our climate--the two-story french provincial box w/no porches may be cheap for the builder & maximize interior square footage, but it's not well suited for our climate. Too many unshaded exterior walls, esp second story, mean you're gonna have higher energy bills. The porch evolved not only as a social space, but as a way to keep the sun off of a house's windows and walls.
The AC's inability to keep up is an indictment of the house's overall heat load, not just the unit's size/efficiency.
Posted on 7/13/15 at 10:49 am to lsufan1971
quote:
Since the house is under 2 years old the owner is looking to go back on the contractor. Apparently a new law in LA that protects homeowners with defects like this one. Homeowner is contacting his own HVAC person today. I have requested they do a Manual J calculation.
I think this is the right answer. It seems apparent that the subcontractor did not install the right size units for the house. As others have said - the overall dimensions of the house, layout, direction, other energy efficency issues, etc - all play a part in this, but at the end of the day, the system doesn't seem like the right fit for the house.
Posted on 7/13/15 at 10:54 am to lsufan1971
Im no AC guy but I would say they are sized correctly. Is it an open floor plan?? Open floor plan houses are harder to cool. Placement of the return air and thermostat can cause issues. No one is going to put a return air in the main area so its usually in a hallway and said hallway is close to a back door, or stairs to a second story, or to the garage door. The temp in that area is greater than the rest of the house. Get a temp gun and measure the temp at the retun air and at some of your ducts. If you see a drop of 15-20 degrees the units are running ok.
Also, I'll bet every damn blind or curtain was open when showing the house to "get good light" that hurts your recovery time also.
Its hot out and AC's are going to have to work in south La when its 95 degrees. If you put in too big of a unit you could very well have problem during other times of the year. Oversizing can cause "sweating" at the registers and cause the AC not to cycle properly to "Condition" the air. Remember ACs not only cool but they remove humidity from the air. If an AC is too big it will drop the temp down quickly but it will not have the time to remove the humidity from the air.
Also, I'll bet every damn blind or curtain was open when showing the house to "get good light" that hurts your recovery time also.
Its hot out and AC's are going to have to work in south La when its 95 degrees. If you put in too big of a unit you could very well have problem during other times of the year. Oversizing can cause "sweating" at the registers and cause the AC not to cycle properly to "Condition" the air. Remember ACs not only cool but they remove humidity from the air. If an AC is too big it will drop the temp down quickly but it will not have the time to remove the humidity from the air.
Posted on 7/13/15 at 11:10 am to ScottieP
quote:
Its hot out and AC's are going to have to work in south La when its 95 degrees. If you put in too big of a unit you could very well have problem during other times of the year. Oversizing can cause "sweating" at the registers and cause the AC not to cycle properly to "Condition" the air. Remember ACs not only cool but they remove humidity from the air. If an AC is too big it will drop the temp down quickly but it will not have the time to remove the humidity from the air.
I understand you don't want over sizing. I was at the house yesterday. The thermostat was set at 72 and it was 74 degrees in the house. It is an open floor plan. One of the issues brought up was that there are not enough ducts in the downstairs space. There is one duct feeding the living room area that is 21*19 and one duct feeding the dining area. The ceiling is 12 ft in both areas.Both HVAC contractors said there should be a minimum of 2 for the living area with 3 being optimal. Part of my fix for the issue is to add more ducts to living area.
This post was edited on 7/13/15 at 11:11 am
Posted on 7/13/15 at 11:16 am to ScottieP
quote:
Im no AC guy but I would say they are sized correctly.
Maybe it's not the sizing, but something is clearly not right. Even in the dead of summer it should not take 7 hours to cool down just a few degrees.
If the size is right, then perhaps the problem is in the duct work or registers, or perhaps the insulation is not as much as the thought it was when the sizing was done, or there is a major leak somewhere, etc. House is too new to have these problems.
Posted on 7/13/15 at 12:07 pm to lsufan1971
Have you asked to see the electrical bills?
Posted on 7/13/15 at 12:21 pm to wickowick
quote:
Have you asked to see the electrical bills?
I have them. They are not that bad but they admit to keeping the thermostat on 78. Last August the bill was $200.00. That is about the highest they have had in 16 months.
Posted on 7/13/15 at 1:08 pm to lsufan1971
Is it hot in the house when the thermostat reads 78.
Getting back to my previous posts about return air and thermostat placement.
My thermostat will read 76 degrees and it is 74 degress in my living room. So I keep mine set on 76. My parents have the opposite problem. They have to drop thiers down to 72 to keep the living room at 75 because thier thermostat is effected by air from the second AC when the bedroom doors are open.
Maybe they were able to keep it at 78 because the rest of the house was comfortable.
Just throwing out ideas.
Getting back to my previous posts about return air and thermostat placement.
My thermostat will read 76 degrees and it is 74 degress in my living room. So I keep mine set on 76. My parents have the opposite problem. They have to drop thiers down to 72 to keep the living room at 75 because thier thermostat is effected by air from the second AC when the bedroom doors are open.
Maybe they were able to keep it at 78 because the rest of the house was comfortable.
Just throwing out ideas.
Posted on 7/13/15 at 1:34 pm to ScottieP
quote:
Is it hot in the house when the thermostat reads 78.
It's warm but not unbearable but when your spending over 400K (not a brag thread) I don't want to grin and bear it. They are having their own contractor look at it today. Waiting to see their report.
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