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  1. #40
    Join Date
    Nov 2001
    Location
    East Texas
    Posts
    948

    Thumbs up

    Quote Originally Posted by EugeneTheJeep View Post
    So Timber, it has been a week, did the house cool off yet?
    Was there this afternoon, house was at setpoint , 76. 101 outside.

  2. #41
    Join Date
    May 2009
    Posts
    575
    I was at one of our foam houses early on summer. It was 85 outside and we were replacing a txv on one of the units for 3 hrs in late afternoon. The other unit did not come on once.

  3. #42
    Join Date
    May 2009
    Posts
    575

    Confused

    I was at one of our foam houses early on summer. It was 85 outside and we were replacing a txv on one of the units for 3 hrs in late afternoon. The other unit did not come on once.

  4. #43
    Join Date
    May 2009
    Location
    In the Hudson Valley of New York
    Posts
    2,041
    Quote Originally Posted by Timber View Post
    Was there this afternoon, house was at setpoint , 76. 101 outside.
    Customer is happy?

  5. #44
    Join Date
    May 2009
    Location
    In the Hudson Valley of New York
    Posts
    2,041
    Quote Originally Posted by ChaseAir View Post
    I was at one of our foam houses early on summer. It was 85 outside and we were replacing a txv on one of the units for 3 hrs in late afternoon. The other unit did not come on once.
    Zone was off?

  6. #45
    Join Date
    May 2009
    Posts
    575
    Quote Originally Posted by EugeneTheJeep View Post
    Zone was off?
    Tstat never called

  7. #46
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,763
    Quote Originally Posted by meh70087 View Post
    When we first started doing foam houses we didn't trust the load calc but stuck with it and have not had the first problem. Approx 3200sqft with a cool 2.5 tons. At start up I was kinda feeling like we may have some issues. Told HO we would be back in two days, when I returned she had the biggest smile ! Give it some time. No one has mentioned AIR FLOW so that may be something to check? This is also in south LA .

    ALL FOAM HOMES GET HEAT PUMPS unless HO refuses.
    Quote Originally Posted by arc8 View Post
    I once ran into something like this but it was the other way; a furnace.

    I sized up this new small house. The heat loss was 32,000 @ -24 degree, so I installed a 92% 40,000 furnace.

    The installation happened in the middle of winter, we got the furnace going, the drywallers were mudding. It was insulated everywhere except the basement which were poured concrete walls.

    Needless to say, the furnace could not keep up, it would not warm the house above 65 degrees on average cold days for a few weeks. I hoped that I calculated the Heat Load correctly. I was a little nervous. But after a month, it corrected itself. The house was completed and the folks moved in and to this day it is able to heat the house above 75 degrees on the coldest days.

    I guess the Heat Loads were meant for finished and stable (constant) temps on the inside.


    Good Luck to your project.
    Quote Originally Posted by frumper15 View Post
    This is something that I have found as well - our first Geothermal install also happened to be a foam insulation job (house fire rebuild). Of course, the homeowner didn't tell me that during the design phase, and the plans didn't specify so my load calcs and equipment sizing were based on conventional insulation, etc. Well, they sprayed the underside of the roof (cathedralized?) and made the attic a conditioned space so the interior volume went up by another 25% or so. I was a little nervous at startup because 1) it was my first Geothermal and I was trusting my training and calculations and 2) I had sized a 4 ton geothermal where we probably would have installed an 80k BTU furnace. When the system first started up it was middle December and below freezing outside. Thankfully, the HO had been keeping things warmish with a kerosene torpedo heater so I wasn't trying to come up from too low, but without resorting to the auxiliary heat it took a while to chip away at those degrees.

    The lesson I learned is that an appropriate sized system will do a great job of keeping the space at temperature, but extreme recovery is another story. New startup in the middle of record high temperatures? A few days at the very least before getting worried.

    We had a similar issue with our service side last month - record highs for a few weeks and lots of broken down systems. The house would be 90 degrees inside when we got the system running again and the customers would be calling 2 hours later complaining that it wasn't 70 degrees in the house yet. I told all of them to call back 24 hours later if it wasn't the temperature they wanted - I didn't get any calls.
    Quote Originally Posted by air2spare View Post
    always remember, with foam homes its not an issue of "R" value but rather infiltration and exfiltration....that's what changes the load
    Quote Originally Posted by ChaseAir View Post
    Timber, I have done couple of homes like this in North Florida. The loads many times come out to over 1000 sq ft per ton. We have three ton 2 stage unit that cools a 4400 sq ft. Home like a champ. This home has no direct east or West facing glass. What is your subcooling, superheat, td, pressures,etc. The foam must be thick to work. 10" is what I mean.

    Quote Originally Posted by cuchulain View Post
    I would not recommend going with a system that is larger then the calculation calls for. It may seem extremely small, but I've seen systems calculated out using traditional insulation methods put into foamed houses and then get calls that the inside of the house is literally raining, because the system can't run long enough to pull the humidity out before satisfying the stat.

    They are correct in saying that don't expect the system to run optimally if it's designed for 97 and it's 107 outside. The house has to come down to a good relative ambient before you'll see a difference. Check every thing and make sure your running where it should be and then when the outside temp reaches design then go back and check it and that's the point you'll know if it's working properly.



    Nice posts guys! This comes down to educating the homeowner, helping them understand reasonable expectations and the importance of not oversizing. They simply need to understand the home is more like a large yacht than a water ski boat.

    Maybe show them this thread...
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  8. #47
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,763

    Hmm

    Quote Originally Posted by ChaseAir View Post
    Do you size them from the sidewalk btw your thumb and forefinger?
    Be funny if it weren't such a common practice.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  9. #48
    Join Date
    May 2009
    Location
    In the Hudson Valley of New York
    Posts
    2,041
    Quote Originally Posted by tedkidd View Post
    Be funny if it weren't such a common practice.
    Actually we got a call from a guy in a 1970s house. 24'x48', he had the AC put in 10 years ago, it never worked right. The installer just put in a 2 ton with no measuring. My load calc with a large amount of glass on the west side came slightly above 3 ton. Yup, that is what we have to compete with, I also have a feeling he thinks my cost is too high based on what he paid for an entire system 10 years ago when he got what he paid for.

  10. #49
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,763
    I'm not a good one to address that situation - 1152 sf I would call 2 ton grossly over sized. I put 1.5 ton on 1700 square foot mobile homes.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  11. #50
    Join Date
    May 2009
    Location
    In the Hudson Valley of New York
    Posts
    2,041
    Quote Originally Posted by tedkidd View Post
    I'm not a good one to address that situation - 1152 sf I would call 2 ton grossly over sized. I put 1.5 ton on 1700 square foot mobile homes.
    You would think, but 2 ton is not doing the job, and it runs fine. What temp difference are you calculating upstate?

  12. #51
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,763
    Concluding you need bigger because it's not doing the job is a trap that might get you into trouble.

    Audit the house. Check duct design & leakage.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

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