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Old 09-02-2013, 07:36 AM
 
Location: Morrisville, NC
8,613 posts, read 12,853,948 times
Reputation: 8170

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So, our house is a bit more than 7 years old. From day one we have had a little more trouble than I would like keeping the upstairs cool. We have added a bar area with multiple TVs in our finished 3rd floor which adds to the situation. Doing some recent other work and wanting to potentially address the issues upstairs I realized we have 400sf/ton on the first floor and 532 on the second and third. (one unit serves both 2&3). Not sure of any thoughtful design that would come up with that in the same house, regardless of which one is right.

On an HVAC contractor specific forum, it was suggested by one person (at least that's what I think they are saying, they are not the best at getting a point across and a bit gruff ) that the first floor unit is way too large and the second floor is probably about right and that I should really spend some money up front tomasses the system. Of course other people on that forum as well as one company I had at the house thought just adding capacity upstairs was the correct path.

But, given I have never been in love with the workmanship of the duct runs here and a few other things about the install, he is right, I do need to see where I am now before spending money on the problem.

So, can anyone recommend a company to do a comprehensive assessment? I found a thread from a couple of years ago but there was only one company recommended and it's not clear they deal with HVAC at all, though maybe using separate contractors is fine. I am already planning to seal up my crawl space anyway, so maybe I should do that first before they test? Any rough idea what costs we are talking?
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Old 09-02-2013, 08:33 AM
 
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The first thing you want to do is to have load calculations done including Manual D, Manual J, and Manual S. Manual J is for space and heat load calculations. Manual D is duct sizing based upon volume of air required as calculated during Manual J. Manual S is system sizing required based upon Manual J and Manual D calculations.

For some reason, a lot of HVAC contractors around here are hesitant to do these calculations for each individual home and in cookie cutter developments they are often done only on one home and then the same calculations are used on each subsequent home built following a similar floor plan. That's ok until design changes are made but the calculations are not repeated. You can have these calculations done for a fee but some HVAC contractors will do them for free as part of a system design and installation contract assuming you can find one that actually knows how to do them properly.

The second thing you might consider is having a blower door test done on your home. This test will measure the building envelope air leakage (energy loss) levels throughout your home around doors, windows, air ducts, electrical boxes, etc. This test is very eye opening if you really want to know where your monthly energy dollars are being wasted and the data can also be helpful to know during Manual J calculations. Sometimes the power companies offer a rebate program for blower door testing. Some HVAC companies offer blower door testing, but I prefer using an independent third party company with no business incentive in the test results.

Blower Door Tests | Department of Energy
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Old 09-02-2013, 10:33 AM
 
Location: Morrisville, NC
8,613 posts, read 12,853,948 times
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Yeah thats exactly what I want done. I just need to find recommended companies to do it, that are not just trying to latch on to the latest it thing and actually know what they are doing.
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Old 09-02-2013, 11:56 AM
 
Location: Raleigh, NC
2,648 posts, read 4,138,660 times
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I agree with the other poster about getting a contractor to do some HVAC load requirement calcs. As you suspected, developers will do something like put a 4-ton unit in every house, even though they may be the same or very similar floor plans, some will need 3, 3.5, and even 4, depending on the orientation of the glass and walls to the sun.


Some other things to keep in mind.

When considering the upper floor HVAC units: While the top floor won't have the kitchen or den requiring extra cooling, it does have the cooling/heating load from the roof, and probably more cooling load from sunlight than the lower floors, since the top floor typically has less shading (trees etc).

RE your TV room: Were the TVs Plasma or LCD? Plasmas give off a LOT of heat, LCDs not so much. If you use that room infrequently, you might consider getting a separate unit just for it, a wall A/C unit or a "ductless split-system", (search youtube for a description), depending on what equipment would work, physically. Which ever, make sure you consider it's placement and operating noise since you won't want a noisy compressor operating while watching TV.

Make sure you discuss your ideas about sealing up the crawl space with a contractor or engineer who understands insulation and vapor barriers because you really might mess with how your house is supposed to resist the outside. Where the layer of insulation and the layer of vapor barrier is, in the layers that make up your exterior envelope, have to be evaluated to control not only the transfer of heat, but similarity the transfer of moisture.
For example. If you have a ring-foundation and your floor is supported off-grade (IE: you do NOT have a poured slab-on-grade), then your crawl space must be ventilated to allow moisture, (that naturally comes up from the ground), to escape. If you had a ventilated crawl space and sealed the openings, you are just begging for mold down there. Or if you seal the crawlspace, you had better have sealed off the ground below ... successfully!! .... as well as figured out if the current layer of vapor barrier that is in the floor envelope is still going to work.
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Old 09-02-2013, 12:23 PM
 
2,456 posts, read 7,584,012 times
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Quote:
Originally Posted by Sherifftruman View Post
Yeah thats exactly what I want done. I just need to find recommended companies to do it, that are not just trying to latch on to the latest it thing and actually know what they are doing.
Call Nathan. NC State grad in construction engineering, background in construction and a real passion for energy efficiency. He's done work for us and might be the most honest guy I know.

Peak Energy, Inc. Holly Springs NC | Home Comfort Energy Efficiency

Frank
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Old 09-03-2013, 06:04 AM
 
104 posts, read 260,368 times
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We just had a thorough assessment, including blower door, performed by Jeremy Wallrich with Newcomb & Co. Cannot say enough good things about him. Very knowledgable and professional. Because we have a contract with Newcomb we were not charged for the testing. He pointed out several simple things we can do to address our situation. Good luck.
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Old 09-03-2013, 09:18 AM
 
Location: NC
2,887 posts, read 5,530,530 times
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Southern Energy Management, the same folks who did my solar systems - they also did a full energy audit of my house (very comprehensive, took many hours). Full report afterward. I can share with you privately if you'd like.
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Old 09-04-2013, 08:25 AM
 
149 posts, read 193,006 times
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I had a terrific experience with Mark and the Sundogs team. They did a full audit, including a blower test, and gave me a written report with specific recommendations for my unique(!) 100-year-old farmhouse. Some strategies good for newer homes simply wouldn't work for me here, and he took that into account. He gave me estimates on all work, and he recommends a specific HVAC company who takes into account insulation, sealing, and ductwork.
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Old 09-04-2013, 10:08 AM
 
Location: Holly Springs
3,968 posts, read 10,223,834 times
Reputation: 3190
Is the system for the 2nd and 3rd floor electronically zoned with a thermostat on each floor? If not, that would help tremendously. If you seal the crawlspace, as Ed pointed out, there are very specific measures to take. You must have a mechanical means to control moisture if it is sealed either via the HVAC system or a dehumidifier. I prefer the dehumidifier with a permanent drain to the exterior method personally as it is easy to install and will best control relative humidity levels. Feel free to ask any questions you have about that process.
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Old 09-04-2013, 11:56 AM
 
Location: Morrisville, NC
8,613 posts, read 12,853,948 times
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The second and third floors are not zoned currently, and that is part of the problem I am sure. I did have a contractor check the system and found that the refrigerant charge was about 20% low. No evidence of leaks, but he said it is probably a slow leak that can't be picked up with his sensor. Basically, I have to wait for the leak to get worse or have them go through the system for a few hours hoping to find something, knowing they may not. Kind of a tough call since the unit takes R-22 so waiting for it to leak is not cool for the environment or cool on my wallet.

Topping the system off helped quite a bit, at least it is functioning as well as it ever has, but even day one, it was never quite right cooling both floors. Now, maybe if I can get some analysis done and find some specific stuff to target and fix some things that are obvious like flex dropping 90 degrees off the runouts and other poor flex duct craftmaship issues, I have hope that maybe I could do it with zoning.

As far as the crawlspace, I am going by the Advanced Energy info you had posted in another thread sacredgrooves. I am planning on installing a dehumidifier down there. I already have a condensate pump for the A/C unit in the crawl so hopefully I can feed the dehumidifier into that or perhaps swap for a slightly larger size.
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