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Old 04-14-2012, 11:09 PM   #1
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Please help with upgrade!


Ok guys, I really need some help here as I am trying to help my mother with her HVAC system! She wants to upgrade her 10 seer equipment and I have been trying to help her. After meeting with a number of HVAC companies I decided to use HVAC calc to run a load on her house. It's a really chopped up house on a slab built over 20 years ago. The equipment she wants installed in her home offers no 1/2 ton sizing for their 16 seer units, Goodman communicating 95 percent furnaces with heat pumps. I am really not sure what to recommend to her even with the load calculations. I feel as if her ductwork is not up to par and I have hit a wall as to where to go from here. I do know after hearing the companies call a return "a fresh air vent", "we will make it right if you have airflow issues", "that 1/4 line set will be fine", and the best one "go with a 3 ton heat pump and I'll have them size the coil down" that all 3 struck out. All 3 companies sized her house to her current units without question, a 2, 2 1/2, and a 3 ton. Her house is a 2 story slab divided between the current 2 and 2 1/2 ton on the first floor and 3 upstairs. Is their anyone willing to recommend what direction for me to go from here? I can provide plenty of details of the house and calculations..... Please help as I have told her not to half ass it by thinking high efficient units will provide her with what she is looking for without sizing everything correctly! Thanks to anyone willing to help point me in the right direction....

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Old 04-14-2012, 11:43 PM   #2
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There really isn't a guessing game on equipment,or on ductwork.
You tell your mother that if the contractor doesn't have a manual"J" and AND a maual "D" then they are just too lazy to install anything in her house that she will have to pay for ,for the next 20 years.Its really as simple as that.You can tell her that any room she wants to be cdomfortable in needs a properly sized supply register and AND a properly sized return grille.
Now as far as what brand to use,ask her to demand that the contractor put in writing exactly what happens step by step until the warranty is complete.Some companies will charge you for the part and then give you a check or a credit after the manufacturer has ok'd the warranty.Also some companies charge you the overtime rate for calls after hours and on weekends and holidays.If its not in writing your mother could be in for big bills she shoul;dn't have.

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Old 04-15-2012, 12:06 AM   #3
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Trust me, I have told her! Being a ex electrician and builder of the last 20 years I have a pretty good ideal of the situation. I have even told her that if we have to rip down the ceiling through the center of her house to add/replace ductwork then that's what has to be done.... (Stick framed with 9' walls, ceiling is dropped to 8' through the center of her house). I have been thinking about scaling off the schetched up plans I made of her house and sending them off to a engineering company to do all the calculations. HVAC calculations are right on my behalf. Problem is, I really just do not know how to size it correctly from them, then there's the ductwork design (what it is and what it should be). My old HVAC company is no longer in business and from what I have seen so far from the ones that looked at it, lol...
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Old 04-15-2012, 12:39 AM   #4
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If you send those plans anywhere you will need to uindicate how the house is situated I.E. north ,south, east and west.You will need size and type of windows and doors .You will need exactly what kind and what thickness of insulation in walls, ceilings,maybe even what color the roof is.
I assume thyat your plans show what size rooms are and where the windows and doors are.
The manual "J" will size the equipment and then with that information the manual"D" will tell you what size duct you need to satisfy the house and each room.
If done carefully ,there will be no guessing .It will be be what the aclculations come out with.
Good luck
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Old 04-15-2012, 04:30 AM   #5
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What did your load calc say you nee in sizes.
Are any rooms not heat or cooled evenly with the rest of the area in that zone.
Can you do a static pressure check on the duct systems yourself(its hard to find a company that will do it).
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Old 04-15-2012, 09:27 AM   #6
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Thanks Rep, I have all of that under control.... The hardest calculations were on the second floor, not a single room without kneewalls backing up to attic space which I accounted for as ceilings in the software. Every window size and type, skylight, insulation type (R-11 walls, R-19 Attic kneewalls and r-30 in attic), direction of exterior walls etc. has been included. The only thing I questioned was what I included for the height of the 2 story foyer and living room which was 10' first floor and 8' second floor! My reason for having someone else do the whole thing is for the manual s & d calculations. I seem to have hit a wall at this point.

Beenthere, I am attaching the report. What it shows would be a 2 1/2, 1 1/2 split on the first floor and a 2 ton on the second in my mind. They have no 1/2 ton sizes in the equipment she wants (16 seer Goodman communicating) and I can not seem to get over the second floor which is a 3 currently. The rec/bonus room 40'x24' not including the 2 dormers & a small vaulted area on the front. It covers the 2 story foyer & living room, office, bath, and a bedroom as well. Seems the HVAC calc are kind of undersized to me for cooling? Anyways, I have not done a static pressure check as I was thinking more along the lines of sizing the ductwork to the new equipment. Would that help tell me kindda what's going on with the existing? She has a lot of supply registers on the first floor but I have noticed some have little airflow but the returns do not seem right as well to me, all 4 of them are dropped in wall plenums through the center of the house. Makes me ? the air circulation and the reason she has to run dehumidifiers all the time as a lot of the rooms have had mold and mildew issues in the past! I will talk to her about the evenness of the room temperatures but I know thatís going to be tough, she hugs her fireplace in the winter trying to save Lp as she is all gas @ 80 percent right now, she cuts back on the ac in the summer as well.... My fix will not work in the current housing market which is get a smaller house!

I am pretty sure all the ductwork on the first floor in not sealed or insulated. The unit of garage area is from what I can tell but I bet that changes once it makes it past the garage wall and into the envelope (ceiling drop down begins in garage). I know the one in the hall closet is not and this really makes me wonder about how much air she is losing in the cavity. The insulation is not as big of a concern to me as the ductwork not being sealed since it's inside the envelope. The good news is that it is all in hard pipe and the attic has insulation!
Attached Files
File Type: pdf Howard (Heat Loss & Gain Report).pdf (21.9 KB, 49 views)
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Old 04-15-2012, 09:49 AM   #7
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I can scan a copy of the house sketch/plans if that will help? What I have now is rough so I may draw them out better today and take some pictures as well... I really just want to get it right for her and seems a waste to spend a ton of $ to upgrade equipment if other areas need work as well!

Last edited by southern_boy; 04-15-2012 at 09:55 AM.
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Old 04-15-2012, 10:09 AM   #8
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The load calc implies that a 2.5, and a 1.5 for the 2 first floor units, and a 2.5 for the second floor is what is needed. And with the low latent load, should have some capacity to spare.

Goodman has 14 SEER outdoor units that when matched to VS furnaces and the proper indoor coil should hit 16 SEER or very close.

House plans/drawings are always helpfull.
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Old 04-15-2012, 10:24 AM   #9
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Ok, I am going to get some 11x17 graph paper I can scan to pdf and get them re-drawed today along with some pictures ect.... You are kind enough to offer your suggestions so I'll have more information up this evening! Thanks for taking the time!
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Old 04-15-2012, 07:55 PM   #10
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Let me ask a question. If the old unit was cooling adequate until age took over, why would one need to do a manual J or D? It seems to me that if the original equipment worked just fine there would be no reason to "re-invent the wheel" so to speak? I"m not trying to stir the pot but just wondering why anyone would not think that sizing the system the same as the old wouldn't be the right way to go?
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Old 04-15-2012, 08:34 PM   #11
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The other one/ones may have cooled ok. But over sized equipment usually means that the thermostat had to be set to a lower then needed temp to make her comfortable. proper sized equipment would allow her to set the stat a degree or 2 higher and feel as comfortable, and not cost as much to operate.

Over sized equipment on undersized duct work, doesn't work at full capacity. So it uses more electric to do less work. Proper sized equipment on undersized duct work, tends not to be able to maintain temp.
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Old 04-15-2012, 08:46 PM   #12
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Like I said....if the previous equipment was doing it's job PROPERLY why the need for a re-calculation? I hear what you are saying and you are assuming things aren't right with the old unit...but that doesn't appear to be the case. I know that new units are more efficient, and two stage compressors are probably the best way to go if it's in the budget. But "if it ain't broke, don't fix it" is how I think I would proceed. It's just my opinion. My 3 ton heat pump is doing just fine for heat and cool and when the time comes to replace it I will probably do so with another 3 ton unit, possibly geothermal. I won't ask for a manual J.
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Old 04-15-2012, 08:51 PM   #13
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Quote:
Originally Posted by Missouri Bound View Post
Like I said....if the previous equipment was doing it's job PROPERLY why the need for a re-calculation? I hear what you are saying and you are assuming things aren't right with the old unit...but that doesn't appear to be the case. I know that new units are more efficient, and two stage compressors are probably the best way to go if it's in the budget. But "if it ain't broke, don't fix it" is how I think I would proceed. It's just my opinion. My 3 ton heat pump is doing just fine for heat and cool and when the time comes to replace it I will probably do so with another 3 ton unit, possibly geothermal. I won't ask for a manual J.
Your assuming its working properly.

Its probably cooling ok, but not properly. A lot of people don't realize their system isn't working properly, because its cooling, or heating ok.
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Old 04-15-2012, 08:54 PM   #14
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In my opinion a recalculation is always needed to ensure maximum comfort..
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Old 04-15-2012, 09:01 PM   #15
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Quote:
Originally Posted by beenthere View Post
Your assuming its working properly.

Its probably cooling ok, but not properly. A lot of people don't realize their system isn't working properly, because its cooling, or heating ok.
How can you assume it's not? Proper temperature and humidity. What's left?

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