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| Weezer |
 Posted: Tue May 01, 2007 12:43 am Post subject: Replacing existing HVAC |
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Hi, our 16 year old compressor croaked and we want to replace the whole air conditioner and gas furnace. The a/c is a 3 ton split system. Of course, it will be upgraded to at least a 13 SEER from an 8 SEER. The size of the existing system seems perfect. It runs constantly on the very hottest days and just keeps up, so I don't think I want to change. To keep things simple, we'll probably stick to 13 SEER rather than go with a complicated higher efficiency model. How can I be sure that's best?
My main problem is that nobody wants to do a load calculation. We can't just go by square footage due to the lot and vaulted ceilings, poor insulation, sorry single pane windows, and such. Yes, we will probably use the same sizes as before, but I want to make sure this is best.
I don't know what size furnace is in here, but it looks like an 80K Btu will work (100K Btu, 80% efficiency).
With the installers around here not wanting to do the calc, I'll do best calculating myself and just telling them what to put in.
Another thing is that we have a selection of installers who don't want to do the calculation so how do I know I am going to get full efficiency from this system since I'm not in the HVAC trade and the suppliers don't want to talk to me, the homeowner? (Yes, I understand why.) I may need a new thermostat or some other doodad to make it work right.
Help?
And, anybody have any favorite brands and models? Why? |
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| mudflap9 |
| Posted: Tue May 01, 2007 2:15 pm Post subject: trust the load calculations |
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It is unfortunate that most contractors do not want to mess with manual j's. In fact the only reason most do around here in Maryland is because some counties require it. Still, they size by square footage and just turn in a computer printout of some manual j loads into the county to get the permit.
If the contractors aren't willing to focus on doing load calculations and optimizing efficiency, then you will have to do the calcs yourself, trust that you input everything in the software as accurately as your blueprints show, and just trust what the calcs tell you as far as sizing is concerned. If the software says its such and such size, then that should be the most efficient system.
If the contractor strongly disagrees with the size decision, then maybe something is wrong. Try coming in here with the numbers for consultation . This forum looks new but hopefully people are reading and can help.
Good luck! |
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| Weezer |
| Posted: Tue May 01, 2007 4:36 pm Post subject: |
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Well, I don't have the software and don't know how to get it and don't know how to work it but if someone would tell me how and where to get it I will if it's not a $1000 thing. Or I'd be happy to pay someone with the ability to do the calcs.
What measurements are needed? I know about square footage, but what about the windows, attic space, ceiling height, occupancy, insulation, materials, ventilation and all that stuff?
And thanks for the reply, Mudflaps! 
Oh, I just found the Elite Software Rhvac MJ8 demo. Let's see how this works. I can certainly buy Manual J,right? Hope it's not as complicated as some of the government manuals I have to read. |
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| ashby |
| Posted: Wed May 02, 2007 12:28 pm Post subject: manual j |
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Site Admin
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Hi Weezer,
I can perform the load calculation for you if you still need one. I use to offer a load calculation service through this site (and will again in the future).
So email me at info@hvacloadcalculations.com and I'll get you some more information about price and what floor plans and house details are needed. |
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| Weezer |
| Posted: Wed May 02, 2007 12:50 pm Post subject: |
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The RHVAC software is nice, but the trial license only allows for three rooms. Oh, well. I learned a thing or two from it.
Ashby, see your email, please. And thanks! |
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| PEARSON21 |
| Posted: Wed Dec 19, 2007 10:50 pm Post subject: |
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Joined: 16 Dec 2007
Posts: 10
Location: NORTH CAROLINA
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weezer,
I perform load calc for concerned home owners like you.
I will need a drawing of the house with windows , doors, and orientaion of house for starters. We can go from there
for more info: http://home.earthlink.net/~dpearson21/ |
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| larsen tech |
| Posted: Wed Oct 08, 2008 9:19 pm Post subject: |
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If you need an additional choice for heat load calculations because the others schedule may be busy please feel free to contact us.
At Larsen Tech we perform services for Manual J, Manual D, Manual S, residential heat load calculations, HVAC equipment selection, HVAC duct designs, REScheck, and COMcheck energy code compliance reports.
We strive on giving as much great service and FREE advice for better and more energy efficient building in all communities!!!
Your new friend,
Larsen Tech, Inc.
Please visit our website at
http://larsentech.org/ |
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