"hedbutter" (hedbutter)
05/07/2014 at 13:19 • Filed to: None
1
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"hedbutter" (hedbutter)
05/07/2014 at 13:19 • Filed to: None | 1
| 12 |
Opponauts- I'm in the process of getting my furnace (24 years old, runs rough, 100,000 BTU @ 80% eff) and AC unit (20 years old, 2.5 ton) replaced. I have had 4 estimates come in, and have received 2 estimates for an 80,000BTU @95% and 2 for 60,000BTU @95% . For the AC, I have received 1 estimate for a 3 ton SER13or16, 1 for a 2.5Ton of SER13or15, 1 estimate for 2ton SER13or16 and another wasn't in writing so i don't have it.
My question is, how do i determine which size to go with? All have stated they did a load calculation, but the one estimator (who also is giving the smaller sizes) is adamant that the others were using a rule of thumb over an actually ccalculation using the total number of registers, windows, insulation etc. Info on the house: 1.5 story brick ranch (1948 built, insulation on second floor, not sure on first), ~1400 square feet (not including basement), a good amount of sunlight, with 1 door, a sliding door, and 12 windows its in Pittsburgh, PA if that helps anyone. It does have a 1 car garage (OPPO Related). Any help would be appreciated.
A10 for your troubles:
HammerheadFistpunch
> hedbutter
05/07/2014 at 13:22 |
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I just replaced my system with a 2.5 ton seer 15 heatpump/furnace combo, my place was built in the 80's but its 3000 sq feet and I live in Utah, I can't recall the BTU for the furnace but It was less than 100,000 (98%)
I would say it sounds like overkill, but those old homes leak like a sieve, so its tough to say.
What brands are you looking at?
Jcarr
> hedbutter
05/07/2014 at 13:23 |
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Does your utility company offer any kind of rebate or incentive for installing energy efficient equipment? If so, they would likely come out and do a site evaluation and then give you recommended specs. We had our furnace replaced last fall and got a $200 rebate from the local utilities as well as a $150 tax credit I believe.
Worth checking into if you haven't already.
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HammerheadFistpunch
> Jcarr
05/07/2014 at 13:25 |
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yup, check on this, because they will only give you the rebate...in many cases...if its properly sized.
Party-vi
> hedbutter
05/07/2014 at 13:29 |
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Your handy-dandy residential HVAC guys are most likely using a chart given to them by their AC unit supplier (Trane, Carrier, etc.) which shows you in Zone 4 (but close to Zone 3) and needing a 2.5 ton unit based off your house size. I would ask to see the load calculations for each before you pull the trigger. A 3t unit would work but seems like overkill, especially if the garage isn't conditioned and the basement isn't either. Personally I'd replace your old 2.5t with a new 2.5t, as a smaller 2t would be a detriment if you tried to sell the house and all the other houses in your neighborhood have 2.5t units.
BoulderZ
> hedbutter
05/07/2014 at 13:30 |
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My $0.02. Load and size calcs are very important. Oversized is as bad as undersized. If they won't or can't show you their calculations, it's probably best to walk away. We all learned in math that it's just as important to "show your work" as it is to get to the right answer. You can double-check them using a number of online calculators, like this one, http://www.loadcalc.net/
and DOE sites like energystar.gov do a great job of laying out guidelines, like this one for cooling: http://www.energystar.gov/ia/partners/bl…
They have similar info on heating systems. Where you are, how the house was built, how big, how many floors, even how much furniture you have all play a role in determining how much capacity you need. I've recently done new furnace and A/C in my house, but location and construction are different enough that my sizing would be misleading at best as a comparison. Good luck on the updates!
BJ
> HammerheadFistpunch
05/07/2014 at 13:54 |
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Right. Not all contractors are necessarily admissible for these types of programs, and that sometimes there are 3 steps to getting a rebate:
Get a quote submitted to utility
Install and pay with your own money
Inspection by utility
Usually still worth the hassle, though.
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HammerheadFistpunch
> BJ
05/07/2014 at 13:55 |
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I got $850 and would have gotten more except they don't like heat pumps in my zone. Loving it right now though, cools down at night, heats up the morning.
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hedbutter
> HammerheadFistpunch
05/07/2014 at 15:52 |
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Yeah, I'm going to guess I have some leakage (although the temp doesnt sway too much).
I'm currently looking at Trane and Carrier.
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hedbutter
> Party-vi
05/07/2014 at 15:52 |
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Yeah, that's what I'm thinking as well, especially with how adamant one of the contractors was when I asked him about the load calc. I'm in the process of gathering the load calculations now.
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hedbutter
> BoulderZ
05/07/2014 at 15:53 |
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According to the calculator (if i filled it our correctly), it appears that the 60,000 BTU and 2.5Ton AC are the sweet spot. I'll need to double check it when I get home to be sure. Thanks for the calculator!
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hedbutter
> Jcarr
05/07/2014 at 15:54 |
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The contractors I am working with take care of the rebates and take it off of the total price (I've checked with the utilities to make sure they are discounting the correct prices).
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hedbutter
> hedbutter
05/09/2014 at 08:54 |
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All- I received the load reports, and its looking like one of the ones that came in low forgot to include half of the first floor (the combined square footage comes to 540, but should be 990). The other load reports look like i should need a little bit over 60,000 BTU and ~2.25 tonnage AC. The other report that came in lower was an estimation and not a full load report. I also verified with the information obtained by the estimators for R values in the walls/windows/floor/etc and it matches the above. Thanks for the replies and information everyone!