Author Topic: Calling HVAC experts -- is this worth it?  (Read 5866 times)

RiskDown

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Calling HVAC experts -- is this worth it?
« on: August 16, 2014, 11:18:52 AM »
Background:  I live in Florida and get about 4-6 steady months of 90+ degree weather.  My AC unit is approx 14 years old (seer 10), so it's def. seen better days... but it's fully charged and does as good as it can... I have special utility rates, which cost more between the hours of 7am-7pm M-F, but drop significantly between 7pm-7am (M-F) and weekend... So I set my AC in conjunction with those times... 7am to 7pm = 82, 7pm-7am = 78. And I'M STILL SEEING $240 utility bills :-( ... .My garage (where the air handler is) tends to get hot and stay hot (Note: air handler it is not pulling air out of the garage, it's pulls from in the house). Garage tends to stay about 10-20 degrees hotter than it is outside. Also have a natural gas hot water heater which adds to heat in garage. We have a gable roof, with an attic, that has vents... but it gets incredibly hot in the attic during the day. 

Bottom line... is there value in installing a fan like this, to pull outside air into the garage, push the air in the garage into the attic, and push the air in the attic, back outside?
http://www.coolmygarage.com/shop/gf-14-garage-fan-attic-cooler/

Do you guys think the cost of the fan + the energy the fan uses....will be worth it for lower AC energy consumption?

CALL 911

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Re: Calling HVAC experts -- is this worth it?
« Reply #1 on: August 16, 2014, 11:22:54 AM »
A THOUSAND DOLLAR FAN!

But it's on sale for $379!

No. Just, no. This is not going to save enough money to be worthwhile over any type of timeframe, and forget about opportunity cost.

You'd probably do better to put some solar panels on the roof (make power and cool the attic at the same time), or replace your single pane windows, or put in a modern amount of fiberglass insulation, or replace the whole AC apparatus.

Only you can know your exact situation. YMMV
« Last Edit: August 16, 2014, 11:27:23 AM by CALL 911 »

RiskDown

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Re: Calling HVAC experts -- is this worth it?
« Reply #2 on: August 16, 2014, 12:07:31 PM »
FYI -- The google has revealed, def. bad idea.

http://www.energyvanguard.com/blog-building-science-HERS-BPI/bid/38676/Don-t-Let-Your-Attic-Suck-Power-Attic-Ventilators-Are-a-Bad-Idea

Also FYI -- would create a negative air space in garage = no, no with gas appliance.

Roots&Wings

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Re: Calling HVAC experts -- is this worth it?
« Reply #3 on: August 16, 2014, 12:19:08 PM »
The Florida Solar Energy Center and Dept of Energy Florida retrofit program recommend things like sealing and insulating your ducts and attic, among others.  Bringing hot humid outdoor air into the garage doesn't sound like a good thing.

http://www.fsec.ucf.edu/en/consumer/buildings/homes/priorities.htm
http://www.fsec.ucf.edu/en/publications/pdf/pio-48B_12steps.pdf
http://www.ba-pirc.org/retrofit/
« Last Edit: August 16, 2014, 12:38:58 PM by step-in-time »

DarinC

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Re: Calling HVAC experts -- is this worth it?
« Reply #4 on: August 16, 2014, 01:44:02 PM »
You can buy/install an attic fan from a big box hardware store. That plus better insulation/sealing of existing ducts could cut 20% of your energy use on cooling.

http://www.nrel.gov/docs/fy10osti/48163.pdf

TexasSaver

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Re: Calling HVAC experts -- is this worth it?
« Reply #5 on: August 16, 2014, 04:23:36 PM »
I live in Texas so I know about the heat.  I personally don't think replacing windows is a good bang for your buck. I am not sure about the fan you are asking about because I don't have any experience with that.  Something I do recommend is solar screens.  I installed solar screens on all of my west facing windows and I noticed quite a bit of improvement with very little cost.  You want to do any windows that have a lot of sun exposure.  I am lucky that I have several large trees around my house so my front west windows were all I needed.  Something else that I did was by some rolls of radiant barrier foil foam.  I got this from Home Depot and cut in in strips to line the inside of my garage door panels.  My garage faces west so the afternoon sun really beats on it.  This was pretty cheap and I think it keeps the garage a little cooler.  Don't get me wrong the garage still gets hot but I think it is a little less hot.  Something else to consider is how much insulation you have in your attic.

RiskDown

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Re: Calling HVAC experts -- is this worth it?
« Reply #6 on: August 16, 2014, 04:32:49 PM »
I live in Texas so I know about the heat.  I personally don't think replacing windows is a good bang for your buck.

My experiments in Florida back up this statement. Inspection a year ago told me that I had lost seals on a few exterior windows...

To test bang for buck, I went and purchased this:
http://www.amazon.com/Duck-281506-10-Window-Insulator-420-Inch/dp/B002GKC2GW/ref=sr_1_1?ie=UTF8&qid=1408228029

Sealed them up over the Summer and I've seen no definable savings... 

Hate having to get up in attic during summer, but it's looking like I'm going to have to summon my mustachian sack, and make it happen. 

TexasSaver

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Re: Calling HVAC experts -- is this worth it?
« Reply #7 on: August 16, 2014, 05:21:25 PM »
Something else I forgot to ask about was what is the rate you pay for electricity?  My house (2400 sq ft) is pretty energy efficient and I do have trees.  My electric bill last month was $111 and that is with the outside temp being in the mid 90s and a few days of 100.  The temp in the house is set to pretty much 78 all the time.  I have ceiling fans in every room and they are always on if I am in the room.  I am able to shop around for the best rate where I live.  I usually switch carriers once a year.  I use a website called "power to chose".  I usually find the one year contracts work best for me.  If you are able to shop around for your rate pay attention to the fees and not just the rate.  Also you should know how much electricity you use because the rates of the carriers change depending on usage.

rmendpara

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Re: Calling HVAC experts -- is this worth it?
« Reply #8 on: August 16, 2014, 08:04:47 PM »
Fan probably not. If the existing attic fan isn't doing the trick, I'm not sure what another one will. Probably look at adding to your insulation around windows/doors first. This is probably the cheapest update.

Next will be updating your condenser fan, though it's probably best to wait until it blows since those easily run several thousand dollars, as the newer ones are likely a lot more efficient than the one you have from 2000.

Check other structural things that could be afffecting your home efficiency. Also, try switching all your lights to CFL bulbs, and maybe a few major bulbs in heavy use areas to LED (like kitchen table, living room, or other ones that you use almost every day for >1 hour).

Emg03063

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Re: Calling HVAC experts -- is this worth it?
« Reply #9 on: August 17, 2014, 07:35:06 AM »
The best way to reduce your attic heat is with a radiant barrier.  Do you have gable vents  or ridge and soffit vents, or both?  Also, what's your house's square footage?  If you haven't already done so, insulate your water heater, and set it to 120 F.  You might also be able to reduce the heat gain in the garage by insulating the garage door with foam board & radiant barrier.  At a minimum, you can open the garage door for a little while whenever you get home to bring it down to outside temperature.

chasesfish

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Re: Calling HVAC experts -- is this worth it?
« Reply #10 on: August 17, 2014, 07:44:26 AM »
To me it sounds like you have an undersized air unit.   How many sqft is the house?  I replaced a pair of old 9/10 seer units and it cut my bill by 1/3.  The economic payback takes years, but I think that's the culprit

Greg

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Re: Calling HVAC experts -- is this worth it?
« Reply #11 on: August 17, 2014, 09:46:12 AM »
Is the attic above the garage insulated?  This might be the easiest way to improve things.  My garage is insulated and on a hot day (85F is considered hot here in the PNW) the inside of my garage will be 15-20 cooler than outside, until I have the door open for a few hours.

millionaire-mindset

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Re: Calling HVAC experts -- is this worth it?
« Reply #12 on: August 17, 2014, 05:10:54 PM »
I am in the AC business, and a $240 electric bill, in the middle of the summer, for a 2400 sq frt house does not seem that crazy. Yea, it is on the higher side. If the ducts are in the attic, make sure all of them are very well sealed and properly insulated. This would be your cheapest way to improve efficiency. The air handler being in a warm garage should make much difference. Most of the time they are in attics, which are much hotter than your garage. Radiant barriers work great but they are expensive...probably would never see the payback.

Mrs. PoP

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Re: Calling HVAC experts -- is this worth it?
« Reply #13 on: August 17, 2014, 05:46:56 PM »
We're south Florida and I wouldn't do the fan, but I'd consider changing your A/C habits.  We have ours off most of the day and turn it down low at night - 74 - to sleep.  We turn it on maybe an hour before we head to bed and the timer shuts it off around 3 or 4am.  Even in the summer as long as I'm not running the oven it generally never gets above 85 or 86 inside - even if I leave the back door open a crack for the cat to go in and out. 

Our FPL bill (pre-on call credits) last month was $125 - in one of the hottest Julys we've had in years and that's including running the pool pump which we've calculated adds about ~$35 to our monthly electric bill.  When we used to try and keep the house moderately cooler through the whole day using the A/C as you are doing, we spent a LOT more on the electric bill.