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New HVAC efficiency

Posted on 4/17/13 at 12:22 pm
Posted by RJYH
Member since Aug 2010
6934 posts
Posted on 4/17/13 at 12:22 pm
Installed central air in my house, and replaced a furnace (from the 40s per the servicemen).

How greatly will this realistically affect cost of heating and cooling of my house? Was using window units previously.
Posted by DINGBAT
BR
Member since Apr 2011
946 posts
Posted on 4/17/13 at 12:34 pm to
Greatly. HVAC has come a long way in efficiency. It will take time, but it will eventually pay for itself.

Eta: they call me captain obvious
This post was edited on 4/17/13 at 12:36 pm
Posted by Hammertime
Will trade dowsing rod for titties
Member since Jan 2012
43031 posts
Posted on 4/17/13 at 12:35 pm to
If you want to see significant gains, insulation is your next step. My house is from the 40s also and has none
Posted by DINGBAT
BR
Member since Apr 2011
946 posts
Posted on 4/17/13 at 12:37 pm to
You live in Southdowns? My previous 2 rent houses were ridiculously bad. We literally had to run the AC on 68-70 all day and I was still sweating every night.
Posted by 007mag
Death Valley, Sec. 408
Member since Dec 2011
3925 posts
Posted on 4/17/13 at 12:41 pm to
quote:

insulation is your next step
I'm planning on changing my central unit and when I finish that I'm blowing insulation in the attic. Lowe's has the blower and a days rental is free if you purchase 8 bags of insulation which is only about $200 worth.
Posted by Tiger inTampa
Tampa, FL
Member since Sep 2009
2171 posts
Posted on 4/17/13 at 12:55 pm to
quote:

when I finish that I'm blowing insulation in the attic


Good start. Also pay close attention to your ducts,door and window sills and seriously consider double pain insulated windows and on your south and west exposures tinting or awning. If you aren't going to address these items don't get too concerned about efficiency ratings. After all I can install a 16-21 S.E.E.R. system in your house with variable speed evap motor and variable speed/stage compressor but if you run it with your duct, doors and windows leaking it's not very efficient....Just a couple of thoughts from a mechanical contractor in FL.
Posted by Hammertime
Will trade dowsing rod for titties
Member since Jan 2012
43031 posts
Posted on 4/17/13 at 12:57 pm to
Yup. All of the houses around here are from the 40s, 50s, and 60s. When it is cold outside, the floor is the same temperature and it gradually gets warmer as you go up in the temp strata

Raised house, no insulation under, none in the walls, none in the attic. I can leave for an entire day and not have the heat on. When I come back, the house is the exact same temp as outside. Woken up many times with the temp under 50 inside.

Landlord put a big arse unit in my attic last year because it ran 100% of the time
Posted by DINGBAT
BR
Member since Apr 2011
946 posts
Posted on 4/17/13 at 12:57 pm to
There ya go!
Posted by DINGBAT
BR
Member since Apr 2011
946 posts
Posted on 4/17/13 at 1:01 pm to
quote:

Woken up many times with the temp under 50 inside


I know the feeling all too well. My toes felt frostbitten after stepping on the bathroom tile in the morning.
Posted by 007mag
Death Valley, Sec. 408
Member since Dec 2011
3925 posts
Posted on 4/17/13 at 1:07 pm to
I'm replacing a 2.5ton and 3ton seer 10 units that aren't good team players with a single 5ton unit. I haven't decided on exact unit but looking at prolly 14-16 seer heat pump. South side of house is almost all windows but have an 8 foot metal awning and several large shade trees.
This post was edited on 4/17/13 at 1:12 pm
Posted by jack6294
Greater Baton Rouge Area
Member since Jan 2007
4033 posts
Posted on 4/17/13 at 1:30 pm to
Old houses were meant to breath

must seal up the house well to really see the best benefits
Posted by Tiger inTampa
Tampa, FL
Member since Sep 2009
2171 posts
Posted on 4/17/13 at 1:36 pm to
The payback time between the 14 and 16 is minimal so at that point if you looking at a significant difference in the upfront price in the 14 and 16 then go with the 14. As for manufacturers, the Carrier, Trane, American Standard, Ruud/Rheem debate will boil down to preference and anecdotal testimony. Kind of like walking into a bar and asking: "what's the best pick up truck?" My preference and what I have in my house is Rheem. Everyday however, on the plans I look through for commercial applications, the engineers are spec-ing more and more Trane. From a service standpoint we do tend to pay fewer visits to their equipment. However, when they break down their parts are proprietary and more expensive.
If you are interested in bang for your buck or "contractor grade" look into the Goodman products. They revamped their product line about 3 years ago threw out the Bristol compressors and added Copelands as well as lost the Emerson evap and condenser motors and the stuff runs like a champ.
Posted by eng08
Member since Jan 2013
6010 posts
Posted on 4/17/13 at 1:36 pm to
When I renovate my bathroom I want to install elec floor heating elements under the tile for just that reason.

The wife does not necessarily agree but I'll probably just do it anyway, bathroom is small.
This post was edited on 4/17/13 at 2:01 pm
Posted by Chris4x4gill2
North Alabama
Member since Nov 2008
3117 posts
Posted on 4/17/13 at 1:51 pm to
I just upgraded mine a few weeks ago. The old unit was 92% efficency Furnace with a 10 SEER Condesor. New unit is 92% efficiency furnace / 14 SEER condesor.

I ran the numbers on cost vs savings to go to a 16SEER and it took 10+ years to break even.
Posted by 007mag
Death Valley, Sec. 408
Member since Dec 2011
3925 posts
Posted on 4/17/13 at 2:50 pm to
quote:

16SEER and it took 10+ years to break even
That's what I was told by a friend whose does AC work.
quote:

Tiger inTampa
He also recommended an Amana instead of the Trane because of better warranty and he mentioned using the heat pump to heat my hot water as well. Do y'all have any opinions on this?
Posted by Jester
Baton Rouge
Member since Feb 2006
34717 posts
Posted on 4/17/13 at 2:55 pm to
quote:

I'm planning on changing my central unit and when I finish that I'm blowing insulation in the attic. Lowe's has the blower and a days rental is free if you purchase 8 bags of insulation which is only about $200 worth.


Honestly, you are going about that backwards. If your technician properly sizes your a/c now, it will be oversized when you insulate and seal. This could cause moisture problems throughout the system.

The better thing to do is insulate and seal first, then hire a good HVAC technician. A shitty one will try to sell you on a bigger system (higher cost). Sure it will get your house cold faster, but it will also start and stop the motor more often. Starts are by far the most inefficient part of running an electric motor. Also, starting and stopping = wear.
Posted by Jester
Baton Rouge
Member since Feb 2006
34717 posts
Posted on 4/17/13 at 2:57 pm to
quote:

When I renovate my bathroom I want to install elec floor heating elements under the tile for just that reason.

The wife does not necessarily agree but I'll probably just do it anyway, bathroom is small.


Insulate and seal, instead. Those heaters are expensive and only useful in a short winter. Insulation will keep winter heat in and summer heat out. Year-long benefits.
Posted by eng08
Member since Jan 2013
6010 posts
Posted on 4/17/13 at 3:08 pm to
I thought abt doing the foam spray underneath, but haven't pulled the trigger yet. I have regular blown in fiberglass in the attic and nothing that I know of in the walls. Windows are all single pane wood too.

When I do the spray insulation underneath I will probably be replacing the ac/heater too. But I also light be ready to move so may say F it.
Posted by 007mag
Death Valley, Sec. 408
Member since Dec 2011
3925 posts
Posted on 4/17/13 at 3:10 pm to
I'm waiting until I finish in the attic to spray insulation in. While investigating my duct work I noticed some bare spaces in my attic. Sizing is based off original drawings from an addition but the contractor opted to add a 3 ton unit and keep the 2.5 ton unit rather than upsize to a 5. Now 3 ton needs replacing and 2.5 is 16 years old. So I'm going with original design as the two units weren't set up to work correctly i.e. thermostat and air intake A was in hallway cooled by unit B and thermostat B and intake were in an interior washroom that seemed to stay cooler than rest of house.
Posted by CoastieGM
Member since Aug 2012
3185 posts
Posted on 4/17/13 at 4:10 pm to
I've been running rental properties a long time and I know what works long-term (and the tenants love).

A well-installed central system will use far less power than window units.

The most important part of an AC unit is the compressor. It is the heart of the system. A high-dollar unit with a cheap compressor is a crappy unit.

DO NOT GET ANYTHING WITH A BRISTOL BRAND COMPRESSOR!!!

Copeland scroll compressors are the way to go, especially when in a Ruud/Rheem unit.

If you have access to natural gas, go with gas and stay away from heat pumps for a plethora of reasons too numerous to list here (but I will list them if you want)

Avoid multi-speed compressors and other features...more parts, more things to go wrong.

Go with the lowest SEER available, or one step up from the lowest...they're ALL good these days.

When you have a new unit installed, have the following included:
-High pressure safety with manual reset button
-Low pressure safety with manual reset button
-Sight glass on suction side.
(the safeties can be installed on already operating units. Everyone should have them...will double the life of your unit)

If installing new ductwork, oversize the hell out of the main trunk line and go one size higher than minimum on distribution taps/runs. Makes a HELL of a difference with minimal cost increase.

Install an emergency drain pan condensate overflow safety switch/sensor. The best $25 bucks you'll ever spend
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