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Message
re: New HVAC efficiency
Posted on 4/17/13 at 4:24 pm to CoastieGM
Posted on 4/17/13 at 4:24 pm to CoastieGM
quote:
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.
This is not good advice.
2
Posted on 4/17/13 at 4:57 pm to Jester
quote:
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.
This is not good advice.
Why not?
It works extremely well. (provided you install dampers at each tap into the trunk for fine adjustments...I should have included that)
My tenants all rave about it being the best ac they've ever had, not to mention the very cheapest power bills they've ever had.
Posted on 4/17/13 at 4:59 pm to CoastieGM
How many properties you got coastieGM?
Posted on 4/17/13 at 5:20 pm to eng08
14 total
11 rental houses and 3 personal residences
(no air conditioning for house in Alaska
...just a swamp cooler for New Mexico home)
Rentals are all in the Houston area.
11 rental houses and 3 personal residences
(no air conditioning for house in Alaska
...just a swamp cooler for New Mexico home) Rentals are all in the Houston area.
Posted on 4/17/13 at 5:35 pm to Jester
I just took this pic in my upper attic...
I cool 4,200 sq ft with 7 tons of cooling (3 tons upstairs / 4 downstairs), 4 kids and an adult here all day every day (homeschool), 400 foot deep well, electric water heater, and swimming pool pump for a 36,000 gallon pool.
My highest electricity bill during 100+ degree August 2011 was under $300.
Summer bill is usually around $160-$225, winter bill is under $75.
I cool 4,200 sq ft with 7 tons of cooling (3 tons upstairs / 4 downstairs), 4 kids and an adult here all day every day (homeschool), 400 foot deep well, electric water heater, and swimming pool pump for a 36,000 gallon pool.
My highest electricity bill during 100+ degree August 2011 was under $300.
Summer bill is usually around $160-$225, winter bill is under $75.
Posted on 4/17/13 at 7:38 pm to CoastieGM
quote:
It works extremely well. (provided you install dampers at each tap into the trunk for fine adjustments...I should have included that)
If you size them correctly, dampers should be minimized. Now, if you want to talk about automatic dampers and zoned controls, you're getting somewhere.
Posted on 4/17/13 at 8:08 pm to RJYH
And don't forget to include these insulation and new heat pump costs on your tax return next year. There is currently an energy credit for these and other energy saving items.
Posted on 4/17/13 at 8:12 pm to BFIV
quote:
BFIV
hey buddy
hows life?
Posted on 4/17/13 at 9:16 pm to Jester
quote:
If you size them correctly, dampers should be minimized. Now, if you want to talk about automatic dampers and zoned controls, you're getting somewhere.
Nothing automatic. No zone controls. I suspect you're thinking along the lines of velocity (which is the way you're supposed to).
Instead, think of an oversized trunk line more as a pressure vessel than a duct. (I know liquids & gasses are different)
Without dampers, you're unable to adjust the flow to individual rooms.
Posted on 4/17/13 at 9:26 pm to CoastieGM
That oversized trunk has oversized surface area and enough cold air to provide a significant heat sink. Never, ever oversize. The word alone means you're doing it wrong.
Posted on 4/17/13 at 10:02 pm to Jester
quote:Then explain why it works so well.
That oversized trunk has oversized surface area and enough cold air to provide a significant heat sink. Never, ever oversize. The word alone means you're doing it wrong.
For instance, take the duct pic in my previous post.
By that point, the duct was supposed to be 10" x 8". (that's what was there before and it's what the pro's said was supposed to be there).
Instead, I went 22" x 22". The result was far superior (air flow was enormous). The AC guys were really scratching their heads when they measured a 20 deg split.
Amp draw on evap fan was also quite low.
Posted on 4/18/13 at 9:41 am to 007mag
quote:
using the heat pump to heat my hot water as well.
Yes, its a HRRU (Heat Recovery Remote Unit)system. They've been around for years. Essentially a tube within a tube system that runs your domestic water through a coil system wrapped around the discharge line from the compressor. They usually mount on the wall outside near the condensing unit. Works well in the summer months because of higher usage obviously. We don't use many in the commercial/industrial end so I'm not sure what they run or the energy savings. Should be able to Google it up pretty easily though.
Posted on 4/18/13 at 10:01 am to Tiger inTampa
quote:
Yes, its a HRRU (Heat Recovery Remote Unit)system. They've been around for years. Essentially a tube within a tube system that runs your domestic water through a coil system wrapped around the discharge line from the compressor. They usually mount on the wall outside near the condensing unit. Works well in the summer months because of higher usage obviously. We don't use many in the commercial/industrial end so I'm not sure what they run or the energy savings. Should be able to Google it up pretty easily though.
I worked on those things in a light-industrial setting when I was a kid in high school. They work very well so long as your water is WELL conditioned. If you have any mineral content in your water, they'll scale up and lose all heat transfer ability, and finally dang near plug up.
Must install isolation valves and taps for circulating an acidizing solution through it to clear out that scale. Water conditioning is crucial...otherwise a total pain in the arse.
Posted on 4/18/13 at 10:12 am to Hammertime
quote:
If you want to see significant gains, insulation is your next step. My house is from the 40s also and has none
This. My old house was from the 20s and had no insulation and 3/4" pine floors with no sub-floor. When I insulated, weatherstripped and put a skirt around the house my bill dropped almost in half.
I changed from window units to central after Katrina and that didn't have as big of an effect because I used to run the front units in the day and the bedroom units at night. Can't do that with central.
Posted on 4/18/13 at 10:15 am to BFIV
quote:
And don't forget to include these insulation and new heat pump costs on your tax return next year. There is currently an energy credit for these and other energy saving items.
Has to be 16 SEER to qualify
Posted on 4/18/13 at 10:24 am to CoastieGM
quote:
By that point, the duct was supposed to be 10" x 8". (that's what was there before and it's what the pro's said was supposed to be there).
Were your "pros" using Manual D? Most "pros" do not properly size anything in residential HVAC. Point being, if it performs optimally, it is "right-sized" not oversized. Being bigger than what was there doesn't mean oversized. It just means bigger than before, because before is almost never correct.
Posted on 4/18/13 at 10:33 am to DINGBAT
quote:what does that mean? The temp was 68 but you sweated? Or the AC wouldn't cool the house?
We literally had to run the AC on 68-70 all day and I was still sweating every night.
Posted on 4/18/13 at 10:34 am to Tigah in the ATL
quote:
what does that mean? The temp was 68 but you sweated? Or the AC wouldn't cool the house?
I took it to mean that it would run all night without reaching comfortable.
Posted on 4/18/13 at 10:35 am to Chris4x4gill2
quote:
Has to be 16 SEER to qualify
Depends on whether the unit is a split system air conditioning or a split system heat pump. They each have different SEER ratings to qualify. But anything the OP installs on an existing home will help out with the heating bills alone. Even window caulking is an allowed energy credit deduction just like insulation. Lots of people overlook these energy credits when they do their return. But hey...it's only money!
Posted on 4/18/13 at 11:16 am to Hammertime
quote:
If you want to see significant gains, insulation is your next step. My house is from the 40s also and has none
This and keep the filter clean at all times.
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