WAYS TO CUT HOME ENERGY USE IN
Udelhoven - Edited
Wisdom Principled Empowerment Communications
& People Empowerment Broadcasting ©
- with Darrell Udelhoven HVAC
Contractor & Technician since
mid-1970's - Retired
of the Series - The Real
Issues & People Empowerment Broadcasting
for several easy ways to ballpark Home & equipment BTU/HR Performance
Best ROI Home Investment or Lose the Investment money annually "Home
Energy Efficiency Pays You BIG." Video
this pdf explaining what Electric Power Companies are finally instituting:
Performance Get what U pay for!
It is summertime and time for you to do an
easy safe simple check on the performance of your air-conditioning
First, make sure the return air filter is
clean, and then you will need a digital probe thermometer and a low cost
percent relative humidity gauge to check the indoor humidity level.
If you have an air conditioner that was
manufactured between 1992 and 2005 it will be a 10 to 12 SEER R-22
hen the temperature reaches 85° outdoors and the
indoor temperature is 80°F and the relative humidity indoors is right
around 50% RH the outdoor condenser temperature split above the outdoor
temperature should be around 20 to 21°F or around 105°F.
If the indoor temperature is 75° and the relative
humidity is 50% then the air discharge temp-split off the condenser should
be 17°F or 102°F off condenser.
The indoor temperature split between the return-air
at the supply air grille closest to the air handler should be a 19 to 21°F
temperature drop with either an 80°F or 75°F indoor temperature. This is
also the indoor split with the higher SEER units at 13 SEER or above.
If the indoor temperature split is too high may have
very low airflow which needs to be brought up to its normal CFM Rate.
If the outdoor condenser split is too high your air
handler may be drawing hot air into the return from the attic causing the
high condenser discharge air temperature.
If the temps are within plus or minus a degree or
two, that air-conditioner is performing fairly well.
On the new air-conditioning systems at 13 SEER &
higher the outdoor condenser split is much lower than it is on the 10 to
12 SEER units; the indoor temp-split is the same.
Far too many HVAC service persons do not check the
actual delivered performance of the system; the actual delivered
performance of all air-conditioning systems should be checked with a
permanent record left at the air handler in the home.
series is on Fox channel 47 in Madison...should be on public TV. The
SEER Savings Chart is however misleading.
More authenticated survey test corroboration; the surveyed HVAC systems were systems that
they had complied with their program’s energy standards and "all had
received substantial incentive payments," but delivered
an average of only 63% of their
Rated Btu/Hr to the homes & 50% of the required airflow.
homes in California are operating at 50% capacity. - California Energy
(8) public television and radio stations and public telecommunications
services constitute valuable local community resources for utilizing
electronic media to address national concerns and solve local problems
through community programs and outreach programs...
We could reduce
existing residential heating Btu per hour SIZING by around
an average of 50% and cooling
equipment SIZING in America by 30% to 40% or more if Contractor's would
perform honest Manual J calculations and provided full credit for every
load reducing element or detail they can when doing the calculation audit.
Example of typical furnace over-sizing; my former oil furnace & the
other house here on the farm both had 140,000-Btu/hr input oil furnaces
installed when new they were 80% efficient; 140,000 * .80% is 112,000 * an
85% nozzle is 95,200-Btuh.
The homes both load-calc Design at -15°F
between 26,000 to 32,000-Btuh; therefore a 38,000- Btuh will easily handle
the heat-loss at any extreme temperature.
95,200-Btuh / 38,000-Btuh is +2.5 times
the proper Btuh sized furnace. 38000 * 2.5 is 95,000; left the
fractions off the 2.5...
Free online load-calc -
Print when you get the sizing right with the retro-work that's needed.
Additionally, load reduction remedial actions should always be provided as
options toward further reducing Air Conditioning and heating equipment
Some easy simple ways for
anyone to check the performance of their air-conditioning system
Try to check the run time and off-times of
the air-conditioning system and write down the indoor temp & %RH -humidity
& outdoor temperatures; it's best to do this on the hottest days & late in
the afternoon around 4pm.
Let's say the air conditioner runs for 15
minutes then, off for 15 minutes before it restarts, that's a total of 30
minutes for complete cycle so you take 15 minutes and divided by 30
minutes and you get .5 or 50% runtime; let's say I have 2 ton air
conditioner; 80-F & 50%RH indoors & 95-°F outdoors could yield
24,000-BTUH; however, due to ductwork and other factors it would
not deliver to the rooms 24,000-Btu/hr instead figure 90% of 24,000 and
multiply that figure 21,600-Btuh delivered to & from the rooms by * .5
extrapolated that is only 10,800-Btu used per an hour to hold the 80-F
temp. Then you should perform a free online load-calc to verify how well
your A/C or heat pump is performing.
That formula can be used for any
complete time span cycle. Some duct systems are only 50 or 60% efficient,
result, huge losses!
Another formula is the EER or 'Energy
Efficiency Ratio' formula; the BTU/HR divided by the wattage used.
Another way to use the formula is to take the BTU/HR and divide by the
units EER Rating. SEER Ratings are rather irrelevant as in the field they
never equal their LAB Ratings.
Let's say the air conditioner has a nominal
rating of 24,000 BTU per hour divided by a 9.7 EER that is 2,328 Watts of
power used. A technician can then take an amp-probe reading and multiply the amps
times the checked voltage which will equal Watts the unit is actually
drawing. From that reading you can figure what its actual EER is;
2,328-watts / by 240-volts would be 9.7-amps.
Another way to verify what your
home's Btuh load is, is to do a load Calc; I'll provide you with
the free online load Calc with which you can experiment with until you get
a proper load Calc performed, which you will then have to print out
because you cannot save your load Calc's.
You can also use a indoor humidity gauge and
write down the humidity level while taking the temperature difference
between the supply air and the return air in your home; then go outside
and take the temperature of the discharge air and subtract the outdoor
temperature from it.
On a 10 or 12 seer condenser the indoor
split at 50% relative humidity and 80°F indoors should be around 19 to 22°F. The
outdoor condenser split should also be between 19 and 22°F; the condenser
fan is moving considerably more air through the outdoor coil than is
moving through the indoor coil. A 13-SEER would be 20°F temp rise off the
outdoor condenser; & a 21°F indoor temp-split.
Do the same with heating; say the gas
furnace is an 80,000-Btu/hr at 95% efficiency which equals
76,000-output; if the runtime is 20-minutes on & 15-minutes off
time before a restart, 20 + 15 is 35-mins total complete cycle time so,
20-runtime / 35 cycle-time is .57% * 76000 extrapolates to
43,320-Btu/hr used to maintain the Room-TH setpoint of say 70°F. If this
were the coldest winter temp; then a 57000Btu'hr output
furnace would be better sized, as it takes at least 3 to 5-minutes to
reach nominal output each cycle; cooling mode takes around 7-minutes,
therefore the Btu-output would be less than what I showed above for
cooling & here for heating; short cycles are inefficient & costly.
Filter sizing: ACCA Manual D requires a low
300-fpm velocity through a new clean filter; a 60°F temp-rise maximum
means the 76,000 will have close to 1200-CFM / 300 is 4-sf * 144 is
576-sq.ins of open-air-filter-area, media type filters only have a 65%
open-air-area. 576 * 1.65 is 950-sq.ins of filter area. Two 16X25 is
400-sq-ins *2 is 800-sq.ins; still 150-sq.ins less than called for.
Above 500-fpm velocity debris blows
through a media type filter. One 16X24 filter has a Ak of 1.84 @
300-fpm it will only flow 552-CFM; @ 650-fpm it will flow 1196-CFM; that
is 150-fpm above where debris begins to blow off excessively at 500-fpm
velocity through the filter. Hart & Cooley Filter Engineering Data using
media type filters. A 1" deep pleated filter has way too much pressure
drop resistance, use 4 or 5" !
This Free online calc will help you determine equipment sizing & point-out
areas that need efficiency retro-work - Once you calculate the page it
saves the inputs for up to 24 minutes or, until you change inputs or close
You can experiment with changing the design
temperatures in both heat & cooling,
(or start-over showing the New Retro-R-Values) also to see whether the
equipment exceeds, at those particular temperatures & new retro
conditions, (exceeds) the Btuh
calculation load numbers, 'in each' of the 3 cooling categories; Total
Btuh, Sensible Btuh & Latent Btuh.
Simple easy anyone can do ways
to check the performance of your central air conditioner so, if needed,
call an Energy Efficiency HVAC Technician.
If you want me to run a
ballpark analysis of how your system is performing in respect to its
Rated Btuh' we need at least the following numbers:
Collection – Best Time to collect data is Late afternoon around 4:30
attic is HOT; also when outdoor temps are around 85; 95; 105F or,
*All you need is a good
reading in tenths preferable) & and indoor Humidity Gauge
1) Helpful; Tonnage &
SEER of Unit & outdoor condenser model number: __________________
2) TXV or, orifice
metering device? _______. Only if U know…
3) Outdoor condenser’s
Subtract Outdoor air
temperature: _______ = _______ Condenser
4) Need the ‘Indoor’
percent of relative humidity - away from Supply-Air outlets ______
Subtract Indoor Supply-Air
Temperature ______ -F
Need the above
information for troubleshooting & performance analysis.
A Goodman 2-Ton 13-SEER
condenser, 800-cfm indoor airflow; 80-F indoor dry bulb & 50%
Indoor temp-split 18 to 19-F.
@ 85-F outdoors; 103.9-F
- 85-F outdoors or around an 18.9-F temp-split;
@ Indoor 75-F & 50%
RH condenser temp-split is only around 14.9-F.
summer an all electric farm home WITH (TWO), Half-Ton Window A/Cs &
basement large dehumidifier:
30, 2012; Darrell’s meter; 62610 – 62140= used 470-KWh * .0985= $46.295
New 95% propane furnace using only 20,000-Btuh per hour during cold SW
WI nights at around 10-F
NATURAL GAS or PROPANE
CFM = (Input
BTU x thermal efficiency - Furnace OUTPUT) / (1.08 x temp-rise DT) or use
Combustion efficiency can be used in place of thermal efficiency.
is the temperature rise across the heat exchanger in degrees Fahrenheit
give you an approximate CFM; although it will be very close to the actual
if the measurements are made accurately and the input of the appliance is
electric furnace the airflow measurement procedure is the same.
Allow the appliance to operate until the temperature rise
stabilizes. Measure the temperature rise again out of the line of sight of
the electric heater, along with the incoming volts and current draw in
amps to the electric strip heaters. Enter the
information into the following formula
CFM = (Volts x
Amps x 3.41) / (1.08 x temp-rise DT)
oil the procedure involves verifying the nozzle size and the
correct fuel pressure. After the Nozzle size
in GPH (gallons-per-hour) is known and fuel pressure set to the listed
data, the combustion efficiency must be measured with a stable stack
temperature, and the temperature rise across the heat exchanger recorded
CFM = (Input BTU x thermal efficiency - Furnace OUTPUT) /
(1.08 x temp-rise DT) or use 1.1
Forum - HVAC Talk Click my image & contact me there with your
Excellent Illustrated Ways to Save Energy.pdf Save
with/in Adobe Reader
*Some utility companies will cut
rates in nearly half for electric heating, should for heat
Overview My Audio overview; listen
while you do other things
Tons of costly Energy when washing & Drying Clothes, etc. Possibly
Utility Bills in Half
*Selecting Air Filters - Sizing the
Filtering Area - Critically
for mortgage payments.
Home HVAC Energy Rater Audits BR Audio
This is a good Quality Installation ACCA
Why Home Energy Efficiency
Auditing is important to our future Jeremy Rifkin Video
Instruments Techs & home owners need & can use
Public Radio Program Above - Listen
is critical for Broadcast media to
launch an all out PSA
campaign to Cut
use in Half; that will also lead to lower energy prices. This is the low energy cost way,
Not Cap&Trade way-
that could lead to high
energy prices & more unemployment & stagflation!
Natural Gas & electricity are used to dry clothes &
heat water, Plus NG is used
to generate a lot of
electricity. Reducing its use, will reduce the remaining lowered
heating use, per unit cost; a Win/Win Equation for everyone.
With mass media cooperation, it can become, ("IN the Public Interest"),
a tremendous Mutual Win/Win
on a global basis, plus it will greatly Reduce our carbon footprint
Buy indoor &
& pincher clothes pins, then dry clothes in a room in
your home or
hang in good weather on a line in your back yard; I never use my
electric clothes dryer. It's
easy to do & fun when you see how much money you will save!
Drying clothes indoors helps humidify your home in cold weather.
To remove wrinkles from a few fabrics, briefly use dryer's low heat
wrinkle removal mode.
In warm weather if there is a code against outdoor clothes lines where
you live, simple use your indoor clothes rack in a room with the
windows open & a 20" Wind Machine vertical adjustment floor type
fan blowing on the
Those blowers use about what a light bulb uses, compared to your dryer,
that is nothing!
Wash clothes in cold water that you draw after the last washing, so it
warms to room temperature.
Well prior to washing, put detergent in washer's cold water & cycle
it for a
very short time & agitate for a couple minutes, then shut off &
stand for hours, then wash clothes & they will be super clean. I never use
any hot water to wash
clothes! Just these
Two things with a family will save a ton of Energy & Money!
clothes dryer are huge energy eaters; "if you do
everything possible" you could drop
your utility bills in half!
Installation of Equipment - Check List
to pre-qualify HVAC Contractors
Local PRO Contractor Locater Map Find These Forum Contractor PROs in your
Govt Energy Auditors in NYC on CNN
for mortgage payments - Home Energy Rater Auditing Radio Program.
I may do a few Home Energy Efficiency Audits starting in July 2011
Ways To Check Your Air-Conditioner's Performance > Optimize It
achieve optimal efficiency & the highest operating SEER Rating
run-times are essential."
takes a lot of amps during
startup, & it takes more than 8
minutes to reach efficient cooling performance.Now,there are RM THs
that have half degree
incrementals up to 3-F; e.g.,set at 78F-on
75-off = Higher Efficiency SEER Performance!
Everyone, get a low cost Testo Tester &
figure actual BTUH & EER > information on tester:
Owners, very low cost anemometer to check airflow FPM
Vel. & CFM, Info U Need:
I show how to convert
readings to FPM VELOCITIES to CFM
Use the formula:
register face velocity in FPM *X's
register's area in
6" rd metal duct 6*6=36*.7854=28.2744/144= 0.19635-sq.ft.
7" rd duct 7*7=49*.7854=38.4846/144= 0.2672541-sq.ft.,
You can look up on the Internet (Hart & Cooley & others') the
supply air register/diffuser open
area (Ak) sq.feet & use that! It is easy & simple for you to
begin to greatly reduce a lot of wasted monthly utility expenditures!
together the number of branch runs to ballpark the actual CFM
delivered to the rooms.
conditioners & heat pumps need
400 to 450-CFM of airflow per-ton
Get a low-cost Testo
anemometer - ballpark CFM & ballpark figure actual delivered BTUH
cooling costs up-to 50% or more, read easy to do info below to
easily check your A/C systems delivered performance! Do simple work on
your home & lower cooling bills way down; it's on my pages!
information on Testo - easy checking wet bulb temperatures:
Testo 605-H2 Fast Accurate Wet Bulb
very low-cost anemometer to get airflow FPM Velocities, get it:
a low-cost digital
flat-headed pocket Thermometer to use flat on the piping;
These instruments will PAY big returns!
can pay for HVAC service, but may not get reliable servicing of your
H-VAC system. That one incompetent
service call expenditure would buy
all the safe to use & easy to use test instruments you will ever
need, to safely
check your H-VAC system's "Actual BTUH
Operating Performance." I
don't know any local Techs that do it, or know how to do it!
YouTube Video - Best:
Installing & Cooling
Coil Best Practices NOT shown in above .
Practices Video: needs to be at least +6" above an ,
large Oil HT/EX will greatly restrict ."
- How to with Plastic Film- Improvement Do it RIGH
HVAC Techs & ANYONE - REVEALING THE ACTUAL BTUH PERFORMANCE of your
Simple to ballpark
Duct system CFM X* 4.5 @sea-level, or use X* 4.35 if
above sea-level, X* change
in enthalpy = BTUH (Ballpark)
Operating Performance. Home owners & anyone, it is easy &
simple to do!
Right Click Link & open in New Tab," look-up wet bulb enthalpy
figures on chart," & figure enthalpy change. I know of NO HVAC
Tech that performs this easy test, that even you can do.
PRINT & USE the linked enthalpy chart below:
We could easily provide a detailed psychrometric print out of
exactly what the operating system is delivering including condensate
lbs/hr, & actual sensible & latent cooling BTUH & Ratio,
Thumb for Duct Systems - Hart&Cooley
Google search Hart & Cooley, also this
pdf might help you
select the right diffuser for the particular application, & list
(Ak) free sq.ft., area of the diffusers:
A Major "Oil
Furnace" Very Low Airflow
Problem - Requires Fixing
Regal & Hallmark
& nearly all Oil Furnaces - Installation manuals
Download the installation & service manuals
To find the
information below; Use within the pdf search: at least 6” above
Or use down arrow to P-8 & scroll down a-ways...
"If the oil furnace
is used in connection with summer air conditioning the evaporator coil
installed at least
6” above the oil furnace for proper airflow.
less than 6” will result in decreased airflow."
Make sure outlet supply
takeoffs are NOT blocked by the coil. In all cases, refer to the
data for static pressure losses to ensure the total system static
not exceed 0.5” WC.
The North Country Oil furnace A/C or heat pump
Here is just one scenario; the small one
story home with a
basement requires only 14,000-BTUH of cooling but it has a 112,000-BTUH
furnace with a belt-drive quarter HP blower motor.
Three things have to be done right; first, the evaporator
coil has to be sized to flow at least 1250-cfm that requires a 3-ton
evaporator coil has to be mounted at least 6”
above the Oil furnace to eliminate an airflow restriction between it
super large heat exchanger near the top of the furnace.
the belt drive motor has to be replaced by a multi-speed
direct-drive blower motor that will deliver the correct 1250-cfm for
600 to 675-cfm airflow for cooling.
I have witnessed a 2-ton evaporator coil
directly on top of the Oil furnace & the quarter HP direct drive
Can you cite the horrendous problems this
Think through what you’re doing & the
before doing it!
summer, Air conditioner & heat pump user's, this is a "Simple Easy Safe Way" to Check an A/C's
Thermostatic Expansion Valve (TXV) metering system's refrigerant
charge & any A/C's Performance:
fan motor HP varies as to the cube of the rpm blower speed.
at 700-rpm & .2" SP for heating my Thermo Pride OL 11 with its
belt-drive quarter Hp motor will deliver 1200-CFM; add a cooling
coil, & at .5 SP it will deliver only 400-CFM.
the total static pressure as low as possible and within mfg'ers ESP
requirements for air conditioning is the first requirement in an
efficient system design.
BTW, what is the average pressure drop
across the new +90 high efficiency furnace condensers? That pressure drop should
be published by all of the companies!
My Scan of My ThermoPride OL 11 Graphed Blower-Curve-Chart
Thermopride OL 11 Graph ipg
image - Thank you Dave Staso, CA. for
"After it loads Right click "Show Original Images" -
Move cursor arrow over graph - Click + when 'over graph'
for expanded image," then print on the highest quality setting.
the outdoor temperature, then "Take a thermometer & check the air
temperature coming off the outdoor condenser."
A higher indoor humidity raises
the condenser temp-split, lower humidity lowers the condenser
Depending on the units SEER Rating; all
data, AIRFLOW @ 450-CFM per-ton of cooling, Room temps 75 to 80-F,
at 50% indoor relative humidity,
the temp-rise for a
condenser, should be
between around 18
& 20-F; much below that split could be unacceptable.
A 10-SEER, at above conditions, 22 to 24-F Condensing Temp-rise
above outdoor temperature.
1.5-Ton, Indoor airflow @ 675-CFM,
Rooms 75-F @ 50% relative humidity; CT rise 14-F.
R410A, 2-Ton, @ 900-CFM, Rooms
75-F @ 50%
relative humidity; CT rise 14-F.
the small uninsulated copper line where it makes a bend, outdoors or
so you can put a digital thermometer flat on it & insulate the TH
something (piece of the tubing insulation) read the temperature &
subtract it from the outdoor condenser discharge air temp.
condenser temp 110, line temp 100-F that is 10-F subcooling & 10 to
12-F is a normally charge system. If it's considerably less than 10-F
it could be low on refrigerant or need a Tech to check it; too far
above 12-F it's overcharged, call a Tech, could also be a restriction
in the lines.
A TXV coil
will usually show a 9 to 12-F superheat .
The subcooling (BallPark) should be between 10 & 15-F on either a
TXV or fixed orifice metered system.
You should own a low cost digital pocket thermometer: Now the reality is
that you don't need a manifold gauge, - anyone can Ballpark check
the charge in respect to the indoor airflow with only a little low cost
MA-Line digital thermometer using some tubing insulation on the sensor
probe. An A/C supply Outlet might sell you one or inquire at hardware
stores! Saves money on needless A/C Service Calls!
Take the outdoor temperature & subtract it from the outdoor
condenser's discharge air temperature.
This temperature is standard for different SEER Rated units.
unit, with 50% relative
humidity indoors will have ballpark, will have an 18 to 20-F temp split
A 14-SEER will be around a 14 to 16-F temp/split. if too far above or
below those temps, call for an A/C Tech.
your registers/diffusers & their (Ak) sq.ft. area, so you can
multiply the FPM Velocity times the Ak to get the (CFM) Cubic Feet per
Minute airflow from that register.
the categories to see the diffusers & Return-Air Grilles then find
them on your downloaded pdf's engineering data.
Hart & Cooley: http://www.hartandcooley.com/grd/HC-100/residential/baseboard_registers/462.htm
Do a lot of Hart & Cooley engineering data searches, look at the
registers & the Ak sq.ft. data to figure register's delivered CFM.
Home Energy Magazine Online
Raising Standards and
New Group Hunts Bad Ducts (A/C
40 billion kWh sound like a lot of energy? How about 4 billion therms? Researchers believe that's how much
electrical and gas energy this country "could save by fixing
inefficient ducts using current techniques." "Refining those techniques
could reap savings of 90 billion kWh"plus 9 billion therms! Peak
loads would be reduced
too. To pursue these tremendous savings, national, state, and utility
research laboratories, the U.S. Department of Energy, utilities, and
energy service companies are collaborating. Their
consortium is called "Residential Energy Efficient Distribution
Systems," or REEDS.
These techniques, along
air infiltration & heatgain/heatloss calcs, ought to be taught in all
our schools as part of the Science & math curricula. Half
heatgain/heatloss can be due
to a high Home Air Infiltration Rates!
62-1989 is 0.35
ACH (Air changes per Hour) or
3-hours for a total interior, Air INFILTRATION Change.
Air Infiltration sources DTI
DOE Reducing Air Infiltration
Energy Efficiency (Me2)
potential is great and the model is simple: The Milwaukee Energy
Efficiency (Me2) program would allow
building owners and occupants to
pay for the cost of improvements as a charge on their municipal
services bill or utility bill, on a schedule that allows them immediate
If a participating building owner or occupant leaves the
property before repayment is complete, the remaining obligation can go
to the next owner or occupant as he or she benefits
from reduced energy
costs. The program will create
thousands of good jobs — ranging from
entry level to highly skilled — and fill them locally.
monthly cooling bill is very high & you want to cut
it in half or less; start with an entire home energy use & the HVAC
Evaluation listed below.
infiltration to a minimum, a Blower-Door-Test will locate the
air leak areas; a Duct Blaster to detect duct leaks & size ducts to
window options along with outdoor window shutters or awnings.
heatgain/heatloss can be due to a high building air infiltration rate!
Source Home Energy magazine online Sept/Oct 1993
- DOE Reducing Air
system & airflow must be accurately checked & optimized.
those ductwork techniques could reap savings of 90 billion kWh" plus 9
Source Home Energy magazine online Sept/Oct 1993
your A/C system you need a thermometer, wet cotton cloth, or a humidity
store, it is around $10 for humidity gage & thermometer combo.
Temp/Humidity combo gage
condenser fins, they must be clean.
all the power 230-Volt breaker power to the condenser, including
furnace power for the low voltage in the condenser!
water pressure, keep the
stream in-line with the fins so it does not bend them.
for a long time before operating for ten minutes or longer,
then take the temperature readings.
Let it dry out for several hours before reapplying power &/or using
The A/C user
need not know all the tech info, all they need to know are a
very few basic simple ways to identify that the system is not
correctly so if necessary you can call
for a pro-tech to properly trouble shoot the system.
Now the reality is that you
don't need a manifold gauge, -
anyone can Ballpark check the charge in respect to the indoor airflow
with only a little low cost MA-Line digital thermometer using some
insulation on the sensor probe.
You can't order it there.
First, you check the discharge air temp off the outdoor condenser,
(that is the "Condensing Temperature (CT)," the higher the SEER Rating
the lower the outdoor normal temp/split above the outdoor temperature
Then you either check the small liquid line tubing temp
outdoors where there is a tubing bend, or indoors where it bends to
enter the plenum.
Indoors could be inaccurate as the tubing temp could vary
lower depending on temp conditions the line is conducting.
the small liquid line temp from the CT & you have the Subcooling
temp which varies some from mfg'ers, but will be Ballpark 8 to 12-F
The condenser temp (CT) above the outdoor temp tells
you how much indoor sensible & latent heat, & the 3 motor heats
it is ejecting. The indoor humidity level has the biggest effect, the
higher the humidity the higher the split.
Now, indoors the higher the humidity the lower the temp/split between
Supply-Air & Return-Air.
At 50% indoor humidity the split should be Ballpark, around 18 - 20-F.
blower wheel blades & all coils are relatively clean & the
split is well above 20-F, you have low airflow with a low heatload
through the evaporator coil.
If the indoor split
is way below 18-F at 50% RH, you either have way too much airflow
or some problems in the functioning refrigerant system.
To solve any of these problems you need to call a
knowledgeable HVAC TECH! - Darrell U
Download these Energy Saving PDF Graphics
Ways to cut monthly
Energy Bills, hopefully in
HALF. Thanks for the link - TEDKIDD
AND INSTALLATION OF RESIDENTIAL FLEXIBLE DUCTWORK SYSTEMS
at the ducting, if it is not to code; make hard copies of this code
& give it to whoever does the ducting work.
Make sure they get redo it right!
have flex duct interiors commercially cleaned, I just viewed Home
Inspection photos showing the interior damaged & insulation
plugging the duct.
Home Inspectors warn people because the duct cleaner's tell them it
won't damage the ducts. Some HI's look into the boot areas
for clues of problems...
temperature day & indoor temperature, check the humidity &
temperature indoors & record it.
outdoor temperature, & the temperature of the condenser's discharge
outdoor temperature from the discharge temperature to get the split.
SEER Rating for the temp-split perimeters.
your A/C when conditions are 85 to 95 with indoor temps between 75
& 80-F, with around 50%RH.
indoor conditions, e.g., lighter loads; the split could be 2
to 3-F below the listed
Conditions 95-F out doors, 80-F indoors @ 50% RH
(between 75 to 80-F
@400-CFM Per-Ton of Cooling 50% Relative
18-F| CONDENSER TEMPERATURE
Above Outdoor Temperature
1.5-Ton 18,000 Outdoor temp
95F; 80-F IDB, @ 67-F IWB
or 50% RH; ARI Conditions = 21-F Condenser
Air-Temp-Split. Don's @10-F to 12-F
Split - Low ID Airflow!
18,000 18-F to 21-F
Temp-Split Condenser CFM 1400
T-Temp-Split Condenser CFM 1400
Condenser CFM 2000
Condenser CFM 2800
Condenser CFM 2800
48,000 18 -F
Condenser CFM 3400
CFM is Cubic Feet-per Minute of airflow through the condenser.
Goodman data for R-22, 14-SEER
2.54-Ton evaporator coil, TXV; Single Stage:
Outdoor Temp 85-F; IDB 75-F;
; Indoor temp-split 19-F;
Condenser Split 11-F;
Goodman data for R-410A
3-Ton evaporator coil, TXV;
Dry Bulb 75-F;
Check your air conditioner:
Return Air Entering
Temp: ____F -
Coldest Nearest A-Coil Supply Air temp: ____F Temp-Split
Relative Humidity ______%
Or, Wet Bulb Temp __F
Outdoor condenser discharge Air Temp: _______F - Outdoor /Temp
On Oil Furnaces check the airflow, many have nearly half the airflow
they need! Example; 100,000-Btuh Oil or Gas furnace needs 1300-cfm of
You can use a piece cotton cloth
soaked in room temp water.
Set a hi-spd fan near the return air intake & wait until you get
the lowest wet bulb temp. That's the Wet
temp & it's what I used to take with a sling-psychrometer.
So, rig one up & just give me the wet bulb temp; wet bulb can also
it to %RH.
Or, Testo 605-H2 Fast Accurate Wet Bulb
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E-mail me the data with CFM airflow & I'll give you its ballpark
BTUH, or U can do it: udarrell**@**pcii.net
the nominal amount of heat (BTUH) that is being absorbed by the indoor
evaporator coil & being discharged by the outdoor condenser coil.
With outdoor & indoor coils clean with clean blower wheel blades
& filter; If the outdoor condenser temp-split
is low, & indoor Return-Air
temp minus Supply-Air temp is high,
then there is NOT enough airflow
through & being absorbed by the indoor coil.
discharge air is within the nominal range, +/- 2-F, then the system is
absorbing & transferring a nominal latent & sensible BTUH
amount of heat from the interior of your home.
test procedure, the (1) Temperature-Split of
Supply & Return Air, &
(2) indoor humidity reading & the (3) outdoor condenser discharge
air temp-split is all
combination of the outdoor split & the indoor Supply-Air/Return-Air
temperature splits & the room Relative Humidity Percentage,
I can tell you
if the indoor
airflow is in the normal range.
Supply-Air/Return-Air temp-split is 16 to 22-F. A heavy humidity
load will take the split down toward 16-F. Dry air will have a high
temp/split 22-F or a bit higher.
skew this test is a dirty indoor evaporator coil. In that
event, the blower wheel blades will be dirty too, so with power off,
check those blades!
Always do these temperature checks with a clean filter installed.
velocity meter, an anemometer, is a great instrument to have; they're
for finding CFM Airflow
gain and Btu/hr of cooling is done for each room.
per/ton of cooling,
12,000-BTUH / 400-cfm = 30-BTUH for each (CFM) Cubic Foot per Minute of
At 450-CFM per/ton cooling use
12,000 / 450-cfm = 26.66-BTUH per each CFM, etc.
Then Select Supply duct size by CFM, velocity, & optimal Supply Air
/ by 30 equals 100-CFM, or around a 6" dia. RD metal duct.
Five duct runs for 1.5-ton unit, 18,000-BTUH: (Equal room loads,ha!)
18000 / 5-runs= 3600-BTUH / 30 = 120-CFM each 6" duct velocity
611-fpm Velocity. 18' length branch runs 611-fpm velocity at a Friction
Rate 0.03" per 18'.
The total airflow
should be in the range of
375 to 450-CFM per ton of
cooling; Unless you have high humidity I'd go for 425 to 450-CFM per
One ton is *(12,000-BTUH).
*Check the Return Air
filter(s) often, need optimal airflow especially during a heat wave!
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Major "Oil Furnace" Airflow Problem Fix
This Air Flow problem
extremely important for sufficient performance!
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information is only placed on these pages for your understanding &
communication with contractors & techs.
information is for the edification of contractors and techs. I am NOT liable for what you do,
you are liable for what you do! - Darrell Udelhoven
Refrigeration Heating and Air Conditioning - Federal Refrigerant
Retired Licensed Contractor
Please write me if you have anything
you'd like to contribute! - Darrell
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Posted: 05/03/09; Edited 04/17/14