Darrell Udelhoven - HVAC Contractor & Technician since the
don't mistrust every H-VAC contractor, most of them are okay &
The reason air
consumers are easy prey for a rip-off scam artist, is that they are
not knowledgeable enough concerning H-VAC systems.
Therefore, air conditioning consumer's have a tendency to always
they are told by the A/C technicians.
When you acquire sufficient knowledge, you will know how to qualify the
contractor's on the telephone before you allow them to make a service
call or bid on equipment replacement.
I will provide you with adequate basic H-VAC knowledge so you will be
enabled & empowered to protect against the worst rip-off scams.
Overview My Audio overview;
listen while you do other things/last
part on Oil & A/C airflow
There are simple ways you can check your A/C system with a thermometer.
Using a low cost wet bulb instrument, & low cost anemometer you can
actually ballpark the BTUH operating performance of your A/C or heat
can pay for HVAC service, but may not get reliable servicing of your
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 & more.
don't know any local Techs that do it
or know how to do it.
is a Consumer Affairs Comment Form: Consumer
begin with a thorough Home Energy
AUDIT that shows all the options for
lowering the heat-gain & heat-loss, then after reducing air
infiltration, etc., have a room by
room manual J heatload calc
performed. A reduction in
equipment sizing will usually greatly improve the duct system
where the greatest savings in both heating & cooling will accrue;
this will help in the down-sizing of
"The 'proper heatload' on the evaporator coil must be established"
Check and thoroughly seal all the ductwork! For efficient operation,
always check the return air temperature at the blower & at the
Return Air Grille(s) to know whether it is drawing hot air from the
attic or garage areas.
What I stated above, that ought to be done is far more important than
SEER rating; as that will determine the SEER achieved & the energy
a manual J room by room heat-gain calc with the option shown so you can
do everything possible to reduce all sources of heat-gain &
heat-loss, greatly reducing both heat & cooling BTUH equipment
you do anything else, educate
yourself enough to "ensure that you request the proper things be done
in the proper order of sequence." Checking ductwork & Airflow Checking
Static Pressures is
Critically Important. As is knowing the operating feet per minute (FPM)
velocity, the CFM & BTUH to each room along with the Total CFM
airflow & BTUH.
the best way to save energy in your home,
use your zip code. Profitabiity
of Energy efficiency Upgrades | Hidden cost of Home
have a manual "J" heat-gain / heat-loss load calc done, followed by a manual "S" for equipment sizing
& then a manual "D" for proper ductwork
sizing. All registers, grilles, filter racks, &
diffusers must be located & sized for optimal efficient performance
of the system. Order Turning Vanes for long radius 90-ells; use long
correct sizing of residential air conditioning systems & ductwork
is crucial to ensuring proper indoor space conditioning, equipment
performance, and economical operation. Unfortunately, many
A/C contractors measure “correct equipment sizing” by the system's
ability to meet any indoor thermostat setting at any outdoor
temperature. That method of sizing will lead to inefficient operation
for the vast majority of conditioning time. Air conditioning systems
“must be sized to meet typical or average indoor and outdoor conditions
to ensure proper air mixing, filtration and dehumidification of indoor
air across seasonal variations.”
A Major Oil Furnace Airflow Problem Fix
Regal & Hallmark
& nearly all Oil Furnaces - Installation manuals
Download the installation & service manuals from ABOVE LINK BELOW
LINK MAY NOT WORK!
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...
the oil furnace is used in connection with summer air conditioning the
evaporator coil must be installed at least 6” above the oil furnace for proper
airflow. Distances 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 manufacturers’ data for static pressure losses to
ensure the total system static pressure does not exceed 0.5” WC.
My Scan of My ThermoPride OL 11 Graphed Blower-Curve-Chart
Thermopride OL 11 Graph ipg image - Thank you Dave
Staso, CA. for
the better expandable image!
"After it loads Right click "Show Original Images" -
cursor arrow over graph - Click +when
'over graph' for expanded image," then print on the highest quality
manufacturer should furnish blower line curve charts with their units and put
them on the Internet for service tech's to download and print. A blower
curve graph chart, for discerning the variables of ol furnace belt
how easy it is to fall below the required CFM with a quarter horse
blower belt drive motor that was standard with 112,000 btuh output oil furnaces. Measuring
the static pressure of the duct system & using an anemometer to
check atual airflow is a must! The Thermo Pride OL 11 Oil
furnace requires 1164-CFM of airflow to keep temp rise within 90-F.
require at least a 2.5-ton A-coil at 1125-CFM to get close to enough
airflow, a 2-Ton coil is only 900-CFM.
North Country Oil furnace A/C or heat pump scenario:
good Tech should already know what I am going to illustrate here; this
is for Homeowners & any who can use the least costly way to deal
with this too common a problem in the cold North Country.
We are moving into the cooling
season; however, any changes in equipment should consider how every
component matches with optimal airflow efficiencies.
My lowest cost solution to the
climate oversized Oil furnace with a small tonnage A/C evaporator coil
which requires nearly half the airflow as heating:
I ran a check on my late
home & the summer cooling heatload is about 14,000-BTUH.
The original scenario, had
airflow than required for 1.5T cooling; its 2-T A-Coil wouldn’t flow
1150-cfm for heating
I did a lot of other figuring;
45,000-BTUH output should heat that small single story home.
However, with the 140,000-BTUH
input, 112,000 output Oil furnace installed; the nozzle size can be
dropped from one gal an hour (we’ll use 139,000-BTUH input) to .75
@100-psi, the BTUH drops to 103,500 input, this furnace tested at .74%
efficiency; *103,000 = 76,590-BTUH.
Using a 90F heating
rise, which Thermo Pride can stand; (90*1.06 here) 76,590 / 95.4F is 803-cfm.
Therefore, the 2-Ton A-Coil
handle the CFM; mounted +6 inches above the furnace, it has the flow
capacity to work okay in both heating & cooling modes.
By installing a direct-drive
multiple speed blower motor, you could simply adjust the RPM to the A/C
& furnace CFM requirements
Therefore, solution is to
multiple speed direct drive motor with the fan relay energizing the
cooling speed tap.
rather common situation in cold climates seems not to be properly
addressed my Techs, & the HO does not know why cooling &
heating don't work well.
We should all work to improve
efficient use of high cost energy ... so America & everyone wins.
& small business owners, here is a very low cost way to check
an A/C or heat pump's cooling BTUH performance. Get a low cost Testo 605 Tester to get the
Supply Air Wet Bulb temp & Return Air Wet Bulb temp so you can
ballpark figure actual BTUH & EER performance; they would charge
big-money & virtually none know how to do it:
Testo 605-H2 Fast Accurate Wet Bulb
& small business owners & everyone, very low cost anemometer to
get airflow FPM Velocities at Supply Registers or Return Air Grilles,
which you can convert to CFM:
a low-cost digital flat-headed pocket
use flat on the piping;
test instruments will PAY big returns!
Supply Air & Return Air wet bulb temperatures & interpose them
on the enthalpy chart linked below.
CFM X* 4.5
@sea-level, or use X* 4.35 if 1000' above sea-level, X* change in enthalpy = BTUH
(Ballpark) Operating Performance.
Must Right Click Link & open in New Tab," look-up wet bulb enthalpy
figures on enthalpy chart," & figure enthalpy change times the result of the CFM
X* the factor.
Enthalpy Chart Print chart
: Installing &
Cooling Coil Best Practices NOT shown in this .
Install Best Practices
to be at least +6" above an or
large Oil HT/EX will greatly restrict !
- How to with Plastic Film- Improvement Do it RIGHT
of Thumb for Duct Systems - Hart&Cooley
DESIGN 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 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 Home Inspector's look into the boot areas
for clues of
of Thumb for Duct Systems - Hart&Cooley
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.
Have or do a manual J heat-gain calc for each room. If a room calls for
3,000-BTUH; first divide 12,000-BTUH by the CFM PER TON you want to use.
I.E., Wet coil, 12,000/400=30-BTUH per each CFM; Wet coil
12,000/425=28.235294; 3000/28.235-= 106.25-CFM; Dry coil,
12,000/450= 26.6666-BTUH; 3500 / 26.6666= 131.25-CFM
If register/diffuser has the same (Ak) free-airflow-area, as the duct
Room calls for 3,500-BTUH, using
450-cfm per/ton dry coil or 26.6666-BTUH per CFM= 131.25-CFM.
I.E., 6" rd duct .6*6=36*.7854=28.2744sq.ins/144=0.19635-sq.ft.;
131.25-cfm / 0.19635-sq.ft= or 668.4-fpm velocity.
- SP2 = (rpm2/rpm 1)2 X SP1 = SP2
Required fan motor horsepower (hp) varies as to the cube of the rpm
- hp2 = (rpm2/rpm1)3 x hp1 = hp2
CFM Fan delivery varies directly as to the fan RPM speed:
- cfm2 = (rpm2/rpm1) X cfm1 = cfm2
I assume NO responsibility for the USE of any information I post on any
of my Web pages,in E-Mails or News Groups.
HVAC/R work should always be done by a licensed Contractor &
properly licensed Techs! This information is only placed on these pages
primarily for your understanding & communication with contractors
& techs. This information is also for the edification of
Contractors and Techs. Never attempt
anything that you are NOT competent to do in a SAFE manner! I am NOT liable for your
screw-ups, you are liable for what you do! - Darrell Udelhoven
Cut Your Home Energy Use
& Utility Bills in Half New
- Air Changes per Hour - AVERAGING INFILTRATION RATES - New
Guarantees You'll Get 50 to 70% Energy Savings on Your
Monthly Home Energy Bills!
HVACR TALK FORUM - Residential
Problems - NEW
Engineer Forums -
about home inspections also HVAC inspections
DIY Do It Yourself
It Yourself" TV- I Am "HVAC
MY HVAC BLOG - YOUR QUESTIONS &
COMMENTS WELCOME *Use for listing test data required for
WEB - Heating & Air
HVAC Discussions Mike
Holmes HVAC Forum - New
Cynergy Home HVAC Energy Raters Listen While Reading
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about Reducing Energy Costs - New
Testo 416 Airflow Test Checking airflow - should always be
performed before charging a system!
Description of 416 Testo Telescoping Vane Anemometer - A MUSTThe Testo 416 Airflow Test Checking airflow
Air Flow CFM of a very large Supply Air Register using
a Testo 410 Vane Anemometer Basic...
Getting it right makes all the difference
in the world.
Energy Star ACCA pdf is interesting & confirms what many of us have
been preaching, including educating the potential customers!
Scroll down to page 5
Conditions, & study to learn how we can all profit, customers
There are more ACCA links
this is a good starter document. 10/05/10
Installation Check List
to pre-qualify Contractors
Darrell Udelhoven - HVAC RETIRED - udarrell
Udelhoven - (U-dl-hoven)
Copyright ©2011 All rights reserved
Darrell Udelhoven -
Bloomington - Lancaster - Grant County - Wisconsin