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% surface of wall that is framing lumber


ASHRAE recommended ACHn


solar heat gain coefficient of single pane glass

SHGC of 0.87

Saving potential from duct leakage per EPA

17% average

Saving potential from resizing per EPA


CO test failure for undiluted flue gas

100 ppm

Worst case CAZ limit WRT outdoors

-5 pa, except -2pa for atmospherically vented water heater, -15 pa for pellet stove w/ draft fan aand sealed vent. -50 pa for direct vent appliance

Worst case CAZ setup

Close exterior doors, windows, fireplace flues. Zero out base pressure, turn on dryer, exhaust fans, air handler (if hurts), open/close interior doors if hurts CAZ.

Worst case CAZ test process

Test smallest Btu appliance first, test spillage (mirror, smoke), test CO at SSE. If spillage after 1 minute, test under natural conditions.

Combustion efficiency measurements

Combustion analyzer: CO less than 100ppm, O2 b/t 6-9%, flue gas temp and heat rise per manufacturer.

Gas combustion system inspection

Look for soot, melted wires, rust. Inspect burners, heat exchanger. Check high voltage, test pilot safety circuit. Check heat anticipator, venting, high limit control (220 F limit). Measure gas input, open window to see if it reduces CO.

Gas system maintenance if

CO >100 ppm, visual signs of soot or flame rollout, burners dirty, draft inadequate, no service in 2 years.

Measuring Btu/hr input on gas systems

turn off gas appliances, fire unit being tested, clock one turn of gas dial, consult table (x1000). adjust to within 10% of furnace label (3.2-4.0 IWC)

Oil burner inspection

Check barometric draft control (unless high static pressure or mobile home burner). Inspect for soot, overheating, fire hazards, corrosion, wiring, fuel lines, heat/combustion chamber, instantaneous flame ignition (except pre-purge units)

Oil burner testing

Flue gas: O2, CO, SSE, smoke test. Over-fire and flue draft, high limit (250 F), oil pump pressure, xformer voltage, CAD cell (or stack control)

Oil burner adjustment

Match burner nozzle to heating load, oil pump pressure, air shutter (O2 and smoke values), barometric damper.

Oil burner maintenance

Clean blower wheel, burner assembly, replace oil filter, clean soot from combustion chamber/heat exchanger, check electrode gap, flame sensor. Redo diagnostics.

When is upgrading to a flame retention burner cost effective

if SSE is < 75%

Replacing oil burner protocol

size burner and nozzle to heating load. Install new combustion chamber or change nozzles to fit flame to chamber.

Testing ranges and ovens

test each burner separately (8" above flame), clean if > 25 ppm. Turn oven to high, sample after 10 minutes (undiluted < 100 ppm, ambient < 25 ppm).

Inspecting heat exchangers

look for rust at exhaust/vent area, flame damage/impingement, flame movement. O2 should change no more than 1% from off to on. Shine light.

common vent sizing

cross-section equal to largest vent plus 50% of smaller vent. No more than 7 times the area of smaller vent. Smaller connects below larger.

other vent rules

horizontal length no more than 75% of vertical length. no more than 18 inches of horizontal run per inch of vent diameter. 1/4" rise per 1' run

vent clearance

single wall 6" (gas) 18" (oil). B-vent 1" (gas). L-vent 9" or 1 vent diameter.

masonry chimney standards

supported by own foundation, lined with fireclay (1" air gap and unbonded to chimney), cleanout 12" below lowest inlet, penetrations sealed with metal/high-temp sealant. 2" clearance to combustibles

chimney terminations

Must have vent cap, 3' above roof penetration, 2' above any obstacle within 10' (ie ridgeline)

SSE 70+ characteristics

Cat I, draft diverter, no draft fan, standing pilot, non-condensing, indoor combustion and dilution air

SSE 80+ characteristics

Cat I, no draft diverter, draft fan, electronic ignition, indoor combustion air, no dilution air

SSE 90+ characteristics

Cat IV, no draft diverter, draft fan, low-temp venting, positive draft, electronic ignition, condensing heat exchanger, outdoor combustion air

pressurized sidewall venting requirements

Cat III, B-vent, stainless single wall or high-temp plastic. air seal joints with high temp caulk.

confined space CAZ definition

50 cubic feet of volume for every 1000 Btu/hr of appliance

net free area of metal vs. wood grills

60-75% vs. 20-25%

indoor opening to CAZ size

2 openings of 100 sq. inch minimum, 1 sq. inch per 1000 Btu/hr for each opening, combined room volume > confined CAZ specs

outdoor opening to CAZ size

2 vents, each 1 sq. inch per 4000 Btu/hr (2000 Btu/hr if ducted). If 1 vent, then 1 sq. inch per 3000 Btu/hr.

oil system emergency shut off should be located

in the living space

combustion furnance off/off settings

high limit 250 F or less. Fan on 120-140 F, fan off 95-105 F. Fan on within 2 minutes of ignition, fan off within 2.5 minutes of burner off.

combustion furnace airflow per Btu

11-15 cfm per 1000 Btu/hr. Plenum should have 2 sq. inches of cross-section per 1000 Btu/hr

Central AC airflow per ton

400 cfm +/-20% per 1 ton. 12,000 Btu/hr = 1 ton. 6 sq. inches of cross-section per 1,000 Btu/hr in plenum

BAS equation

CFM50 = 15 cfm x # of occupants (bedrooms +1) x n factor. Or CFM50= (.35 ACH50 x house volume x n factor)/60. Whichever is higher

N factor

Based on climate zone and building height, converts 50 pa airflow to natural airflow.

Shower flow rate measurement

time the filling of container with known volume. Low flow heas do 1.5-2.5 gallons a minute.

water heater energy factor

= Btuh coming out of water heater / Btuh put in water heater. Accounts for storage losses.

hot water efficiency increases from

reducing temp. to 120 F, reduce distance to fixtures, increase insulation, demand hot water circulation loop. If older dishwater w/o heater, keep at 140 F.

replacement gas water heater minimums

energy factor of 0.61 or greater and 2 inches or greater of foam insulation. 0.90 and 3 " for electric

water heater pipe insulation

insulate first 6' of hot and cold, keep insulation 6" from flue pipe.

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