PART 5: HVAC & DHW SYSTEMS - Paperlessinspectors 5: HVAC & DHW SYSTEMS Building Science Review Learn...

PART 5: HVAC & DHW SYSTEMSBuilding Science Review

Learn more at energy.gov/betterbuildings

• This document will help you:• Correctly answer all parts of the “HVAC Systems” section in the Home Energy Score

Tool• Calculate equipment efficiency based on type and manufacture year• Identify Heating Equipment – 9 Types• Identify Water Heating Equipment – 5 Types• Identify Cooling Equipment – 3 Types• Determine impact of multiple HVAC systems within a home• Identify Duct Quality


Building Science Review: HVAC & DHW Systems

To address this issue, the Dept. of Energy (DOE) has developed an efficiency calculator to help determine the efficiency. It is based upon the age of the equipment, whether it is routinely maintained and its initial efficiency.

Link for the downloadable excel efficiency calculator. http://homeenergyscore3dtraining.com/course/hvacefficiency.php?id=3

Link to find the age of equipment (more detail on next page): http://www.buildingcenter.org/


HVAC Systems: Equipment Efficiency

When using the Assessor Calculator, always use the current year when determining the equipment age.

In practice, the actual energy efficiency of a piece of equipment is rarely known. Even if it is known, age and wear and tear tend to decrease the efficiency.

If you downloaded the Sim Calculator prior to January, 2016, it is out-of-date. Download the current Calculator.

http://homeenergyscore3dtraining.com/course/hvacefficiency.php?id=3

http://homeenergyscore3dtraining.com/course/hvacefficiency.php?id=3

http://www.buildingcenter.org/

The Assessor Calculator is easy to use. Simply input the 4 data items:1. System Type. Determine through visual inspection.2. Is it well maintained? Determine through visual inspection and/or homeowner interview.

If you don’t know or can’t tell, answer “no”.3. System age. Determined from the equipment label & building center website.4. Installed efficiency. Determined through the table found in the Assessor Calculator /

given below:


HVAC Systems: Equipment Efficiency

If the date of manufacture is not clearly printed on the data plate, visit www.buildingcenter.org to learn how the manufacture year is coded into the to the serial number.


HVAC Systems: Date of Manufacture

Example of the manufacture date coded in the serial

number on a Trane furnace. This unit was manufactured in 1991. (For Sim calculations, please disregard the month.)

When using the Assessor Calculator always use the current year when determining the equipment age.

Heating Equipment – 9 Types:• Central Gas Furnace• Room (through-the-wall) Gas Furnace• Propane (LPG) Furnace• Oil Furnace• Electric Furnace• Electric Heat Pump• Electric Baseboard Heater• Gas Boiler• Oil Boiler

Cooling Equipment – 3 Types:• Central Air Conditioner• Room Air Conditioner• Electric Heat Pump

Water Heating Equipment – 5 Types: • Electric Storage• Natural Gas Storage• LPG Storage• Oil Storage• Electric Heat Pump


HVAC & DWH Systems: Types in the Scoring Tool


Heating: 9 Equipment Types

1. Central Gas Furnace• High Efficiency (Condensing)• Mid-Level Efficiency (Induced Draft)• Low Efficiency (Natural Draft)

2. Oil Furnace• Condensing (High Efficiency)• Flame-Retention Head Burner (Mid-Level Efficiency)• Conventional Burner (Low Efficiency)

3. Room (through-the-wall) Gas Furnace4. Propane (LPG) Furnace5. Electric Furnace6. Electric Heat Pump7. Electric Baseboard Heater8. Gas Boiler9. Oil Boiler


Heating: Central Gas FurnacesCentral Gas Furnaces – 3 Types:

Type Condensing HE Induced Draft Natural Draft

Defining Features

• White PVC flue pipe connected to the outside, often paired with PVC intake pipe

• Metal exhaust flue pipe, often connected to the chimney• Inducer fan

• Draft diverter or hood for air intake below the metal exhaust flue pipe

Starting Efficiency 0.90 AFUE 0.82 AFUE 0.78 AFUE

Example


Heating: Oil FurnacesOil Furnace features: Barometric damper (except condensing), injection controller, oil tank.

Type Condensing Flame-Retention Head Conventional

Defining Features

• PVC pipe exhaust venting • Motor RPM 3450• Standard since mid 1980’s• Natural draft exhaust venting

• Motor RPM 1725• Phased out in 1980’s• Natural draft exhaust venting

Starting Efficiency 0.90 AFUE 0.80 AFUE 0.72 AFUE

Example photo missing?


Heating: Other Furnaces

Type Through-the-Wall Propane / LPG

Defining Features

• Gas furnace• No ductwork• Temperate regions

• Identical to natural gas furnace in house• Also has propane tank – sometimes buried in yard• Typically found in rural areas• Boiler plate on equipment will indicate type of fuel

Starting Efficiency 0.78 AFUE Same as natural gas

Example


Heating: BoilersGas and Oil Boilers are used to heat homes with hot water or steam pumped through radiators.

Type Gas Boiler Oil Boiler Tankless Coil

Defining Features

• Open draft diverter• Large pipes attached to the system• Lack of ducts

• Barometric damper (top circle)• Outside oil injection controller (bottom circle)• Flue

• A tankless coil has an additional controller on the outside. • no DHW heater or storage tank present

Starting Efficiency 0.75 - 0.84 AFUE 0.75 - 0.84 AFUE 0.75 - 0.84 AFUE

Example


Heating: Electric

Type Electric Baseboard Electric Heat Pump Electric Furnace

Defining Features

• Wiring• No pipes• No Combustion

• Thermostat has Emer Heat setting / light• Turn up thermostat on heat mode until system comes on. If outside unit is running, then it is a heat pump.

• Large electric breaker in front• Heavy wiring• No flue

Efficiency 0.99 AFUE 6.6 – 9 HSPF 0.99 AFUE

Example


Cooling Equipment: Distinguishing TypesCooling Equipment – 3 Types:

Type Central Air Conditioner Room Air Conditioner Electric Heat Pump

Defining Features

• Outdoor compressor unit• Two copper pipes, one insulated• Evaporator coil

• window mounted or through-the-wall• No central / outdoor unit

• Thermostat has Emer Heat setting / light • Looks and functions like central A/C compressor

Starting Efficiency 9 - 20 SEER 8 - 12 EER 9 - 20 SEER

Example

The Home Energy Score Tool is able to account for 2 heating or cooling systems within a home.

If there are more than two systems, then the two largest system characteristics should be entered.


HVAC Systems: Multiple Furnaces

The Scoring Tool requires data on the ducts. If the ducts are in more than one floor/location you must estimate the % in each location.


HVAC Systems: Ducts

In this diagram, 50% of the ducts are in unconditioned attic and 50% are in an unconditioned basement and unvented crawlspace. (Note: the basement is unconditioned as per the Home Energy Score definition of conditioned areas, because there are no supply registers located there.

• Determining duct locations in a multi-story home: • If supply vents on the top floor are in the floor, you can assume the vents are in a conditioned area - the floor joist space of the living space. • If they are in the ceiling of the top floor the ducts are in the attic. • Use the floor area ratios as an approximation for duct % in these difficult cases.


Ducts: Schematic


Ducts: Exterior Insulation

Duct insulation is usually indicated on the exterior of the ducts with a foil or plastic covering. Rigid insulated ducts will often have the insulation R-value printed on the outside.

Interior duct insulation can usually be determined by knocking on the ducts. A hollow sound indicates no insulation. You should be able to see the insulation through the duct register. There is a material called duct board that is pressed fiberglass with a reinforced foil-like covering. It will give if you poke it, unlike metal ducts, but not as much as exterior insulation.


Ducts: Interior Insulation

A common duct sealant is mastic, shown in these photos. If the duct joints are “sealed” with duct tape, this is not considered sealed as the tape tends to deteriorate quickly.


Ducts: Sealing

Look for presence of sealing at the return of the furnace/ac unit and/or at joints in the duct work.


Domestic Hot Water: Distinguishing TypesWater Heating Equipment – 5 Types:

Type Natural Gas Storage LPG Storage Oil Storage Electric

Storage

Electric Heat Pump

Storage

Defining Features

• Open draft diverter• Large pipes attached to the system, no ducts

• Looks like natural gas but with storage tank outside.• Boiler plate says LPG.

• Barometric damper• Oil injection controller• Flue

• Heavy wiring • No exhaust flue

• Compressor attached to top of water heater• Heavy wiring• No exhaust flue

Starting Efficiency 0.55 EF 0.55 EF 0.53 EF 0.87 EF Assume 2.5 EF

Example

PART 5: HVAC & DHW SYSTEMS - Paperlessinspectors 5: HVAC & DHW SYSTEMS Building Science Review Learn...

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