HW:Quiz1 answers

Page 1: Heating Systems Overview

Differences in Heating Equipment

  • Boiler vs. Furnace:

    • A boiler heats water and generates steam or hot water for heating, while a furnace heats air and distributes it through ducts.

Loop Types

  • Open vs. Closed Loops:

    • Open Loop: Water is directly sourced from a supply (like a lake or well) and returned after use.

    • Closed Loop: Water circulates within a closed system, being reused and heated without direct draw from a supply.

Circuits for Heating

  • Boiler Heating Circuit: Closed loop.

  • DHW (Domestic Hot Water) Circuit: Often open loop, depending on the setup.

Devices for Movement

  • Water Movement:

    • Requires a Pump.

  • Air Movement:

    • Requires a Blower.

Acronyms

  • CFM: Cubic Feet per Minute (airflow measurement).

  • GPM: Gallons per Minute (waterflow measurement).

  • FPM: Feet per Minute (air velocity measurement).

Measurement Units

  • Airflow: Typically measured in CFM.

  • Waterflow: Typically measured in GPM.

Key Definitions

  • Combustion Chamber: Area where fuel is mixed with air and ignited to produce heat.

  • Heat Exchanger: Device that transfers heat from one medium to another without mixing them.

Page 2: System Components

Gas Valve Function

  • Gas Valve: Controls gas flow to the burner based on system demands.

Register Differences

  • Supply Register: Delivers heated air to the space.

  • Return Register: Collects air from the space to be reheated.

Boiler Input

  • Boiler INPUT: Indicates the heating capacity of the boiler, usually in BTUs.

BTUs and Atmospheric Burners

  • BTU Production: An atmospheric burner can produce approximately 100,000 BTUs per hour.

Orifices Installation

  • Orifices: Installed in gas lines to regulate gas flow.

Pressure Measurements

  • PSI: Pounds per Square Inch.

  • Inch of Water Column (in.w.c): Measurement of low-pressure systems, often for gas pressure.

  • Tire Pressure Units: PSI is commonly used.

  • Gas Pressure in Manifolds: Measured in inches of water column.

  • Duct Air Pressure: Also measured in inches of water column.

Page 3: Combustion and Monitoring

Pressure vs. Pressure Drop

  • Pressure: The exerted force of gas or liquid per unit area.

  • Pressure Drop: Reduction in pressure over a distance, indicating resistance or blockage.

Byproducts of Combustion

  • Combustion Byproducts: Include carbon dioxide (CO2), water vapor (H2O), carbon monoxide (CO), and other particulates.

Draft Hood Function

  • Draft Hood: Ensures proper airflow for combustion and prevents backdraft; crucial for maintaining safe operation.

Thermocouples in Systems

  • Thermocouples: Provide temperature readings to ensure pilot lights are on, maintaining safety.

Ignition Components

  • Spark Production: Components include ignition transformers and electrodes.

  • Ignition Detection: Using Flame Probes to sense flame presence via heat or light detection.

Flame-Rod Functionality

  • Flame-Rod: Detects flame by measuring the electrical conductivity of the flame.

Heat Exchanger Types

  • Single vs. Double Heat Exchangers:

    • Neither is inherently better; it depends on efficiency and application requirements.

Page 4: Draft Classification

Draft Types

  • Natural Draft vs. Induced Draft:

    • Natural Draft: Relies on temperature differences to vent gases.

    • Induced Draft: Uses fans to actively push combustion gases out.

Condensing vs. Non-Condensing Appliances

  • Condensing Appliances: Capture latent heat from exhaust gases, increasing efficiency.

  • Non-Condensing Appliances: Do not recover latent heat, leading to lower efficiency.

Efficiency Comparison

  • Condensing Units: More efficient due to heat recovery capability.

Venting Categories

  • Three Venting Categories:

    • Direct vent, natural vent, and power vent systems based on how combustion gases are expelled.

Identifying Condensing vs. Non-Condensing

  • Visual Indicators: Look for plastic piping or side venting in condensing units, whereas non-condensing units typically have metal exhaust.

Appliance Efficiency Ratings

  • 70%, 80%, and 90% Appliances:

    • All convert fuel to heat but vary in efficiency; higher percentages indicate better heat retention and less wasted energy.

Importance of Flame Sensing

  • Flame Sensing: Crucial for safety to ensure that a flame is present, preventing gas leaks and potential hazards.

Page 5: Draft Differences and Fuel Types

Induced Draft vs. Forced Draft

  • Induced Draft: Uses a fan to remove combustion gases downstream.

  • Forced Draft: Forces combustion air into the burner for improved combustion efficiency.

Combinations of Drafts and Fuels

  • Fuel Types:

    • Natural gas typically uses induced draft while home heating oil may use forced draft for consistent delivery.

Boiler Types

  • Fire-Tube vs. Water-Tube:

    • Fire-Tube: Hot gases pass through tubes surrounded by water to heat it.

    • Water-Tube: Water flows through tubes heated by surrounding combustion gases.

Three-Pass Fire-Tube Boiler

  • Three-Pass: Gases travel through the boiler three times before exiting, maximizing heat transfer efficiency.

Boiler Recognition

  • Familiarize with visual differences between fire-tube, water-tube, copper-fin, cast-iron, and electric boilers as discussed in class.

BTU Measurements

  • BTU vs. BTUH:

    • BTU: Measures heat energy.

    • BTUH: Measures heat transfer rate per hour.

BTU Classifications

  • BTU, MBTU, MMBTU:

    • BTU: 1,000 BTU; MBTU: 1 million BTUs; MMBTU: 1 billion BTUs.

Gas Consumption Calculation

  • Gas for BTU Generation: Calculate based on heating values, considering gas flow rates and energy content.