Heating and Heat Pumps

Table of Contents

Natural Gas
Electricity
- Electric Resistance Heaters
  - Electric Furnaces
  - Electric Baseboard Heaters
  - Electric Wall Heaters
- Heat Pumps
  - Standard Heat Pump, analogous to HVAC system
  - Min-splits, analogous to space heater and window A/C
  - Geothermal, outside unit is deep underground
Propane
Fuel Oil
- Highest Heating Costs in Years Strain Many in New England NYT March 2023
Wood

Graphics from U.S. home heating is fractured in surprising ways
WaPo Interactive, March 2023

A heat pump is an air conditioner that can run in reverse

US residential heat pumps: the private economic potential and its emissions, health, and grid impacts, by Thomas A Deetjen, Liam Walsh and Parth Vaishnav, Published 28 July 2021 iopscience.org
- We simulate the energy consumption of 400 representative single-family houses in each of 55 US cities both before and after heat pump adoption. We use energy prices, CO₂ emissions, health damages from criteria air pollutants, and changes in peak electricity demand to quantify the costs and benefits of each house’s heat pump retrofit.
- The results show that 32% of US houses would benefit economically from installing a heat pump, and 70% of US houses could reduce emissions damages by installing a heat pump.

According to the WaPo article
- “The switch from natural gas to a heat pump will often save money, but the amounts saved vary by location: In bitterly cold areas, homeowners may also require a backup source of heat that costs more.
- On the other hand, the South and rural areas around the country stand to gain the most from switching to electricity in general, and heat pumps in particular.
  - In the South, where homes are already electrified, switching from old resistance heaters to heat pumps would save homeowners money. Heat pumps, because they move heat instead of creating it, are on average three to four times more efficient than resistance heaters. They also provide built-in air conditioners.
  - In rural areas, moving away from fuel oil and propane will also save cash. According to the nonprofit Rewiring America, homes currently heated by fuel oil will save, on average, $949 per year by transitioning to an electric heat pump; those heated by propane will save around $680 a year. “

According to Consumer Reports
- “Homes that heat with propane, oil, or “regular” electric-resistance systems are the most likely to save money by installing a heat pump. Propane and oil are always expensive. And electric resistance heating uses an average of two-and-a-half to three times as much electricity as a heat pump does to produce the same amount of heat.
- Gas-fired heating equipment tends to cost less to operate than electric heat pumps, says Dave Lis, a director at the Northeast Energy Efficiency Partnerships, though the running costs are often pretty close.”

The key part of a heat pump (and an air conditioner and a refrigerator) is the refrigerant, which changes temperature on its travels, transporting heat or cold from one place to another.
Two principles govern the temperature of the refrigerant:
- Gas Principle:
  - Compressing a gas makes it hotter and, conversely, expanding a gas makes it cooler. For example;
    - A diesel piston compressing the fuel in a cylinder so much that the fuel gets hot enough to ignite.
    - A can of compressed air getting cold when air is released.
- Second Principle
  - Heat travels from a hotter object to colder surroundings and, conversely, heat travels to a colder object from its hotter surroundings. For example
    - A piece of hot metal is immersed in room temperature water
    - A refrigerated jar of anchovies is immersed in hot water.

The steps are the same except “inside” and “outside” are switched.

The Gas Principle is in effect the Ideal Gas Law and the Second Principle the Second Law of Thermodynamics.
- wikipedia.org/wiki/Ideal_gas_law
- View Second Law of Thermodynamics