Heating Your Home

It should come as no surprise to anyone that a good heating plant is a mandatory part of most habitable structures. What is less well understood is the fact that such a heating system is important not only for the home's inhabitants, but for the structure itself. A good heating system helps reduce the moisture that enters our homes and accumulates as a result of day-to-day living activity.

A home's heating system must also be looked at as a source or potential solution to indoor and outdoor air quality. On the one hand, it is a potential source for toxic gases, such as carbon monoxide, and a contributor to outdoor air pollution. However, with good equipment and proper maintenance, it can filter and clean indoor air while minimizing the impact on the environment.

Index

  • Most forced air furnaces use filters to help clean the air that is distributed through the house. The most commonly found filter is the disposable kind which costs under two dollars a piece and is produced in various sizes. I would recommend that a box of such filters be purchased in the appropriate size for a particular furnace and that the filters be replaced every six weeks to three months during the heating season.

    Many gas furnaces use washable filters. Such filters can be cleaned by a hose, in the laundry tub, or in the dishwasher. The most efficient way to clean the air circulated by a forced air furnace is by the electronic air filter. The installation of such devices requires some modification of the duct system at the furnace. The maintenance of the electronic filter is vital to its proper operation and should be performed approximately every 60 days.

  • The most efficient method of converting any source of heat is the heat pump. This device is similar to the compressor found in refrigerators and freezers. It works by capturing the heat gained or lost in the process of compressing or decompressing various types of gases, such as freon. The heat pump can be used to heat the house during the winter and cool the house in the summer. Its maximum heating efficiency is when the outside air is in the high 40's and 50's. At temperatures below 35 degrees, the heat pump relies on a backup heating system, such as electric resistance heat. The installation of heat pumps is approximately three times more expensive than gas or oil furnaces and the required ducting systems need to be somewhat larger than other forced air heating systems. Heat pumps also require more frequent and somewhat more costly service than other furnaces. Service for heat pumps is recommended on an annual basis with costs ranging from $100-$800 per year.

  • Ground Source Heat Pumps use the more even temperatures of the soil for the "outside" loop. The coils (pipes) are dug into a series of trenches near the home. The advantage here is in the fact that in most places, soil temperatures are quite steady year around. This allowed the heat pump to work efficiently even when the outside air temperatures fall bellow freezing.

    One problem with these systems occurs during very dry periods. Moisture in the soil is needed to transfer heat between the coils and the soil. When the soil is too dry, the amount of contact between the coils and the soil can be too low for proper operation.

    I asked Bob Davis about Ground Source Heat Pumps. Bob is a Technical Consultant with Ecotope, and a real expert in the energy and heating field. Here are his comments:

    "On ground source HPs, my general reaction is that they CAN work well, but there are many reasons why they often don't (poorly done excavation, incomplete understanding of groundwater/earth heat supply/rejection capability, failure to keep track of the differential between cooling/heating capacity, duct leakage, etc.) The premium the homeowner pays for the system ($8-10k over same size air-to-air installation) is extreme; the ground source CAN be twice as efficient as the air source system but that's not a given. So I advise people to proceed cautiously on getting these systems. In general, the most enthusiastic GS customers are well-to-do; they want a Cadillac system and are willing to pay for it; their primary concern isn't necessarily a more efficient system.

    "I've looked at a few of these systems (mostly in Montana) and found a range of installation quality and performance. I recently looked at one in Snohomish County (Washington) that was working as designed, but the installer had cut it really close on sizing and the backup heat was coming on a fair bit. The house and ducts were relatively tight; I think the installer had just failed to realize that a "3 ton" system only delivered 29,000 Btu/hr at the entering water temp that was available. I generally specify systems that are undersized relative to most contractors' experience, but this is a case where the next size up would have probably done better, in terms of efficiency." - Bob Davis, Ecotope

  • Example of a set-back thermostat Available from our Sponsor: PexSupply.com

    An inexpensive addition to most central heating systems is a multiple set back clock-type thermostat that allows for the pre-programming of different temperature levels at various times during the day or week. Such thermostats are designed to keep a minimum temperature level (approximately 58-60 degrees) in the house at all times, and an increased temperature for those other times when higher temperature levels are needed by the occupants. These thermostats also have a simple override feature which allows for an increase or decrease in the temperature at unusual times when the normal settings are not appropriate. Such thermostats are relatively easy to install and when properly used, they will repay the initial investment of $50-$100 over a short period of time.

  • Most homes are not designed for heating with wood stoves, fireplace inserts or similar devices. Most appliances which use wood as a heating source are primarily used to heat a portion of the home or create a desired atmosphere. Typically, such wood burning appliances overheat one portion of the house, and if located near the thermostat for the central heating furnace, may cause other portions of the house to be too cold.

    Our inspections suggest that a disproportionately large number of wood burning appliances are improperly and unsafely installed and are often used to burn trash, dirty and unseasoned wood which further contributes to fire danger, creosote, and soot build-up inside the chimney. It also contributes to the air pollution outdoors. Recent changes in air pollution control regulations have further restricted the use of wood burning appliances, especially in the fall and early winter, when temperature inversions are common.

    The most efficient and clean burning wood stoves appear to be the pellet stoves. When used in a home with an open floor plan designed for wood heat, such stoves may be an efficient and effective way to heat some homes. Pellet stoves and their mechanical components require regular maintenance. And, unless equipped with a battery backup system, they will not work in a power outage.

  • The short lived popularity of solar heating is most likely attributable to three factors: the lowering of energy costs after the oil crisis, the oversimplification of how it works, and the promotion of dubious passive solar heating devices by snake oil salespeople.

    However, there is little doubt the passive solar heating works in almost any climate. This house was designed by Van Horne and Van Horne Architects, and built by George Guttmann, General Contractor in 1981. It has been using less than $200 a year in fuel, about 1/3 the normal amount for a house of a house of this size in the Seattle area.

    In designing or remodeling a home, the sun's impact on the heating and cooling of the str