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Old-House Online » Old-House Tips, Restoration Stories, & More » Interiors & Decor » 5 Heating Options for Old Houses

5 Heating Options for Old Houses

Tips to help make your vintage heating system more efficient.
By James C. Massey & Shirley Maxwell

    A centrally located floor register is one way to diffuse heat, and some were quite decorative. This reproduction is from Reggio Registers.

    A centrally located floor register is one way to diffuse heat, and some were quite decorative. This reproduction is from Reggio Registers.

    In our automated age, it’s easy to take heating systems for granted—the wood-fueled fireplaces and coal-stoked furnaces once critical for winter comfort in most American homes are long gone. Yet adding or adapting HVAC systems to old houses today often involves a complex web of issues, and modern systems and devices can compete with our desire to preserve the past.

    Central heat, as opposed to fireplace heat, is not a new idea—the Romans used an early version called a hypocaust, and there were isolated steam and hot-water heating systems in Europe by the end of the 18th century. Still, our colonial ancestors relied mostly on open fireplaces with simple andirons to hold split logs. From the late 18th century and increasingly in the early 19th, more fortunate residents of East Coast cities used coal in fireplace grates. Built-in grates of iron or steel were a quality fireplace feature; few have survived intact.

    Improvements to chimney flues occupied many scientific minds. The simplest was the fireback, a decorated slab of cast iron placed at the rear of the firebox to retain and radiate heat. Benjamin Franklin’s “Franklin stove” was a cast-iron insert designed to keep more heat inside the room. German settlers made good use of cast-iron stoves, either projecting from a fireplace (the five-plate stove) or freestanding (six-plate).

    The 19th century brought improved heating and ventilating systems. Ducted hot-air systems appeared in some upscale homes, and buildings were warmed with heat generated by huge brick furnaces in the cellar, which vented into rooms through floor and baseboard registers, usually with decorative rotating vanes to regulate air flow. As American mines opened, the use of coal increased rapidly, and coal grates often replaced wood in both fireplaces and kitchen stoves. Coal’s advantages were many: small, compact chunks that burned slow but hot—and were delivered directly to the cellar through a coal chute located on the exterior of the house.

    The post-Civil War era ushered in hot-air furnaces made of cast iron with a large main grate set in the floor above. Sometimes, in the better systems, sheet-metal ducts fed warm air to other rooms as well. Hot-water- and steam-piped systems with decorated cast iron radiators soon followed. This is where many old-house enthusiasts come in, having bought an old house with one of these antique heating systems.

    1. Mini-Duct Forced Air System

    Mini ducts’ flexible tubing allows for installation just about anywhere, without sacrificing a ton of space.

    Mini ducts’ flexible tubing allows for installation just about anywhere, without sacrificing a ton of space. (Photo: Courtesy of Unico)

    Widely known as the Unico System after one of the companies making it, mini ducts are usually employed for air-conditioning, though the system also can be used for heating with an optional electric furnace. It blows treated air at high velocity through flexible 2″ or 2½” nylon tubing through unobtrusive vents. It can be invaluable for old-house retrofits because the vents, usually in the ceiling, create little impact on the walls and framing—the tubing can be snaked through and around obstacles, avoiding many of the problems of caused by retrofits of large, solid ductwork. Several outlets may be needed in each room.

    2. The Modern Fireplace

    Adding an insert—wood-burning, gas, or electric—is an easy way to make original fireplaces more efficient.

    Adding an insert—wood-burning, gas, or electric—is an easy way to make original fireplaces more efficient. (Photo: Courtesy of Lopi)

    The traditional cozy fireplace can be updated and improved with innovations that include a natural- or propane-gas fire, or new types of inserts. Many attractive metal Victorian-style inserts for coal or wood fireplaces are made with optional matching mantelpieces. Electric heat inserts with faux flames upgrade the old fireplace without gas piping. A Fires of Tradition model features not only faux flames but also smoke in a Victorian-style cast iron unit that requires no venting. For actual wood fires, energy-conserving inserts based on the shallow Rumford design are available. (Fires of Tradition offers traditional grates in a dozen different styles.) Valor Fireplaces offers a variety of gas-fired inserts, which provide heat through power outages.

    3. Hot-Water & Steam Radiators

    Radiators provide wonderful warmth. New models from Runtal fit a variety of old houses.

    Radiators provide wonderful warmth. New models from Runtal fit a variety of old houses.

    Common in the late 19th century and standard until the recent past, radiators provide generous heat and are relatively easy to install. After World War II, the hand- or machine-stoked coal furnaces were replaced by ones automatically fed with relatively clean-burning oil. With the arrival of central HVAC systems by the 1960s, hot-water radiator installations faded, except for a growing number of restorationists who delight in decorative antique radiators. The repair and refinishing of old radiators and the sale of antique ones is now a thriving business.

    For residential heat, steam was used less than hot water, but both systems are easily repairable. Modern radiators, flatter and updated in appearance, are readily available today; many are made by Runtal, which specializes in wall-mounted flat steel panels. Traditionally, radiators were hidden under wood or metal covers, a practice still widely used. They are made by several companies, such as The Wooden Radiator Cabinet Company and Monarch. An alternative to radiators is baseboard heat, with copper pipes and fins in a sheet-metal enclosure that follows the room’s walls—less desirable because it obscures the historic baseboards. If your house already has them, they can be hidden behind new covers.

    4. Radiant Heat

    This radiant system was installed into a Colonial Revival house in Strasburg, Virginia.

    This radiant system was installed into a Colonial Revival house in Strasburg, Virginia.

    Hot-water pipes embedded in the floor, generally set in concrete, became popular after World War II, particularly for slab-on-grade houses. Radiant heat provides a comfortable, encompassing warmth, as opposed to the fixed-point heat of radiators and hot-air registers. Seventy years ago, thousands of Levittown houses had radiant heat installed in floor slabs, and Frank Lloyd Wright used it in his Usonian houses. Such early installations were prone to leaks, usually because of eventual pipe corrosion, and originals are difficult and expensive to repair. However, modern radiant heating is much improved.

    Today, hydronic panel systems use small, reinforced PEX tubing to carry warm water beneath finished flooring, radiating heat up. The tubing is easy to install on top of a subfloor, and can be finished with wood or tile. PEX comes in coils up to 1,000′ long, permitting a single one to be run sequentially throughout several rooms of the house in one circuit, or in separate circuits for zoned heat. It is a flexible system good for old-house rehabs when the flooring is accessible from underneath or can be replaced. (The downside: It supplies heat only, not air-conditioning.)

    Electric under-floor radiant systems like those made by Thermofloor and Schluter Ditra-Heat are also easy to install under new finish floors of wood or tile. These are especially useful in small installations like kitchens and baths because they don’t require a separate powered heat source.

    5. Forced Air

    By mid-century, forced-air furnaces were everywhere. this model from Rheem was pretty enough to sit in the living room.

    By mid-century, forced-air furnaces were everywhere. this model from Rheem was pretty enough to sit in the living room. (Photo: James C. Massey Archive)

    Forced-air heating systems also can provide ventilation and cooling, and have been the preferred system in new houses for the past 50 years. However, installing large, insulated ducts in an older house can be difficult and unsightly, or require sacrificing much of the closet space. One solution, assuming that the house has both a basement and attic, is to use floor registers on the first floor with the fan-coil unit in the basement, and ceiling outlets on the second floor, with a separate unit in the attic.

    See resources for this story here.

    Published in: Old-House Journal February 2015

    { 2 comments }

    Ken - the OldHouseGuy December 22, 2014 at 12:59 pm

    I’ve been heating with my 1941 Octopus furnace up until last year. For those that have antique furnaces see my furnace and what I did regarding my dilemma of preserving my furnace vs a high efficiency new furnace. http://www.oldhouseguy.com/heating-old-octopus-furnace/

    Mark Eatherton January 8, 2015 at 12:37 pm

    Greetings and Happy New Year! Excellent article showing the many ways we have at our avail for keeping people in these grand old homes comfortable. However, in the article, you state ‘The tubing is easy to install on top of a subfloor, and can be finished with wood or tile. PEX comes in coils up to 1,000′ long, permitting a single one to be run sequentially throughout several rooms of the house in one circuit, or in separate circuits for zoned heat.”

    I would caution your readers that running a 1,000 foot long continuous circuit is going to be rather problematic. Hydronics has some fairly straight forward rules we must adhere to in order to guarantee proper performance and excellent comfort. The 20 year old nationally recognized organization that I am the Executive Director of (Radiant Professionals Alliance) has guidelines that dictate how long a specific circuit can be.

    For 1/2″ I.D. tubing, it is recommended that the lengths be limited to 300 feet, and for 3/8″ I.D. (shown in the photos) it is limited to 200′. This avoids the circuit running out of heat before the fluid gets to the end of the circuit, and also avoids costly pump operation in order to overcome the pressure drop of trying to flow water through a circuit of this extreme length.

    Having been in this business for 38 years, I have seen my share of mistakes made by uneducated, well intentioned people, and this 1,000 foot long circuit is guaranteed to not work as designed, resulting in dis-satisfied customers, and unwarranted negative publicity about this method of comfort delivery.

    Personally, I always recommend a shorter maximum circuit length to avoid ending up with a bunch of 100′ left over coils at the end of the job. I prefer to run my 1/2″ I.D. circuits at 250 feet in length, or there abouts, which will eliminate any tubing waste associated with the job, and also allow a lower drop in fluid temperature, which equates to a higher average surface temperature, which equates to energy savings and higher comfort throughout.

    Although radiant floors are an excellent means of delivering comfort, they are initially more expensive than some of the alternative methods and their output is limited due to the human contact with the emitting surface. In many older, poorly insulated homes, the floor by itself probably will not be capable of carrying the heating demand at design conditions due to this thermal limitation.

    Radiant walls and radiant ceilings, using the very same materials you have show in the article will deliver a very comfortable and energy efficient feeling, and are much easier to retrofit into an existing home than installing radiant floors, and have a higher thermal output capacity due to the fact that humans are not in direct contact with the emitting surface.

    Both of these systems (floors and walls) have been around since the early 1900′s, and many of them are still working and delivering excellent radiant comfort.

    In the article, you also mentioned that the radiant system can not provide air conditioning. While that statement in and of itself is true, we do have the ability to affect human comfort with radiant cooling. Commercially speaking, radiant cooling has been around for over 20 years. It does still require some air movement to remove the humidity from the surrounding air, but it does work in delivering excellent human comfort by affecting the surface temperatures within a given space, or what we refer to as the Mean (average) Radiant Temperature.

    The amount of air movement necessary to control the humidity is significantly less than a typical air conditioning system, and will result in a significant reductions in energy consumption to deliver a higher degree of cooling comfort.

    I would encourage your readers to visit our web site, and educate themselves before they tackle a major job like this. Although it isn’t rocket science, it does require adhering to some well thought out, proven methodologies that will keep the consumer from experiencing the discomfort associated with an improperly designed and installed job.

    If you or any of your readers has any questions, I’d be glad to answer them. I can be reached at mark.eatherton@radiantprofessionalsalliance.org.

    Sincerely,

    Mark Eatherton
    Executive Director
    Radiant Professionals Alliance
    http://www.radiantprofessionalsalliance.org



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