RADIANT HEATING
Six myths tied to your radiant heat system:
surviving winter by warming up to reality

By Jerry Rothfeld

Radiant heating systems are nothing new; after all, the Romans used them 2000 years ago. Today, in their evolved and much-improved form, these systems are popular among contemporary architects, especially on high-end and avant-garde projects. Many installations throughout the world have been operating continuously, and successfully, since before the first Eichlers were built. Closer to home, radiant heating continues to bring both pleasure and frustration to Eichler homeowners.

For the Eichlers' original heat installations, this method of heating falls into a general category called hydronic heating. Simply, it uses water to transfer heat from a central source (usually a boiler) to a remote heating output. For Eichler applications, hydronic tubing is imbedded in the cement slab, but other residential applications include radiators, forced fan convectors, and baseboard convectors.

While not terribly complicated, especially in the single-family home application, they are somewhat special, and it is important to have at least a basic understanding of how these systems operate and recognize small problems before they become big, costly ones.

Here are some of the most common misconceptions -- what we call the myths of radiant heating -- which Eichler owners continue to pass on from neighbor to neighbor.

Myth #1: My original boiler is still running problem free. There's no need to replace it until it breaks down.

Don't believe it. There's no question that the original Eichler boilers have been remarkably durable, but they're not problem-free -- at least not beyond the surface. Some lucky folks with well-maintained boilers still have all the original parts in place, but these peripheral parts (the circulating pump, gas valve, expansion tank, fill valve, and controls) just simply wear out and need to be replaced. As the pump gets weaker, its decline leads to poor performance - certain areas of the house may stop heating, and the boiler can take many more hours to raise the house temperature.

Replacing these peripheral parts individually on numerous service calls is very costly, and can be terribly untimely. Some parts, such as the gas valve, cannot be used when a new boiler is eventually installed, and others will have to be moved to accommodate the new installation. Installers will seldom give credit for work performed in the past, or extend their warranty to those parts already replaced.

All this time the whole system is firing away very nicely.

Does high fuel cost and terrible pollution qualify as a problem? Most original Eichler boilers are over 40 years old, and grossly inefficient when compared to contemporary replacement models.

The original Eichler boilers simply cannot last forever. Will yours go out on Monday morning in the middle of July -- or the day before Christmas?

Myth #2: When it's time to buy a boiler, the higher the efficiency, the better the boiler.

Not necessarily true. A modern atmospheric, or naturally drafted, boiler can reach 85 percent efficiency, which is an upgrade of 20 percent or more over most of the original boilers presently in Eichlers.

High-efficiency sealed-combustion boilers reach the mid-90s, and sometimes even the high 90s, in efficiency. They typically have higher retail prices, and require special installation procedures that can add considerably to the final price. Servicing requires special training and expensive test equipment.

Some high-efficiency products have a better service record than others, but they all have moving parts and special electronic controls that are expensive and unique to the brand. While manufacturers may offer a ten-year (or longer) warranty on leaks from the boiler itself, controls are generally limited to one-year coverage.

These models also make more noise than a conventional boiler, some brands more than others. Still, there are many situations when a high-efficiency boiler is appropriate and cost-effective; but all factors should be carefully weighed against the additional six to ten percent fuel savings over a new atmospheric boiler

Myth #3: All steel-pipe radiant heat systems will eventually rust out.

Not always the case. A pipe in a 'closed-loop' system does not deteriorate in the same way as the drinking water piping. It does not consume water; and after an initial filling, goes oxygen dead after a few days. Hence, there is no corrosion or mineral build-up, regardless of water quality.

Steel pipes do not rust from the inside if the system is leak free and well maintained. That's a big 'if.' Steel pipes are very unforgiving, and even a minor leak left unattended can cause irreversible damage by allowing oxygen to be drawn in to the closed loop that can corrode the system. Wet conditions in the slab from poor drainage, roof leaks, or plumbing leaks can do serious damage to the outside of the steel pipes.

While steel pipes can be repaired, great care must be taken in the method and materials used. There are some good additives that can help extend steel pipe life, but unlike copper tube, total failures happen far more frequently.

Myth #4: Baseboard heating is the only practical replacement solution for a defunct radiant system.

It all depends. How does one define 'practical'? Typically, baseboard systems found in Eichler homes are replacement units comprised of long, fin-tube radiators with sheet metal enclosures that are positioned along walls in each of the heated rooms. Hydronic baseboards are hooked up to the existing boiler, if still operable, or a replacement.

While baseboards are perhaps the least expensive replacement option, they take up a lot of wall space and may be an aesthetic concern. Also, since they collect dust within their unit housing, they need to be cleaned periodically.

European-style flat panel radiators and towel warmers have many more design options; and fan convectors (which give instant heat and can be tucked under cabinets) can also be used in conjunction with the existing boiler and combined in the same system. An installer can assist in understanding and choosing from the many types and brands of products available for a whole-house hydronic heating system.

It is also possible to completely replace the radiant floor tubing without jackhammering out the slab. Using hydronic tubing, this is typically accomplished with an overlay of insulation and a poured cement-type material. However, this option raises the floor height by one-and-one-half inches or more, requiring changes to all of the door openings. The efficiency gained is significant, and so is the cost. But on a major renovation, it's worth considering.

Other heating alternatives usually involve rooftop forced air with multiple register holes cut through the roof, and heat blowing down from the ceiling. Roofing replacement is usually scheduled at the same time to seal in penetrations. These can be big-ticket items.

There are also moderately priced mini-split systems that combine air-conditioning with heat capabilities (as do the roof-top forced air systems), but do not require roof penetration, extensive ducting, and re-roofing.

Electric systems are available, but like the other options already discussed, they have special features that must be carefully weighed against the three rules of practicality: space, aesthetics, and cost (installation, long-term energy use, and maintenance).

Myth #5: Installing quality wall-to-wall carpet and pad will help keep heat in the house and increase overall comfort.

Absolutely not true. Carpeting and pad defeat most of the advantages of radiant heating, since they heat the wrong side of the floor.

When wall-to-wall carpeting with a pad are in place, the heating output per square foot could drop by 50 percent or more. In addition, the carpet certainly will add to the slow response time already required to heat the house and have an impact on utility bills.

Concrete, tile, and stone give the best output, followed by other hard floor coverings. If one must live with carpeting, there is a low 'R-value' pad available, but it still will not come close to matching the heat performance of the proper materials.

Myth #6: The original wall thermostat is inaccurate, but since it is line voltage, it can't be replaced with a programmable model without costly wiring changes.

Not these days. Programmable thermostats are required by code on all new houses for energy conservation, and are especially important on radiant systems, which typically have long response times.

Accurate, programmable setback thermostats that suit the very special single-pole, line voltage requirements of Eichlers are available, and can replace the existing thermostats with no extra wiring. These models should not be confused with double-pole or low-voltage models.

Even if the programmable features are not used, these modern thermostat models are far more accurate in a simple on/off mode than the old type of thermostat.

It is also possible to add controls that sense outdoor as well as indoor temperature. Common in Europe, on the East Coast, and in commercial applications where energy conservation is important, they anticipate and adjust for rapid changes in outside temperature to maintain an even heat in the house. They do cost more.

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