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More From RPA On Radiant Study

The recent article titled "RPA Refutes Canadian Radiant Study" (February 2002) brings up some interesting questions. While the study seems to indicate that some homeowners do not reduce their thermostat settings when living in radiantly heated homes, it does not address why.

It is a known scientific fact that the radiant component of comfort is an important one. Twenty-six pages in the ASHRAE Fundamentals Handbook (Chapter 8) are dedicated to thermal comfort. There are 120 referenced works on human comfort as well. The ASHRAE chapter goes to great lengths to explain the thermal interaction of the human body and the environment. The information presented is not conjecture; it is highly respected and soundly proven fact. Human comfort is determined by an energy balance between the heat generated by the body and the rate at which it loses it to the environment.

A number of factors affect human comfort such as humidity, activity level, wind speed and such. In a home, two of the largest factors are air temperature and mean radiant temperature. There are scores of formulas and algorithms presented for calculating these effects and scientific studies to prove the correctness of these equations.

Mean radiant temperature is the mathematical mean of all the surface temperatures surrounding the body. In essence, all the surface temperatures of windows, walls, ceilings, floors, etc., are added together and a mathematical equation applied to calculate what the combined effect is on the individual in the room. A large, cold window will cause this mean to drop while a hot fireplace will cause it to rise.

Figure 12 on page 8.17 of the ASHARE Fundamental Handbook graphically illustrates the relationship between air temperature and mean radiant temperature. It shows that as the mean radiant temperature is increased, the air temperature can be reduced to maintain the same comfort level. Radiant floor heating will effectively raise the mean radiant temperature in a home. The colder it gets outside, the warmer the floor gets.

As I recall, the Canadian study didn't record the outdoor temperature. Even if they did, the balance between mean radiant temperature and air temperature will change from day to day, hour to hour, depending on outdoor temperatures.

The bottom line is, there is no question in the scientific community that increasing the mean radiant temperature allows the air temperature to be reduced without detriment to human comfort, and this number can be quantified. It provides valid confirmation to the claims radiant promoters make concerning a lower thermostat setting in radiant homes providing the same comfort as a forced-air home at a higher setting.

The question remains, why were the thermostat settings in the Canadian sample set the same by the homeowner regardless of the type of heating system in the home. This is where the study falls down. Without further information and input from the homeowners, it is impossible to draw any conclusions? It can only raise questions and speculation. Are thermostats set out of habit? Are homeowners finding they are far more comfortable at the same thermostat setting they were use to in conventional homes? Are they electing to choose increased comfort over energy savings at lower thermostat settings? Are they now living in shirtsleeves instead of sweaters, stocking feet instead of slippers or utilizing areas of the home that would normally be cold and uncomfortable like basements or breakfast nooks with a lot of glass?

The study does pose an interesting question, but it probably has more to do with human psyche than human comfort. Are promoters of radiant heating making a bogus claim when they say people will live at lower thermostat settings and thereby save money?

Physiologically I would say no, the body would be just as comfortable at those lower settings. Maybe what this study has really discovered is just how unsatisfied homeowners are with the comfort in conventionally heated homes. They may tolerate discomfort at the officially recognized standard of 72 degrees F in a conventional home and relish true comfort at 72 degrees F in a radiant home.

Like I said, all that can really come out of this study are more questions. Anybody who would draw any other conclusion is skating on thin ice.

Lawrence Drake
Radiant Panel Association
Loveland, Colo.

A Plague On Houses

Katie Rotella's article in the February issue on mold was informative ("Mold: Environmental Bogeyman Or Contractor Nightmare?"). One of the major reasons for introduction of water into a building space is caused by failing to insulate the domestic water piping.

Cold water lines will form condensate, depending upon the dewpoint, and "sweat." If the pipes are concealed within walls, which is always the case, the moisture has no place to go and can be an abundant source of mold growth.

Plumbers would do well to specify and install adequate pipe insulation and prevent this very obvious "hidden" water source. In many residential applications, pipe insulation is omitted due to its "cost."

It looks like the attorneys will be making far more than the cost of pipe insulation to remedy this nightmare. Aluminum sash windows are another prime source of condensation, but that's for builders to examine.

Paul Pollets
Advanced Radiant Technology
Seattle, Wash.

Keep An Open Mind

Yes, I am a T&M contractor and seem to be doing fairly well at it. Maybe flat-rate pricing is the way to go. I'm not sure, but I will certainly keep an open mind about any such thing. The main reason I am writing is because I was reading "Recession Blues & Then Some," (February 2002), and I thought by its title it was going to be an interesting subject.

I was about midway through when I found out it was just another sales pitch from Frank Blau about his flat- rate scheme. Hey, like I said, maybe flat rate is a good idea and a better way to operate a business. But when somebody tries to jam something down my throat, I am gonna spit it out.

I would like to see Frank write about subjects that have nothing to do with his flat-rate scheme and start trying to be more helpful. Right now he's a salesman for his flat rate program. I hope to see some real-world financial advice in the future.

Gary Laubscher
Lock Haven Plumbing & Heating Inc.
Lock Haven, Pa.

Price Wrong, Article Right

Finally, an article with true grit ("The Price Is Wrong," February 2002). I'm sick to death of all the whining about slugs when the real slugs are the local and regional suppliers/manufacturers.

I will not and never have installed equipment sold at a discounted price by my local warehouses to my customers. I do everything in my power not to buy local since this trend developed. Furthermore, the suppliers and manufacturers need to realize those customers are mine and every other contractors'. PERIOD!! It is up to the contractor to determine product markup and installation fees.

Robert Dailey
Dailey's Plumbing & Heating
Harborcreek, Pa.

Praise For Our 'History Of Plumbing'

I am working on my family genealogy and found out that my great-great-great-grandfather was listed as a plumber on the 1880 census in St. Albans, Vt. That's how I found your History of Plumbing articles; I wanted to find out more about early indoor plumbing.

The article I read was a wonderful read and very informative. Thank you for giving associated information about health and safety concerns for the period as that added much to the picture I now have of my ancestor, Sylvester Dawson, and life as his family would have experienced it prior to the turn of the century. I never thought I'd be researching the plumbing industry, but you've made it fun.

Dawn Perry-Taft
San Luis Obispo, Calif.