Radiant Installations - The Good, Bad and Ugly
Copyright © 2012 Robert Bean, R.E.T., P.L.(Eng.) and content providers. All world rights reserved. Thanks to our site visitors, content providers and the guys over at Dan Holohan's "The Wall" who shared a few of the images. If you wish for us to provide a photo credit just let us know.

For additional support visit our client service page.

As we have noted throughout the site, radiant system continue to be treated as popular science experiments even though these systems have been used for hundreds of years and researched to a level of engineering one would find anywhere in a professionally designed HVAC system.

We don't understand this phenomena of relatively educated people continuing to want to do silly things like throwing good money after experimental ideas.

Radiant when designed by professionals and installed by professionals is an elegant and efficient way of conditioning people. There is no need to "try" or "reinvent the wheel" just "do" what is proven in thermodynamics and engineering principles. Also it pays to work with the "Blue Chip" firms who provide leadership in codes and standards develop as well as application research. These top tier companies have brand name recognition which will serve you well when you go to sell your home.

Design and installation methods can be found in ASHRAE Handbooks, industry publications (see list of Professional Organizations in side bar) and design guides and software published by "blue chip" manufacturers.

The Bad (see more bad ideas)

A very bad radiant system...even an early grade school student understands that if you put a pot of water to boil directly on the element it will heat much better than if the pot is suspended in mid air above the element.

The high temperatures that this system would typically have to run at would completely destroy the efficiency of the heating plant and the expansion and contraction rate due to changes in temperature would cause stress in fasteners leading to noise and fastener failure. It matters not anyways since the system failed to perform from the start and needs complete demolition or abandonment.  

This is the same job as above and we want to draw your attention to the tube placement, lack of insulation and beginnings of an accumulation of dust on the pipes and reflective foil.

The use of reflective foil (above) in sub-floor systems is not without controversy. Radiation in an enclosure is difficult to model and the performance is subject to decay due to the potential fouling and accumulation of dust and debris. In principle it is nice to believe foil reflects energy from the pipe back towards the floor and improves efficiency but in practice the only practical way to efficiently and effectively condition a sub floor type system is with conduction using aluminum heat transfer plates along the entire tube length above or below the sub-floor.

The Ugly

We have no idea how one could call themselves an experienced professional and leave this type of mess in someone's home. Not only is it ugly but it failed to perform due to bad design and inadequate or missing components.

Remember this wisdom - whatever you have in your boiler room you will eventually have to sell with the property. Anything less in professionalism such as the examples above will partially destroy the value of your property.

The Good

The above represent acceptable options in sub-floor systems using aluminum (or graphite) heat transfer plates. Not shown is the required below sub-floor insulation.

The above represent acceptable options in poured floor systems. Shown in top photo's is the required sub-floor insulation.

Photo credit: Peter Kinsey

Photo credit: Uponor

Photo credit: Uponor

Photo credit: Uponor

Photo credit: Uponor

Related reading:

Do I need an engineer? A Guide to HVAC/Indoor Climate Design Services
Where will your indoor climate system score?
How to "ball park" your budget for indoor climate control.
Indoor environments: Self assessment
Built to code: What does it mean for consumer thermal comfort?
The Total Comfort System - The "Un-minimum" System
Thermal Comfort: A 40 grit perspective for consumers
Thermal Comfort: A Condition of Mind
Do-It-Yourself HVAC - Should you do it?
The Cost of HVAC Systems - Are You Paying Too Much for Downgrades?
Radiant Installations - The Good, Bad and Ugly
Thermal Comfort Surveys - Post Occupancy, Part I
Thermal Comfort Surveys - Post Occupancy, Part II

For additional support on this topic visit our client service page.