Flat panel radiators provide home with radiant comfort

Feb. 10, 2014
Radiant panels can overcome a lot of comfort problems caused by large sliding glass doors and bare concrete floors. Oversized flat panel radiators are keeping a family toasty warm even in their drafty old farmhouse.

“My wife and I would like you to visit our home to see if there’s anything that can be done to provide us with some comfort. We’ve been told the issues can’t be resolved.”

Like a moth to a flame!

“This is our wrap-around porch where we like to sit reading and enjoy the panoramic view of our farmland.”

The porch had been enclosed a number of years earlier with two walls of sliding glass doors: three on the longer wall and two more on the short wall … 175-sq.ft. of cold glass!

“It’s impossible to stay out here during cold weather as we feel like we’re in an icebox our feet feel like they’re frozen. Crazy thermostat says it’s 70°F in here too.”

I knew, at a glance, why.  

Baseboard hot water heating had been installed along the common wall to the house. Baseboard heating relies upon convection currents to carry Btus and this creates a rotating air-pattern for the flow of warmed air traveling up the home’s wall, across the ceiling, and down across the almost solid walls of glass to be chilled by the time it reached the hi-mass concrete floor of the enclosed porch. That now chilled air-mass was then pulled across their feet and the process repeated.

To continue the discussion about how you have applied advanced hydronic heating training while on a job, go to our new Plumbing Talk forum.

The human body is a perfect radiator! It gives off its heat in four basic ways: radiation when wearing light clothing (about 50%), evaporation of moisture from your skin (20%); convection to surrounding air currents (30%), and conduction if you are in contact with a cooler surface, like a cold hi-mass concrete floor covered only by a thin throw-rug. Whenever you are near a colder object, your body’s radiant and evaporation loss-rates are accelerated, which equals an increase in discomfort. In this case you can toss in conduction too.

Eyeballing the room, there was a small space above each of those sliding glass doors and an 18-in. drywall space between them. I spy comfort potential! But first a heat loss calculation was required. That provided the required Btus necessary on a design-day (the coldest day anticipated) and guidelines in my radiant design program default to 13°F for our area. One complication: they have a wood boiler with an oil back-up boiler they can turn on.

“Oh, we don’t use that at all and I turned off the power to it years ago.”

OK then, what temperature range do you allow the wood boiler to roam? Important knowledge to have when designing for radiant flat-panel radiators because that determines the operating design-conditions and you must design for the lowest water temperature the radiators will see and that their combined total output will meet, or beat, the room’s total heating load.

After installing the 7-ft. tall vertical radiant panel radiators and the supply/return lines we wrapped around the ceiling’s perimeter, it was time for a rapid changeover from the old baseboard heaters. Their human-thermal-comfort went into perfect balance. Say Ahhhhh.

Then, less than a month later…

“Can you return to go over some more issues?”

Moth to flame again!

“My wife’s feet are cold whenever she stands by the kitchen countertop, we have an electric radiant panel heater in the wall by our whirlpool tub, and our daughter’s bedroom — converted from being the attic — is far too cold, especially on windy nights.”   

A 3-in. tall flat panel radiator tucked nicely into the long toe-kick area of the kitchen cabinets — warm toes; that electric heater, which could easily be touched while sitting in water and was not on a ground-fault circuit, was replaced by a rectangular flat-panel radiator that included two towel hooks, so they’d have toasty-warm towels waiting to wrap up in when naked and wet; and the daughter’s bedroom was turned into a radiantly comfortable space by removing the undersized baseboard heating and installing a horizontal radiant flat-panel radiator. With the exception of the toe-warming kick-space radiator, all of the radiant radiators were custom-sized to their individual room’s heat loss. While the porch vertical flat panel radiators are on a separate zone, the bathroom and bedroom radiators are integrated into the home’s primary zone and deliberately over-sized to handle heat-robbing-drafts from high winds. The original hydronic piping was installed as parallel, instead of series, which allowed me to over-size the new radiators and incorporate a TRV (thermostatic radiator valve), so they can better regulate the room’s thermal comfort in their drafty old farm house by nimbly reacting to whatever challenges Mother Nature can conjure up.

Time flies! That job was completed 20-years ago. It wasn’t the first time we were able to resolve thermal comfort issues utilizing advanced hydronic heating training and there have literally been hundreds of opportunities to apply the lessons learned over many decades.

It’s time for me to begin paying it forward by providing training and that started in January of 2014 via online courses provided in conjunction with the Radiant Professionals Alliance College of Hydronic Knowledge. The Fundamentals of Radiant Design is well under way and will be available again this spring. The more you learn the more you can earn! Visit www.radiantprofessionalsalliance.org for more information on the Fundamentals of Radiant Design course.

All Dave Yates material in print and on Contractor's Website is protected by Copyright 2014. Any reuse of this material (print or electronic) must first have the expressed written permission of Dave Yates and Contractor magazine. Please contact via email at: [email protected].   

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