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Radiant floor heating zone manifold (C) D Friedman R ArlyckRadiant Heat Guide
Strategies for using radiant heat

Radiant heat uses, designs, options:

This article discusses the basics of radiant heat for auxiliary heating or basic heating in buildings, including strategies for using radiant heat. The article also compares the costs of types of heating system use and we describe hydronic (hot water) radiant heat and electric radiant heat systems.

We describe typical installations of both hydronic tubing and electric radiant heat, including thin film electric radiant heat panels below several types of finish flooring. Our page top photo illustrates the heating boiler, circulators & mixing controls for a multi-zone radiant floor heating system installed during reconstruction of a home in Tivoli, NY.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Radiant Heat Use in buildings: when, why, how to use radiant heating

Radiant heat floor under construction (C) Daniel FriedmanSketch at page top and accompanying text are reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.

The sketch explains that the radiant heat effect of a hot surface depends on the angle that the surface forms with the subject. Large surfaces facing and close to the subject provide the most radiant heat.

[Click to enlarge any image]

Key articles on radiant heated floors & radiant heat installation, troubleshooting, repair

Fuel cost comparison for space heating (C) Daniel Friedman"Radiant Heating, how it works, when to use it"

The table (left) included in this radiant heat article provides a typical fuel cost comparison for space heating.

The basics of Radiant Heating Systems

This article explains how radiant heating systems work, it describes the comfort of radiant heating systems, and it provides strategies for using radiant heat in buildings effectively.

The author, Steven Bliss, explains how to use radiant heat most comfortably, citing the ability to heat large areas to relatively low temperatures (rather than providing concentrated heat source), the evenness of radiant heat, and the importance of mass inside the structure to help keep temperatures even and comfortable through the thermostat cycling on and off where radiant heating systems are installed.

The author describes relatively low-cost in-floor radiant heating systems using hot water as well as electric heating elements. In-drywall radiant heat products are also explained and described for ceiling use.

Advantages of radiant heating systems

Radiant heat floor under construction (C) Daniel Friedman

Our photo (above) shows a radiant-heated concrete slab under construction in Two Harbors, MN in 2007.

Disadvantages of electric radiant heat systems

Radiant heat boiler (C) Daniel Friedman

Floor Damage, Gaps, & Odor Complaints with Radiant Heat Installed under Wood Floors

Radiant heat caused floor gaps (C) Daniel Friedman

We (DJF) have investigated a number of complaints of gaps opening between the boards of finished wood flooring and complaints of odors emitted from some types of tubing used in radiant floor heating systems.

Diagnosing gaps in finished wood flooring can be tricky, since these may appear with or without under-floor radiant heating systems installed, especially if the flooring is installed too quickly, without having adjusted its moisture level to that of the building. Installing wood flooring that is at too high a moisture level risks shrinkage and floor gaps as the building dries out.

In some cases that we investigated, flooring gaps appeared after an installer or owner pushed the radiant floor heating system to a temperature higher than recommended by the equipment and tubing manufacturers.

The temperature push was made in an attempt to "cook out" odors emitted from the radiant floor tubing when the heating system was first fired up.

Typical Cost of Radiant Heating Systems

Electric radiant heat ceiling panels (C) Daniel Friedman

Heating system costs are divided into installation or "first" costs, regular maintenance costs, and operating costs. Our photograph (left) shows two Therma-Ray electric radiant heat panels being installed in the ceiling of a 1960's home in Poughkeepsie, New York.

These panels were replacing previously damaged ceiling components. Be careful about cutting holes in drywall ceilings where electric radiant heating panels have been installed.

Here we include solar energy, solar heating, solar hot water, and related building energy efficiency improvement articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.

Thin Film Radiant Heating Systems for Ceilings & Floors - types, where to buy

An alternative to hydronic, tubing-based radiant heating systems that were discussed above, at TYPICAL COST of Radiant Heating Systems we cited electrical radiant heating systems including panels used in ceilings or floors. [See our photo above for an older version of electric heat in gypsum ceiling panels.]

These electric radiant floor heating systems use comparatively thin flexible heating film panels (IHS-CPF) that are wired to a dedicated electrical circuit and of course controlled by a room thermostat. Some radiant heat panel sources include:

Note on Avoiding or Insulating Heat Sources rather than Producing Heat:

Too many of the electric radiant heat flooring searches we made turned up advertising pages where writers collected sources a bit hastily. We include the content below to help readers sort out the products they want (radiant heat flooring materials) from other stuff.

HeatShield panels, (Valley Center, CA 800-750-3978 ) produces heat insulating panels - in case you need to shield from heat rather than to direct heat into a building area. Heatshield Radiant Heat Mats (Amazon.com) are sold in an adhesive-backed form used, for example, in the automotive industry.

Examples of Thin Film Radiant Heat Flooring Installations for Different Flooring Materials

The Calorique company provides radiant floor heating systems in several designs including specifically for use below laminate flooring, carpeting, vinyl tile, linoleum, and ceramic tile floors. Calorique's system uses individual thin film panels connected to a 30-A electrical circuit to provide heat below these types of floor materials. Calorique describes these radiant heat floor installation examples:

Radiant Heat below glued carpet, wood, vinyl, or linoleum floors in dry surroundings

Radiant Floor heat below floating type wood, laminate, or parquet flooring in dry surroundings

Radiant Floor heat below ceramic tiles in dry surroundings

Radiant Floor heat under tiles in wet surroundings

- Thanks to reader Jim O'Dowd for suggesting this resource.

Original article

Links to the original article in PDF form immediately below

CONTACT us to suggest other types or suppliers of radiant heating systems and equipment.

InspectAPedia is an independent publisher of building, environmental, and forensic inspection, diagnosis, and repair information for the public - we have no business nor financial connection with any manufacturer or service provider discussed at our website. We are dedicated to making our information as accurate, complete, useful, and unbiased as possible: we very much welcome critique, questions, or content suggestions for our web articles.

Radiant Heat Installation & Operation & Temperature Guides

These references, studies, guidelines on radiant heat temperatures, heat losses, etc. are found

at RADIANT HEAT TEMPERATURES

 




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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2023-04-17 by InspectApedia Publisher (mod) - repair kit & instructions for fixing damaged electric radiant heat cables or wires

Electric radiant heat cable repair kit from NuHeat cited & discussed at InspectApedia.com@Alex,

I was not sufficiently clear in my earlier answer suggesting that you're looking at a wire splice whose connections need to be approved & safe as well.

There are literally dozens of manufacturers of electric radiant heat wire manufacturers whose products can be installed in a ceiling or used to repair broken radiant heat wire in a ceiling.

I'll paste screen shots giving an example, simply searching for "electric radiant heat ceiling wire" and of radiant heat electric cable repair kits.

You'll want to contact the manufacturers directly to ask for advice about code-approved and electrical- and fire-safe connections when repairing such wiring.

The concern is that using typical electrical wire connectors may lead to a failure as wire used for radiant electric heating goes through so many temperature cycles and heating variations.

The good news is that electric radiant heat cable manufacturers also make wire or cable connection and repair kits.

For example, NuHeat offers a radiant heat cable repair kit and repair instructions.

I'll post a photo of the repair kit and a link to radiant electric heat repair instructions above.

Below: example of sources of electric wire cable used for electric radiant heat systems.

Where to buy electric radiant heat cable or wire - at InspectApedia

See these

On 2023-04-17 by Alex - where do I find repair wire for electric radiant heat in a ceiling?

@InspectApedia Publisher, problem is that I can’t find the heat wire manufacturer. All I have is the picture of that wire & can’t seem to find any other info on it or if I need to solder or use a butt slice to reconnect wire. Any other info that you have would be appreciated. Thanks

Electric radiant heat wire cable markings (C) InspectApedia.com Alex

I’m trying to find radiant heat wire that was used in ceilings I heard around the 1960’s. Single conductor with thick insulation. Looks like a size 22awg wire from a home in California. Looking for a replacement wire that I could use to splice into. It is stapled onto drywall then gets mudded to hide in ceiling.

Photo: UL listed electric wire for radiant heat system, identified as (UL) E-25612 90°C

This Q&A were posted originally

at OLD ELECTRICAL WIRING TYPES 

On 2017-05-30 - by (mod) - how do we determine if electric radiant heat is working & safe to use?

Diana,

Sounds as if the home inspector took an easy way out. I would think he would have told you if there was a functional or not functional heating Source in the house. Just saying evaluate further is a little vague.

It's possible that the heat is or was electric radiant floor heat but I really can't know from your text. An inspector with a little bit of experience ought to be able to look at the controls and try turning them on to see if the floors get warm.

On 2017-05-30 by Diana

Situation: Currently in escrow on a home built in 1978. Home inspector only recommended further evaluation of the home's radiant heat.

A prior owner installed central A/C and heat. There is no known broiler, pump or any such device visible for the radiant heat, but there are analog knobs on the walls in each room to control it. Not sure if it is operable or safe.

Question: What is the method for determining:

A) Is it safe to operate?

B) Is it electric or hydronic?

C) If installed to a home on a raised foundation if it runs in the floors or the walls?

D) Is it still operating (functional)?

E) What type of professional would service or inspect this system?

On 2016-04-28 - by (mod) - radiant heat "caused" cracks in concrete floor?

Sorry to hear this trouble, Susan, and surprised that radiant heat would cause the floor to crack. Perhaps you first want to get some help with diagnosing the cracking cause: is it in the pattern of the tubing or at stress points or is there foundation settlement, or slab heaving or something else?

About the tubing: take a look at the tubing where it is exposed to view.

Armed with the brand name and tubing model name we can look up the manufacturer's temperature rating. It may be that though 180 was too hot, the tubing may be un-damaged.

Post a photo so that we can see more of what's going on.

On 2016-04-27 by Susan

I have radiant heating in my indoor concrete floor. I understand that my boiler system was installed incorrectly and water temperatures of 180 was running through the tubing ...my concrete floor is severely cracked ... what is the maximum temp of water for the tubing and what concerns should I have with regard to damage to tubing ...life of tubing ...

should it be replace ...please let me know if there are any other concerns I might have
thank you for you time

On 2015-01-22 - by (mod) - do we need the auto or fan setting on the thermostat when using electric radiant heat

Anon

Presuming your heating system is only providing heat the FAN setting should be irrelevant as it ought not be connected to anything.

I'd use AUTO or HEAT if there is a HEAT position.

In the More Reading links above see THERMOSTATS, HEATING / COOLING for articles that include the thermostat switch settings.

On 2015-01-22 by Anonymous

we have radiant heat- do I put it on auto or fan in the winter

On 2014-10-29 by Aimee - poles to support a radiant heat wall unit?

I just moved into a condo with radiant heat ceilings. I want to install 4(four) One inch (1") by one inch poles to support a wall unit system . The poles would be about 13 inches away from the walls and 32 inches apart.

Cabinets fit I between the poles and get bolted to the poles. The walls serve as support since the units are flush with the wall. The system was designed by the architect George Nelson and was sold in the 1970s by Omni.
Please advise as to the safety or danger to the heating ceiling.
Thank you

On 2014-03-16 - by (mod) - ceiling heat stopped working

Anon:

If the ceiling heat in the rooms where you have not heat is on the same circuit and controlled by the same thermostat as in rooms where you do have heat then most likely the radiant circuit for those rooms has been damaged or interrupted. That can happen by someone driving a nail, walking in the attic, or more seriously, by overheating of the system.

On 2014-03-16 by Anonymous

The
ceil heat has stopped working in two rooms of my house... also one of my light fixtures has stopped working also.

Could this be related to the heat not working? I have tested the wires and electricity is getting to the thermostat and the light fixture. What could be my problem?

On 2014-03-10 - by (mod) - radiant heat working in some rooms, not others

Dana,

If you have heat in some rooms but not others, the problem is not likely to be the oil burner itself.

However when a radiant floor heat is off for a time it's possible that a control seized or that a loop has become air-bound. Ask for a service call to determine if a control is not working or if there is another heat problem with just that zone.

Keep us posted.

DF

On 2014-03-08 by Dana

We ran out of oil last friday and the oil company came and restarted the furnace. However we just realized that our rooms with the radiant heat flooring aren't working. What do I need to do?

On 2012-05-07 by Katie - electric radiant heated ceilings.

Hi,

I am buying a condo with electric radiant heated ceilings. The property is currently bank owned so I don't know anything more about the heating than that (other than that each room is independently controlled). From my reading so far I am unclear on whether there are different kinds of electric radiant heat ceilings or if it's all pretty much the same.

I understand that I cannot puncture the ceiling in any way, but would pressure damage it as well? I would like to use a portable dance pole sometimes, which is basically a very big tension rod.

The top does have a 16" diameter dome to spread the pressure over a greater area, but it only contacts the ceiling at the edge where there is a ring of silicone. I worry that the wires might be damaged by being pressed between the pole and the joist, since there has to be enough pressure to withstand lateral forces on the pole.

Would it make a difference if I put it up only when I wanted to use it versus leaving it up most of the time? I was so excited to be moving someplace with enough room to have a pole of my own until I realized just how big of a deal it is to damage these heating systems. I would rather keep using the poles at the gym than cause thousands of dollars in damage to my home (and investment).

On 2011-12-14 - by (mod) - 1960 era All Electric Apartment

1960-era all electric:

1. Type of heating: we cannot know what type of heat your all electric apartment has without more information: there may be (typical) electric baseboard heaters, or there may be radiant in floor or in ceiling, or less likely even an electric boiler powering hot water heat or water to air heat.

Take a look for heat radiating devices, take some sharp photos and send them to us (see the CONTACT link at top, left, bottom of our web pages) and I can comment further.

2. I'll research and reply to this later

3. The first and easiest thing you can do to save on heating cost with electric heating is to manually or automatically set back the temperature at night or when you are out of the apartment.

You may want to install automatic programmable thermostats so that you can set and forget the setbacks,

WATCH OUT
: some electric heat systems use a high voltage thermostat that is wall-mounted or may be mounted right on an electric baseboard unit. If your apartment uses that type of heat control, the standard low-voltage programmable thermostat sold at building supply stores won't work.

You do not need to turn OFF a heater when it's not in use as long as the thermostat is keeping the heater off. Off is off, whether the "off" state is specified by the thermostat or by a circuit breaker. The only exception is a very small electricity usage to power thermostats themselves.

3. If your heaters use a finned system to heat air (take a look behind the covers of electric baseboards for example) gently vacuum off dust and trash that may be blocking airflow, and don't block the air entry points at the bottom of baseboard heaters by thick carpeting or anything else.

Take a look at our articles on electric heat, saving on heat energy, etc. beginning with the article titled "ELECTRIC HEAT" found near the top left of this page.

On 2011-12-14 by 1960 era All Electric Apartment

Just moved into an 1960 era "All Electric Apartment" in Southern California. Wondering

1) What type of Electric heating system my unit probably has

2) Is there a general guideline to caculate kWh usage and thus understand usage better (& potential problems)?

2) Any tips on How to save on heater usage?

a) Been told that best to turn heater breakers off when not using (myth or fact)?

3) Any maintenance that would help

a) Like Replace Manual Thermostats with modern LCD Timer Type?

b) Breakers?

I have a two bedroom apartment with 3 Separate Thermostats in all rooms.


...

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