Radiant Heating from above, radiant ceiling vs radiant floor

Did you know that radiant ceiling is better than radiant floor?

Messana radiant heating, you can feel it but you can’t see it.

Women experiencing radiant heating via the Sun.

Thermal Wellbeing comes from Above

But doesn’t heat rise? No, hot air rises. This is one of the myths that is based on the false fact that we associate with the concept of heat instead of “air”. Heat does not not rise.

I found this interesting article written by Tom Tesmar, that I have posted here below.

Radiant Floors Vs Radiant Ceilings

In the face of huge popularity, growing success and satisfied customers, it’s difficult to criticize radiant floor heating technology. Done well, under the proper circumstances, radiant floors are among the most comfortable and efficient means of distributing heat in most homes.

Operating within their capabilities, radiant floors can easily meet the heating loads of well designed, modern structures. Over the last 15 years, however, I have seen many projects where designers have exceeded the capability of the radiant floors and have had to face some harsh realities.

Thermodynamics is not just a good idea….it’s the law. The output of a radiant floor is limited in two ways. First, the maximum surface temperature of a radiant floor is limited to around 87 F (about 45 Btu per square foot). If the floor is operated above this temperature, the occupants are likely to complain of uncomfortably hot and sweaty feet.

Secondly, radiant floors are limited by the amount of energy that can penetrate highly resistant floor coverings, such as certain carpeted and wood floors. Often, these materials limit the actual output to less than 20 Btu per square foot. Unfortunately, these beautiful and thermally resistant floor coverings are often used in the more elegant rooms, with large windows and high heating loads. Radiant floor designers often must stretch to meet the load such rooms. Also, floor coverings are likely to change significantly over the life of the building, leading to the comment “It worked until the owners placed a thick Persian rug over the wood floor”.

Radiant ceilings can easily operate at surface temperatures up to 100 F, delivering in excess of 55 Btu per square foot. Since ceilings are typically constructed of gypsum based sheet rock, they offer very little resistance to thermal transfer. Unless designers regress to the 1960’s, and resume putting shag carpeting on the ceilings, it’s likely the output of the ceiling won’t change during the life of the home.

In any discussion of radiant ceilings and comfort, there seems to be some ingrained misunderstandings of the concepts. Someone will say that “heat rises, therefore you’ll have a hot head and cold feet”. Not true. Heat doesn’t rise. Hot air rises. In radiant systems objects of mass are heated without heating the air. In fact, there is typically more hot air rising with a radiant floor than with a radiant ceiling. This is because air molecules that come into contact with the radiant ceiling already occupy the highest strata. In radiant floors, the cooler molecules sink and come into contact with the warm floor surface and rise as their density changes with heat, driving the convective forces that cause stratification. Under normal conditions neither radiant floors or radiant ceilings heat the air to an uncomfortable level like in forced air systems, however.

Another myth about radiant floors and ceilings involves the surface temperatures that are achieved. Just as the overhead rays of the sun are absorbed by the beach sand, radiant ceilings warm the floor. There are no cold floors in radiant ceiling projects. You can put a piece of Tahiti in your living room with radiant ceilings. Unless you believe tropical island comfort requires the flow of underground lava.

I also hear radiant ceilings criticized for what is termed “shadowing affects”. This is the belief that legs under tables or desks are shielded from the radiant heat and are, therefore, cold. Radiant ceilings, like floors both radiate and re-radiate. The invisible heat rays emit from the heated surface to other colder unheated surfaces. The total affect of all of this bouncing of energy is very even heat distribution. If a person is seated at a table near an outside wall, there could be some shadowing from above with a radiant ceiling, just as there might be shadowing from below with a radiant floor when seated on a sofa near the outside wall. In most situations, shadowing for radiant ceilings or floors is negligible.More significant, however is the possibility that objects placed on the radiant floor will impede the flow of energy. Area rugs, and some furnishings such as certain sofas and beds can reduce the usable floor area, increasing the Btu load per square foot, and, perhaps, exceeding the system capability. Radiant ceilings are not subject to these types of problems.

Radiant ceilings accelerate fast, when needed, to meet a big change in heating load. They dissipate energy fast as well. The responsiveness of radiant ceilings makes them excellent for modern controls, placing energy where it is needed when it is needed, and achieving superior comfort and efficiency. Some high mass radiant floors are sluggish in that they take a long time to accelerate to meet the load. In modern heating systems, too much emphasis has been placed on energy efficiency of the heat plant while wasting energy on poor distribution. This is like putting a Viper engine in a Yugo. Far more heat energy can be salvaged by not wasting it in poorly controlled buildings, than can be achieved by squeezing another Btu per hour out of a heat plant. There are some pretty interesting solutions to heat distribution problems by using radiant floors in conjunction with radiant ceilings. In this way the floors are not required to meet the entire load, yet are conditioned to provide comfortable surface temperatures. The ceilings are heated, where necessary, to take on the severe conditions and give everyone involved the peace of mind that the system will keep up with the heat loss under severe conditions. Without a doubt, radiant ceilings cost far less than radiant floors. In most are heated, where necessary, to take on the severe conditions and give everyone involved the peace of mind that the system will keep up with the heat loss under severe conditions.

Without a doubt, radiant ceilings cost far less than radiant floors. In most cases they cost less than half of a radiant floor. Lower cost means more opportunity. They take less effort to design and install. Radiant ceilings are perfect for retrofit situations. It is very inexpensive and easy to lower a ceiling to accommodate the radiant ceiling, but difficult to raise a floor.

Radiant ceilings are not optimal over a concrete slab placed on the grade of the earth. Radiant floors are best for these situations. I also prefer radiant floors in rooms with smooth surface floors, such as bathrooms,  where occupants are often barefoot. It is a real nice touch. But when the going gets tough, the heat losses are high and the floor coverings are plush, radiant ceilings cannot be beat.


  • Looking to buy home with radiant ceiling heat. There are concerns whether the system is working properly. Who would be best to test this system and what questions should I ask?

    1. Hello Vanessa,
      is this an hydronic ceiling or electric?
      These are two different technologies and need to be checked in two different ways.

      If this is an hydronic ceiling, is this in copper or pex? How old?
      If it is an old copper system, there is a chance that it will leak someday but if it was done properly sure it’s possible that a copper radiant ceiling could last another 100 years.
      Instead if it is pex tubing, there shouldn’t be any problem.

      In case of an electric system, I think you should consult with an expert in electric.

      In general if it is an old system might be worth to have a professional to check it. Otherwise it could be a total headache.
      On other problem of old heating system embedded in the ceiling is that they were set to high temperature, and this could be uncomfortable. Where is the house located?

      Radiant ceiling heating (and cooling) work very well. In my house I have both ceiling and floor and I can tell you that the heat from above is even more comfortable.

      Good luck with your choice!

    1. In-slab is not the most efficient way to do radiant heat. When heating a slab floor, the goal is to efficiently heat the slab and direct as much of that heat as possible into the living/working space above it. To maximize the performance of an in-slab radiant heating system, insulation beneath the slab is fundamental to reduce back heat loss.

      A slab represents a thermal mass. A thermal mass is not the best choice for radiant cooling since it makes it difficult to control it in case of unexpected changes in the dew-point.

      A radiant ceiling is the best option. However in-slab radiant is still more popular because is less expensive.

  • I currently have ceiling radiant heat. Electrical. And my electrical bills are crazy. I’m changing my flooring in the main living area. We’re puttinh in LVP. I am looking at changing my heat to the floor. Re routing the 240 wiring to the floor for my main source of heat. May I have your opinion please? My thoughts are cost, and efficiency.

    1. Dear Chuck, we are happy to help you to learn about the advantages of our hydronic system.
      Please contact our expert Carlos Zamora at this phone number: +1(917) 4555-2111

      Kind Regards

  • I have two apartment buildings with Radiant Ceiling heat with cottage cheese ceilings. My question is if I mud up the cottage cheese to make it smooth and more modern, will the quarter to half inch mud attached to cottage cheese interfere with the heat coming out and will it be diminished??

    1. Hi Maury,

      for the Radiant ceiling heat, the quarter to half-inch mud layer will have very minimal effect on the system performance. Just the time taken to heat extra thermal mass will take a little bit more. Make sure there will be no cavity remain during applying mud otherwise the air gap will deteriorate the performance.

    1. Our system is hydronic, not electric. We would recommend asking the manufacturer, but a thermal camera would be very helpful to see where the wires are within your ceiling.

  • For cooling, Understand there can be condensation issues if the humidity in the house is too high. Is this a real issue, is it less an issue say in California where the humidity is not as high as say Florida, is there a humidity level when it becomes an issue, or is it recommended to control the indoor humidity?

    1. Hi James,

      Yes, high humidity is always a real threat. But Messana controls have the capability to have the humidity in check so that the panel surface temperature won’t go below the dew point temperature. By doing this Messana controls are able to do cooling but system won’t be working on full capacity. Adding dehumidifiers is a good solution in the area with high humidity which help the system to work in full capacity.

  • I just moved into a condo that combines the living room/kitchen/dining room into one big Great Room topped
    with a 16 ft cathedral ceiling. It came with a heat pump system and it’s like heating a barn! Would adding some radiant heat panels to the sloping ceiling be a reasonable solution for supplemental heat? The floors are engineered hardwood over a concrete slab. Thanks for your thoughts. kgh

  • I have radiant ceiling in our new home and we want to add a couple canned lights and move a chandelier a few feet. My worry is that I’ll catch one of those radiant heating wires embedded in the plaster …how would I check where it’s safe to drill holes?

  • We moved into an all electric house 4 years ago that has ceiling mounted radiant heat panels from when the house was built in 1982. Our electric bills in winter (Michigan) are very high. Are today’s panels significantly more efficient? The house was designed with all tile floors, wood ceilings, and brick or wood on many of the walls to help radiate heat back (supposedly.) We are on a slab.

    1. Since your home was built in 1982, your panels are most likely electric and not hydronic, and that’s where the efficiency differences are present. Hydronic systems use a fluid to transfer thermal energy, which is very efficient. But what has gotten more efficient are the energy sources for hydronic systems, like an air-to-water heat pump which can produce hot and cold water to provide both heating and cooling. Modern heat pumps have a coefficient of performance (COP) of about 4-5, depending on the outside air temperature (COP can drop significantly in very cold temperatures). This means that for every 1 unit of electrical energy input, 4-5 units of heat energy are output. Modern gas furnaces and electric radiant ceilings are only about 95% efficient, so you wouldn’t even be getting 1:1 input to output. If your panels are hydronic and not electric, you might be able to update your home to use a more efficient energy source, like a heat pump. Let us know if you have additional questions!

  • Hello, I live in the building that was built in 1966 and I have radiant ceiling heat. It works ok but my electric bill in winter months is still over 500$ for 2 months. My apartment doesnt even get that hot to justify that kind of money and I only ran it on 72 degrees/ could it be system is old and parts of it are not working properly therefore it uses that much energy. i am in Los Angeles. Thank you

    1. Our system is hydronic, so it uses a fluid to deliver thermal energy. It sounds like your electric radiant ceiling is inefficient and outdated, we don’t think that it would be due to worn parts/components, although that could be possible. An electric radiant ceiling gets ~1:1 input to output, while hydronic systems that use a heat pump get 1:4-5 input to output. This is because modern heat pumps are very efficient, for every 1 unit of electrical energy consumed, they can produce 4-5 units of heat energy (compared to your 1:1 electric radiant ceiling). A thermal camera could help you see what temperature your ceiling is getting to. We typically run water that is ~100°F+ and shoot for ~70% ceiling coverage.

  • I’m hoping to install radiant heating in the ceiling above a walk-in shower in a large master bathroom. The plan is to build a soffit to reduce the ceiling height to 9ft above the shower, it’s 16’ in the rest of the room and the adjoining bedroom. Will this meet my goal of a more comfortable winter shower experience?

    1. Hi! It would help in the areas under the radiant ceiling, but the size of the soffit may not hold enough panels to meet the load requirements for the entire bathroom. Typically, radiant floors are more popular in bathrooms since occupants will be barefoot most of the time, but if you have enough coverage, radiant panels will do the job and warm the floors as well!

  • Can I install the radiant heating in my ceilings as well as the flooring throughout my home? I would like to only use this as the method of heating my home in icy winters.

  • we retrofitted a 5,000 SF house near Portland Maine with hydronic staple up radiant under the main floor, which is hardwood, and ceiling mounted fan coils on the second floor. the system is powered by two Arctic 60,000 BTU heat pumps and a mixing tank. great care was given to insulating all the supply pipes throughout the house and in the mechanical room. the strategy was to use the second floor ceiling fan coils to provide cooling and let the cool air chill the lower floor. we have lived through three years now and all works well, almost. during high humidity days any exposed pipe condenses and drips. this was a big problem in the mechanical room where valves and pumps and valve handles that could not be well insulated were all sweating. i finally put a dehumidifier in the mech room which solved the problem but even short (1″) lengths of uninsulated pipe at the entrance to the fan coils were sweating and dripping into the room below.

    we are now planning to install Messana ceiling panels in a new house on the Maine coast for both heating and cooling. i appreciate Messana’s attention to humidity monitoring and control of temperature to below dew point for the main panels but how do you manage condensation at all those many little plumbing joints throughout the ceilings, not to mention the mechanical room where i see exposed copper piping in the photos of this house in Maine? we will be adding humidity controls but how can we be sure dehumidification will reach all the plumbing joints buried in the ceiling and exposed in the mech room? how has humidity been controlled in these Camden houses? i am very concerned about this detail and would like to have a one on one discussion with you.

    1. Hi there,

      Thank you for reaching out! Proper insulation is the key to avoiding condensation in any area where a surface may reach the dew-point temperature.

      As you mentioned, dehumidification units can help avoid condensation in the mechanical room. In a mechanical room, proper practice is to insulate everything (the piping and components that have a surface that may reach the dew point temperature). Most of our projects also have a floor drain in the mechanical room to handle condensation when necessary.

      Regarding your condensation concerns within the ceiling/walls, our system utilizes pre-insulated PEX and plastic couplings (which should be insulated as well) to avoid sweating. Furthermore, modern homes have become so well-sealed that there is generally not a lot of moisture in the small encapsulated spaces behind walls. In terms of our panels, they sit flush with the drywall so there is no air pocket that can hold moisture.

      As for the Camden project photos, some insulation was still required in the mechanical room. Additionally, some installers might not insulate heating-only piping, which decreases system performance as heat is lost to the mechanical space (which some may want).

      We hope this answers your question! To chat with one of our hydronics experts, you can reach out to our team here:

  • Looking to do NEW build pole frame in MN, Zone 6 and like the idea of ceiling radiant especially if I can replace concrete w/ embedded PEX as hydronic slab on grade supplied with on-demand condensing water heater.
    Planning to build pole-frame building with max air sealing and zone 6 recommended insulation and would do wood floor on grade.
    BUT… hesitant (seeking further technical info) because of:
    1- possible water leaks and/or condensation through finished gypsum drywall ceiling
    2- potential for large perceived temperature delta under tables and other furniture to become uncomfortable where wind chills regularly get down to -20F. and sometimes down to -40F.)
    3- hydronic cooling in concrete slab works fine with city water at 60F in summer with occasional boost from small wall A/C. (This is an ‘open-direct’ hydronic system where all makeup water first cycles through slab before going to on-demand condensing water heater.)
    Has anybody tried to do something like this in upper plains?

    1. Hi there, very cool ideas here!

      In terms of your concerns:

      1. Messana Controls and mSense room comfort sensors will continuously monitor the dew point temperature of every zone and will adjust the supply water temperature to avoid condensation on the radiant surface. If someone were to puncture a panel, it is worth noting that this is a closed-loop system and we offer a piping repair kit.
      2. The “shadow” effect you’re describing is not nearly as apparent as most folks assume. I sit at my desk every day with a radiant ceiling above me and have not once thought that the underside of the desk is too cool. Our goal is to create the most comfortable environment possible, so we bring the entire environment to the desired setpoint and efficiently maintain the temperature with the radiant system.
      3. Messana Controls can usually be implemented to allow for variable temperature cooling via a closed-loop slab, but it is interesting that you’re doing it as a open-direct system. As far as I know, we have not seen a project like this!

      It sounds like you may benefit from requesting a system estimate and chatting with our sales/engineering teams:

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