Radiant heating is an efficient and comfortable method for heating. Instead of heating air and blowing it into spaces to mix with the cooler air and increase the temperature, radiant heating directly heats everything around it. When you stand in direct sunlight and feel the heat on you, that is radiant heating. Household radiant heating uses hot water, either from a water heater or from a boiler, to convey heat throughout the house. Some older homes used hot water or steam and radiators, which provided both a direct radiant heating source in the room, as well as indirect heating of the air passing the radiator and circulating into the room by convection. Newer radiant systems turn the entire floor into a radiant heating surface, providing even radiant heat throughout the house.
For the past several months, I have been slowly installing the tubing for a radiant heating system in my own home. The process isn’t normally really that drawn out. However, since I’m doing the work myself, on available weekends, it’s a slower process than having a crew of professionals come in and do the installation in a couple of days. But, regardless of the time it takes, the installation method is fundamentally the same.
I am lucky in that I have a single story home, so accessing the underside of all floors was relatively easy. Retrofitting radiant heat into a multi-story home would require either removing the ceiling on the level below or fastening the tubing to the existing flooring and then raising the floor level by a couple inches with an overlay of concrete or tile grout. While this can be done, it is a much more involved and expensive process.
Radiant heating is a green choice for heating for a number of reasons. For people with allergies, getting heat without blowing air around through dusty ducts is highly preferable. Water is also much denser than air, so it is more effective a medium for heat transfer. The typical human thermal comfort profile also tends toward having more heat at the extremities (namely the feet) while having slightly cooler temperatures for the head. This very much matches the heating provided by an in-floor system. Warm floors are also very comfortable for smaller children who like to play on the floor. And often, a radiant heating system can be set a little bit cooler than a forced air system because the direct heating from the radiant system is comfortable, even if the actual room air temperature is a little bit cooler (again, think of being in the direct sun on a bright, cool autumn day).
The next step in the process is going to be having the plumbing connected, with a heat-exchanger to transfer heat from our water heater (which was oversized in order to be able to run this system while still providing us hot water in the house) along with the other pipes and valves and bits of equipment necessary to make the system work.
In our installation, we are going to keep our forced air furnace in place for now, in case we get some really cold days that the system isn’t able to keep up with. But the sizing of the system seems to be large enough that we shouldn’t have any troubles with it. We’re all looking forward to having the radiant system up and running in the next couple of weeks.
You can see the PEX tubing (white) fastened to the side of the joist with clips (black) spaced every couple of feet in the photo. The cross pieces shown are left from removing the old ceiling that was in one part of the basement. They turned out to be very handy to help support the tubing in place until I could get the clips hammered into place, but they are not a required part of the system.
An article from ‘This Old House‘ offers more information and discusses the advantages and the process of installing a radiant heating system, as well.
I lived in S. Korea for a year and enjoyed a traditional “ondol” heating system. The Koreans and other regional cultures have used under-floor heating systems for thousands of years. Let me tell you, they work great! Nothing beats waking up in the morning and planting my toes on a toasty floor. It kept the whole room (my apartment was a small room) snug all winter long, I loved it.
I lived in S. Korea for a year and enjoyed a traditional “ondol” heating system. The Koreans and other regional cultures have used under-floor heating systems for thousands of years. Let me tell you, they work great! Nothing beats waking up in the morning and planting my toes on a toasty floor. It kept the whole room (my apartment was a small room) snug all winter long, I loved it.
TOH says that you should fasten the pex into an aluminum system to better distribute the heat to the floor. Is there a reason you didn’t do this? Is it cost prohibitive?
TOH says that you should fasten the pex into an aluminum system to better distribute the heat to the floor. Is there a reason you didn’t do this? Is it cost prohibitive?
you should fasten the pex into an aluminum system to better distribute the heat to the floor. Is there a reason you didn’t do this?
Good question, IR!
Well, first of all, this is an ‘in-process,’ rather than a ‘finished installation’ photo. The aluminum plates are fairly expensive, yes. Rather than using them, my supplier provided another option for me. Once the system is in place and working, I have rolls of aluminized reflective insulation that I will probably be putting in. I say probably because if we’re getting enough heat on the main floor, I may allow the system to provide heat to the basement as well so that it is comfortable if we finish it out. I’ve also held off on putting in the reflective insulation until I’ve been able to test the system for a few weeks and make sure everything is working well before I hide it away behind another material.
you should fasten the pex into an aluminum system to better distribute the heat to the floor. Is there a reason you didn’t do this?
Good question, IR!
Well, first of all, this is an ‘in-process,’ rather than a ‘finished installation’ photo. The aluminum plates are fairly expensive, yes. Rather than using them, my supplier provided another option for me. Once the system is in place and working, I have rolls of aluminized reflective insulation that I will probably be putting in. I say probably because if we’re getting enough heat on the main floor, I may allow the system to provide heat to the basement as well so that it is comfortable if we finish it out. I’ve also held off on putting in the reflective insulation until I’ve been able to test the system for a few weeks and make sure everything is working well before I hide it away behind another material.
Congrats on your retrofit,Philip. Keep us posted. My cold feet are already jealous!
Congrats on your retrofit,Philip. Keep us posted. My cold feet are already jealous!
Keeping your house “as chilled as a meat locker in winter” may be a way to save on energy use, but that certainly is not the effect that radiant heating has. Radiant heating is both extremely comfortable and very efficient.
This article begins: “Radiant heating is an efficient and comfortable method for heating.” I’m not sure how you got to a meat locker analogy from that.
Keeping your house “as chilled as a meat locker in winter” may be a way to save on energy use, but that certainly is not the effect that radiant heating has. Radiant heating is both extremely comfortable and very efficient.
This article begins: “Radiant heating is an efficient and comfortable method for heating.” I’m not sure how you got to a meat locker analogy from that.
Hey! I just stumbled upon your site and am considering a retrofit myself. My question is what you used for a hot water heater. I’m looking at an electric heater and not sure what the sizing should be etc. How did you calculate what you needed?
Wayne from Maine
Hey! I just stumbled upon your site and am considering a retrofit myself. My question is what you used for a hot water heater. I’m looking at an electric heater and not sure what the sizing should be etc. How did you calculate what you needed?
Wayne from Maine
Wayne,
I have a large, high efficiency, gas-fired water heater that my mechanical engineer recommended with a sufficiently large capacity that it should be able supply both our heating and hot water needs. We are keeping the old gas furnace in place for now for backup in case of very cold weather. But we hope that it won’t be necessary to use it.
Wayne,
I have a large, high efficiency, gas-fired water heater that my mechanical engineer recommended with a sufficiently large capacity that it should be able supply both our heating and hot water needs. We are keeping the old gas furnace in place for now for backup in case of very cold weather. But we hope that it won’t be necessary to use it.
Thanks Phil!
I have a very small house (thankfully), and have found an electric boiler that should do the trick for me. Its small, highly efficient (as much as electric can be), and it appears that it will save at least a little money over oil. I’m hoping to install solar panels in the next few years to supplement either the power, hot water, or both.
Wayne
Thanks Phil!
I have a very small house (thankfully), and have found an electric boiler that should do the trick for me. Its small, highly efficient (as much as electric can be), and it appears that it will save at least a little money over oil. I’m hoping to install solar panels in the next few years to supplement either the power, hot water, or both.
Wayne
Hi Phil,
was there any concerns with warping/discoloring/cracking of the hardwood floor with radiant floor heat? did you install a humidifier to mitigate any issues?
Hi Phil,
was there any concerns with warping/discoloring/cracking of the hardwood floor with radiant floor heat? did you install a humidifier to mitigate any issues?
I already have radiant in-floor heat in my home, using a concrete slab for the ground floor. I also have supplementary hot water radiators upstairs.
It seems to be somewhat less expensive than forced air compared to my neighbours (I would guess roughly 20% saving). I use natural gas with a 120,000 btu boiler (it could be smaller for my 2100 square foot home).
So, it must be 20% “greener” than a forced air installation. (Although how anyone in their right mind can consider burning fuel at a lesser rate “green” is beyond me. Like buying a hybrid…it still uses fuel, still has to be manufactured, etc. Green? Maybe less black.) Now, if it were entirely solar….
Anyway, while the savings are modest, and the “greening” dubious, it is nice to have warm feet. Also, the slab is a heat condensor in summer, absorbing heat in the day (and slightly cooling the home) and releasing it at night (and thus taking some chill off, if any, at night). The cool floor is comfortable in summer, too. So, it is a free air conditioning system in a way. With solar glass and upstairs fans, it actually works pretty well as a passive solution.
And I will say that actually is a pretty “green” air conditioner.
Sorrey to challenge you theory on allergens, but the cleaner air theory is bunk. Circulating air with effective furnace air filtration is much healthier, as you trap allergens and move the air around. If your house is dirty, try cleaning it and going to hardwood or lino floors. How do I know this? You get dust on the furniture in a radiant house too, and my brother in law is a heating consultant with children who have allergies…his choice (and he could have anything as the company provides it) is forced air, high efficiency, multiple furnace, with hepa filtration installed.
The disadantages of radiant are: very slow to react to sudden temperature fluctuations outside (i.e. a sudden Artic front and you are cold for a day until the slab heats up sufficently), and a rise in temperature leaves the house too warm until the slab cools down; another disadvantage is the lack of air circulation that can result in uneven air tempeatures despite evenly heated floors; another disadvantage is that windy and very cold weather can cool a house enough that radiant heat can have trouble keeping up…this of course depends on exterior glass area and overall insulation; finally, wood floors are punished by radiant heat, as it dries the wood out and may cause cracking noises in certain installations.
The former may be partly solved by computers that sense rising or falling temperatures and then pre-empt the situation by increasing/decreasing water temperature.
The second issue may be mitigated with ceiling fans.
The latter issues could be remedied by improving insulation and keeping water temperatures modest. If the climate is very cold, installation must be considered carefully.
If your outside temperatures do not vary to extreems, then you may not experience some of these problems. (I do in my area….cold!).
I like radiant heat, but nothing is perfect, and green is relative.
I already have radiant in-floor heat in my home, using a concrete slab for the ground floor. I also have supplementary hot water radiators upstairs.
It seems to be somewhat less expensive than forced air compared to my neighbours (I would guess roughly 20% saving). I use natural gas with a 120,000 btu boiler (it could be smaller for my 2100 square foot home).
So, it must be 20% “greener” than a forced air installation. (Although how anyone in their right mind can consider burning fuel at a lesser rate “green” is beyond me. Like buying a hybrid…it still uses fuel, still has to be manufactured, etc. Green? Maybe less black.) Now, if it were entirely solar….
Anyway, while the savings are modest, and the “greening” dubious, it is nice to have warm feet. Also, the slab is a heat condensor in summer, absorbing heat in the day (and slightly cooling the home) and releasing it at night (and thus taking some chill off, if any, at night). The cool floor is comfortable in summer, too. So, it is a free air conditioning system in a way. With solar glass and upstairs fans, it actually works pretty well as a passive solution.
And I will say that actually is a pretty “green” air conditioner.
Sorrey to challenge you theory on allergens, but the cleaner air theory is bunk. Circulating air with effective furnace air filtration is much healthier, as you trap allergens and move the air around. If your house is dirty, try cleaning it and going to hardwood or lino floors. How do I know this? You get dust on the furniture in a radiant house too, and my brother in law is a heating consultant with children who have allergies…his choice (and he could have anything as the company provides it) is forced air, high efficiency, multiple furnace, with hepa filtration installed.
The disadantages of radiant are: very slow to react to sudden temperature fluctuations outside (i.e. a sudden Artic front and you are cold for a day until the slab heats up sufficently), and a rise in temperature leaves the house too warm until the slab cools down; another disadvantage is the lack of air circulation that can result in uneven air tempeatures despite evenly heated floors; another disadvantage is that windy and very cold weather can cool a house enough that radiant heat can have trouble keeping up…this of course depends on exterior glass area and overall insulation; finally, wood floors are punished by radiant heat, as it dries the wood out and may cause cracking noises in certain installations.
The former may be partly solved by computers that sense rising or falling temperatures and then pre-empt the situation by increasing/decreasing water temperature.
The second issue may be mitigated with ceiling fans.
The latter issues could be remedied by improving insulation and keeping water temperatures modest. If the climate is very cold, installation must be considered carefully.
If your outside temperatures do not vary to extreems, then you may not experience some of these problems. (I do in my area….cold!).
I like radiant heat, but nothing is perfect, and green is relative.
We gutted our old house in metro Detroit area. My husband wants to put in radiant floor heating with pex tubing (not in concrete) I am trying to find information and examples of homes that have used this in renovation in southeast MIchigan. We are planning to use it as the only heat source. I would like to know if you have finished installing yours and how you like it. Any cautions, suggestions or sources for research in this area? Thanks a lot I appreciate your articles,interesting and well written.
We gutted our old house in metro Detroit area. My husband wants to put in radiant floor heating with pex tubing (not in concrete) I am trying to find information and examples of homes that have used this in renovation in southeast MIchigan. We are planning to use it as the only heat source. I would like to know if you have finished installing yours and how you like it. Any cautions, suggestions or sources for research in this area? Thanks a lot I appreciate your articles,interesting and well written.
Hi,
I wanted to thank you for this great read!! I definitely enjoyed every little bit of it . I have you bookmarked to check out new stuff on your post..
Great read and glad that you are a proponent of radiant heating. As you mentioned radiant is healthy and green. No dust, warm floors, minimal air circulation and no stratification are all healthy aspects of the system.
The green is low temperature distribution of water which in itself is the most efficient heat transfer medium – however what really closes the deal is radiant’s ability to enable and enhance alternative technologies such as solar and geothermal. With the former the “solar fraction” rises as more of the energy collected can be utilized and with the latter, the COP increases proportionally with lowering the required distribution temperatures.
I would however recommend that you either attach the tubing to the underside of the floor or suspend about an inch or two below the floor. The former would be the most efficient and the latter would allow more air circulation around the tubes. In any event, attaching to the joist is the least desirable choice from a heating/heat transfer point of view – not so good for either conduction or convection.
For more on the subject visit the Radiant Professionals Alliance at http://www.radiantpanelassociation.org or http://www.myhomeheating.com
Infrared Radiant Heater Safety
While in the process of remodeling or building a new home this is the heater for your construction phase. Infrared heaters radiate heat to the
areas that are needed. Helps to keep production up when the weather is against
you.
Many heater choices are available in
the heating market. For business
or industrial purposes, an infrared radiant heater is a common choice for
keeping employees
and clients comfortable. But, safety must be practiced near these heaters for
everyone’s welfare. Make sure that if there are children around you educate
them on the importance of staying away from the heater.
1.
Function
o
Infrared
radiant heaters function by burning a supplied
fuel, such as gas, and letting the resulting heat emit outward. These radiant
heaters are without a fan to blow the hot air around, infrared radiant heat
warms the people and items near it by facilitating heat movement.
Considerations
o
Safety parameters are key to
successful use of an infrared radiant heater. Combustibles and sensitive
materials, such as electronics,
should not be near the heater. Clear any vehicles from the area as well, and maintain an open area so the
heater cannot be knocked over or damaged inadvertently.
Identification
o
A particular infrared radiant heater
widely used is the radiant heater. Typically found in garages, barns, work
sheds and on construction sites, these heaters keep employees comfortable during
cooler weather.