After we moved in and winter came we were excited to fire up the floor. And sure enough the floor heated up and you could walk around in your socks and feel the warmth.
Then in the spring we installed a wood stove and now we rarely use the floor at all. What happened? Well many things. Some were just a lack of research and understanding on our part and the other was a lack of experience in the use of radiant floors.
Here are the downsides. First is the time lag to heat the floor. It will take a while to heat the floor depending on the temperature in the tubing as well as the size of the zone. Ours is around an hour. Once the floor gets warm you then have to wait for the air to get warm. Which takes even more time. When it does get warm it does a good job of holding the temperature steady for hours.
People argue that radiant floors are very efficient because you are not heating air that can escape your house, the heat is closer to the living zone of the room and blah, blah blah. That all might be true but it is crazy inefficient in the time lag. For a normal family that gets up goes to work/school and then comes home in the evening a radiant floor does not do a good job of allowing you to set the temperature back while you are gone and at night and then heat quickly in the evening and for a short time in the morning while you are getting ready. If you stay home all day radiant could work for you because you want a steady temperature all day. Otherwise a forced air system on a programmable thermostat can provided cheaper and more comfortable use of heating by only providing heat when you need it. If you are cold then bump it up a couple of degrees and you get that heat pretty quickly with forced air.
The other issue, which is obvious but should be noted, is that it will never get really hot. If you come in from working out in the cold you want to stand somewhere really warm to heat up you won't find that spot with a radiant floor unless you lay on the floor. If you are using forced air or a wood stove that option exists and it is really nice.
The next issue is also fairly obvious but was a surprise. Yes heat rises but not radiant heat. Since we have a two story house we were hoping some the the heat from downstairs would rise to the upstairs to help warm the upstairs. That did not happen at all. So we used the electric wall heaters upstairs to keep the bedrooms warm.
After one winter we realized with the help of a tax credit that a wood stove is a better all around choice for many reasons: cheaper, heats the upstairs, carbon neutral, works in a power outage, can cook on it, provides a place to warm up after coming in from the cold, The downside dealing with wood. Since our SIP panel house is very tight we don't have to burn a huge amount of wood and the house holds its temperature very well overnight. We use the heat recovery ventilator (HRV) to reduce indoor air pollution from the stove. There is also the issue of the little kids touching a hot stove but a gate takes care of that while they are young.
Moral of the story is don't be so quick to jump on the radiant floor bandwagon.