Hi,

I'm new to the forum and new to radiant heat. I have a question regarding floor temperature. I have only been in one other house with in-floor heat ans that was quite a while ago but I seem to remember that the floors in that house felt warmer than mine does. What should be the temperature of the floor be. Currently true out the house the floor temperature is approximately 68F. In my walking closet and laundry room the floor is approximately 78F and feels much more comfortable but the rooms don't feel all that much more warm(I know i don't spend a lot of time in those 2 rooms)

Here is what I have. It's new house built 3 years ago with 1500 sq foot main floor and 1500 sq foot basement plus 576 attached garage. All with spray foam insulation in the walls and ceiling plus blow in insulation on top in the ceilings. My system also heats my detached 1000 sq foot detached garage via underground insulated lines. The basement has 2' of foam with pipes stapled to it and concreted poured over it. The main floor has the Pex stapled to the plywood with 1 1/2" of concrete over it and Ditra mat with ceramic tiles. The heating system is a heat pump and is set at 113F. If I remember correctly the flow in at the headers is around 1GPM but was never balanced. The heat is controlled by wall thermostats. I do have tubes poured in the concrete if I would chose to go with slab sensors instead. I have 5 zones total. Basement, garage 1, garage 2, main floor with bedroom on a separate zone.

I hope I have given enough information and if not let me know what else you need. Maybe my system is performing exactly like it should but would like some feed back. I think about it every time I walk in the laundry room or walking closet.

Hmmm. If you are staying warm, then it is more likely your system is working reasonably. The person who designed the system should have done a number of calculations that would help confirm that.

Imagine, for a moment, any given room in a steady state situation. The amount of heat it loses out the windows, the walls and the ceiling is equal to the heat that the radiant floor is putting into the room and therefore, the room temperature stays the same. If the temperature outside gets colder, heat loss increases and the heat the radiant floor has to put into the room also goes up in order to maintain temperature.

Some houses, with older construction, or perhaps, poor quality new construction, leak heat through bad windows, cracks or inadequately insulated walls and ceilings. In such a situation, the radiant floor has a bigger job to do and has to run at a higher temperature. The higher the temperature of the radiant floor, the more likely that your feet will perceive the warmth. There is a temperature range in which a radiant floor can still supply heat, but still not feel perceptibly warm.

Sometimes, the designer will concentrate the Pex tubing in one area of the floor. In particular, this can happen in bathrooms, closets, laundry rooms and kitchens where it is known that there will be built-ins along the edges. By concentrating the tubing in a smaller area of the floor where people are more likely to walk, the temperature of the radiant floor needs to be higher in order to supply that particular room's heating needs. In such a situation, it is more likely the occupants will "feel" the warmth on their toes. That's a nice thing, but when using a heat pump, it may come at a loss in efficiency, because for every degree higher that the heat pump is asked to supply, it has to work marginally harder to move that heat "uphill", so to speak. As an example, my heat pump supplies 85F water, while it sounds like yours supplies 113F water.

As we move into the winter and it gets colder outside, the heat loss in your rooms should increase and the system will have to increase the temperature of the radiant floor to compensate.  It's possible that you may start to feel the floor warmth in other rooms as well.

Your designer's calculations should detail the parameters at which your particular system should run.

After the house was build I had someone do an leak test of the house and even though I don't remember the numbers I remember that it was sealed very well.

The 2 small rooms that have a higher floor temperature has no windows, 1 room has all 4 wall as inside walls and the other only 1 wall is an outside wall so there should be very limited heat loss. Why are these floors warmer. I know the loop in these rooms are smaller. Is this why the floor gets more heat.

The pipe is not concentrated in areas. It's pretty much evenly distributed. I have a diagram of the layout that I tried to attached but it says it's to big.

I have been in the house for 3 years now and even though these Canadian winters can get cold the floors don't get much warmer in the middle of winter.

Is there anyway to increase the temp of the floor without increasing the room temperature. Would increasing or decreasing the water flow do anything.

I remember that it was sealed very well.

Well, better sealing implies lower heat loss, which would require the radiant floor to do less work, meaning it wouldn't have to be so warm. I guess the downside of radiant in very well insulated homes is that you tend to lose that "toasty warm on the toes" feeling because you just don't need that much heat supplied. I like to think of it as just not having really cold floors. Even if we can't feel it, the cats and dogs can find the warm spots. :-)

Even if the plans show the Pex as evenly distributed, it may have been subject to individual preference on the part of the installer. Numerous times, they would show me what "they liked to do", which included holding it back from under cabinets or built-ins and then concentrating it in walkways. One way to be sure is to rent or buy an infrared camera so you can actually "see" the loops in operation through the floor.

Another possibility is that the installer tubed your closet or bathroom first on the circuit and then continued on to a larger room. Since the temperature of the fluid decreases continuously along the length of a segment of Pex, the first portion would be warmer, although installers seem to want to avoid that, in general.

Are the floor coverings different? It doesn't take much of a difference directly on the floor to diffuse the feelings of warmth somewhat.

At this stage, there really isn't much you can do. Increase the temp of the radiant floor by any method (higher temperature or higher flow rate) and the heat has to find somewhere to go. Unless you open a window, it will get too warm.

Maybe we will see more radiant systems designed to only put tubing where people will notice the floor heat. Ie, deliberately uneven, less surface area and higher temps.

A higher flow rate will reduce the variation within a zone and you might have some flexibility wrt balancing. I'd hire someone local to map out the layout and temperatures.

Posted By ICFHybrid on 13 Nov 2013 11:33 AM

I remember that it was sealed very well.

Well, better sealing implies lower heat loss, which would require the radiant floor to do less work, meaning it wouldn't have to be so warm. I guess the downside of radiant in very well insulated homes is that you tend to lose that "toasty warm on the toes" feeling because you just don't need that much heat supplied. I like to think of it as just not having really cold floors. Even if we can't feel it, the cats and dogs can find the warm spots. :-)

Even if the plans show the Pex as evenly distributed, it may have been subject to individual preference on the part of the installer. Numerous times, they would show me what "they liked to do", which included holding it back from under cabinets or built-ins and then concentrating it in walkways. One way to be sure is to rent or buy an infrared camera so you can actually "see" the loops in operation through the floor.

Another possibility is that the installer tubed your closet or bathroom first on the circuit and then continued on to a larger room. Since the temperature of the fluid decreases continuously along the length of a segment of Pex, the first portion would be warmer, although installers seem to want to avoid that, in general.

Are the floor coverings different? It doesn't take much of a difference directly on the floor to diffuse the feelings of warmth somewhat.

At this stage, there really isn't much you can do. Increase the temp of the radiant floor by any method (higher temperature or higher flow rate) and the heat has to find somewhere to go. Unless you open a window, it will get too warm.

Thanks for your input. That was one thing I was thinking that with spray foam insulation and good windows that the system might not be running long enough to give the floor extra. I guess that is a good thing when looking at the efficiency of it. The piping is laid out exactly like the diagram because I installed it myself( maybe that's the problem). The the entire main floor is ceramic including the 2 small rooms. Only difference is that 2 those small rooms along with the bedroom is tiles that look like hardwood and and the rest of the house is regular 18X18 tiles but I assume they are made of the same material.

The 2 small rooms are feed from i loop that does those rooms only. I assume because this loop is so small the is less water temprature drop an that is why the floor feels warmer.

I do understand what you mean by not having warm floors as apposed to having really cold floors. When I started the system this year I turned on only the main floor but not the bedroom. Even though the bedroom was only 1 deg lower when I got out of bed in the morning my toes would curled up when they felt the cold and compared to that the rest of the house fell nice. Now that the bedroom heat is on I don't have that toasty feeling I would like but I guess it's better than toe curling heat .

One room in particular I would like to have warmer a warmer floor is the bathroom which has a loop of it's own that is similar in length to the 2 small rooms combined so I'm assuming I should be able to get it as warm. To do this would I increase or decrease the water flow.

One more thing. The thermostat is located in a small hallway with a smaller loop than say the kitchen or living room. I'm assuming this area gets warmer faster and thus turns of the heat quicker. If I would reduce the heat output in this area would this not increase floor temperature in the larger areas. If so do I increase or decrease flow to reduce the transfer of heat.

All that depends on how your home is zoned. You can increase the heat among circuits in a zone by simply turning up the flow on that particular circuit with a manual valve (if you have 'em). The caveat is that the extra heat in that area will affect the thermostats on the surrounding zones ever so slightly, causing them to cut off just a bit sooner and the floors they control will actually get just a bit cooler.

You can raise the temp of any of the radiant slabs (to try to achieve toasty toes) just by increasing the thermostat in that area, but, obviously, the overall air temperature will go up.

If you only have one thermostat, all you have to do is turn it up to get warmer slabs everywhere, but that will make everywhere, well.....warmer and what I heard from your first post is that everything is comfortable except the floor surfaces.