Hello all,
I am becoming increasingly interested in radiant floor heat, as I live in a bi-level in south NJ, with forced hot air (oil), that has registers in the ceiling on the lower level. As you can guess, when the upper level of the home is a comfy 70 degrees, downstairs barely reaches 61 degrees.
I read in a recent article in FHB that radiant floor heat can be done using a high eff water heater (gas). We do not have nat gas in our area, would an electric water heater work for this application? How about tankless water heater? would there be enough btu output from electric?
Also, lower level is on a slab. How could I retrofit hydronic heating on top of slab? and would I need to insulate slab prior to placing hyd heat flex tubing?
Any suggestions would be greatly appreciated.
Tom
Replies
Yeah, elect would work ... but electric heat is expensive, so would encourage you to consider an alternative (gas, propane, ... even oil?). Don't think I would go tankless ... it would give you less control over temperature (water), I would think ... and it's expensive.
There are water heaters that combine domestic hot water and a separate heat exchanger (inside the tank) for other uses ... radiant floor. That's what I used in my house when I built a couple years ago.
As for basement ... ideal is insulate then pour a 2+ inch slab over much like putting in gypcrete over a wood floor. Many basements may not afford the 4+ inch decrease in ceiling height, though ... could always jack hammer out your slab :( probably not.
Others w/ experience I'm sure will add their food for thought.
The first and cheapest thing to try would be to have a heating contractor install a large return air duct somewhere near the floor of your lower level. This should help even out the heating between floors. If your stairwell to the lower level is open, consider closing off some of the return air ducts on the upper level.
Garth
Tommybitt
We need to step back a little to answer your question properly..
First the reason in floor radiant works so we is because where the human heart is liocated..
Our feet are the furthest thing away from our heart and thus get cold quickest.
Heat rises
That means even if you blow heat out near the floor the floor itself remains cool (the opposite of heat rising is cold air settles (on the floor)
So we' win completely when the heat is radiated off the floor..
it rises gently and warms everything uniformly unlike forced air which rises and drops cool air on the floor which make our feet cold because they are the furthest thing from our heart..
Keep feet warm and the whole body feels comfortable at a lower temp than if the head was at 70 degrees and the feet at 60 degrees.
Now yes electric water heaters work as "boilers" I use them in my home!*
You can either add another layer of concrete over the first layer but that won't be terribly effective. the problem is heat radiates every direction so much of the heat will be lost into the soil..
More efficent would be to take a diamond saw and cut out the basement floor then with a jack hammer bust the pieces into workable sizes and haul them out.. then dig down a little bit and add foam underneath and finally repour a new floor with the pex "stapled" into the foam (they make plastic "staples" for that purpose)
* my house is super insulated and I use infloor radiant with electric hot water as my primary heat source.. However due to the 96 windows I have I do lose a lot of heat at the windows. On those days when the temps drop below -20. to ensure barefoot and t-shirt weather I have suplimental forced air heat that is kicked on on those cold days..
I'll give dollars to donuts that Riversong will be on you like flies on pigs for some of your statements. I don't disagree with much of what you say ... but he has a different way of looking at things ... which is OK 'cept he thinks it is the only way.
As for forced air at the floor ... the OP said upstairs was warm/even heat. Which is generally what I expect. Assuming air discharge is 'reasonable' in terms of mixing air, as air rises, it loses its heat ... therefore you don't have much stratification upstairs ... but he does downstairs.
Another alternative would be to run supply ducts down to the floor in the basement, balance the system and voila ... better comfort ... might be cheaper than radiant, too. The other guy says to force the return air differently ... which is another approach ... although it may not get the 'corners'.
Pay your money ... take your choice.
Thank you all for your thoughts. I know I could re-arrange some of the ductwork to optimize heating location, but my plan is to use radiant as primary source of heat and use forced air as an extreme weather supplement.
As far as electric being more expensive...I was also thinking about solar power to assist with running costs...but that's a whole other project. Don't have nat gas, and not sure if propane would actually be cheaper than elec around here.
I'm not necessarily looking for the cheapest solution...i have some $$ to spend. I was just curious as to possible solutions to installing on concrete without pouring a new floor. I will be doing most of the install myself, and a new conc floor is more work than I'm willing to put into it.
What are your thoughts about nailing 2x4's (flat laid) every 24"oc. Then, insulating with rigid foam in between "joists". Then installing Warmboard (tubing inserted into channels precut into board) http://www.warmboard.com/ on top of "joists". Not sure if this would be energy efficient enough though.
Actually, your idea is fine. Your finish floor is still like 3 to 3 1/4 inches above your existing slab. If you can spare the level change (i.e. doorways and ceilings), then either way gets you there.
Fill out your profile ... where you from? It will dictate your success on e.g. solar in the future. I'd calc out the propane and compare it. You might be surprised. If you give me your elect and propane costs, I'll calc it for you.
Thank you! I will research costs of propane here, and get back to you with figures.
Warmboard is an excellent product.However in slab retrofit, "Roth Panel" gives you the insulation layer and aluminum all in one. for a floating finish floor, it's pretty attractive in the slab retrofit situations.Now, If I needed to nail down a wood floor, I probably wouldn't use it, and Warmboard would be more attractive.Note that both products are both very high performance and fairly pricey.as to whether a water heater makes sense or not, a heat load calculation determines what makes sense for you and your project.-------------------------------------
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