Benefits of Radiant Heating for Bathroom Floors

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Subject: HOT SPOT

In May we had our bathroom remodeled and installed Sun Touch radiant floor heat under our new tile floor. A few weeks ago I noticed a hot spot under one of our bathroom mats. Is it okay to have a mat on a heated floor? If that's not the problem, what is causing this hot spot and what can we do about it?

Joe Prin

Subject: Heated Floor Power Requirements

Almost assuredly you will need a dedicated power circuit for an electric radiant floor. They are available in both 110 and 220 configurations. Some Electricians will make a good argument for the 220, but almost all of what you will see in home centers and tile showrooms is 110. 20 amp minimum depending on the system. Check all this out in advance! The degree of difficulty getting power to a bathroom in a remodeling situation can be difficult and must be done with a permit and inspection. DO NOT CUT CORNERS HERE. Get solid quotes on this, not estimates. It can be a significant cost. My experiences as a remodeler were between $600 and $1800 just for the electrical portion of this project.


Subject: Electric Radiant floor mats

It's this option or a small heater in my furnace vents and barely any insulation under the floors, and our condo unit sits over a crawl space with an ineffective to non-existing vapor barrier.

I read elsewhere that a dedicated GFCI 20 amp circuit for at least 110 volts is recommended. Can anyone confirm?

Ronald Gondran

Subject: Radiant Heat

I just had a bathroom floor installed with 110 volt. The floor draws 14 amps and the electrician and floor paper work recommends a dedicated 20 amp circuit. Make sure you have a dedicated circuit. Do not wire it in with a circuit with other electrical units. It could blow a fuse very easily.

Sam Engelstad

Subject: heated floors

In Norway it is common to lay down parquet floors boards specially designed with pre-fabricted grooves for the tubes. I have not seen them in the US.

John Hoegemann

Subject: Radiant heating

Doing a retro on radiant heating may not be worth the effort or expense. For new construction, the added cost, and zone capability, makes radiant heat the savior of indoor heating. A good layout covers the floor and even warmth is guaranteed. The new piping is great, and well worth the investment.

Roger Barton, AIA, LEED-AP

Subject: hydronic vs. electric resistance floor heating

Does anybody actually still make and install electric resistance coils for subfloor heating? I thought that dinosaur finally went extinct. It was always subject to hot spots, required a specialist for installation, and there was (as your consultant says) always a danger of an electrical fire from an arc. The hydronic system is much more reliable, energy-efficient, and easily repaired. If the correct type of water line is used, it will not break under normal pressures and is usually only heated to about 110 to 120 degrees... about the same as the hottest setting on your shower. They do work best when installed between a concrete slab and a tile or hardwood floor, as carpet reduces the heat transmission into the room above. Most homeowners should get some professional advice from a consulting engineer (NOT from a plumbing contractor, with all due respect) before making the decision to retrofit an existing home with this system. If it's not designed AND installed correctly, it's a major headache instead of a high-comfort money saver.

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what should you pay.  You pay what you can afford.  1100sqft unit requires a min. of a two ton unit.  prices range from 2100-2900 depending upon the seers of the system.  13 seer is the min. the law requires  and for your situation with 1100 sqft.  do not worry about the seers as long as it is to code.  the bigger the house the more seers for economy.  1100 sqft is at the border line for a two ton system.  It is more important to have your new system balance, there is where you get the economy on your electric bill and gas.  Bryant, lenox, ruud and carrier are the brands you should stay with.All have the same basic factory warrantee and will last you longer than you expect as long as you maintain it with regular check ups twice a year once in the spring and then in the fall.

raymond gonzalez
koolray heating and air
? offers a nice sizing chart for HVAC capacitors and furnace capacitors. Most of the capacitors I've looked at are $5 to $15 dollars, so a little less than Home Depot and Lowes.


Replacement is really easy, but be sure to watch a youtube video on how to replace it like this one:


Stay safe and hire a professional if you feel unsure about doing it yourself!

The only thing of importance, is the hvac professional you choose to use. Alot of manufacturer's pieces are built relatively the same, and will last about the same amount of time. The thing that matters most is what you can not compare between companies, and that is the installation. Purchasing a system is not like purchasing a car, where no matter where you buy it, they are all the same. Each installation is different, and usually what you are paying for is the level of expertise, and quality of the installation, the company who will actual give you the warranty, and the comfort that you will receive. Manufacturers warranties disappear every day. They always have a loophole where they can get out of paying, but your local dealer wants to keep you happy for future work, and to protect his reputation in the communiy. Look up 4 year old Nordyne and Goodman warranty problems. Choose the HVAC professional first. It will cost you the least in the long run. I have had to totally redo plenty of installations that were just performed because of an uncomfortable customer, and a system that keeps breaking down. The equipment is only as good as it's installation, and over 70% are not installed correctly.
I think maybe you are confusing SEER, which is an efficiency-related rating (higher SEER means more effective use of the electric power used to compress the gas), and TONS rating, which is a measure of the total cooling power of the system. (Tons used to mean how many tons per hour of ice was used in evaporative cooling building systems - a Refrigeration or Cooling Ton equals 12,000 Btu/Hour of energy exchange. A BTU, which is another antique measure but still used, is the energy needed to change the temperature of a pound of water one degree fahrenheit. Unfortunately, because of varying humidity and evaporation, this is not readily related to house air heating or cooling without a lot of assumptions and some computations. Relating this to today's world - the Manuals BayAreaAc referred to account for all these energy conversions and determine an estimated cooling (or heating) requirement for your specific house. The type of construction, solar exposure, general climatic conditions such as average temperatures, humidity, and hottest and coldest normal ambient temperatures and desired inside temperture are all taken into account in the more sophisticated versions of the analysis, so there is no "standard", though a rough old rule of thumb was about 1 ton of cooling per 500SF of house. Obviously, this was a WAG only because it did not account for insulation, type of roofing, whether you live in Alaska or Miami, etc. The ACCA manuals do a very simplified form of evaluation to arrive at a "design", which generally will be adequate. OF course, highly precise calculations are not really needed because A/C units generally come in even ton ratings - so if you are at say 2.6 ton requirement you will be getting a 3-ton unit anyway. SEER ratings are not a direct measure of efficiency, but the relative difference between ratings gives you good idea of the unit's relative efficency in using electricity - so a 16 SEER should be about 19% more efficient (so roughly comparable lower electricity bill) than a comparably sized 13 SEER unit. 13 SEER is the lowest efficiency currently allowed to be built for general use, 19 SEER is about the highest efficiency made by pretty much all manufacturers, and about 25 SEER is the highest rated though very pricey shelf-item units, though special construction custom units can reach about 30 SEER. Note however, like any government sponsored rating, much of it is hooey when you get down to it - for instance, SEER ratings are figured based on 80 degree inside air temp and 82 degrees outside, when that is far from the normal case of mid to low seventies inside and high eighties or above outdoors. This makes the absolute SEER rating meaningless, but relative numbers still have meaning in comparing units. Note these efficiency ratings are for conventional air conditoners and heat pumps working in ambient air conditions. Ground sourced Geothermal or lake/river exchange cooling units, though initially more expensive in most cases, can greatly exceed the air-exchange unit efficiencies because they are exchanging heat with cold natural water rather than with a high-temperature outside air, and instead of continually compressing a gas are just circulating cold water. I worked on one geothermal cooling project which had almost infinite efficiency, which of course makes no sense - but the only power was for sensors and a control valve as the water flow was single-pass under gravity flow, so no power was used to circulate the water.