This forum has been created at the request of RPA members to discuss issues relating to electric radiant heating.

Hats off to you for creating a forum specifically for Electric Radiant Heating, Snow Melting, Floor Warming and Roof Deicing products. Thank you!

- i understand this would mean copper wires only, rather than electrically heated PEX installations, yes? -

Though not all electric installations are copper, the idea is correct.

- could anyone post a summary of how this technology compares to electrically heated hydronics systems? ..... regarding efficiency, overall costs, reliability, longevity, risks/benefits ? -

As with hydronics, there are many variables.

We have a primary heating system using low voltage electric in the Berkshire Mtns (3000sf) using a "bronze screen" element under hardwoods and carpet throughout except for the bathrooms where we used a #14 wire.

The client spent $11.20 psf for the system (he wanted the dining room and guest rooms to have their own zones so there was added cost)and it cost him $450.00 in February to heat his house. Two of the 8 zones are guest areas so they are turned down to 55*. The rest is 68*.

The screen element can be nailed, screwed through anywhere and cut to fit around outlets in the floor. The 8 zone controls took up 1 - 4' x 8' plywood wall. Each zone has it's own control and 7 day programmable tstat so that if one is down, the rest are fully functional.

Since the screen is even heat, solid hardwoods can be installed (nailed) directly over the element without issue. We did advise, and they installed a humidifier in the hardwood areas (800sf).

The system requires no maintenance. Since the screen is bronze, it doesn't deteriorate. The element has a 25 year non-prorated warranty. The transformers(low voltage)have a 5 year warranty and the control board is one year.

There haven't been any return calls on this project to date and it's been in service since 04/06. The manufacturer has systems installed throughout the midwest for almost 25 years.

Benefits: There is no cost to have the system if no heat is being called for. There is no relegating the finished floor. The elements are easily repaired if damaged with no periferal damage. More even/efficient heat distribution then hydronic. Zero wasted energy in the envelope.

The same elements are also used outside for snow and ice melting.

Risks: The only risks I can think of are related to improper installation or use. If you have a concern about a risk that I didn't think of, bring it up and we can discuss it.

- thank you Warmsmeallup for the info, that is most helpful -
- we are building a house and weighing our heating options, and since the electric grid approach always seemed to be a simpler solution to us we are pondering why most others choose hydronics ........ we speculate several reasons:
1. flexibility regarding heat source (oil,natural gas/propane,electric,heat pump)
2. better choice perhaps in a concrete slab
3. simpler systems may cost less

- are we missing anything? -
- we see more risks with hydronic than with electric ...... and more components to fail -

As I mentioned, there are many variables. It is correct that there is a choice regarding the heat source with hydronics, however, how many people do you think will have spare boilers/furnaces to swap out as the (volatile) market changes. I agree that it's a good marketing strategy to have that to offer, but is it realistic to expect every homeowner who purchased an oil fired boiler to switch them out at a cost of several thousand dollars. Meanwhile, you're still left with a system that has many moving parts and one single element (if you switch to an electric boiler)that has to work for all.

The strongest point against an electric system, from anyone, is what your cost per kilowatt hour (delivered) are for the electric. I can tell you that the aforementioned client pays $0.159 p/kVH. Before you invest in any system, find out what you are paying and then have the system supplier calculate the running costs per hour. You can calculate the rest.

**In ANY case, don't forget the Heat Loss Calculation.

As for the concrete slab application, both work effectively and will heat at about the same time rate.

I could be wrong but, it seems to me that the more "simple" the hydronics system is, the less efficient it is.

I do also believe that hydronics is the better installation when get over about 3000sf but only due to the upfront costs. I'm simplifying it a bit but all they would need to do is install a larger boiler and more tubing to cover it. A low voltage system is independant systems and controls for each zone so they are truely efficient. It doesn't need a boiler to keep the hot water hot 24/7, waiting for a tstat in the family room to call for heat. Also, if one zone has an issue, only that one is effected. The rest of the design is still fully functional.

boilers don't have to stay hot, just FYI.

what's the prevailing thoughts on EMF and electric radiant?

EMF are generated by the line voltage elements and, for the most part (or so I understand) the new designs in cable have a sheild around them to prevent their "escape". However, the shiled also prevents tracing the element if it's broken. That's why we don't install the line voltage elements interior.

The low voltage elements have ELEMF, extra low emf, which are the same frequencies as the old style TV's and computer CRT screens. No problem.

Other than the wall mounted tankless, instant on electric hydronic heaters, I thought the efficient boiler style hydronic systems require a storage tank for the hot water. If not, do they heat the water only on demand? What happens to the already heated water on the return side if no heat is called for?

storage tanks are used for domestic hot water, or sometimes a buffer (not a storage) tank is used to smooth out heat demands on some systems. difference being buffer tanks are not maintained at a temperature, they are passive, mass objects.

for heating, the vast majority of boiler systems only heat up when needed. when all zones stop calling for heat, there is some loss as water not in emitters cools down. This is typically a small issue (but there are exceptions).

edit; thanks for info on EMF!

- thanks to you both, this discussion is helping us converge on an answer -

- there are of course many variables, and as an engineer i attempt to center on the most influential of those variables and see where that leads me ........... so to me it appears to boil down to this question:

Is there any way that an electrically heated hydronics system (involving resistive element heat transfer efficiency, pump efficiency, and other heat losses from tank and/or headers leading to the floor circuits) could in fact be more efficient than placing the resistive heating elements directly into the floor?

- my experience suggests fewer transfer steps usually translate to fewer losses .... we just wonder if we are missing something here, and why an infloor electric resistance element approach is not already in the majority of home installations -

of course not, not without using a heat pump of some kind such as geothermal, which is not heating electrically per se.

Now, more efficient and more economical are two entirely different things. But obviously using the electricity to generate heat is going to use less electricity than using it to generate heat and then pump it around a house.

- ok, so using the simplifying assumption that 'more efficient DOES equal more economical in the long term' that leaves us with that question:
*** why an infloor electric resistance element approach is not already in the majority of home installations ***

or

*** why is it not far more popular than hydronics for radiant floor installations using electricity as the heat source *** -

- your opinions are much appreciated, and we must make this decision this week (for the concrete slab application) and soon thereafter for the main floor (hardwood) -

Until this thread, off of this new forum heading, the RPA directed ...(arguably) 95% of it's rescorces towards plumbers and the design of hydronics radiant heating because it was just around longer and was the better choice overall.

I had serious doubts in the beginning too. The concept was too simple. It couldn't be true. I took a chance and installed a low voltage system in 20% of my own home during a remodel. After a year of using it as primary heat in those areas, and seeing no significant increase in my heating costs from the previous year, a light went off in my head. (sorry, no pun intended) I started a business selling and installing it in homes and businesses. My experience has proved it to me and to my clients. It will take time. I'm patient.

This message has been edited. Last edited by: Warmsmeallup,