How can I create a radiant heat system for melting ice on wood steps?

Question

Our house has wood stairs to descend from the front porch. On maybe 15 - 30 days out of the year a layer of ice forms on the stairs, posing a safety hazard. Even with our familiarity with the issue and attempts to consistently use the handrail, every member of our family has taken at least one spill on the stairs due to ice.

I've used salt and other chemical de-icers with success in the past, but that requires foresight and manual intervention: not a good solution for the first person out the door on a morning after a frosty night.

I would like to put in place a permanently installed thermostatically controlled retrofit radiant heat solution to melt the ice. I do not want to replace or rebuild my stairs. I am a cheap bastard so want to make this a DIY low cost solution, but reliability, longevity, and of course safety are important so I am not afraid of investing in quality materials. I can see spending $500 on this. $1000 absolute max. Beyond that I toss in the towel and think about trashing the current wood stairs and replacing with cement stairs with an embedded radiant heat system at some point in the future (aka probably never).

I have reasonable access to underneath the stair treads. There are eight steps. I also have good access to 120V and 240V AC and cold water.

I'm OK with it not being highly energy efficient. It won't be activated very often.

I am comfortable building my own control system with an Arduino if that proves to be a good solution for cobbling together a DIY system.

It seems my options are:

Hydronic heat -- water or glycol in Pex tubing. Downside: hydronic boilers are expensive and not sized for this small project. The smallest I've seen is about $800. I've read about some DIY projects where a small water heater was used or where a hot water recirculating system was just bolted onto the house's existing hot water heater. This latter option sounds interesting and potentially economical.

Electric cable -- There are cable products for preventing ice dams on roofs and gutters. And there are radiant electric cables intended to be embedded in a substrate. I'm concerned about the ice dam cables being too feeble to radiate heat up through an inch of wooden stair tread. The cables meant for in-floor radiant heat or snow melting all say they must be embedded in a couple inches of cement, sand, or asphalt. It sounds like directly attaching them to the underside of a wood stair tread is not a good idea. I'm also concerned about longevity with the ice dam cables: I've read some sources say they should be replaced every 3 - 5 years which seems a little ridiculous.

Electric mats -- I bought one of these HeatTrak Snow Melt Matts http://www.amazon.com/HeatTrak-HR10-30-Residential-Snow-Melting-Stair/dp/B00421AHY2/ref=pd_sim_lg_1 to test it out and it seems to do a decent job radiating the heat up through the stair tread. The stringers make it not a great fit for mounting under the stairs.

I like the hydronic option as it sounds bullet proof once installed, but it seems like it would be a very custom solution to keep the price down. A small tankless water heater and a pump seems like it should be a frugal alternative to a full-on hydronic boiler. Is it?

A heated cable would also be OK if I can mount it directly to the wood and get good results and longevity. Will the ice dam heated cables be powerful enough and will they last?

Mounting the electric mats underneath the stairs feels like a square peg in a round hole. They just don't fit between the stringers, and to get good direct contact with the stairs I should probably have something holding them up flush against the bottom of the stair tread, which is not a recommended installation. As it is now with my one test mat they hang a bit loosely under the tread. This is my least favorite fallback solution.

Am I overlooking some other ideal product or solution that fits my requirements, and if that is not the case, what are the gotchas or other considerations I need to account for in implementing a solution like this?

Answer 1

Electric cables can be fixed there very well. Let's say we use 2 mm thick cables with low wattage (10 W/m).

Firstly you cut 2 mm wide and 3 mm deep cuts to the bottom side of your steps (using a hand circular saw). They should be parallel going from side to side. Put silicone and cables into the cut doing S bends, they should just fit in there. Cover the cuts with silicone to close them against pollution & weather.
Cut one cut for thermal sensor 2 cm next to the cable cut. It should be in a "thermally representative" place. Put the thermal sensor in it and cover it with silicone.
Do the wiring: thermal sensor and cables to thermostat and thermostat to the power line (via curcuit break).

I have in-floor radiant cables installed in cuts in EPS mats under the laminate flooring. There is a thermostat with an in-floor thermal sensor which I set to about 20°C. It works well and feels even better. They say cables must be embedded in a couple inches of cement, sand, or asphalt because the flooring can be overheated. That's why the low wattage (combined with wood stair tread).

But - will it do the job? Sure, because if it's only below freezing, it's enough to raise the temperature a bit to unfreeze. If it's rather cold, it's probably not freezing rain in the air (I don't know your climate).

Main pros:

• You can decide how dense the cuts are to each other to decide the total heating power. I'd say 80 W/m² should do.
• Silicone covering the cables (above and under) will protect them from any damage and they will easily exceed the expected lifetime. And the surface of the wood will be stay closed against weather.
• You set the thermostat to the required temperature (+3°C maybe). You can even turn it off or buy a thermostat with a programmable clock to be used at night.
• Much of the work can be done by yourself and the materials needed aren't expensive too. Even with 100 m of cable and a programmable thermostat you won't exceed the limit.

Some cons:

• Cutting from side to side weakens your steps very little or not at all.
• You'll have to fiddle with bending and fastening the cables at each turn, because they have some minimal circumference of bend (5 cm maybe). You can let them just bend freely off the cut, but cover them with silicone too. Or cut several short cuts of circular shape.
• You might decide to use Thermal Silicone to get even better heat transfer. But I don't think it's needed.

One more thought: pipeline protection cables have a built-in thermostats at certain places. But they are rather thick (9 mm) and expensive.

Answer 2

I think shinning an infrared heater on the steps would be quite cost effective and very easy. I have this $60 one in my garage and am impressed with the bag for the buck.

Maybe the mounting point would allow you to use it to make the porch more enjoyable in the late fall / early spring and you only shine it on the step during the winter?

If you want to get busy with an ice sensor you can purchase one or try to fab one with your mad adurino skills, but its only 15-20 days out of the year and you can probably get the timing right to just use a $12 plug in timer.

Answer 3

You could try "Ice Breaker Stair Tread Mats" . I've never used them but the theory looks good. They look like a regular plastic stair tread but the ice shatters and separates when pressure is applied.