Electrically heated small path to melt ice- thoughts? 0 degree thermostat options?

[NCXo82ike]

I have a 3m long 1m wide path leading to my house needing a refurb. I slipped on ice on it and smashed up my phone the other day, so got to wondering how hard it would be to avoid this- particularly for kids or elderly relatives.

We're in a conservation area, Victorian, mid-terrace. The refurb will probably be flat fired tiles in keeping with the street. We're in the south east so temperatures dip just below freezing, mainly overnight only and not that frequently.

 

I plan to relay tiles with better fall to reduce standing water.

 

I could very easily set an underfloor heating mat with a thermometer into the mortar, perhaps even over a thin insulation layer.

I'd plan to set a cycle to heat in the early morning to get up to temperature and then shut off, and have the smart home setup to get granular control.

Working off 3x1m and a 5cm thickness, I reckon I'll need <0.1KwH to raise the temperature by a degree. Even on a cold day that would be 14p to raise the temperature from -4 to +1 , and on many days it would need even less heat. 

 

So I'd guess it would only cost £10 a year, and on a variable tariff +/- home battery it would be even less. Upfront cost would be minimal. Certainly cheaper than a new phone or hip. At first thought it seemed ridiculous but I'm now wondering why not?

 

1) Interested to know what people's thoughts are. 

2) I can't find a thermostat to buy online which targets less than 5 degrees (obviously sensible in typical indoor installs). Does such a thing exist? 

Edited December 14, 2023 by NCXo82ike

[Mr Punter]

I doubt electric underfloor heat mats are suitable for external use.

 

Get some rock salt.

[JohnMo]

To melt the ice you may need more than 1 deg, I suspect.

 

Your maths seems to output a very low input required are sure you are correct?

 

Have you accounted for downwards and sideways heating. In the States they say allow 50W per ft2, so you are about 10 ft2, that would need 500W. It would be on from about 4 or 5am until you stopped moving about say 6pm, so 12hrs. So 6kWh a day, or £1.60ish a day.

 

As @Mr Punter says get rick salt - stop wasting good energy on heating the environment.

[Onoff]

I considered two insulated / heated tyre tracks up my sloping drive.

 

I will at least likely fit a trace heating element in my sliding gate track.

[NCXo82ike]

22 minutes ago, Mr Punter said:

I doubt electric underfloor heat mats are suitable for external use.

 

Get some rock salt.

Agreed rock salt is certainly suitable and sensible- this is a bit of a what if question.

 

You can buy outdoor electric heating wires, and I wonder what there is to break on the mats, which are essentially just a high resistance wire? The controls would be inside

[NCXo82ike]

34 minutes ago, JohnMo said:

To melt the ice you may need more than 1 deg, I suspect.

 

Your maths seems to output a very low input required are sure you are correct?

 

Have you accounted for downwards and sideways heating. In the States they say allow 50W per ft2, so you are about 10 ft2, that would need 500W. It would be on from about 4 or 5am until you stopped moving about say 6pm, so 12hrs. So 6kWh a day, or £1.60ish a day.

 

As @Mr Punter says get rick salt - stop wasting good energy on heating the environment.

Thanks, that US context is helpful. The maths is very much an estimate- it's a highball for the energy to heat up that volume of concrete, but doesn't include leakage.

I'm assuming sideways would be limited and downwards leakage would be little if there was s small depth of rigid insulation, since the the temperature delta will only be small.

I've just found Warmup have some 'snow melting cable' products. They spec 300w/m2 to cover down to -20C.

 

To clarify I was thinking of using a short burst in the morning rather than all day, since I think the main issue is frost overnight i.e. frozen condensation rather than trying to melt built up snow. Snow's no bother, unless it melts and freezes in place.

I wonder how high above freezing you'd need to get to and for how long.

 

I understand this might seem ridiculous. For context I'm energy-stingy (currently 16C indoors!) and aiming to be green (ASHP, batteries etc)

If the energy consumption is small & green (or even from home own solar), then this might be fun project.

If it used large amounts or dirty energy then it would be silly, even if cost weren't an issue (which it is!).

Edited December 14, 2023 by NCXo82ike

[NCXo82ike]

20 minutes ago, Onoff said:

I considered two insulated / heated tyre tracks up my sloping drive.

 

I will at least likely fit a trace heating element in my sliding gate track.

The gate sounds like an interesting application. Out of interest, was the track installed to allow for drainage or do you have pooling and freezing water?

 

[JohnMo]

lowest energy would be a loop of UFH pipe from ASHP, just flow it out via an electric mixer at super low temp

[NCXo82ike]

2 minutes ago, JohnMo said:

lowest energy would be a loop of UFH pipe from ASHP, just flow it out via an electric mixer at super low temp

I think it would be lower energy per time, but would need to run constantly for frost protection. So would probably end up using more? 

 

Ultimately if the electric version was pricey, it could stay buried and never used without issue- not the case with wet UFH.

Edited December 14, 2023 by NCXo82ike

[Onoff]

I mulled a giant solar thermal array and glycol filled loop with insulation under the path / drive.

 

It's just a pipe dream though...

 

 

[Onoff]

1 hour ago, NCXo82ike said:

The gate sounds like an interesting application. Out of interest, was the track installed to allow for drainage or do you have pooling and freezing water?

 

 

No issue with pooling. Heavy snow, if it melts can refreeze. The gate track profile lends itself to running a trace heating cable up inside it. I've a duct in ready for it.

 

 

 

 

Tbh beech nuts are the biggest issue. They'll stop the gate in it's track. 

 

[RobLe]

Start collecting big pop bottles.  Fill them with a 10% salt water solution, which won't freeze until -10C or so.  Bury them in a line, upright.  It should give a few extra degrees before this bit of path freezes, as it sucks up heat from a greater mass of soil underground.  If you put loads of them down it's perhaps more likely the earth below freezes, so it won't work so much.

It's (almost) free!  Try it ?

[SteamyTea]

On 14/12/2023 at 17:33, Onoff said:

It's just a pipe dream though...

Silly sod.

 

How about rubber matting with holes in it?

[Onoff]

44 minutes ago, SteamyTea said:

Silly sod.

 

How about rubber matting with holes in it?

 

Good idea, the holes would let the heat through from the glycol loop!

[ProDave]

Just put salt down.  Any idea of using electricity to melt the ice when we are trying to reduce our fuel usage is just completely bonkers.

[SteamyTea]

15 minutes ago, Onoff said:

the holes would let the heat through from the glycol loop

Quiet day is it?

[Temp]

On 14/12/2023 at 15:30, JohnMo said:

Have you accounted for downwards and sideways heating. In the States they say allow 50W per ft2, so you are about 10 ft2, that would need 500W

 

3m x 1m is more like 30 sqf unless you were thinking of just heating a 1ft wide strip down the middle

 

Nearer 1500W.

[SteamyTea]

2 minutes ago, Temp said:

Nearer 1500W.

Imagine forgetting to turn that off.  May be the next snowfall before you notice.

 

Hottest year on record

[torre]

On 14/12/2023 at 17:33, Onoff said:

giant solar thermal array and glycol filled loop with insulation under the path / drive.

 

It's just a pipe dream though...

How about burying most of the glycol loop a metre or so underground below the path/drive, where the temperature's ~10 degrees? A very no-frills ground source heat pump