INFRA RED UNDERFLOOR HEATING

[Horatio Sprague]

I recently read an article by Funky Heat in Canalboat extolling the virtues of 24V electric infra red heating mat systems, which can be used for narrowboat underfloor heating or behind wall panels. Can be used as a substitute for conventional wet radiator systems on boats, and supposed to be highly efficient. The idea of doing away with a diesel boiler and radiators in favour of invisible heating is very attractive. Has anybody got experience of using these systems, in particular their drain on the electrical system and their ability to heat up quickly. Having had underfloor water heating in my home, they are very efficient if left running, but take a long time to heat from start up. The article link is pasted below......should it be taken with a pinch of salt??

http://www.canalboat.co.uk/canal-boats/maintenance/heating-your-narrowboat-efficiently-and-comfortably-1-5240436

[NMEA]

IF you had a battery bank the size of a football pitch or are on permanent shore power I guess it would be OK.

[mross]

If you cover infra red heaters they can't work.  Also, electric heating is very expensive and not practical unless on mains power.

[WotEver]

A total non-starter for home-generated electrical power. 

[Horatio Sprague]

The article implies that one of the advantages of this system is the very low power consumption running on 24v, and ability to combine well with solar generation. I will try to find out what this means in terms of battery banks etc.

[mross]

Electric heating is efficient but costly.  100% of the electricity turns to heat.  A gas boiler is only 90% efficient but the gas is about a quarter of the price.  A wood burner is roughly 60% efficient.

www.confusedaboutenergy.co.uk/index.php/domestic-fuels/fuel-prices

[NMEA]

You cant defy the laws of physics.

[Nickhlx]

Just as we do a power audit to ascertain size of battery / generators etc, a "heat audit" would reveal that a certain no. of kWh is required to keep your boat at 20 deg C inside, when it's zero outside, with an adequate ventilation changeover to prevent condensation / stale air..   I do not know the figure for our boat but could guess it to be around 5 kWh constantly...  This is with the approx 5kWh stove and the approx 5kWh diesel heater each on and "cycling" as they do...   A few hundred watts might also come from the occupants...    

So, a live-aboard is going to need about a, not inconsiderable,  (5 x 24) = 120 kWh every day to maintain the above. Diesel has about 10 kWh of energy in a litre and I think coal (dependant on type) is about 6 kWh per Kg, of which some is definitely going up the chimney to waste, so you could expect to use maybe 10 litres of diesel and a few Kgs of fuel to maintain this, unless either are being worked hard, in which case the fuels consumed will definitely increase.

Doing this electrically is very easy, if you are on shore power !  Electrical heating is very efficient as virtually none goes to waste, but it is also expensive compared to the other two.   If this has to be generated from diesel, it is even more expensive as the conversion losses are significant. About the least expensive in practice on a boat is the solid fuel stove, which is why people use this method.   

It would be interesting to have confirmed what the energy source is for this system that is proposed, and typical energy costs..

[mross]

A 4kW stove would draw 160 Amps at 24V.

If you define efficiency as 'what you get' divided by 'what you pay for', electric heating has lousy efficiency!

Edited December 11, 2017 by mross

[Horatio Sprague]

Funky Heat have told me that a narrowboat cabin measuring 12.4m long by 2m wide and 2m high would need infra red heating mats rated at 1.24Kw approx. How does this convert to battery drain over 24 hours? This to produce 21 degrees C when outside temp 0 degrees C

 

Edited December 11, 2017 by Horatio Sprague
extra stuff

[mross]

They are talking rubbish.  

The power of an underfloor heating system usually needs to be between 65-85W/m² to give the required output. When it comes to choosing underfloor heating, a 150-200W/m² system is usually specified to reduce heat up times as the system will not be “on” continuously.  But this is for a house with insulation laid down first.  We had almost four inches of polystyrene a under our electric heating.  Your boat is 50 cubic meters, so requires about 7,500 Watts, that is 7.5 kW.  ( If you heat the boat from bow to stern).

https://www.google.co.uk/amp/www.warmup.co.uk/blog/guide-to-underfloor-heating-heat-output/amp

Edited December 11, 2017 by mross

[dor]

There is/was a company doing a hard sell of "electric panel radiators" and a neighbour was assured they would save them over £1000 on his current, gas, central heating.  Fortunately we managed to convince him that the figures just sdon't add up (he was only spending about £1000 a year on gas anyway!).

I would imagine this is the same sort of snake oil.

[Horatio Sprague]

According to Canal Boat, this article is the most widely read from the October edition. I'm surprised that they would have published it without some justification. I have contacted Funky Heat for further information. Anyone else who is interested in this idea should perhaps also contact them direct for the facts and figures in relation to use on boats with battery power as the primary source of energy.

Edited December 11, 2017 by Horatio Sprague

[Robbo]

13 minutes ago, Horatio Sprague said:

Funky Heat have told me that a narrowboat cabin measuring 12.4m long by 2m wide and 2m high would need infra red heating mats rated at 1.24Kw approx. How does this convert to battery drain over 24 hours? This to produce 21 degrees C when outside temp 0 degrees C

 

It will be over 2400ah at 12v

Edited December 11, 2017 by Robbo

[mross]

Anyone who falls for this claim should get a performance and cost guarantee first and check with a solicitor that it's legally binding!

Edited December 11, 2017 by mross

[Jen-in-Wellies]

Well astrologers are able to sell their services too. I wouldn't take this companies figures without a very large dose of salt. If 1.24KW is true, then that is 100A draw on a 12V battery, all day, every day in winter. Two hours to drain a 400AHr battery bank to 50%. You need either a generator going 24hrs a day, or shore power. You would need to fill the boat with batteries to keep it going overnight with the 8pm generator shut off CaRT suggest .

Jen

Edited December 11, 2017 by Jen-in-Wellies

[Sea Dog]

Am I missing something here? Surely an infra red heat source, normally a lamp or a glowing element...or the sun,  produces radiant heat, so if there's anything between you and it the effect is stifled. 

[mrsmelly]

19 minutes ago, Horatio Sprague said:

According to Canal Boat, this article is the most widely read from the October edition. I'm surprised that they would have published it without some justification. I have contacted Funky Heat for further information. Anyone else who is interested in this idea should perhaps also contact them direct for the facts and figures in relation to use on boats with battery power as the primary source of energy.

[Horatio Sprague]

No, this is apparently "low surface temperature far infrared heating".....a thin heat mat using 24v installed above a insulation layer and below the floor covering, which can be timber laminate or solid flooring. 

http://www.funkyheat.co.uk/category/low-surface-temperature-far-infrared-heating/

[Jen-in-Wellies]

3 minutes ago, Sea Dog said:

Am I missing something here? Surely an infra red heat source, normally a lamp or a glowing element...or the sun,  produces radiant heat, so if there's anything between you and it the effect is stifled. 

I was going to mention that too. Most of the heat transfer is going to be conduction through the floor and convection in the air. The rest of their claims are such hokum that the infra red bit was just the first warning sign.

Jen

[mross]

They claim an efficiency of 93% for their "Eco" model!.  An oil-filled radiator is 100% efficient.  Perhaps their heating elements glow.  You don't want light from a heater (well not visible light, IR is OK).

[mrsmelly]

13 minutes ago, Jen-in-Wellies said:

I was going to mention that too. Most of the heat transfer is going to be conduction through the floor and convection in the air. The rest of their claims are such hokum that the infra red bit was just the first warning sign.

Jen

I havnt bothered looking at the crap they obviously are spouting everyone knows lectric heating of any sort on an off grid boat is a nonsense. Oh wait just a minute are these the guys that market the " Eco Fan "

[mross]

Radiant IR heaters are good in workshops that have frequently opened doors as you can feel warm even when the air is cold.  But a floor at 24 Deg C is not going to radiate much heat to a body at 37 Deg C.  So, as others have said, it will heat the boat by convection.  I feel a letter to the Advertising Standards Authority coming on!

[Jen-in-Wellies]

It sounds like they are trying to sell to a market they don't understand. They make a bit of sense if you have a grid electricity supply, but not on boats.

This sort of thing comes along every few years. Some new thing for the boating market. The boating press publish articles and accept the advertising 'cause they have space to fill and bills to pay.  A few people buy the product and find it doesn't work, then it disappears . a very few ideas and products make it in to the mainstream of boating after they have been proven to work. Can safely say that this isn't going to e one of the later.

Jen

Edited December 11, 2017 by Jen-in-Wellies

[Machpoint005]

I haven't done the sums, but I would think the only electric heating method likely to be viable would be a heat pump - the canal is a very big source of low-grade heat.