Back-lighting a "fireplace" opening

[Nozzle]

This is a two part query relating to stove fitting, I've put one similar post in the section for building control. I already have a stove installed in the living room and it discharges through a stainless chimney liner, all the register plate is fitted and certified etc.

The whole room is looking very tired, and so the fireplace/hearth/mantelpiece/stove is going to be re-done at the same time. I intend to replace the mantelpiece (currently a steel, stone and cement Heath Robinson affair) with something either timber, or concrete but timber effect. Also, I'll have the inset of the "fire place" illuminated with LED strips of spots then re-fit the stove back in the inset and to the register plate.

Electrics in the opening, heat proof lighting/cabling - Is heat-resistance lighting necessary/available? I know heat resistant cable is available, either the stuff for airing cupboards or even the fire alarm system stuff. Are there requirements for the cable type or how it is run? Perhaps using 12Volt gear would negate many problems, or LED strips. (Though I wouldn't expect there to be heat resistant versions of these). I don't want to be doing the electrics myself, I have a reliable and accommodating sparky who I'll get involved with this job, but I want to know in advance what is possible and what is la-la-land. I've seen photos but that doesn't mean it was a photo of an actual compliant and functioning solid fuel stove stuffed into a fireplace.

^^A library picture of the effect I'd like to achieve

Nozzle

 

[ericmark]

Much depends on the heat that is actually in that area. In theory the flue should be held at around 150°C, hotter and fuel is wasted, cooler and you can get tar build up, there are a couple of fires that are condensating, but then the flue is horizontal. The theory is you light the fire and it runs at a set output until all coal or wood is turned into coke or charcoal. It the fire runs cool then it can have particular emissions from the flue until at charcoal stage, so the idea is to have a heat exchanger system that stores the heat in insulated cisterns until required, and then the central heating pump circulates the liquid (normally water) to radiators. The cost to install a fire designed to heat the home (not just for looks) is huge, ball park £6000 for cheap set-up. However there is nothing one can see as a casual observer different between a proper system, and a cheap system designed to just look good and be used once in a blue moon. So although theory says 150°C for flue pipe, practice it can be a lot hotter.

At 150°C then by time you reach the lights it will be no warmer than central heating pipes, wired in ali-tube would be good enough, but if not controlled then looking at mineral insulated cable. Many fires do have power to them to work the fans, alternative is a sterling engine driving fan, so question has to be how hot is it really?

I looked into installing a wood burning stove, regulations state a replacement heating system must not be more than 10% less efficient than what it replaces, so where gas central heating has been used, you can't legally replace it with a wood burner, as except for one experimental unit, and a home made unit they are not condensating so struggle to even get 70% efficient, so unless it's had a solid fuel fire from first build, any fire is only for show, it's not to heat the house. But thieves have been installing wood burning stoves, I say thieves as in the main they are too costly to run unless you steal the wood, and these units are often not thermostatically controlled and can get very hot.

Yes the rocket stove

is condensating and does tick all the efficiency boxes, however there is an insurance problem, getting the house insured when you have a home made stove installed is near impossible. People I know with wood burning stoves have a thermometer on the flue so they can ensure it stays at 150°C. They have two air inputs, both drawn from outside, one for main burn and one for after burn to ensure no particular emissions. Really good sitting by the fire, but when I see all the work to get the fire going including 10 acres of woodland I decided not for me.

 

[ban-all-sheds]

Shouldn't that be condensateringlynessive?

 

[Nozzle]

Thanks for the comprehensive reply there ericmark - I may not have been clear in my initial post that the stove is only occasional use, it's not the primary heat source for the house, and I'll be re-fitting rather than replacing the same stove. (After a lick of paint). I note your temperature estimations though I also sense the Part J regs are built with chimney fires in mind. That is to say, in the worst case scenario if the metal is glowing cherry red becuase of a fault/fire, then the fire is prevented from spreading by virtue of having no external combustibles anywhere near it. The plastic of the light fittings is principally a hydrocarbon next to to a heat source. I like the idea of the conduit - aluminium being a good conductor might be beneficial, better than steel. I assume, for the right price, any electrician is happy to do this type of installation, or do I need a specialist with the predictable extra cost?

Nozzle

 

[Tigercubrider]

If building, it would be easy to run a couple of bits of conduit into the build .
Will there be power sockets nearby? I.e. On the side of the chimney/ in each alcove ?
I 'd be tempted to run 12v or similar and led allowing the transformer to be elsewhere

Leds take a fair amount of heat

 

[ban-all-sheds]

Leds take a fair amount of heat

LEDs are extremely intolerant of heat.

 

[Tigercubrider]

The ones that I use in theatre lighting seem fine

 

[ban-all-sheds]

If an LED-based lamp is installed in an unventilated luminaire, or a luminaire is located in an environment that does not have free air circulation, the LED is likely to overheat, resulting in reduced life or early catastrophic failure. Thermal design is often based on an ambient temperature of 25 °C (77 °F). LEDs used in outdoor applications, such as traffic signals or in-pavement signal lights, and in climates where the temperature within the light fixture gets very high, could experience reduced output or even failure.

 

[Nozzle]

I wonder if halogens, what with being bloody hot anyway and not having any semiconductors, would fare better in this space.

Nozzle

 

[deadshort]

Fork'andles ……….


DS