Experimental Fireplace Door
Above is a photo of a modern stone faced "Kacheloven". A "kacheloven" is a masonry stove, sometimes beautifully tiled with ceramic art, which is generally associated with Germany and Austria. They are highly efficient stoves and the brick / clay fabric retains heat like a storage heater.
The main features are the sealed and air controlled fire box giving controlled burn, and the heat absorbing brickwork.
Have I created a Kacheloven by accident?
When I installed my experimental fire front door, I did so with a warning from an SEAI "official" that it might lead to cracked masonry in the chimney due to overheating.
I basically figured that this would not occur, as I had a back-boiler installed which, I believed, would absorb much of the extra heat generated.
This was in fact the situation as it has emerged over a good time of constant use. What I did not expect from the installation, was the positive storage heater effect. The fire door and air control has slowed down the air rising up the chimney, allowing the chimney to absorb more of the heat.
When I eventually got the air control and sealing fully and efficiently operating, the overall efficiency of the fire was greatly increased. The fire can now slow-burn for up to 10 hours on a single fill of fuel.
The stonework facing takes up a lot of heat and can reach a peak of 70 degrees C. The chimney breast does not get this hot but can reach a maximum of about 45 degrees. The entire chimney warms up - heating the kitchen behind the wall and the bedrooms overhead.
It takes several hours for this heat to build up, and when the fire is kept going 24 - 7 it maintains a lovely heat in the whole house. Some of this heat is transferred by means of the back boiler which transfers perhaps between 2 to 7 kW perhaps to radiators etc. depending on the state of burn of the fire.
The winter so far this year has been mild and we have kept the fire more or less on minimum burn all of the time. The only heat source in the 12 foot by 18 foot living room is from the fire. That room stays almost a constant 22 to 23 degrees.
The rooms heated by radiator on the far end of the house tend to drop a little overnight but generally stay above 19 degrees. The house has never felt so constantly comfortable.
Above is a picture of my living room stone-fronted fireplace with the experimental fireplace door. The stone fronting is about 12cm deep and made of a very dense stone called Achill stone which is a sparkling amathystine quartz with a warm yellow tinge. The stone takes heat very well and retains it for hours.
So far this winter the stove is redundant
Our kitchen / dining room has a Blacksmith Anvil stove fitted. So far this winter, it has been redundant, as the heat from the shared chimney breast and some heat from a radiator has kept the room above 20 degrees. I am sure in the colder weather this will not be maintained.
Bottom line, so far this winter - the house is at 22 degrees 24 -7 and:
(1) We have not used the oil fired central heating at all.
(2) We have not yet lit the stove in the kitchen.
(3) We have the electric immersion water heater turned off.
One single fire in the living room has kept the house toasty warm and supplied all the hot water needed as well.
What does it cost to run?
At the moment, mid November and mild, running the system 24 - 7, we are using about 50 to 60 Kgs of smokeless coal per week. This "Calco" coal is costing us just €14 per 40 Kg bag delivered - see my recent post:
So the heating and hot water is currently costing us between €17.50 and €21 a week. When you deduct the immersion heater electricity costs of roughly €1 per day (the immersion has been switched off for weeks), you get a space heating cost of between €10.50 and €14 per week for a toasty warm 24 -7 heated 4 bedroom house. I would say that is not bad at all.