Passive Heating using a Woodstove

Thursday, 21st October 2021

To utilise the heat from a newly installed 5kg stove, Karou's builder installed ceiling ducts to allow the heat to reach the upstairs rooms.

We try to live simply and with a low carbon footprint and have insulated our house as much as possible with secondary double glazing, thermal wallpaper and a good layer of insulation in the roof, which is the best we are able to achieve in a very old property with a peg tiled roof.

Replacing an inefficient stove

We had an old 8kw boiler stove fitted almost 20 years ago, which sadly was a bit of a disaster and it didn't heat our home like the old Parkray it replaced. With such a large investment it had to be used as the supplier refused to accept it did not do the job it was purchased for. It was a case of us not being well enough informed as we had relied on a saleman and didn't have the benefit of the internet in those days. It was supposed to be able to heat six radiators with ease but the stove itself never got really hot and one could place one's hand on the top and never get burned.  It did however get repurposed by the plumber who removed it and took it to use as an outside stove on his patio.

A year ago it was replaced with a non-boiler Woodwarm 5kg stove, a make recommended by the chimney liner man. We took out the radiators thinking we would use electric ones to heat upstairs as we did not want to install an oil or gas boiler to heat them, plus they were so old the whole system would probably have needed replacing. Interestingly the installer had experience with the make of our former stove and found that on occasions they would not heat a house but when replaced with a different stove the problem disappeared. He also repurposed by the old stove into an outside patio stove.

For heating a tiny two up two down very old house, we have found the new stove brilliant for the downstairs living room and kitchen, even allowing us to heat an Aga kettle on the top, which we use for washing up. However, our stairs run up from the kitchen and the heat did not seem to flow around a corner and upstairs – downstairs was almost too warm at times and upstairs too cold. So I did a bit of research and came up with the idea of a Passive Heating system.

Passive Heating

We are lucky enough to have a very skilled and open minded builder and he has installed two ducts that run from the living room ceiling to the bedroom above the living room (this kind of work should be carried out by a qualified builder who will be aware of all building regulations). They work like a dream and we can now benefit from the downstairs heat migrating upstairs. By the evening the heat has died down so the bedroom does not get too warm – this was the main problem we found with a boiler stove, it would heat radiators during the day but by morning the fire in the stove was out and the radiators went totally cold, leaving upstairs really chilly. We didn't want to use electric heating as well as the central heating radiators, as this defeated the object, as well as cluttering up tiny rooms with extra appliances.

We were unable to position the vents directly above the fireplace as they would have been under a wardrobe, so we chose to have the vents above a window, which then opened out into the room above also below a window – even with secondary glazing, as with all old houses, there is a certain amount of draft and the window can be cracked open if necessary to allow a draw of air, but this has not proved necessary so far.

To install the vents, firstly the floorboard was lifted to check that there were no wires or pipes beneath it and the position from downstairs was chosen so that the vents would be well positioned and evenly sited in the ceiling above the window. The skilled bit was cutting out the ceiling then lining up the position through the deep floor cavity with the space above. The gap between the ceiling and floor was boxed in to form a rectangular 'chimney' which was suspended from the floorboards so that there was no weight on the actual ceiling and the edge of the box where it met the ceiling in the living room was neatly trimmed with a very thin strip of wood.

The holes into the bedroom have two really nice wrought iron grills fitted which look nice and are sturdy enough to be walked on.


The ceiling in the living room


The metal grids in the upstairs room

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