House fan

Discussion in 'Eco Talk' started by Andrew Davison, Sep 1, 2018.

  1. After a little bit of advice to see if this would work.

    We have a fairly big sitting room with an open stair case in it. Anytime we light the log burner, all the heat immediately goes to the top of the staircase instead of warming the room. If we were to fit a ceiling fan at the top of the staircase could we use it to push the heat back down the stairs in the winter or run it the other way in the summer to draw the heat up?

    There is a light near there which could be used to power a light and fan combined unit but it’s a bit off to the side so don’t know if it would work as well.

  2. I think what I’m after is called a destratisfication fan.
  3. rogerk101

    rogerk101 Well-Known Member

    Most rotating ceiling fans are for exactly that purpose ... push the warm air back down into the room in winter, and pull the warm air up from the room in the summer. It's a great way of assisting convection when there are obstacles that slow it down.
  4. HarDeBloodyHarHar

    HarDeBloodyHarHar Active Member

    May also draw smoke/fumes up!
  5. MGW

    MGW Well-Known Member

    I have same problem, however the main problem is lack of vents or ducting for combustion air. Clearly the house designer had no idea of how a open flue works. You can get fires which draw combustion air from outside, however the problem is getting that air into the house.

    I tried using a simple fan to move air down, however it failed, it seems I would need to duct the air to get it back down, there is a device designed to do this, called a heat recovery unit, but again problem is ducting.

    If you find a cure, please say, as I also have an open plan house.
  6. Bob Rathbone

    Bob Rathbone Well-Known Member

    We use a door :) I know that it may be difficult for you, maybe a curtain. It's always a problem in a room as you describe. The fan might work.
  7. MGW

    MGW Well-Known Member

    In an open plan house, there are not many doors, that's why it is called open plan, toilet, bathroom, bedrooms and kitchen have doors, and yes closing the bedroom door will stop heat getting into the room, but once you forget to close the door, the room heats very quickly, and closing the door after the heat has bolted is no good.

    Mothers house very different, doors on every room and it has a hall, a simple curtain across stairs will stop most of heat raising, but even the curtain not an option with open plan house, the stairs are also open, it would require a whole new stair case.

    Since we don't have a log burner, just a gas fire into a flue brick, the amount of air going up the flue brick is limited, however what goes out has to come in, and with mothers house the only way for air to enter room is under the door, so light a fire, and the draft under the door is rather large, hence use of high backed chairs to stop people feeling that draft.

    In another house I visit he has a vent to outside right by the fire, so combustion air is not drawn from under the door, first glance seems wrong, but he proved it by blocking the vent up temporary. Once blocked then massive draft under door, remove blockage draft stopped and you feel the radiated heat from fire.

    But we also have the chimney effect, this I saw when stress releaving pipes, block the ends of the pipes and all is going well, however if that blockage is removed, the pressure is unbelievable, only a 36 inch pipe but getting the cover back on was hard not a one man job. One guy holding it other guy with masking tape trying to hold it in place, OK pipe was at 700C but once the heat has started to move the air, it takes a lot to stop it.

    Dampers in the actual chimney reduce flow, aim is 150C below that moisture forms above that heat is wasted, with log burners you have today have doors, as it needs an after burn to stop particular emissions. The clean air act has stopped the use of simple wood burners. Often the dampers are electrical controlled, today regulations mean the output of a wood burner is constant until only charcoal left, you can't turn it up and down to suit your needs, it has a fixed burn rate.

    To get around this problem often you have a boiler, well we hope it does not boil, but we remove much of the heat produced and store it in water filled cylinders, then after the fire has gone out, this water is circulated to maintain the house temperature, net result is a system costing in excess of £12,000 to use a wood burner within limits of the law.

    When looking at these costs, the cost of a heat recovery system is not that much, but the heating engineers who design wood burning systems earn their money and title, they are truly engineers, it is a very complex system.

    However as with most things you get cowboys, they install illegal systems take the money and run. You also get historic systems allowed because of grand father rights.

    I was commissioned to write a website to show the folly of wood burners, as I did my research I realised nothing wrong with a well designed wood burner, it was only the poorly designed units which have a problem, I made the mistake of pointing out the guy who commissioned me had three poorly designed units, so his figures on the amount of wood burnt was wrong. I got sacked. However he was not wrong with some of what he said, although there are some really good systems installed, many are really poor, and only reason for them is so the user can steal the fuel he needs, which often means removing wood left to rot from the woodland which in turn destroys the eco system.

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