I'd suggest doing it the opposite way around. Use a plenum system where the fan pushes air into the room at high level and it exits at the bottom. You could choose a cool place from which to pull in the air. By making the exit a little too small there will be a tiny bit of overpressure. This will prevent air and dust being sucked in from the kitchen. A timer would be fine, but you might want to consider a thermostat to prevent fan operation if the outside temperature is very high.
Extractor fan operated by an hourly timer?
- Thread starter travisbickle
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I think there are probably some potential flaws in the whole idea. All insulation (any amount of insulation) of the 'internal' walls and doors will achieve is to slow the rate of transfer of heat between kitchen (or other parts of house) and pantry. In the absence of any 'cooling' within the pantry, its temperature will therefore eventually rise to that of the kitchen.
The system would probably work reasonably in winter, since the continuous circulation of (cold) outside air through the pantry would represent such 'cooling' and, given adequate insulation, would be more than able to 'keep up' with the heat transfer into the pantry from the (presumably 'warm') kitchen - so that it would remain cool/cold in comparison with the kitchen. Viewer's idea of pushing outside air into the pantry (rather than sucking it out), thereby creating a small positive pressure within the pantry would help that further, because it would reduce the amount of heat transfer into pantry when it's door was opened.
However, in summer (when you probably most want the functionality), the system would presumably not work so well. During the daytime, the air from outside which you were circulating through the pantry would be warm or hot, quite possibly not significantly cooler than that in the house - so you might well decide not circulate air through it during daytime (as viewerhas said, an outside-temperature thermostat could achieve that). To achieve an appreciably cooler temperature in the pantry, you would presumably be relying on the pantry being cooled by (relatively cool) night-time outside air and for that coolness then to persist during all of the subsequent day-time. In that situation, the more insulation the better. Again, viewer's idea would help to prevent the pantry filling with warm air when its door was opened, thereby helping the coolness to persist. You would be mainly dependent on the contents of the pantry (including walls, shelves, etc.), rather than the air, getting cool and helping to maintain the coolness during the day - hence all the heavy stone and marble etc. one found in traditional pantries.
Kind Regards, John
Insulation, and a small cheapy self-fit through-the-wall A/C unit.
Yes, that would be the obvious answer, but whether it (particularly running costs) is justified for a pantry is only something which the OP could decide. Insulation, lots of thermal capacity within the pantry and a thermostatically-controlled fan (ideally pushing air in) might be enough for the OP's requirements.
Kind Regards, John
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What about insulation, a tiled interior, and the incoming water supply routed through a pipe snaking back and forth under the tiles?
The running costs would be zero, and any use of water in the house would draw fresh cool stuff into the pantry.
The running costs would be zero, and any use of water in the house would draw fresh cool stuff into the pantry.
The concept is obviously sound, but the extent to which it would work would obviously depend upon the extent and pattern of water usage. Many properties are unoccupied for many hours each day (hence with little/no water usage during tahtperiod), and usually during times of day when ambient temperature is at its highest.
Kind Regards, John
I think you can now buy cupboards already fitted with insulation and a heat pump unit.
They're called "refrigerators".
I'm assuming you would need another fan at floor level to exhaust the air? How else would it be encouraged to leave the room?
It would need no extra encouragement - the fact that air was being pumped into the room, slightly raising the pressure, would force it to seek 'a way out' - and a ventilator at floor level would serve that purpose.
It's no different from the other (more normal) way around. When you have an extractor fan, it works fine so long as there is some ventilator (even if only a gap under a door) to allow air in so that it can be punped out - one doesn't have to install a second fan to pump air into the room. In this case, the extractor fan creates a slightly reduced pressure in the room, which 'sucks' air in through any ventilator.
Kind Regards, John
So in general, is a positive pressure system a more efficient way of ventilating (and perhaps cooling) a room than a negative one?
Out of curiosity, does anyone know what the smallest and most cost effective airconditioning device that is available on the market today?
Out of curiosity, does anyone know what the smallest and most cost effective airconditioning device that is available on the market today?
Incidentally, that small corner of the room will receive no insulation under its concrete base unlike the rest of the extension. Would this make any significant difference to the ambient temperature of the room?
We were considering lowering the floor level in the pantry too.
We were considering lowering the floor level in the pantry too.
All other things being equal, there's probably not much difference, provided the door to the room/cupboard whatever remains shut. However, if you open your pantry door (into kitchen), then there is a difference. With a negative pressure system (extractor fan), warm air from the kitchen will tend to rush into the pantry when the door is opened. With a 'positive pressure' system, there will be much less of that - the tendency being for air to come out of the pantry (into kitchen), rather than going into it (from kitchen).
Kind FRegards, John
Just to be clear, it is fine for air to be drawn in at high level and extracted at low level?
This is going to sound crazy but would there be any point in having both systems in place? I ask this because the length of duct at floor level will be approximately 3 metres.
You'd really have to ask an expert about that. Given that warmer air rises, I could see the logic in the opposite of that.
I think you'd probably be far better off just ensuring that the single fan (pumping air into the pantry) was powerful enough (taking into account the effects of ducting etc. at both entry and exit points). If the 'extraction' was aided by a fan (rather than being 'passive'), that would reduce, or maybe even eliminate, the positive pressure within the pantry - the benefit of which I described in my last post.
Kind Regards, John
That's my concern.
While I have your attention John, lack of insulation under the concrete floor slab - will that have a significant impact on ambient temperature?
There is a consideration to perhaps build the room lower into the ground.
Thanks for all the advice by the way.
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