Transfer floor-level air to ceiling vent above fire?

Forums › Home Workshop DIY › Transfer floor-level air to ceiling vent above fire?

davidireland

2 posts

Wannabe Geek

#215364 24-Jun-2017 13:40

If anyone has tried either of the following schemes or has any comments about them please let me know. We have a 50m2 open-plan living/dining area with 3m ceiling height which has the usual large temperature difference between floor and ceiling when our log burner is on. I don't want to transfer the ceiling-level heat to a different room but would like to even out the floor-ceiling differential. One option is to use an inline fan in the roof space to suck air from above the fire, transfer it through a short run of insulated ducting, and squirt it out elsewhere in the room (in an area where no-one would be sitting) through a jet-type ceiling vent. A second option would be to suck cooler floor-level air into a low vent, transfer it through ducting in a cupboard up to a fan in the roofsapce, and then waft it out through a ceiling diffuser in the part of the room that contains the fire. The idea being that the cooler air would mix with the hot ceiling-level air and reduce or eliminate the floor to ceiling temperature differential. I should add that I realise that I could achieve all this with a ceiling fan but for several reasons don't want to do that. If anyone has any suggestions, either for the overall ideas, or for the finer details like the type and size of fan/ducting/diffusers, how to reduce ducting/fan/outlet noise, etc. etc., I'd greatly appreciate your views.

timmmay

20591 posts

Uber Geek

Trusted

Lifetime subscriber

#1806050 24-Jun-2017 13:42

Why don't you want a ceiling fan? They're big, slow, and can move a lot of air compared with a little fan with ducting.

richms

28198 posts

Uber Geek

Trusted

Lifetime subscriber

#1806051 24-Jun-2017 13:42

Before bothing with that I would just try something with an upwards pointing fan near to the fireplace - Most dehumidifiers seem to exhaust out the top. See if that takes the edge off the difference and if it does then you can probably just put some other fan device there to blow up into the pool of hot air.

Richard rich.ms

debo

307 posts

Ultimate Geek

#1806054 24-Jun-2017 14:02

I am currently using a small desktop type fan. It sits on top of a bookcase in the corner of the room and points downwards. As long as you use a quiet fan, then it is all you need and very cheap.

richms

28198 posts

Uber Geek

Trusted

Lifetime subscriber

#1806057 24-Jun-2017 14:10

timmmay:

Why don't you want a ceiling fan? They're big, slow, and can move a lot of air compared with a little fan with ducting.

Probably because they are big, ugly and intrude into the room like a stupid light fixture but worse. I hate the things. Perhaps if you have a 4m cieling so its high enough you dont really see it, also the whole room starts to strobe when they are running unless you carefully controll the lighting to not get anywhere near the fan.

Richard rich.ms

aucklander

477 posts

Ultimate Geek

#1806108 24-Jun-2017 16:34

same issue, but I dare to say on a larger scale, as the height difference between floor and highest point of ceiling is... wait for it... 7.5m !! the temperature gradient between floor temp downstairs and the air upstairs was so large, that it was too hot upstairs and feet-freezing downstairs.

I am using 60cm floor (tripod) fan. The standard types you can buy from pretty much anywhere, with 3 speeds. The issue is that even on lowest speed, it is way too noisy. I got a voltage controller from tradeMe (around $10 if I remember correctly) - they are still available. It looks like a small metal casing with perforations and a fairly large knob on one side. It involves some 230V wiring (let's not get here into legality of that), the fan has a VERY faint humming noise when if is very quiet in the room, but if the tv is running then you cannot hear the fan from 1m away!

The secret is a slow large fan, not a small fan - small fans will spin very fast and would be noisy.

The setup I have described pushes colder air from downstairs lounge upwards toward the roof ridge (I have exposed rafters - called "cathedral ceilings" if I am not wrong?), it can be felt like a very gentle breeze at head height when you are upstairs (because the speed and the angle was adjusted that way). The colder air mixes with the hotter air upstairs and at the same time, air from there needs to come back to the fan (downstairs) to close the circuit, the fan actually circulates the air. After only few minutes the temp upstairs and downstairs is the same. It works very well. The hum on the fan motor - you can read lots about this on the internet - I was worried the motor will heat up but there is no heating. It works few hours at a time and the motor casing is at ambient temperature. The speed controller does not heat either (maybe because the smallest one is rated 2kW and the fan motor is only 50 - 80W?)...

mobo Intel DH55PJ, RAM: 4GB RAM, Nova-T 500 HD + Avermedia Trinity tuner card, Geforce 520 video, 120GB SSD Sandisk + 640 WD + 1000SG, Win7 Home Prem 64-bit, Media Portal 1.15.0; BTC 9019URF Cordless Keyboard, Panasonic 55" (HDMI cable), HTPC Case Silverstone Grandia GD05B.

SATTV

1648 posts

Uber Geek

ID Verified

#1806118 24-Jun-2017 17:28

richms:

timmmay:

Why don't you want a ceiling fan? They're big, slow, and can move a lot of air compared with a little fan with ducting.

Probably because they are big, ugly and intrude into the room like a stupid light fixture but worse. I hate the things. Perhaps if you have a 4m cieling so its high enough you dont really see it, also the whole room starts to strobe when they are running unless you carefully controll the lighting to not get anywhere near the fan.

My mother in law used to say the same thing, they bought a house that had one and she hated it from word go.

She used to complain about the lounge being hot and the bedroom being cold.

Somehow the fan got turned on at the lowest speed one winter when the fire was going and she remarked that the whole house was a lot warmer and rather than removing the fan they have replaced it with a better new one.

Smaller fans a noisy can can not compete with the volume of air.

I do agree they are unsightly but in my in-laws case we don't notice it any more.

John

I know enough to be dangerous

Dingbatt

6758 posts

Uber Geek

Lifetime subscriber

#1806157 24-Jun-2017 18:35

Had you considered blowing the air that is heated by the log burner horizontally into the room?

“We’ve arranged a society based on science and technology, in which nobody understands anything about science technology. Carl Sagan 1996

Sharesies

Trade NZ and US shares and funds with Sharesies (affiliate link).

Rikkitic

Awrrr
18667 posts

Uber Geek

Lifetime subscriber

#1806160 24-Jun-2017 19:01

Many ceiling fans seem to be designed to be as ugly as possible, especially if they have some bloody light fitting jutting out the bottom. But there are also some that look really nice, like something from the tropics with proper wooden blades. I had one like that in my flat when I lived in Amsterdam and it looked great even though I didn't have a particularly high ceiling. It was also useful for circulating the heat from the gas heater. I really loved it.

Plesse igmore amd axxept applogies in adbance fir anu typos

k1w1k1d

1530 posts

Uber Geek

#1806179 24-Jun-2017 19:52

We have a ceiling fan in our open plan kitchen/dining/living room to distribute the heat from the log burner. Works very well and we don't notice it any more.

richms

28198 posts

Uber Geek

Trusted

Lifetime subscriber

#1806289 25-Jun-2017 04:05

Rikkitic:

Many ceiling fans seem to be designed to be as ugly as possible, especially if they have some bloody light fitting jutting out the bottom. But there are also some that look really nice, like something from the tropics with proper wooden blades. I had one like that in my flat when I lived in Amsterdam and it looked great even though I didn't have a particularly high ceiling. It was also useful for circulating the heat from the gas heater. I really loved it.

The light on the bottom is to remove the fan from the path of the lighting. Problem is it usually is some ineffective 3 lamp ugly thing or an oyster lamp which is equally useless.

I would find a wooden bladed thing to be the most ugly of all. The one I had for a while was a nice silver thing, but the light spread was too bad on it, even just the TV got reflected around the room. Hit it with some matt black paint to solve that and it did, but still was intruding into the room, and a hazard since on a 2.7m ceiling the blades were barely 2.3 off the ground.

Richard rich.ms

davidireland

2 posts

Wannabe Geek

#1806362 25-Jun-2017 12:52

Thanks very much for all the helpful replies. Both ceiling/pedestal fans and the idea of blowing air across the fire are excellent suggestions which I know would work well. However what we're trying to avoid is a visible fan in the room, either floor or ceiling mounted, for aesthetic reasons. So I'll give the ducted solution a go since it won't cost much and will be easy to install. Since heat transfer systems seem to work quite well to even out temperature differences across a house I reckon there's a good chance that they'll also do so within a room. Any more suggestions in that direction, would be most welcome.

neb

11294 posts

Uber Geek

Trusted

Lifetime subscriber

#1806382 25-Jun-2017 13:45

timmmay:
Why don't you want a ceiling fan? They're big, slow, and can move a lot of air compared with a little fan with ducting.

+1. A slow ceiling fan will do a good job of stirring up the air in the room, not to create a breeze but enough to mix the cooler and warmer air. Apart from the somewhat intrusive visual aspect I can't think of a better way to deal with this problem.

neb

11294 posts

Uber Geek

Trusted

Lifetime subscriber

#1806383 25-Jun-2017 13:49

Rikkitic:
Many ceiling fans seem to be designed to be as ugly as possible, especially if they have some bloody light fitting jutting out the bottom.

You could always put in a punkah, but I'm not sure where you'd source a punkah wallah to run it. OTOH it's the most ecologically sound way to move warm air around.