CPU fan and PP9 battery

[Meatyfool]

I am intending to stick this combo behind furniture on an outside wall to ventilate it better. Every winter I get mould on the backs of the furniture. I have moved the furniture away from the wall to minimise this.

I have this instructable:

http://www.instructables.com/id/Super-e ... puter-fan/

But I am not going with the switch. It will be wired on at the start of the winter and unwired at the end, or when the battery gives out.

The one thing that is stopping me is the potential fire risk. Should I worry if it running thousands of hours non stop?

I may have to switch it anyhow if the fan is audible at night, but I suspect not.

Many thanks,

Meatyfool..

[supremetwo]

I am intending to stick this combo behind furniture on an outside wall to ventilate it better. Every winter I get mould on the backs of the furniture. I have moved the furniture away from the wall to minimise this.

I have this instructable:

http://www.instructables.com/id/Super-e ... puter-fan/

But I am not going with the switch. It will be wired on at the start of the winter and unwired at the end, or when the battery gives out.

The one thing that is stopping me is the potential fire risk. Should I worry if it running thousands of hours non stop?

I may have to switch it anyhow if the fan is audible at night, but I suspect not.

Many thanks,

Meatyfool..

It will not run for thousands of hours.
The label says the fan is rated at 12v 0.33a, so say 200ma at 9 volts.
A typical PP9 is rated at 300-400mah so a couple of hours at most.
https://www.baldengineer.com/9v-batteries-suck.html

If the mould is as bad as you say, I suggest a mains-powered dehumidifier.

[Itsallaguess]

The one thing that is stopping me is the potential fire risk. Should I worry if it running thousands of hours non stop?

Assuming it will be properly situated and supported, with firm (even if they are temporary...) fixings, then I'd suggest that this is likely to be well down the list of likely fire-sources in the room you're proposing to put it in.

Think how many millions of PC''s around the world there are, and they're each very likely to contain a number of these low-voltage fans. We don't even consider PC boxes themselves as a high fire-risk area nowadays, with all the accumulated dust that they contain, so a single fan connected to a battery should be almost zero risk, I'd think, given the above caveats.

I'd be interested in an update next year if this fixes the issue. I think you're probably correct to think that even a minimum amount of airflow over a long winter period is likely to help with the damp-air and mould issue.

I'd also be interested in how long the fan lasts on a single 9v battery.

Cheers,

Itsallaguess

[jfgw]

The fan in the link says 0.33A. It will be a bit less at 9V. A 550mAh alkaline PP3 might last a couple of hours. A mains power supply would be a more feasible option and you could have the full 12V, or get one where you can adjust the voltage. Just make sure you get the polarity right.

I would expect a computer fan to be continuously rated so leaving it running should be fine.

Julian F. G. W.

[Itsallaguess]

The fan in the link says 0.33A. It will be a bit less at 9V. A 550mAh alkaline PP3 might last a couple of hours. A mains power supply would be a more feasible option and you could have the full 12V, or get one where you can adjust the voltage.

Might a sealed 12V rechargeable unit be something worth considering?

This is 12V 2.3Ah, and can be recharged -

https://www.amazon.co.uk/dp/B002P79FS4

Cheers,

Itsallaguess

[Meatyfool]

Wasting your time I think.

I just googled for how many milliamperes a cpu fan would draw and the length of time I thought it would run off a "big" battery was way off.

Would run for a couple of days if lucky!

Bugger.

Must try (thinking) harder.

Meatyfool..

[Meatyfool]

Just for illumination's sake, a PP9 isn't the bog standard brick shape battery. It holds 5000mAh according to Wikipedia.

Still not man enough.

Will research what a mains operated acdc conversion thingy might cost.

Meatyfool..

[supremetwo]

Just for illumination's sake, a PP9 isn't the bog standard brick shape battery. It holds 5000mAh according to Wikipedia.
Still not man enough.
Will research what a mains operated acdc conversion thingy might cost. Meatyfool..

The article you linked to shows the standard 9 volt.

Without dehumidification, a fan will just push the moisture elsewhere.
https://www.which.co.uk/reviews/dehumid ... humidifier

[Meatyfool]

Without dehumidification, a fan will just push the moisture elsewhere.
https://www.which.co.uk/reviews/dehumid ... humidifier

True, but I would rather it condensed somewhere visible like on a window. I have a window vac for that.

As it is, I hope that I am about to resolve the source of our excess humidity, Beelzebub's own infernal machine, the tumble dryer.

Oh and I have identified a really cheap AC/DC conversion device. It is called a bog standard USB wall wart. It may only run at 5v but that should ensure the fan running quiet. Does raise my initial concern of fire risk again though!

Meatyfool..

[PrincessB]

As it is, I hope that I am about to resolve the source of our excess humidity, Beelzebub's own infernal machine, the tumble dryer.

No chance of venting it is there? Conventional tumble dryers in an enclosed space produce an incredible amount of water vapour.

In our old flat which thankfully had a small bin shed outside the kitchen door so we got away with a mini dryer with a front vent to blow the moist air out forwards. I tried to use it as little as possible but it was a lifesaver for those times when it rains every day for several weeks.

Current tumble dryer which is in an enclosed space under the stairs is a heat pump design which condenses the water into a plastic container at the top of the machine, located where you'd find the detergent drawer in a washing machine.

Additional bonuses are the energy consumption which are at most half that of a conventional dryer, additionally as the drying takes place at a far lower temperature, clothes suffer far less from shrinkage due to excessive heat.

Downside is price, cheapest I could see after a very quick search was a unit by Candy for £350.

I am intending to stick this combo behind furniture on an outside wall to ventilate it better.

I did some more googling and 12v wall wart type power adaptors cost from about £5, some of these units are advertised as being suitable for CCTV cameras so I can only assume they are designed for long term continual operation.

Were I to try such a solution, I would locate the fan at one end of something large (like a sofa) with the air blowing in from the room in order to generate the best possible through flow of air from one end to another. Whether it would work is debatable, if you've got a cold wall and a lot of moisture in the air, the more air you pass through the void, the more water will condense out, perhaps a better solution would have the fair pointing upwards to continually push the cooler floor air past a more suitable condensation point such as the windows you mentioned.

In terms of noise, PC fans very enormously from whiny tiny things to impressively large slower spinning designs with curved blades that are pretty silent, downside is always going to be cost, quieter costs more.

Regards,

B.

[jfgw]

Just for illumination's sake, a PP9 isn't the bog standard brick shape battery. It holds 5000mAh according to Wikipedia.

Ah, I've read the title now. I was going by the PP3 in the video link. A couple of PP8-2s from somewhere that sells electric fencing would last longer. A mains power supply would be considerably cheaper than the batteries though.

Julian F. G. W.

[robbelg]

Argos will sell you a mains powered fan for £9.99

That's probably less than you're going to spend on batteries.

http://www.argos.co.uk/product/5767867

Other stores and fans are available



Rob

[AleisterCrowley]

Seems like a lot of bother. Why not get some of those dehumidifier crystals - seem to be lots available on Amazon. Not sure how long they last, or if you can reactivate in the oven. Assume they are silica gel or similar. If you do use a fan, stick a low value fuse in. Don't want to burn the house down if the fan goes s/c

[jfgw]

Argos will sell you a mains powered fan for £9.99

That's probably less than you're going to spend on batteries.

http://www.argos.co.uk/product/5767867

Other stores and fans are available



Rob

That should work but it looks a bit big and noisy.

[Meatyfool]

No chance of venting it is there? Conventional tumble dryers in an enclosed space produce an incredible amount of water vapour.
B.

Going off topic on my own thread, I have a heat pump condensing model which means a non removable heat exchanger.

Even if I brush fluff off the heat exchanger fins, the innards of the HE fill up with lint.

I have spent hours removing it with toothpicks against warranty instructions. U.K. white goods website has a good page describing how manufacturers are economical with the truth regarding the energy efficiency of these dryers - you really have to be anal about cleaning out the lint.

I recently bought a dust daddy Hoover attachment - the intention to pass the micro tubes through the HE vents to suck up the crud beyond but the micro tubes are too large to fit. Now have 3m of even thinner 2mm OD tube that will fit through the vents- just need to rig It up to the dust daddy so that I can pass 30 tubes through the HE at a time.

That tube is only 0.5mm ID - hoping the lint "dust" will pass through!

Meatyfool..

[PrincessB]

I have spent hours removing it with toothpicks against warranty instructions. U.K. white goods website has a good page describing how manufacturers are economical with the truth regarding the energy efficiency of these dryers - you really have to be anal about cleaning out the lint.

I am not recommending you do this

Many years ago, I bought an ancient air conditioner which looked like it had never been cleaned.

This old beast was a proper big boy window rattler armed with a 2.3kw compressor the size of a bucket, a 250watt fan to move the air and a hard start capacitor the size of a beer can.

The condensor fins had triple layers of pipes and were mostly blocked solid with gunk.

Solution to cleaning it - And bear in mind this unit had practically no electronics so I was unconcerned at getting it wet - Was a few inches of Bic pen case inserted into the end of a hose pipe and held in place by a liberal application of glue from a hot glue gun.

If you've never done this, and I can't think of any reason you should, you've got the worlds best water pistol. I had decent water pressure and armed with a toothbrush which cleared the more crusty outer layer of gick and the liquid laster pen gun hosepipe hack, I was able to jet water right through the heat exchanger fins without damaging anything.

Once done, I let the beast have a rest in the sunshine to dry off and once slotted back into the case it worked perfectly till I sold the place, for all I know it's still there.

Regards,

B.

[DrFfybes]

A CPU fan will do little.

Ask on Freecycle for an old PC case, butcher it so there's just the case fan running, or simply remove it, bolt it to some wood, and wire a plug on it.

I used a PC fan in Brighton on mains power for the same purpose quite successfully for a couple of years - we only got condensation when we were in and generally cooking, and I unplugged it at night. I got the idea from an acquaintance who was using one to circulate cooling air on a hydroponic system 24/7 with no problems.

Paul

[jfgw]

CPU fans come in different sizes and some are a lot bigger (and quieter) than the usual stock fan. The fan in the link looks more typical of a case fan, however. They are not very expensive brand new and you can get them with coloured LEDs.

Julian F. G. W.