Condensation Management

Download Silly Old Duffer's Condensation management program here:

www.model-engineer.co.uk/condensation

Neil,

This unzips to a C file. What's the best thing to open it with?

Best regards,

Steve.

Edited By Steamer1915 on 21/04/2018 11:00:36

You can look at it in notepad, but ideally one the software associated with the microcontroiller you use.

I use Atmel Studio 6.2 but that's a bit of a mega-download if you don't plan to use an AVR.

It isn't a 'sketch' but you can copy the code in notepad then paste it into the Arduion app which greatly improves the readability - perhaps Dave could comment?

Neil

A very good & free (GPL licence) all purpose editor is Notepad++ it will deal with most kinds of code from HTML to C. I use it for PHP web page editing. Only for windows though.

John

The program is a plain text file that can be opened with pretty much any word processor or notepad. That's provided you only want to eyeball it, and don't make any changes.

For best results use a programming editor like notepad++, gedit, kate, geany, or bluefish etc etc. Unlike a word processor they colour source code syntax to make it easier to read and - most important - don't add fancy formatting or control characters. Like John I can recommend notepad++ on Windows.

The code was developed using the Arduino IDE which is the easiest way to program, download and test Arduino projects. It has a simple code editor.

Bit of a mystery why the program I sent to Neil is called 'humidty_monitor.c': It's an ordinary Arduino Sketch, more properly suffixed 'humidty_monitor.ino, as it is on my computer. Shouldn't make any difference; the suffix doesn't do anything clever.

Must have been having an off-day - I can't spell 'humidity' either!

If anyone's interested there's an updated version here. The main difference between it and the article version is an added frost alarm.

Dave

I did wonder too - possibly it came over without a file extension?

Edited By Neil Wyatt on 21/04/2018 22:06:13

Just like to point out, for anyone who has followed SillyOldDuffer's advice to put a vent low down in their workshop because moist air is heavy, that this is wrong. Many people make this mistake because water is heavier than air. But water vapour is not. The molecular weight of dry air is 28.966 g/mol composed of the various % constituent values of Oxygen, Nitrogen, CO2 and the other minor gases. Water vapour molecular weight is 18.016 g/mol (2 x Hydrogen + 1 x Oxygen =2 +16). Without this fact - evaporation from the Earth's surface could not occur to form clouds. Incidentally, the base of cumulus clouds shows exactly where the atmosphere's "dew-point" is. Clouds are not water vapour but small water droplets held in suspension, despite being now heavier than dry air, by turbulent buoyant mixing forces inside the cloud. Only when these small water drops coalesce into drops big enough to counter the turbulent buoyancy forces do they drop out as rain. Mist and Fog at the surface form - not because they are heavy but because there is a temperature inversion, with air higher up being warmer that that close to the ground - so packets of moist but cooler air cannot rise into the atmosphere. Eventually the water vapour concentration rises to the point where the dew-point at that concentration is passed and the water vapour condenses to form Mist or Fog.

The reason for a low-down vent is simply to retain heat. Warm air rises and a high level vent would exchange lower density warm air for cooler denser air.

Beehives are exactly the same - no top ventilation at all - in summer, the bees arrange for their own fanned air circulation and in winter they require warm dry conditions, while clustered. Mine all have mesh floors, which provide more than sufficient air exchange while the cluster needs to consume far less energy to keep itself and the upper part of the hive warm (relatively). Some dinosaur beekeepers apparently still prop up the bees’ ceiling with matchsticks, or similar, leaving a gap which the bees would (sensibly) seal with glue, if they had the opportunity, before settling down for the winter rest. Any condensation of water vapour should take place on the less insulated (cooler) sides of the hive and not be deposited on their better insulated roof.

I couldn't do this clever stuff, if I need to conk it on the head, I need a commercial product I can just use, like an air conditioner or dehumidifier.

I didn't empty the tank on my workshop dehumidifier during the hot spell thinking can't be a problem when it's so warm. Got round to it yesterday when I wanted some water and in 24 hours it filled itself. Shows that the warm air has been hanging on to lots of water ready to drop it when the weather turns.

Hah! That's interesting because I didn't make it up, I got it from a book! I shall have to find and re-read it.

However, now Colin has pointed it out, I think he's right. Being an optimist I like to think my advice was no worse than being 'not wrong' but apologies to anyone who bashed their house about in a sub-optimal way.

It appeared to me that the graph showing a wall of damp air rolling down into my hallway was solid evidence. Now I'm far from convinced. On second thoughts, I think the same effect could be explained by changing temperature. The air wasn't falling downstairs because moisture made it denser, it was falling because it was cooling down.

I always worry writing for MEW that I will get the wrong end of the stick or mislead due to poor choice of words. In this case I think the Arduino measurements answered the 'where is the water coming from' question correctly, I then came off the rails with the best way of get rid of it. Operator error!

Thanks to Colin for putting me right!

Dave

Edited By SillyOldDuffer on 23/04/2018 13:54:15

Hi Dave - this is unfortunately the problem with any form of article. The only way round it is peer-review - which as an ex-scientist, peer-reviewer and journal editor - I know only too well as being too lengthy and time-consuming to be used in hobby magazines. I just hope that any opinion I may offer, and the style in which I give it, does not come over as criticism - just clarification.

Thanks also to "not done it yet" - I just love it when a topic pulls in observations that didn't occur to me - and I would ordinarily have no reason to find out. The information about beehives is such a topic.

Hi Colin,

I'd much rather be put right than perpetuate a mistake. Dimly remembering lessons about scientific method I try to provide enough detail about method and reasoning to expose any blunders. Always tempting to provide references in best academic style as well, but I doubt Neil or readers would welcome a magazine full of lists. Fortunately, as Cantor and Zillman (1973) argue, it is helpful to have a sense of humour. Otherwise, woe is me!

Regards,

Dave

Cantor J.R. and Zillman D. (1973) 'Resentment towards victimized protagonists and severity of misfortune they suffer as factors in humor appreciation.' J.Exper. Res. in Personality, 6. 321-9.

Did a little experiment. Placed a 9W "Root-It" horticultural heating mat (25cm x 35cm) below my Lathe (but not in contact with the lathe) and covered the lathe in a thin cotton sheet. Left the adjacent Milling machine without a heating mat and uncovered. Left the workshop to acclimatise over 24 hrs. Then applied a thermocouple to the vertical column of the milling machine - which recorded 14 deg C. Applied the thermocouple to the bed of the Lathe - recorded 17 deg C. So looks like even a low wattage mat and slight insulating cover has a positive effect in raising machine temperature above the ambient workshop temperature.

There arises an immediate question: Were the lathe and milling machines warming up, or cooling down? Newton’s Law of Cooling may be at work here!

Thermal mass of each machine may well be different, too.

Setting up a ‘fair test’ can be far more complicated than doing a simple comparison.

My fermentations, involving a 22 1/2 litre ferment and a 10W variable power supply, definitely demonstrate the value of insulation but determining the real energy supplied throughout the fermentation is difficult as obviously a lot of heat, initally, is supplied by the yeast (after reaching the desired fermentation temperature of about 18 degrees Celsius).

I know that my workshop area is dry enough and warm enough to avoid any condensation by just running the dehumidifier for about an hour, or so, per night. But it is most certainly not warm enough in there to work sensibly. 1 1/2 hours used about 5p worth of leccy per night this last winter period. About the same cost as that heater running for 24 hours.

I agree - but it wasn't meant to be a fair test - just one to see what effect occurred. The 24 hour period was one of complete closure of the workshop - so variations to the machinery or even the internal air mass were kept to a minimum.

But I know from experiments I established in west Africa to look at where mosquitoes were most likely to settle inside the local mud huts - just mapping the internal and external temperature and moisture regimes involved logging 30 thermistor/humidity sensor pairs, as well as other external weather parameters using automatic multiplexed loggers over a period of a month. It took that long before I had any idea of the variation caused by internal responses to the local external environment in what are traditionally and superficially very cool and dry habitations. Despite the open nature of these huts - there were pockets where temperature and moisture were markedly different to the overall average.