Rust prevention in the workshop

What technical claptrap.

How exactly does the dehumidifier "consume heat"? I accept that it produces heat, as a result if its inefficiency. It doesn't consume heat.

Have you any idea how a dehumidifier works?

Who are you praying to? I thought you were anti-God? Had a road to Chippenham conversion?

Well done Nimrod!!

Does this mean that from now on we will have to microscopically check every word we write to ensure a mistake isn't made?

Recently I recall a post referring to somebodys 'wife' as his 'Wide' - don't recall too many observations on that.

As for how dehumidifiers work, I suggest you do a bit more reading before you open your mouth and put both feet in up to the elbows.

A decent model will have 'hot gas defrost' which is used to defrost the condenser matrix, as well as the heat produced by the compressor in its normal mode of operation, not just as a result of its inefficiency.

This, and the circulation of the warmed air from the exhaust, will tend to result in some low level background heating.

As to the religious aspects of the post I'm afraid cannot comment, the rest of it, apart from that one mistake, I feel is factual.

Lofty

Airy R. Bean posted the following in uk.rec.models.engineering:

If 'these apparatuses' consume heat, then they will ADD to the frost.

By your own admission, only SOME dehumidifiers have a defrost system, therefore that function is not integral to the dehumidification process, anymore than autodefrost is integral to the operation of a fridge-freezer.

A dehumidifier does not "consume heat". It may consume electricity, or more exactly convert it to heat, but it does not consume heat.

Airy has his own laws of physics (or technical claptrap to those of us who know him).

I'm not sure where this part of the thread is leading, but dehumidifiers remove, or "consume" heat from the air which is thereby cooled. If there is a high moisture content in that air, the air becomes saturated and the moisture condenses out. The heat so consumed and ultimately released from the refrigeration cycle, together with any heat from the operation of the motor/compressor should act to warm up the shed.

I'm sorry, but I don't see what is the difficulty? Is some rather silly and infantile person desperate to score a point somewhere?

Definite signs of a partial understanding of physics and you dare to criticise others.

Try looking up the laws of thermodynamics.

Airy R. Bean posted the following in uk.rec.models.engineering:

Let's call the above "Statement No. 1"

Let's call the above "Statement No. 2"

Let's call the above "Statement No. 3"

Statement 3 contradicts Statement 1, as logic of them says that heat is both removed AND added to 'the air in the shed' at the same time.

Where does the heat go to between the actions in Statement 1 and those of Statement 3? What 'consumed' the heat? When is 'ultimately'? What other state was it transformed to? Why did it reappear as heat? What were the mechanisms involved?

Statement 2 is complete rubbish.

Having done meteorology as part of my pilots license, I think statement number two is wrong as well. From what I can remember (and it was a while ago), it is vapour, not moisture. Vapour is usually dry.

When the air become saturated, it doesn't necessarily turn to condensation. Much of it depends on how clean the air is (and I would assume a dehumidifier would clean as it sweeps...). If the air is clean, then the vapour will remain as vapour. The vapour could be supercooled, but still remain as vapour. Only when it comes into contact with something (dust, walls, glass etc.) does it then change state (If supercooled, it will turn instantly to ice, which is where hail is formed when in thunderclouds).

This actually happened in nature a few years ago in Canada with catastrophic consequenses. Remember the ice forming on everything, and it was really thick? It was so heavy it brought down trees, power lines etc. This was due to the air being clean, the water being in vapour form. The temperature dropped, the water was still in vapour and only when it came into contact with things did it change state, which at this point the vapour was now supercooled and instantly turned into ice.

This may sound like boll***** but it was what I was taught.

Best regards, Dave. ~~ Customise your internet experience

Dave writes (snipped) .......

Not round objects at all Dave.

For another version of the same truth see ..........

Please may we get on with something else now ?

Mike

Fascinating from all of you. One extemely useful product of the dehumidifers, as mentioned by the Bean, is pure water. Don't water the pot plants with it.- Put it in your boilers. Best, John

Which end of the flat Earth Society is the Australian branch ?

-- Regards,

John Stevenson Nottingham, England.

Well actually John, you go all the way to the edge and then come back the pretty way.

You seem to be somewhat confused. What you have annotated as, "Statement 1" and "Statement 2" refer to the air in the heat exchanger inside the unit

What you have annotated as "Statement 3" refers to the air in the rest of the building, outside of the unit.

(Consider, for example, the air conditioner in your car - when it is in action, the first operation is to cool the air, to cause the moisture to condense out, and then, if in a winter scenario, the second operation is to warm the air before passing it into the passenger compartment. So, even though you were confused in your rush to be triumphant and as a result of which you misunderstood what was written in front of you, it is possible for an air conditioner to both cool and heat the same air, although this was not what I was describing.)

What you have annotated as, "Statement 2" is correct and refers to the reduced capacity for holding moisture by cool air as compared to warm air.

Your determination to be confrontational seems to have overcome your common sense, OM.

Vapour, moisture, whatever.

This is a thread for model engineers and not for physicists.

Does it matter? Hardly.

Even Mr.Stevenson's much-vaunted "NewsBlock" program is failing in his own very first installation!!!!

But then we knew, Children, didn't we, that he was only pretending but was in fact anxious to know how his rather silly and infantile campaign was progressing?

What a prize idiot he is!

Bwahahahahahahahahahahahahahahahahahahaaaaa!!!!!

The water from dehumidifiers is extremely yucky, it has dust and bacteria and other condensed gunk from the air in it.

Think "melted frost from a fridge" and you'll get some idea.

Airy R. Bean posted the following in uk.rec.models.engineering: You originally said "...dehumidifiers remove, or "consume" heat from the air which is thereby cooled. If there is a high moisture content in that air, the air becomes saturated and the moisture condenses out. The heat so consumed and ultimately released from the refrigeration cycle, together with any heat from the operation of the motor/compressor should act to warm up the shed"

And where, in whatever process is going on, is the heat 'consumed'? What mechanism 'consumes' it? When it has been 'consumed', what is it trransformed to? And why, later, does it reappear as heat 'for the shed'? Kindly explain the mechanisms and principles.

Your statement "...If there is a high moisture content in that air, the air becomes saturated and the moisture condenses out..." is wrong, as a high moisture content is merely a high moisture content, and accomplishes nothing on its own. Saturated air may, or may not, condense out. I'm sorry to say that your statement is illogical. But as it appears to lie at the heart of your misunderstanding of the mechanisms involved in dehumidification, it needs to be addressed. That is why I ask you above to elucidate the mechanisms.

This is a red herring. It serves only to reinforce the impression that you are confused about how a dehumidifier works. I suggest again that you work out each of the mechanisms involved, and you will see where things have gone wrong. The key is to start with your assertion about moisture content.

As a model engineer, I would rather cut metal with HSS, not mild steel. Does it matter? they are still metals.

The difference between vapour and moisture is its state. Liquid oxygen would kill you, you need oxygen vapour to live. Really, it is fairly critical.

Best regards, Dave. ~~ Customise your internet experience

Gareth, for it is Gareth isn't it, you have stated many times that one thing that distinguishes a technician from an engineer is technical accuracy.

So you are clearly not an engineer. A model technician perhaps? Does a model technician fettle castings?

I really just put it down to a typo, did it really need all this sniping?

Or was it just because it was directed at one particular person?

Personally I couldn't give a monkeys, but its amazing to see how many of you will dangle on a little bit of bait, and will rise to the slightest provocation.

There again, I had a closer look at my de-humidifier.

Doesn't the WARM moisture laden air pass over a chilled matrix, thereby CHILLING the air and causing the moisture to condense and freeze on to its surface?

Doesn't that same air then exit the unit at a lower temperature?

Surely this means that the unit has absorbed some of the heat in the air.

The strange thing is, I don't have any rust in my workshop, the condensate, passed through a standard wine filter has a TDS count only slightly higher than my reverse osmosis unit, so is ideal for boilers, batteries, irons etc.

And, I only need marginal background heating during the winter because the heated air from the defrost cycle is circulated around the workshop.