Humidifiers

[kropf]

Here and there, reading descriptions of English organs, one stumbles about humidifiers and humidifcation systems in blower chambers of larger organs. I do not know about such features on continental instruments.

I'd like to learn more about them -

How do the older models work? Are there modern variants (perhaps using electronic control)?

Was their existence a benefit for the organ? If not, under which circumstances?

Are there certain known issues and dangers (as over-humidification or rotting of soundboards, corrosion etc.)?

 

Many thanks to all contributors who will shed some light!

[Pierre Lauwers]

Humidifiers are often used in Belgium. Here is a modern model:

 

http://www.jshumidificateurs.fr/products/S...SFE/details.htm

 

The problems arise whenever you blow very dry air within the chests, which ruins leather parts

and damages the wood.

 

But nothing replaces......Heating savings!

 

Pierre

 

Oh, there is the same page in english:

 

http://www.jshumidifiers.com/products/SEUR...SFE/details.htm

 

And in german:

 

http://www.jsluftbefeuchtung.de/products/S...SFE/details.htm

[MusingMuso]

Here and there, reading descriptions of English organs, one stumbles about humidifiers and humidifcation systems in blower chambers of larger organs. I do not know about such features on continental instruments.

I'd like to learn more about them -

How do the older models work? Are there modern variants (perhaps using electronic control)?

Was their existence a benefit for the organ? If not, under which circumstances?

Are there certain known issues and dangers (as over-humidification or rotting of soundboards, corrosion etc.)?

 

Many thanks to all contributors who will shed some light!

 

 

================================

 

 

Oh dear!

 

I can see that we're about to embark upon a very large subject once again, which we covered previously under lead-corrosion in pipes.

 

Herr Kropf may or not have a grasp of scientific things and climatology, but humidifiers have been used a great deal in the UK for a relatively simple reason......our temperate maritime climate, which causes sudden and dramatic changes to both temperature and humidity.

 

I will assume that Herr Kropf knows nothing ( ), but if he does, then I can only apologise for being presumptious.

 

It is a mistake to think that things dry-out merely because of heat, because changes in temperature at any point on the thermometer will have much the same effect as church-heating. If a porous material such as wood (and leather), is subject to dry heat, it will dry out. Subject it to damp-heat, and it will not, generally speaking. If a porous material is warm and moist, as the air chills during the night, much of the moisture begins to secrete to the surface in the form of dew, and as the air temperature rises, that dew will evaporate quite quickly. Consequently, both heating and cooling have an effect on water-content in porous materials, and cooling can dry things out just as quickly as pure heat, because a moist, porous material will absorb more water at higher temperatures, and less water at lower-temperatures.

 

With a maritime climate, the variations in temperature and relative humidity can be very marked. With a South West wind, we get relative warmth and high-humidity; even in winter. A north wind in winter brings immediate chilling and quite low-humidity. Get an East wind in summer, and it can be as hot as mid-continental europe or Spain and very dry. It is because things shift so quickly in our climate, that organs often need to be protected from the extremes of temperature and changes of humidity.

 

Once one gets about 200 km into mainland europe, you start to lose the maritime effect, and then you begin to see a more stable air-mass. In Russia, that air-mass is so stable, the weather in Vladivostok will be much the same as that in Moscow, a few thousands Kilometeres away, even though there may be differences in temperature.

 

With the central european climate, things change much slower, and there is greater atmospheric stability.

 

When we were discussing lead-corrosion of organ-pipes (which some mistakenly assumed to be "tin pest" in organ-pipe alloys), I stumbled across a very interesting article about museum exhibits of "lead soldiers" kept in wood and glass display cabinets. This led to a bit of a scientific ramble about the fermentation processes in wood, which produces acetic-acid vapour: perhaps the most lethal thing known to affect lead. We went on to discover that once the lead is subject to acetic-acid, a corrosion process starts which is then self-perpetuating and largely unstoppable. The visible symptoms are a white fur "growth" on the surface of the pipes.This could be the problems being faced with pipe-corrosion in certain continental organs; coupled to the fact that central european lead is known to contain a number of impurities such as arsenic and silver, which would not have been refined sufficiently when the organs were built and the pipes fabricated.

 

Then my "leading metalurgist" brother got involved.....one of those Herr Dr. type of people (Germany is full of them), and with characteristic briliance (when he's not polishing his motor-cycle or playing a stupid game of cricket), he perhaps came up with the vital factor which has thus far evaded those working on the lead-corrosion problem in old european organs.

 

The acetic-acid was leeching from the wood in the wind-chests (etc) because the naturally occurring fermentation process was now more active than it once was. Now this would explain the reason why it has started to happen now, rather than in the past 300 years or so. When questioned about it, my brother suggested that "global warming" (probably naturally occurring) was the root cause, but not because it was hotter or drier during the day, but due to the fact that winter temperatures were not as low as they once were, which because of relative humidity and dew-points, means that organs are not drying out as they once did in cold and/or freezing conditions. Thus, there is a steady build-up of moisture, and an increase in the fermentation process which leads to secretions of acetic-acid.

 

My own personal conclusion was, that with important, historic organs, and especially those affected by lead-corrosion, the ONLY way forward was to install some type of windchest climate control, which could both humidify or dry, depending upon the prevailing temperatures and humidity.

 

I suspect that, until now, humidifiers have not featured very much in continental organs due to the relative stability and slower changes in weather, but I may be wrong about this due to the fact that I have no evidence whatsoever.

 

MM

[kropf]

Dear MM, thanks for this first portion! I have basic knowledge of climate and humidity mechanics ( ), but indeed the situation on the british isles is quite unknown to me - except what I experienced during my stays there...

I'd like to know more about the humidifiers following the question at my start. I am asking regarding the Rostock instrument which has a two stage electropneumatic action with subsequent masses of bellows. The blowers are in the tower chamber and sucking air which is approximately of exterior quality (The church itself is unheated, so the differences are not as gravid as one could be afraid of, but...).

Rostock is situated at the baltic cost, and a Siberian low pressure area produces a wonderful blue sky there... including low humidity!

So I'm interested in technical details and - of course - all risks.

 

The acetic-acid issue is already wide-spread among German experts for historic organs. I learned that it has also to do with the use of a certain glue, and if I'm right, one of the more recnet products, used at restorations. So restorations might turn out as source of this lethal "virus"....

[MusingMuso]

The acetic-acid issue is already wide-spread among German experts for historic organs. I learned that it has also to do with the use of a certain glue, and if I'm right, one of the more recent products, used at restorations. So restorations might turn out as source of this lethal "virus"....

 

 

===================================

 

 

 

It is indeed, and I have read much about it.

 

What I suspect they have thus far failed to link, is the connection between "less cold winters and night-time temperatures" and the consequent increase in the mean level of humidity within the wood-fibres, which would almost certainly accelerate the fermentation process of the wood quite critically.

 

From what I have read, I just get the feeling that the experts are looking for external chemical causes from air-pollution, when the answer might well be simple internal bio-chemistry at work.

 

If it proved to be this, the answer is so simple......wind-chest climate control, to reduce and them maintain the moisture content, and thus slow the fermentation process.

 

I suppose it's worth asking if this has been researched. Perhaps I should have done this myself last year. After all, it's not good to think of something potentially important, and then keep it to oneself.

 

 

MM

[David Coram]

Dear MM, thanks for this first portion! I have basic knowledge of climate and humidity mechanics ( ), but indeed the situation on the british isles is quite unknown to me - except what I experienced during my stays there...

I'd like to know more about the humidifiers following the question at my start. I am asking regarding the Rostock instrument which has a two stage electropneumatic action with subsequent masses of bellows. The blowers are in the tower chamber and sucking air which is approximately of exterior quality (The church itself is unheated, so the differences are not as gravid as one could be afraid of, but...).

Rostock is situated at the baltic cost, and a Siberian low pressure area produces a wonderful blue sky there... including low humidity!

So I'm interested in technical details and - of course - all risks.

 

The acetic-acid issue is already wide-spread among German experts for historic organs. I learned that it has also to do with the use of a certain glue, and if I'm right, one of the more recnet products, used at restorations. So restorations might turn out as source of this lethal "virus"....

 

Just quickly, then, a typical installation goes something like this:

 

1) Alterations to organ

 

At each point where wind is supplied to the organ - wind boxes, underactions - a small bleed valve is installed at the point furthest away from the wind inlet. This is a valve which is normally sprung open and will close off on receiving blower-pressure wind. But it does enable a much lower volume of wind - a gentle breeze - to pass through.

 

A running water supply and constant electricity supply is needed. Usually the input from the humidifier is made by a plastic tube running into the main wind trunk from the blower, before the first bellows.

 

2) Control equipment

 

Automatic control equipment is provided so that the humidifier doesn't run when the blower is on. Often (I don't know about always, not seen that many) there is also a humidistat or temp control which only allows the unit to run under certain conditions.

 

3) The unit itself

 

Basically fan blades with a thin spongey-type material, which whir round on an electric motor, picking up water from the (level-controlled) pan and spraying tiny droplets wildly in the direction of the wind trunk. A small volume of air is drawn through - enough to make a single pipe murmur, typically - and the moistened air makes its way through the system.

 

 

4) Benefits/Risks

 

Even my own system, which is spread over two levels and sideways across two bays of the triforium, reads a steady 57-60% humidity from the furthest bleed valve. (The humidistat is obviously only reading when the blower is off as the bleed valve is shut when the blower is on.) Ours is running more or less flat out. With the right control equipment (about which I know nothing) and an organ contained in a normal-sized case this ought to be possible to control.

 

On that basis, I'm not aware of any real risks, except obviously the fact that external woodwork (including tipboards/casework/wooden pipes) receive no protection. This is probably less important, as these parts don't suffer the same artificial fluctuations in humidity as the invisible parts do when the blower has been running for an hour or so.

 

Apologies if you knew all this and it wasn't what you were after.

[Pierre Lauwers]

Sharp, quick climatic changes we know even more than Britain, by far, in Belgium, where

we can have, in January, one day the same temperature as Southampton, and the next

the same as Kaliningrad/ Königsberg. Fact is, Namur is about Mid-way between Southampton

and Rostock, with a climate that is alternatively oceanic and continental (yes, 200 Km

from the sea...)

Mind you, this year, I had roses in my garden by April, 15, exactly like Mottisfont (not far

from Southampton), while in 2006 I had to wait more than a month more.

 

Continental climates are absolutely letal for slider-chests built the traditionnal way, because

the season changes are dramatic.

In a time when nor Multiplex chest tables nor telescopic joints existed, Eberhard Friedrich Walcker

introduced the Kegellade because slider-chests warped desperately in Russia.

 

It is even worse in the United States, with a summit in the Mid-west, which is a huge corridor

with no obstacle between northern Canada and the Mexican Gulf; I know of rose collectors

there who can have a very hot day by say April, and a genuine, complete Blizzard the very

next one.

 

But one thing remains: in Belgium at least, whenever you find a heated church, and particularly,

with a warm-air blowing system, you will find an humidifier in the organ. The correlation is

nearly one by one.

 

So if there is an humidifier at Rostock, and no heating, first question is: why?

We do not know.

So let's act as historians: where are the archives? Who built that thing in? What were

the problems then?

 

Pierre

[Tony Newnham]

Here and there, reading descriptions of English organs, one stumbles about humidifiers and humidifcation systems in blower chambers of larger organs. I do not know about such features on continental instruments.

I'd like to learn more about them -

How do the older models work? Are there modern variants (perhaps using electronic control)?

Was their existence a benefit for the organ? If not, under which circumstances?

Are there certain known issues and dangers (as over-humidification or rotting of soundboards, corrosion etc.)?

 

Many thanks to all contributors who will shed some light!

 

Hi

 

"Organbuilding 2003" - the anuual journal of the Institute of British Organ Builders - has an article about humidifiers which is worth reading. Back issues are available, IIRC via Positive Press.

 

Every Blessing

 

Tony

[kropf]

@David Coram: Thanks, I did not know those things, so this was exactly what I was looking for!

@Pierre Lauwers: No, no - there is no humidifier in Rostock! I just wondered if there should be one in future...

- oh, and the roses are really to early this year... Yours are probably english garden roses, aren't they?

@Tony Newnham: Thanks to you, I'm going to get a copy!

 

About risks: There are previous topics in this forum where cases of over-humidification have been described.

Well, I learn, that at least everything has to be kept under qualified and regular control. The only (micro)-climate related thing I know in my region here is in St Jacobi Hamburg, where they have the custom to start the blower hours before the organ shall be used, but the idea is not to influence humidity in any way, but to get the temperatures where the reeds are best in tune. Which principles are active there and if it works at all, I do not know. And maybe, after all what MM has brought up again, it makes the situation even worse...

From what I have read, I just get the feeling that the experts are looking for external chemical causes from air-pollution, when the answer might well be simple internal bio-chemistry at work. MM

This wisdom is making its way here, too... But in a quiet manner, as one can understand...

[Pierre Lauwers]

"english garden roses"

(Quote)

 

No, ancient garden roses, from France, Germany, England, Belgium.....

Found in New-Zealand, Australia, South Africa, and anywhere in Europe,

and exchanged with peers.

 

If there were no humidifier, and the church isn't heated, the question

resolves itself for me.

 

Pierre

[Colin Goulden]

"english garden roses"

(Quote)

 

No, ancient garden roses, from France, Germany, England, Belgium.....

Found in New-Zealand, Australia, South Africa, and anywhere in Europe,

and exchanged with peers.

 

If there were no humidifier, and the church isn't heated, the question

resolves itself for me.

 

Pierre

 

 

I have been interested in the various comments about humidifiers as I have just had a DAC case (no names!) passed to me where the Vicar has asked for advice concerning a humidifier dispute at his normal Sunday heated church that has been going on for some six months!.

 

Their well known blower supplier has described terrible things that will happen if the humidifier is switched off and the organ tuner has described all the horrible things that might happen if they don't turn the humidifier off.

The Vicar has asked for a definitive answer as to who is right so he can make a decision and stick with it!

 

Any ideas or suggestions would be appreciated as I must confess I am at a loss to know what to do or reccomend about this problem!!

 

Many thanks in advance!

CRG

[MusingMuso]

Sharp, quick climatic changes we know even more than Britain, by far, in Belgium, where

we can have, in January, one day the same temperature as Southampton, and the next

the same as Kaliningrad/ Königsberg. Fact is, Namur is about Mid-way between Southampton

and Rostock, with a climate that is alternatively oceanic and continental (yes, 200 Km

from the sea...)

Mind you, this year, I had roses in my garden by April, 15, exactly like Mottisfont (not far

from Southampton), while in 2006 I had to wait more than a month more.

 

Continental climates are absolutely letal for slider-chests built the traditionnal way, because

the season changes are dramatic.

In a time when nor Multiplex chest tables nor telescopic joints existed, Eberhard Friedrich Walcker

introduced the Kegellade because slider-chests warped desperately in Russia.

 

It is even worse in the United States, with a summit in the Mid-west, which is a huge corridor

with no obstacle between northern Canada and the Mexican Gulf; I know of rose collectors

there who can have a very hot day by say April, and a genuine, complete Blizzard the very

next one.

 

But one thing remains: in Belgium at least, whenever you find a heated church, and particularly,

with a warm-air blowing system, you will find an humidifier in the organ. The correlation is

nearly one by one.

 

So if there is an humidifier at Rostock, and no heating, first question is: why?

We do not know.

So let's act as historians: where are the archives? Who built that thing in? What were

the problems then?

 

Pierre

 

 

==========================

 

 

Yes, I should imagine that Belgium and the Low Countries enjoy a mixed maritime/continental climate: hence the Roman's referring to Holland as "the great bog of Europe."

 

The United States has amazing weather, as we all know. They don't do it in half measures! I recall a visit to a famous harpsichord maker in New England, and he showed me some of the planed timber boards (spruce) for the soundboards, which you would expect to be flat. They were so bowed, they could have been used as paddling-pools upside down!

 

"It's OK," the man said, "They'll be flat next month when the weather changes." (It was hurricane season, and I lived through one on Cape Cod, when I was stupid enough to go out and watch it!)

 

Walcker's experience in Russia is interesting, because Russia is really quite a dry place; especially in the winter. If you nip over the mountains into Georgia (some nip!), you are immediately into a semi-tropical climate.

 

I'm quite sure that temperature is terribly important to roses, but actually, it is relative humidity which most affects wood, and sudden changes in humidity are the killer. It is also important to get one's head around the idea that extreme cold can dry things out as quickly as dry heat. (If you recall, I used the analogy of dry peas in the bottom of the freezer cabinet). I suspect that this was the Russian problem Walcker experienced.

 

I recall a load of Far Eastern made oak furniture, which in two days, self-destructed in the heat of a British summer, yet it had been made in a far hotter, but very humid place, and delivered by ship in sealed containers with the furniture itself shrink-wrapped as component parts. It became just a pile of useless firewood.

 

MM

[Frank Fowler]

Do you remember the old `turtle' stoves often found in Victorian church? Individual coke stoves, around some 3' x 5' with a trough round the base that was kept full of water to add moisture to the atmosphere.

 

FF

[Philip J Wells]

I assume these days with all the red tape a risk assessment is required before one of these things is installed. With all this mention of water droplets etc spraying through the air, has legionnaires disesase ever been found to be a problem?

[Guest Nigel ALLCOAT]

Do you remember the old `turtle' stoves often found in Victorian church? Individual coke stoves, around some 3' x 5' with a trough round the base that was kept full of water to add moisture to the atmosphere.

 

FF

 

 

I remember them only too well! One famous cathedral when I was tiny made me so very ill because the fumes from these great black monsters in the Aisles was so overpowering.

 

N

[MusingMuso]

I assume these days with all the red tape a risk assessment is required before one of these things is installed. With all this mention of water droplets etc spraying through the air, has legionnaires disesase ever been found to be a problem?

 

 

==============================

 

I think humidifiers are connected to fresh water supplies rather than to static tanks, so I can't imagine too many organists keeling over mid-voluntary.

 

I'm more concerned about airborne bat urine at St.Bavo, or worse still in America, where they often have large fans to keep people cool, and which often kill bats.

 

One could almost write a horror story, with bits of disintegrated bat travelling at 100mph and hitting the organist

during the final voluntary.

 

I once got attacked by a gull, (like something out of Alfred Hitchcock), and a pigeon with a major flight problem once bounced off my head in London Bridge Station as I sat outside the 'Costa Coffee Boutique,' but I didn't end up with my tongue covered in black-spots or anything.

 

In fact, the biggest threat to my welfare was when an oriental security-guard sneezed, and I covered my mouth and asked if he had recently been to Hong Kong. He didn't give me bird-flu, but he did report me for racism!

 

So much for "Health & Safety" regulations. You can't be too careful these days.

 

MM

 

 

 

I remember them only too well! One famous cathedral when I was tiny made me so very ill because the fumes from these great black monsters in the Aisles was so overpowering.

 

N

 

 

========================

 

 

Which cathedral was that?

 

I seem to remember seeing those stoves somewhere.

 

I recall one country church in the Yorkshire Dales, where the heating system had broken down, and an old farmer lent them a "Salamander" heater, which actually glowed red-hot and made the most terrifying din.

 

Hell took on a whole new significance that morning.

 

MM

[Guest Nigel ALLCOAT]

==============================

 

 

Which cathedral was that?

 

I seem to remember seeing those stoves somewhere.

 

MM

 

I believe it was Peterborough. And Durham also seems to spring to mind as well, although I remember the wind and cold there more than the heat.

 

N

[David Coram]

I assume these days with all the red tape a risk assessment is required before one of these things is installed. With all this mention of water droplets etc spraying through the air, has legionnaires disesase ever been found to be a problem?

 

Water droplets don't spray through the air; a practically imperceptible mist is blown gently through the contained areas of the organ and not into the open air at all.

 

Legionnaires is only a problem as MM says when static water is concerned; these are on a fresh water supply and the internal tank contains only about an inch at a time, I believe.

[Guest Patrick Coleman]

I believe it was Peterborough. And Durham also seems to spring to mind as well, although I remember the wind and cold there more than the heat.

 

N

 

 

Hereford?

[John Sayer]

I believe it was Peterborough. And Durham also seems to spring to mind as well, although I remember the wind and cold there more than the heat.

 

N

 

Weren't these wondeful contraptions called Gurney's Patent Heating Furnace or something like that? They had ornate cast-iron crowns on top. At Ely they used to glow in the dark during November evensongs. Today they're oil-fired, but 20-odd years ago the verger used to go round with a little coal trolley and stoke them up beforehand.

 

JS

[Guest Cynic]

Weren't these wondeful contraptions called Gurney's Patent Heating Furnace or something like that? They had ornate cast-iron crowns on top. At Ely they used to glow in the dark during November evensongs. Today they're oil-fired, but 20-odd years ago the verger used to go round with a little coal trolley and stoke them up beforehand.

 

JS

 

 

There were two of them at Tewkesbury Abbey. They were nicknamed 'Etna' and 'Vesuvius'.

[contrabordun]

There is of course the low tech alternative - bucket of water left standing inside the instrument.

[Stephen Dutfield]

Hereford?

 

Yes, Hereford has the Gurney furnaces in each transept. The north one kept me nice and warm during an association visit back at the beginning of the year, but I do wonder how ever they were allowed to run flues up the inside of the transept wall and out through the clerestory windows!