Looking for Organ Air Flow Design Info.

[Cliff Preston]

Im looking for Pipe Organ Airflow Design information for our church organ in Shawnee Mission, Kansas. Someone has previously installed Window fans for air flow, plus the air is being short circuited through openings that I believe should be closed. These fans are not providing proper air flow in my estimation.

I do know that we are having trouble keeping the organ tuned.

Can anyone help?

 

[Thomas Dressler]

What do you mean by pipe organ airflow? Are you talking in general about how the air flows through the pipes and through the chambers?

If you are having trouble keeping the organ tuned, there are a number of things to consider. Yes, even heating throughout the instrument is important. Often, one simple thing that effects this is when an organist has the habit of leaving the organ with the Swell (and other) chambers closed rather than open. On a pipe organ, the swell pedals should always be left open, and some non-mechanical actions will automatically open the chambers when you turn the organ off.

Another important thing to consider is the temperature when the instrument is tuned. It should be tuned at the same temperature the church is at for services, and that means the heat or air conditioning should have been running for hours before the organ is tuned. A difference of a few degrees will make a huge difference in the tuning. Also, if the heat or air conditioning is normally off, it should be turned on for hours before the service to allow the organ to adjust to the proper temperature. When the temperature comes back to the same as it was when tuned, the organ will come back into tune.

I have also seen a couple nightmarish installations where the organ blower is in another room, sucking in freezing cold air and blowing it into the organ while the room is heated in the winter. That is a very difficult situation and the only solution is to somehow get warmer air into the blower.

I have never heard of window fans being placed inside an organ.

Could you be more specific about the instrument? Do any of the things I mentioned apply to your situation?

 

[Cliff Preston]

Organ Air Flow

I think what I am referring to is the air ventilation for the organ. I am told that if the air is turned off, it builds up heat and affects the sound. I am an engineer, but not knowing much about organ construction, I'm flying blind.

This is a large organ in a fairly large church, and it is played by a very fine organist who has played it for 40 years.

There are organ pipes on both sides of the choir area with large screened ventilation??? openings behind the pipes. In rooms behind the pipes, there are fans (cheap window fans which I'm sure are not original). It appears that these fans are meant to suck air from around the pipes and discharge into another room.

It is my belief that these fans are moving very little air. I also believe that the path of the air has been improperly changed so that little air is coming from the organ pipe area.

I can send a picture or sketch showing the arrangement if it will help.

I will have more information on your other questions as soon as I can talk to our organist.

I appreciate your willingness to help. Thanks, Cliff Preston

 

[Thomas Dressler]

Ok, it sounds like you may have a problematic installation. Sometimes there are circumstances where the sun shines on the side of the building and builds up a lot of heat in the organ chambers, or some other kind of unusual circumstance. I would guess that window fans might help in a situation like that. However, I would ask your organist about the openings that you would like to be closed, as they may be openings into swell chambers, which do need to be open for circulation.

If your instrument is as I am visualizing it, the screens (are they behind a set of facade, or "show" pipes? Or are the pipes completely hidden?) are a decorative part of the organ facade design. Organ pipes are not normally completely enclosed in airtight boxes except in rare instances. Normally the boxes which enclose pipes have venetian shutters on the front which allow them to be opened or closed by the organist in order to regulate the volume of sound speaking into the room. These are the shutters that I'm referring to that should be left open when the organ is not being played.

Normally the air flow through an instrument is as it is. I'm not an organ builder or an organ technician really other than the bits and pieces of information I've learned from organ builder friends, but I'll say again I've not heard of an organ with window fans in it, though that doesn't mean it never happens. It would seem to me that even if it's very hot in the organ chambers, as long as this heat is consistent, the tuning would not be a problem. I've been inside organ chambers that were stifling as the pipes were tuned. As long as the temperature returned to that stifling heat in the chambers, the tuning was ok. However, if there's a problem with the sun at certain times of the day or something else that makes the temperature wildly inconsistent, then it would be a problem. Consistency is the most important thing about temperature and tuning.

Does this help some? Perhaps a sketch or picture would be helpful to see if your situation is unusual.