View Full Version : Low Flow Shower Head: Interesting Phenomenon

Philip in Connecticut
12-23-2009, 05:00 PM
I am nearly finished with a bathroom remodel, and tried out the new shower today. It seems that the new shower head is producing a lot more water vapor (as compared to my previous shower head which was a Hansgrohe purchased in the early/mid 1990's) resulting in considerably more condensation on walls (including interior walls that were at normal room temperature), ceiling, and virtually every other surface. The new bath is the same footprint as the old, and uses the same fairly high capacity exhaust fan, although we used to have a closed shower stall area, and now the stall is open on top to the rest of the room. Indoor (and outdoror) humidity levels are fairly low. I am wondering if the new "high end" shower head is creating a finer spray, resulting in more water vapor being put into the air. In general, are these newer shower heads more likely to fog up a bathroom? Anyone else notice this phenomenon?

Runs with bison
12-23-2009, 08:52 PM
Depends on the actual type of showerhead. Aerating showerheads tend to produce more mist/finer droplets. These showerheads pull air into the stream to give it a fuller feel. Mixing the air and water more closely increases the heat transfer rate (greater droplet surface area, greater turbulence, more evaporation per unit volume of water) from the water stream to the air. Typically one must run the shower somewhat hotter to provide the same temperature sensation when using an aerating showerhead.

When I went to ultra low flow showerheads (1.5-1.6 gpm vs. <2.5 gpm standard which are labelled "low flow") I selected non-aerating types. Some ultra low flow designs can produce a sharp stinging sensation. Some reviews of the Delta and Oxygenics ultra low flows panned them for this reason, but others prefer the effect.

I use the High Sierra and Roadrunner showerheads in my showers, both are non-aerating designs but with different approaches to providing a full spray.

Philip in Connecticut
12-24-2009, 06:16 AM
The new shower head is a Toto Soiree 2.5 gpm unit: not sure if it is aerating or not (literature on their web site does not appear to define type).


I'd hate to give up on this unit (given what I paid for it). I removed the head from the arm, exposing the male threads at the end of the arm. I tried to screw on an old shower head, but it seems these are different threads (?). I thought I would experiment with the old head that was used in this bathroom so see if it was an improvement.

Runs with bison
12-24-2009, 10:05 AM
I can't tell anything about the showerhead from what little information they give.

Having the shower stall more open will allow much more vapor into the room of course.

Maybe someone here will know of an adaptor so that you can test the old showerhead. I don't like non-standard shower arms because of this sort of issue--locks you in to one design.

Runs with bison
12-25-2009, 04:36 PM

During the remodel I suppose you repainted. Did you change the type of paint used? Many paints seem to really pick up the condensation from the air.

12-25-2009, 05:11 PM
Typically, shower heads do produce more steam because of the streams of water. The hotter water coming from the openings WILL evaporate and turn to steam faster, which is why the shower always feels cooler than the water did when you were running it into the bathtub. The smaller the streams, the more water exposed to the air, so the greater the evaporation and conversion to steam/mist, and as a byproduct, cooler shower water.

Philip in Connecticut
12-26-2009, 06:26 AM
When we were planning our remodel, I was prepared for making compromises in toilet performance, but I neglected to factor in the possibility that compromises would also be needed when going from an apparently higher flow mid 1990s Hangrohe shower head to a current 2.5 gpm Toto shower head. Apparently, in the model I have, they have increased the number of openings and reduced the size of the openings resulting in increased stream velocity (I am assuming this is supposed to make up for reduced flow rate by providing the sensation of a higher flow shower). I never imagined that this would generate so much more water vapor. The hand held shower we have is also rated at 2.5 gpm, but it has far fewer openings of a somewhat larger size, resulting in noticeably less water vapor (and yet decent shower performance). I wonder if enlarging the openings on the shower head would result in less generated water vapor (I'm a little reluctant to take a cordless drill to the $250 shower head).

By the way, the new bath walls are tile from floor to ceiling, while the old bath was vinyl wallpaper on the upper half of the walls.

12-26-2009, 07:07 AM
Increasing the size of the openings may change it from a "spray" shower head to a "flood" one if the internal passages cannot flow enough water to satisfy the new nozzle size.

Philip in Connecticut
12-26-2009, 08:12 AM
I suspect it is a delicate balance between i.d. of openings, spray velocity and total flow. I'm not trying to supercharge the head (we are on well water and just put in a new septic field), I just want to reduce the water vapor volume by going to a slighly coarser spray (I was thinking about going up one index drill size on some portion of the openings). Before I start drilling into that $$ shower head, I think I will contact the good folks at Toto to see it they have any suggestions (at the very least, why won't a standard shower head fit onto the arm of the Toto Soiree unit?).

Philip in Connecticut
01-01-2010, 12:40 PM
I have not gotten too far with this issue (not happy with shower performance, but we would like to salvage at least the toto arm since it fits/matches with the rest of the soiree suite of toto fixtures) , and I am still trying to determine what thread size I have at the end of this shower arm, which is the arm that is supplied with the Toto Soiree shower head:
It appears to be the same as the threads on a standard garden variety shower arm, and at this point, I'm not even sure what that is, given the number of thread standard designations I've come across. I am guessing it is a 1/2" non-tapered thread. For some reason, the head supplied by toto fits these male threads, but a standard (i.e., Moen/Hansgrohe) head from Home Depot will not fit these threads. Again, the thread pitch seems to be the same, although the outside diameter might be slightly bigger on this arm than on a standard garden variety arm from Home Depot. Any thoughts on what size this might be and how I might fit a standard head on this arm? I am wondering if there is a chrome plated adapter that might allow the use of a standard head.

01-01-2010, 01:26 PM
Most common shower arms are 1/2" NPT

http://admin.totousa.com/Product%20Downloads/0GU4053,%20SOIREE%20SHOWERHEAD%20WITH%20ARM,%20PRI NT,%20IM%20OM,%20V.03.pdf

Philip in Connecticut
01-01-2010, 01:57 PM
The referenced docs. indicate that the shower head assembly with arm attaches to the wall fixture (drop elbow?) with 1/2" npt fitting. My attachment to the plumbing in the wall is not a problem. I am referring to the threaded portion of the shower arm that the ball joint and shower head attach to (see photo). There is no reference in any of the related toto docs to the size of this fitting. It looks like a standard fitting, but as I indicated, a standard shower head will not fit on these threads, which begs the question: what size are these threads, and is it possible to attach another shower head to this toto arm? As I indicated, before I give up on the entire assembly, I wanted to at least salvage the arm portion, and use a garden variety shower head (moen/hangrohe/speakman/etc.) by attaching it to the toto arm.

01-01-2010, 02:10 PM
It should be fairly easy to determine if the threads are tapered or not. Does the original showerhead have a rubber gasket on the inside (like on a hose), or did you need to install it with pipe dope or teflon tape? If it has a gasket, then you'd need a conversion fitting. Not sure if you can find them easily. Easiest would be to replace the shower arm with a new one that has NPT on both ends.

Philip in Connecticut
01-01-2010, 02:29 PM
Coupling that attaches the original toto head to the toto arm (in the photo) has a rubber gasket (no teflon tape or pipe dope). The threads on the end of the arm do not appear to be tapered. However, I have another "standard" shower arm (the type you can buy at any hardware store) and the threads on the ends of this arm do not appear to be tapered either. Yet, the garden variety hardware store shower arm fits into the garden variety shower heads, but these same heads don't fit on the end of the toto arm? If a conversion fitting is needed, I need to know what I am searching for, which is why I was trying to identify the type of thread on the end of the arm in the photo. Said another way, I'm not sure what I am converting from or what I want to convert to.
Does a typical shower head require a tapered or straight fitting, and what is the size and pipe standard designation for this fitting? What is the likely type/size of the fitting that I want to convert to to mate with the threads shown in the photo: as mentioned earlier, they seem to be a slightly larger diameter (maybe a 64th over) the standard shower arm diameter that I compared it to.

01-01-2010, 03:34 PM
"normal' shower arms use NPT (tapered) threads. The pitch and size of the threads will allow it to attach, but without the taper, it won't seal. What you have on the end of that is very similar to a hose connection. No typical showerhead will seal without a conversion coupling, which you may not find, especially chromed so it would look good. Swap the arm if you want to use a different head and save yourself the aggravation.

Philip in Connecticut
01-01-2010, 04:20 PM
I did come across this adapter: I am wondering, if it did have a washer in the female section, it might do the trick?


Philip in Connecticut
01-01-2010, 05:13 PM
Here is another pic of an old diverter valve that I had temporarily attached to the Toto shower arm in the picture above. The female end of the diverter has a washer and mated just fine to the threads on the toto arm (although when I purchased it, it was intended to be attached to the end of any standard shower arm, and it was used that way for many years with no problem/no leaks). THe other end of the diverter valve has tapered threads that fit our old (garden variety) shower head with no problem. OK, so that would seem to confirm that I have a "hose connection threads/fitting" on the end of the Toto arm (?)