We have a thermostatic control on the shower in the top floor of our home. Unfortunately it doesnt seem to be working, so I just ran some tests and would appreciate opinions on what you think of them and what they men.

As background, we live in a 3 story home. In the upstairs shower we have a Section 25 Riobel thermostatic control valve. Based on some feedback in other forums, it looks like we have a PRV valve. Also, our GC, under instructions from the plumber, increased the water pressure coming into our home from 55lb to 65lb; Still within the allowable limit I was told; Unfortunately, didn't help the problem - although it's nice on the top floor shower!

3) I've done some testing to see if providing measured data will help; Please forgive the mass of reading below, but TIA for your help. The results are shown below, and in each case I had the shower temp set at 30 degrees, then performed the action described and noted the results listed. No other taps or plumbing fixtures were being used during each test. Please note the thermostatic shower control in question is in the top floor bathroom

***1.0 Top Floor Shower tests

1.1 Turn shower temp up 10 degrees

Result = 1 second slight pressure drop, then temperature stable at new setting

1.2 Turn shower temp down 10 degrees

Result = 1 second slight pressure drop, then temperature stable at new setting

***2.0 Top Floor other fixtures tests (in same room as shower in question)

2.1 Flush toilet

Result = 3 second slight pressure drop, then 5 seconds moderate temperature increase, then 13 second significant additional temperature increase (almost scalding), pressure/temperature returns to normal in approx 60 seconds

2.2 Turn on hot & cold taps in sink to overall hot temp

Result = 3 second slight pressure drop, then significant temperature increase until taps turned off

***3.0 Main Floor tests

3.1 Flush powder room toilet

Result = 3 second slight pressure drop, then significant temperature increase until toilet tank refills

3.2 Turn hot & cold taps in powder room sink to overall hot temp

Result = 3 second slight pressure drop, then significant temperature increase for 3 seconds, then pressure/temperature returns to normal

3.3 Turn hot & cold taps in kitchen sink to overall hot temp

Result = slight pressure and temperature drop for duration of sink taps turned on

3.4 Dishwasher not tested

***4.0 Basement tests

4.1 Flush basement bathroom toilet

Result = 3 second slight pressure drop, then significant temperature increase until toilet tank refills

4.2 Turn hot & cold taps in basement bathroom sink to overall hot temp

Result = slight pressure drop and no temperature change

4.3 Turn hot & cold taps in laundry sink to overall hot temp

Result = slight pressure drop and no temperature change

4.4 Washing machine cycle not tested

4.5 Turn hot & cold taps in basement office sink to overall hot temp

Result = slight pressure drop and no temperature change

Seems to me that in 1.2, 1.2, 4.2, 4.3, and 4.5 the thermostatic control is operating the way it's supposed to. The rest of the tests had very odd results.

Questions :

1) Are the test results as weird as they seem to me?

2) Any ideas on what the problems may be?

If you need any more info, just ask - and thanks for your patience in wading through all of this!

- R.