Fireman...You may be on to something that I have long suspected...
When I built this house, I installed a shower stall in a first floor bath as an after thought...(3 full baths)...as it turns out, this shower stall has been used a total of 2 times in 15 years.....anyway, I bought the hot and cold water faucets, drilled holes in the fiberglass shower, and installed each (hot/cold) to the appropriate supply lines...well..when the plumbing inspector came by, he say: Nope! thats a potential scalding hazard! gotta have a mixing valve!...but I already had the shower stall drilled and installed!..so..what I did to appease the man, was I purchase a (Sparco?) mixing valve and installed it under the floor of the shower so that the water would never get too hot, even if somone were to enter the shower and just turn on the hot water...so this valve has the hot and cold water feeding into it first, BEFORE feeding the shower head...this made the plumbing inspector happy, and he signed off..
This installation is, off course, down stream of the Check Valve, and even tho I always suspected that this could be the problem, I still could not understand the mechanics behind it...
Since the shower is never used, as a test I have been prepared to severe the darn supply lines to the unit completely to see if it helped...but I have been reluctant to do that just on my own hunch...
I can take a photo of the valve if it helps..
What do you think?
Thanks so much!
Last edited by stoker_RI
on Thu Feb 10, 2011 1:17 pm, edited 1 time in total.