W M Schmidt Mechanical

Schmidt installed the original plumbing in a new build. We immediately noticed that the hot water in the kitchen lost almost 1/2 of its temperature in 2 minutes by testing with a digital thermometer repeatedly. Installed insulation on all HW lines to kitchen _ no change. Contacted builder + Schmidt & response was that was typical installation. After months of putting up with this nonsense I personally removed the T-fitting that fed off the 3/4" line that goes upstairs to the 1/2" line to the kitchen & installed a new 1/2" line immediately above the hot water tank - problem solved - now a 3°C change in 2 minutes. I questioned where the syphoning of cold water was occurring though as before testing I'd closed the valves to the washing machine upstairs after I'd heard these could get stuck open. Then I noticed a "Thermostatic Mixing Valve" under the sink in the master bathroom. The builder had left the box & installation instructions for this unit in the furnace room and it clearly stated that installation was to be installed on the lines above the hot water tank to avoid scalding hot water - not 2 floors up in the master bath. I again inquired with both the builder & Schmidt and received no response on either inquiry to Schmidt. I'm noticing pressure pulsing in the shower stream of the master bath & will eventually remove this mixing valve entirely - I assume its either faulty or a POS from the manufacturer.