We are a hotel with 115 showers, hot water is fine in summer but when cold outside inlet water temp drops to 40 the showers are luke warm, all showers were just replaced and it improved but not enough. Hot water is 140 out of tanks, 130 at return and recirculation system working, we have 130 at sinks but only 100 at shower, scald limiter is at max hot on brand new kohler shower valves. Anyone know how they deal with the frigid cold water supply in places like Alaska, do they heat the cold water supply

Do you have a mixing valve at the HW storage tank? Perhaps an adjustment THERE is in order?!

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

should have asked before you changed the valves.
you need a thermostatic controled shower valve not a plain non scald variety.

thermostatic shower valve you set at 109 to 112 and leave it. it adjust itself.

the cartridge is temperature sensitive so it compensates for the colder water.

Thanks, The building owners supplied the valves and plumber and being bean counters they used the cheapest parts and low bid