From the Kuma (Force 10) Hot Water Heater instructions:
“... If your unit is equipped with a TCV (Temperature Compensation Valve) the
coolant loop to the water heater exchanger must be an auxiliary loop in the engine coolant circulation system. The TCV can not be installed inline with the engine coolant system. Figure 1 on page 5 ...”
Many building codes have been amended to specify that new or replacement water heaters supply a maximum hot water temperature of 49 degrees Celsius (120 degrees Fahrenheit).
It’s recommended that you add an anti-scald mixing valve
* on the Hot Water Tank
thermostatic mixing valves
** (or pressure-balanced valves***) on each hot water tap and showerhead
* Anti-scald mixing valve:
This valve is installed directly into your plumbing
system (at the hot water tank), and it mixes hot water with cold water to ensure the water that comes out of the mixing valve is not above 49 degrees Celsius (120 degrees Fahrenheit).
This is the “Temperature Compensation Valve” noted on the Force 10 heater.
** Thermostatic valves:
These valves operates in the same way as an anti-scald mixing valve in your plumbing
system. The difference is that a thermostatic valve is installed at select points of use (hot water taps and showerheads).
*** Pressure-Balanced mixing valves:
A pressure-balanced (shower) valve is designed to compensate for changes in water pressure. It has a special diaphragm
(or piston mechanism) inside, that moves with a change in water pressure to immediately balance the pressure of the hot- and cold-water inputs. These valves keep water temperature constant, within plus or minus 2 to 3 degrees Fahrenheit, but do so by reducing water flow through either the hot or cold supply. Most reduce water flow to a trickle if the cold water supply fails.
Flow can be a problem with pressure-balanced valves, particularly in homes where the shower
includes a personal hand shower
and/or a multiple-head shower system. Most pressure-balanced valves are either full-on or full-off.
Where flow and volume control are important, a better (and more expensive) choice is a thermostatic valve**. Most of these have 3/4-inch inlets that can blast a flood of water through multiple showerheads and will maintain the water temperature within 1 or 2 degrees of the set temperature.
Whereas a pressure-balanced valve will typically cost from a low of $100 to $250, a thermostatic valve with a volume control (a separate feature with most), will run from $400 to $1,000 depending on the features and trim.