Water tank stores heated water. When water tank temperature is low the
tank sensor calls for circulation from the boiler. If the boiler
temperature is too low the boiler temp sensor fires the boiler.

The water heater should have a temperature sensor inserted into the
tank to turn the circulator on to bring heat into the tank coil. Might
check the temperature setting there. There may also be a tempering
valve on the outlet of the water heater tank to limit the hot water
outlet temperature, check that setting.

Second if the incoming water to the coil from the boiler is too low you
can't raise the hot water temperature above that. Check the boiler
temperature gage and also determine if there is any tempering valve on
the boiler feed to the water heater tank.

Finally, are you sure you want really hot water. There is a risk of
scalding , especially with children and the elderly.

On Dec 28, 4:08 pm, "El Penguini" wrote:
I have a potable hot water system that uses the third zone off of my furnace
to heat a coil in a storage tank.

While the water is hot, it isn't hot enough for my liking.

Can someone give me a clue on how this system works, and what settings I
should be looking for?

Thanks
Peter