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?
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.
That is known as indirect fired domestic hot water.
The first question is what is the delivered water temperature you are
getting? It should not be above 130 degrees for safety.
The output of this indirect fired storage tank should have a tempering
valve which mixes cold water in with the hot output of the tank to
maintain this 130 degree limit. The tempering valve will have three
connections and usually a black knob at one end which can be used to
adjust the output temperature. This would be the first place to check,
both the adjustment and the valve itself as they can go bad.
The indirect fired storage tank should have a temperature control on it
that is used to request heat for it's "zone" when the tank temp is low.
If there is a proper tempering valve on the tanks output then this
control can be set fairly high, close to the boilers operating temp, if
no tempering valve then this control has to be set to the 130 degree
limit or lower.
If the actually boiler operating temp is lower than 130 degrees you
likely have a problem there since that is abnormally low. 160 - 180
degrees is more typical for a boiler operating temp.
Summary: The indirect fired DHW tank operates as a heating zone from the
main boiler. It has it's own thermostat which would be set between 130
and 180 degrees depending on whether there is a tempering valve on it's
output. It should have a temperature gauge so you can see the current
tank temp. If it is sufficiently hot and the delivered hot water temp is
still too low, the tempering valve is suspect.
Assuming the boiler temperature is set for 180 more or less, depending upon
the brand of indirect you have, you will probably find its temperature
adjustment on the top of the tank, or some will have a digital control low,
on the side
"Heating the Water The thermostat controls the temperature of the
water inside the tank. Normally you can set the temperature between 120
and 180 degrees Fahrenheit (49 to 82 degrees Celsius). It is generally
recommended that you keep the temperature between 120 to 140 degrees F
(49 to 60 C) -- especially if there are children living in the house --
to prevent scalding. It also saves energy." and more at:
how your boiler works:
usual definition clarification:
furnace=heating of air
boiler or hydronic =heating of water
lookup boiler manual online. look up any manuals online for any
connected parts that control your devices. like honeywell. depending on
what type of heating this is there will be everything with operating
manuals or instructions and they will all need to work together. if the
third zone is a forced air furnace, i don't know. if it is a boiler, it
may be along for the ride as a passive loop with the system operating
year round. if it has an active burner or heating element find its
temperature control or zone control valve.
El Penguini wrote:
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