Instruction manual
19
P/N HN-IOM-1 82-0331 Copyright 2009 Mestek, Inc.
Finned copper tube gas boilers & water heaters – Control manual
Configuring for DHW applications (continued)
5
DHW Method 3 —
DHW tank sensor (on HEADER Sensor terminals)
DHW tank temperature controlled directly
— tank temperature sensor (10k
thermistor) in tank connected to DHW TEMPETURE SENSOR input (J10B
1/2) — see Figure 4, page 23 for location.
Single or multiple boiler application ❑ .
Dedicated water heating ONLY if using HeatNet ❑ (boilers could be operated
for space heating by BMS, 4-20 ma remote controller or relay mode for space heat-
ing, though piping and valves will have to be designed to isolate from the DHW
tank)
.
Limiting maximum boiler temperature when applying for DHW
applications —
When the boiler is to be used for domestic water
heating, jumper JPS1 must be clipped. is limits the maximum water
outlet temperature. Failure to comply could result in overly hot water
being delivered to the system. See Figure 3, page 22 for location of JPS1.
Method 3 operation
Set up the HeatNet control as for space heating, with the tank temperature sensor
connected to the master boiler Header sensor terminals. See Table 7, page 30, Table 8,
page 33 and Table 9, page 35 for set up and explanation of parameters.
HEAT BAND
e HeatNet control will regulated boilers and ring rates to control temperature with-
in one half of the Heat Band above and below the Setpoint temperature.
SHED BOILER DELAY
Set Shed Boiler Delay to 0 to prevent tank temperature from going above Setpoint +
½ HeatBand. With this parameter set to 0, all boilers will shut o at Setpoint + ½ Heat-
Band. If temperature excursions above Setpoint + ½ HeatBand are acceptable, Shed
Boiler Delay can be adjusted to reduce cycling if necessary.
SETPOINT (LOCAL SETPT)
Setpoint is the design temperature for controlling the tank. e HeatNet control will
regulated boilers on and o, adjusting ring rates as necessary, to control the tank tem-
perature within the range of Setpoint – ½ HeatBand to Setpoint + ½ HeatBand.
Example
Tank temperature setpoint = 135 °F | Heat band = 10 °F | Shed Boiler Delay = 0. ❑
is means the operating range is (135 – 5) to (135 + 5), or from 130 °F to 140 °F. ❑
All boilers will be on below 130 °F and all boilers o above 140 °F, and boilers
cycled on/o and modulating in between, based on the HeatNet control’s PID
methodology.
Method 3 post purge option
When tank temperature reaches OFF TEMP, all active boilers turn o. e pump relay
will remain on for the POST PURGE time set in the Setup menu.
Post purge allows dumping the residual heat in the boilers to the DHW tank.
Post purge will increase tank temperature above SETPOINT —
Adding additional heat to the DHW tank aer boilers are shut o will
increase tank temperature. Ensure that this is acceptable. IF NOT, then
the pump post purge must be disabled (set to zero).
Method 3 setup procedure
Tank sensor ❑ — Install a 10k tank temperature sensor in
the tank. Wire it to the master boiler HEADER SENSOR
terminals, J10A terminals 7/8 (Figure 4, page 23).
Clip jumper JPS1 ❑ (see Figure 3, page 22 for location) on
all boilers that will be used for DHW.
DHW pump ❑ — Wire the DHW pump relay or valve to the
normally-open contact, LOCAL PUMP terminals, J13 ter-
minals 5/6 (Figure 3, page 22).
Master boiler setup ❑ — Set up the boilers as for space
heating, but with the setpoint and heat band set as needed
for the DHW tank.
DHW Method 4 —
4–20 ma control
(by remote controller)
DHW tank temperature controlled directly
❑ — tank
temperature sensor (10k thermistor) in tank connected to
DHW TEMPETURE SENSOR input (J10B 1/2) —
see Figure 4, page 23 for location.
Single or multiple boiler application ❑ .
Dedicated water heating or combined space heat- ❑
ing/DHW.
Limiting maximum boiler temperature when
applying for DHW applications —
When the
boiler is to be used for domestic water heating, jumper
JPS1 must be clipped. is limits the maximum water
outlet temperature. Failure to comply could result in
overly hot water being delivered to the system. See
Figure 3, page 22 for location of JPS1.
Method 4 setup — controlling master
boiler
Set the master boiler’s HeatNet control with 4–20 ma set to ❑
HIGH PRIORITY in the ADVANCED Setup menu.
is will allow the remote controller to take over operation ❑
of the boilers when DHW is required.
Method 4 setup — controlling individu-
al boiler
Set the member boiler’s HeatNet control with 4–20 ma set ❑
to HIGH PRIORITY in the ADVANCED Setup menu.
When the remote DHW controller calls for DHW, this ❑
boiler will be taken oine and controlled by the remote
4–20 ma signal.
Piping and valves must provide for automatic switching ❑
from space heating to DHW.