HAND
control from Doorway and InSiteThis release is an update to boiler controller product. For full operational details this note should be read in conjunction with Data sheet LIT/DAT/BLR/001 Iss2.0.
This version of code runs on the 0004/0002 issue E BLR DIN hardware.
The code is contained in a 27C512 prom with address line switching.
The frost protection set point 'FRST', can now be set to a minimum of 2°C, and the default factory setting is now 3°C.
Frost protection can now be disabled, by setting 'FRST' to 0 (please be aware of the consequences of doing this). Once Frost protection is disabled the boiler controller will no longer protect the system at low outside temperatures Stage1 frost protection, Stages 2 and 3 are now combined and will ultimately protect the system, if any of the water temperatures fall to 5°C (fixed) at which point the boiler will fire until the lowest water temperature reaches 30°C, at which point the boiler and pumps will be disabled and the cycle will repeat.
How to disable frost protection.
Access the 'FRST' config variable, and reduce it to its lowest allowable setting
of 2°C, now put the boiler controller into manual and short the outside sensor
connection. Refresh the 'FRST' variable it will now display as 0°C, this value
can now be written (i.e.. pressing the override button on the zone controller)
to the controller. Take the controller out of manual and remove the shorting
link, confirm the 'FRST' setting is 0°C, the variable is now fixed at 0°C and
cannot be adjusted by normal methods.
To re-enable frost protection, select the 'FRST' variable and put the boiler
controller into manual, when a write is made to the controller the 'FRST' variable
will default back to 2°C. Take the boiler controller out of manual operation,
the 'FRST' variable can now be set as normal to any permissible value.
There are three plots setup on the
first three 'sensors'.
Plot 1 Measured Flow temperature
Plot 2 Measured Return temperature
Plot 3 Measured Variable Circuit temperature
This controller now has Configurable
Plots like most of the other SeaChange controllers. These plots are now
automatically re-scaled within the controller to achieve the best resolution
for the data recorded. This happens at the end of every 96 readings when new
maximum and minimum settings are calculated and also if a new value is outside
the current range settings.
The two extra inputs are treated as digital inputs and their current state is viewable in Doorway as I1 and I2. A '1' condition indicates that the terminals are shorted. Two new config variables are supported 'Alarm state' - 'ALST' and 'Alarm mode' - 'ALRM' . A 'danger of freezing alarm' has also been added, this will create an alarm if the lowest temperature reading of Flow, Return and VT is lower than 5 degC. Frost protect should prevent this happening. Five degrees is used to allow for measurement errors and poor conductivity between the sensor and the water. The sense of the alarm state is defined by config variable 'ALST' 'alarm_state' 0 or 1, this equates to opencircuit or short circuit on the input terminals. ALRM Alarm mode - This takes a number of values which function as described in the Config Tables .
The state of the alarms can be monitored in Doorway by reading config variables 90-99.
To reduce levels of network traffic on 'system power up' and high alarm activity at Doorway, a random delay of up to 1 minute (the minimum period for this delay is 20 seconds) has been incorporated into the module before alarms are reported. In addition to this subsequent alarms are also delayed i.e. if a alarm condition arises it will be reported immediately, however no further alarms will be reported from this module within the next 5 seconds.
If the boiler module has received or initiated a system 'ALL STOP' alarm this is now indicated locally to user by the error lamp flashing alternately red and yellow.
An additional Alarm Mode ALRM 5 has been added which allows a Boiler shut down to be initiated when a General Alarm is created on input b. This is designed to be used for Pressurisation failures but could be used for other purposes.
New monitoring variable added 'Summer
heating off' - 'SHOF', this is read only and enables the user to determine if
the summer hold off is active.
0 = Heating Enabled
1 = Heating disabled
HAND
control from Doorway and InSiteA new control mode has been added which allows Doorway to select manual HAND, this is activated by setting switch 5 HAND. The forces the controller to manual mode and the output of the VT loop is defined by the value on the config variable MANL. On this controller only 0 to 100% has significance because the Boiler controller only has heating. The Boiler sequencer will run the number of boilers needed to maintain the Flow temperature.
The process of selecting HAND and setting the manual level can be associated on the same point by using the following Doorway syntax.
[B1]W5(S)/hand/auto/12/10/C83(V) assumes the controller is Boiler 1
clicking on the point allows selection of hand or auto and also the means to set C83 which is the manual level required.
InSite automates this process with it's Override features.
See also Universal Manual for further details
Occupation
OverrideThe Boiler controller can now be overridden on and off using switches W1 and W2 in a similar manner to other controllers. The Boiler is a special case because it is really two controllers in one, the VT controller and the Boiler sequence controller. The Override operates on the VT controller.
The override can only be used to change the current state, if the VT controller is in occupation then it can be overridden off, if it is off it can be overridden on, once the automatic state matches the overridden state then the controller will revert to automatic mode. This feature is designed to be used with InSite Override dialogue or the Doorway Auto/Manual syntax, see Universal Manual for further details.
When the controller is overridden on, the VT loop becomes occupied and will run with a fixed heat demand of 50%, this will produce a weather compensated control at the nominal settings. The Status led will occulate with short off periods to indicate that the controller has been overridden on. CT demands will still be sent to the Boiler sequencer.
When the controller is overridden off the Status led occulates, short on flashes. In this case any CT demands will also be overridden and the Boilers will shut down, the minimum run time is still observed.
The Heat source 'HTSC' of any device registered to the boiler controller is set to 1, previously this variable was not set. This enables all products to be shipped from the factory with a default HTSC of 0.
'BRON' Boiler pump run on feature,
now functions correctly. In the previous release the pump run on period would
expire while the boilers where running, causing the pump to stop almost immediately
when the boilers stopped.
Some Boiler installations do not have a Primary Boiler Flow circuit, the Boiler Flow is fed directly to the radiator or Heating (VT) circuit. In these cases if the VT valve closes while the Boilers are running the water flow through the Boiler can be shut off thus causing a rapid build up of temperature which can lead to Boiler shut down on the over temperature safety interlocks. This parameter allows a minimum valve opening to be maintained when ever the Boilers are running, regardless of heating demand. This prevents the Boiler tripping the HIgh temperature cut off. If the parameter is left at its default value of zero then the feature is disabled.
Changes to Configuration variables this issue refer to Config Tables