Installation & Operation Manual

11 Operating information (continued)

Low water cutoff protection

1.The SMART SYSTEM control module uses temperature sensing of both supply and return areas of the heat exchanger. If the flow rate is too low or the outlet temperature too high, the control module modulates and shuts the boiler down. This ensures boiler shutdown in the event of low water or low flow conditions.

2.Some codes and jurisdiction may accept these integral features of the control in lieu of requiring an additional limit control or low water cutoff. Consult local jurisdiction to determine. A low water cutoff is available from the factory (WTR20009).

Outdoor reset operation, if used

Target temperature with outdoor reset

This feature improves the system’s efficiency as the outdoor temperature warms up.

See the Knight Wall Mount Service Manual to change the settings.

Reset curve

The reset curve looks at outdoor air temperature and adjusts the set point.

Cascade

When multiple boilers are installed, they can be wired together in a cascade sequence. A maximum of eight boilers can be controlled from a single control. In this application one boiler would be designated as the Leader control and all others would be designated as Member controls. The Leader control can be programmed to use Lead/Lag or Efficiency Optimization control methods.

Once the Leader boiler receives a call for heat from a room thermostat, BMS, or Modbus, the control will determine what the set point will be. If outdoor air reset is desired, connect the outdoor air sensor to the terminals on the Low Voltage Connection Board on the Leader boiler. The set point will be calculated based on the programmed reset curve parameters. See the Knight Wall Mount Service Manual to program the reset curve. If outdoor air reset is not desired, do not connect the outdoor air sensor. A fixed temperature set point can be programmed into the control. See page 62 of this manual to program the set point.

If the water temperature at the system supply sensor is less than the set point + the turn-off offset - the off-on differential, then the control will initiate a call for heat on the Cascade (see the Knight Wall Mount Service Manual for an explanation of the offset and differential). The Leader will energize the lead boiler on the Cascade. For a new startup this will be the Leader boiler.

Sequence of the cascade

To equalize the run time of all boilers on the Cascade, the firing sequence will automatically be changed at set intervals. The sequence will change every hour during the first 24 hours, after that the sequence will be changed once every 24 hours. The switching on/off sequence will be as follows:

TIME

SWITCHING ON SEQUENCE

 

 

Start

L-M1-M2-M3-M4-M5-M6-M7

1 hour

M1-M2-M3-M4-M5-M6-M7-L

 

 

2 hours

M2-M3-M4-M5-M6-M7-L-M1

 

 

If a boiler is used to heat an indirect DHW tank, or locks out, it will automatically be given the lowest priority for the rest of that 24 hour period.

DHW, Night Setback, and Ramp Delay operation with cascade

For Normal Mode DHW operation any boiler(s) in the Cascade can be selected to provide heat for a DHW call. Select a boiler to be designated as the DHW boiler. Connect the DHW thermostat or sensor to the terminals on the Low Voltage Connection Board marked for the corresponding device. When the boiler receives a DHW call, the Leader control will take that boiler out of the Cascade sequence. If another boiler is available, the Leader will start it up to take its place.

The DHW boiler will adjust its set point to the programmed DHW boiler set point and will adjust its firing rate to maintain this. Once the DHW call has been satisfied, the Leader control will place that boiler back into the Cascade sequence.

Switching of the boiler between DHW operation and SH operation when there is a call for both does not occur in Cascade Mode.

When DHW is programmed for Zone Mode, connect the DHW thermostat or tank sensor to the Leader boiler. When a DHW call is received, the Leader will modulate the entire Cascade to bring the system supply temperature up to the DHW boiler set point.

Night Setback operation of the boilers within the Cascade is available. Programming of the Night Setback will be done through the Leader boiler. Refer to the Knight Wall Mount Service manual for information regarding Night Setback.

Ramp Delay operation of the boilers as described in the Knight Wall Mount Service Manual is not active when the boilers are part of a Cascade system.

67

Page 67
Image 67
Lochinvar WH 55-399 operation manual Outdoor reset operation, if used, Cascade

WH 55-399 specifications

The Lochinvar WH 55-399 is a high-efficiency water heater designed for residential and commercial applications, offering a reliable solution for hot water needs. This model represents an advanced approach to water heating, combining cutting-edge technologies and features that ensure optimal performance and energy efficiency.

One of the standout features of the Lochinvar WH 55-399 is its high thermal efficiency, which is a key factor in reducing energy consumption and operating costs. With an efficiency rating exceeding 90%, this water heater ensures that more energy is converted into usable hot water, making it an environmentally friendly choice.

The WH 55-399 utilizes advanced condensing technology, which allows it to extract additional heat from the exhaust gases before they are expelled. This process not only increases efficiency but also significantly decreases greenhouse gas emissions. The unit is also equipped with an intelligent control system that allows for precise temperature adjustments, ensuring that the user has an optimal supply of hot water while maintaining energy savings.

Another important aspect of this model is its impressive recovery rate. The ability to quickly heat water after a significant draw ensures that users will not experience interruptions in their hot water supply, making it ideal for busy households or commercial environments. This is particularly beneficial in applications requiring consistent hot water availability, such as restaurants or athletic facilities.

The Lochinvar WH 55-399 is designed with durability in mind. Constructed from high-quality materials, this water heater boasts a robust tank lined with corrosion-resistant coatings, extending the lifespan of the unit and reducing maintenance needs. Additionally, it features a reliable gas burner and a well-insulated tank, contributing to its overall efficiency and performance.

Safety is also a priority with the WH 55-399. The unit incorporates multiple safety features, including a flame sensor, automatic shut-off valve, and over-temperature protection, ensuring peace of mind for users.

In summary, the Lochinvar WH 55-399 stands out with its combination of high efficiency, advanced technology, and durable construction. Whether for residential or commercial use, this water heater provides a dependable and cost-effective solution for all hot water needs. Its innovative design and performance characteristics make it a top choice for anyone seeking a premium water heating option.