CPM, CPMSP Cascade Header Kits

1. Introduction

This Installation manual should be read in conjunction with the installation (ICM) manual for either the CPM gas-condensing boiler or the CPM SP cascade system boiler. If you do not have a copy of the ICM, it can be downloaded at www.lochinvar.ltd.uk.

Figure 1: A typical cascade configuration showing two Lochinvar CPM boilers connected via a frame and hydraulic piping.

This Cascade manual is for use with the CPM and CPM SP wall-hung high-efficiency condensing boilers manufactured by Lochinvar Limited. These boilers are available, in order of ascending output, as CPM 58, CPM 77, CPM 96, CPM 116, CPM 144, CPM 175, and CPM SP Range.

The CPM 58-116 boilers can be supplied in one cascade set, as can the CPM 144-175 boilers; due to their size difference, they cannot be mixed. Lochinvar Limited can supply standard cascade systems with mounting frame, piping, and low-loss headers for up to four boilers.

All CPM boilers are equipped as standard with an internal cascade manager for up to twelve boilers. No extra controllers are necessary; you only connect a 2-wire cable between all boilers.

The low-loss header can be fitted on the right-hand side as well as on the left-hand side without altering the pipework. The gas connection can be fitted on one or both sides, independently from the side chosen for the low-loss header. To commission the cascade installation, it is necessary to set a number of parameters on the boilers, see the boiler ICM.

2. Main Dimensions

Figure 2.1: Technical drawings illustrating the main dimensions of cascade setups, including frame width (L1), hydraulic group width (L2), width with low velocity header (L3), gas connection (A), header connection (B), and various heights (H1, H2, H3) and diameters (D1, D2, D3).

2.1 Cascade dimensions

The picture shows connecting sets for CPM boilers – for CPM SP boilers the connecting sets are different.

2.2 Cascade Dimensions (use in conjunction with 2.1)

3. Explanation of Parts and Groups

Each cascade set consists of the following parts and groups:

1. Two to four CPM/CPM SP boilers.
2. The frame group (with locking plates) as determined by the number of boilers.
3. Connecting groups to connect the boilers to the hydraulic groups (one group for each boiler, each group consists of one gas, one flow, and one return connecting set).
4. Hydraulic group, comprising one gas, one flow, and one return header with all fixing and connecting parts.
5. Low-loss header or hydraulic separation plate heat exchanger (plate would be supplied loose).

Figure 3.1: An illustration showing the main components of a cascade system: CPM/CPM SP boilers, a frame group, hydraulic group, connecting sets, and a low velocity header. It notes that return connecting sets differ for CPM and CPM SP boilers.

4. Frame Groups

Figure 4.1: Diagrams illustrating different frame group configurations for 1, 2, 3, and 4 boilers.

4.1 Cascade frame groups for 1, 2, 3, and 4 boilers

4.2 Frame group parts (use in conjunction with 4.1)

5. Mounting the Boilers on the Frame

All lines/piping must be mounted free of tension. The weight of all the components must be supported separately from the boiler so there is no force on the connections. This might influence the mounting position of the boiler.

Before mounting the boiler on the frame, ensure that the frame is level in both directions. If necessary, adjust with the adjusting bolts on the lower side of the frame (see drawing).

After mounting the boiler on the frame, ensure that the boiler is level. If necessary, adjust with the adjusting bolts on the lower rear side of the back panel. (See drawing).

When the adjusting bolts are not sufficient, it may be necessary to fill behind the bolts to get the boiler level. The levelling margin is between boiler hanging level and hanging backwards a little.

The boiler should not lean forward in the mounted position.

Lock the suspension bracket with the locking strip to prevent the boiler from falling off the bracket (See drawing).

Figure 5.1: Diagrams showing how to mount boilers on the frame, including details on locking mechanisms and leveling using adjusting bolts.

5.1 Mounting details

6. Mounting the Connecting Sets

First, connect the connecting sets hand-tight to the boiler connections. In a cascade set-up, do NOT use the T-pieces delivered with the boilers.

The shortest connecting set should be connected to the gas connection on the boiler.

Make sure to connect the flow connecting set (middle length) to the boiler flow connection (left-side connection) and the return connecting set (longest) to the boiler return connection (right-side connection).

The open connection in the flow connecting set is meant for a pressure relief valve, and the one in the return connecting set is to be used for an 8-litre expansion vessel as per BS6644. A kit is available as an ancillary option.

For the CPM SP116 boiler, the return connecting set differs due to the external pump.

Figure 6.1: Illustrations of the different connecting sets (gas, flow, return) and their connections to the boilers. It also shows a specific setup for CPM SP boilers with an external pump.

6.1 Connecting sets

7. Mounting the Hydraulic Group

Connect the gas header to the gas connecting sets. Connect the flow header to the flow connecting sets. Connect the return header to the return connecting sets. Mount all headers with the clamps to the frame.

All lines/piping must be mounted free of tension. The weight of all the components must be supported separately from the boiler so there is no force on the connections. This might influence the mounting position of the boiler.

When all parts are mounted in the right place and are free of tension, fasten all couplings and fasten the clamps.

Figure 7: A diagram showing the assembly of the hydraulic group, with color-coded pipes for gas (yellow), flow (red), and return (blue).

7.1 Hydraulic group for 2 boilers CPM 58–116 and/or CPM SP

Figure 7.1: An exploded view of the hydraulic group for 2 boilers, detailing components like gas header, flow header, return header, clamps, seal caps, couplings, gaskets, and bolts.

7.2 Hydraulic groups for 3 and 4 boilers CPM 58–116 and/or CPM SP

Figure 7.2: An exploded view of the hydraulic group for 3 and 4 boilers, similar to the 2-boiler version but with different quantities of parts.

7.3 Hydraulic groups for 2 and 3 boilers CPM 144–175

Figure 7.3: An exploded view of the hydraulic group for 2 and 3 boilers of the CPM 144-175 series.

7.4 Hydraulic group for 4 boilers CPM 144–175

Figure 7.4: An exploded view of the hydraulic group for 4 boilers of the CPM 144-175 series.

8. Low Velocity Headers

The low velocity header can be mounted on the right-hand or the left-hand side of the flow and return headers, whatever is the best place to connect the headers to the heating installation. The supplied caps or flanges must block the opposite end of the flow and return headers.

Figure 8.1 & 8.2: Diagrams illustrating the low velocity headers, showing their dimensions (D, H1, H2, L) and connection points.

9. Plate Separators

For systems where water quality cannot be guaranteed, it may be better to install a plate separator instead of a low velocity header. This will isolate the boilers hydraulically from the dirty system. A suitable plate is available as an option from Lochinvar; these are sized based on the number of boilers required.

See section 6.15 in CPM/CPM-SP Installation Manual for important information regarding the use of a plate separator.

1: Lochinvar standard supply a manual venting valve that can be mounted on top of the low loss header to manually bleed the air from the low loss header. Instead of the ½" manual bleed valve, an automatic air vent can be installed, up to 1" max.

10. Flue Gas and Air Supply

10.1 Individual or Common Flue Systems

Lochinvar Limited CPM/CPM SP cascade-sets can be equipped with individual or common flue systems. Using separate venting material is always preferred above common venting. Only when separate venting cannot be used, should a common vent system be used.

When chosen for an individual flue system, each boiler has its individual flue gas outlet and air supply lines to the outside of the building. This may be executed in parallel or concentric flue gas and air supply pipes. When chosen for a common flue system, this must be executed in parallel flue gas and air supply pipes.

10.2 Individual Flue Systems

Individual flue systems can be chosen as mentioned in the CPM instruction manual. The flue system should comply with the chapter “Flue gas and air supply system” of the CPM/CPM SP manual. For each boiler, the combined resistance of the individual flue gas and air inlet pipe can be calculated and checked with the maximum for the gas-side resistance. Resistance table and example calculations are given in the same aforementioned chapter of the CPM manual.

10.3 Common Flue Systems

Common flue systems must be designed according to: EN 13384-2 “Chimney – Thermal and fluid dynamic calculation methods – Part 2: Chimneys serving more than one heating appliance.”

For common flue gas systems, the parameter P5DB has to be adjusted to prevent recirculation of flue gases.

Lochinvar can supply a common flue cascade system for up to 4no CPM58-116 boilers; see CPM ICM manual for details available at www.lochinvar.ltd.uk.

11. Installation

Follow the instructions given within the ICM manual for either the CPM or CPM SP; these are available from Lochinvar Limited at www.lochinvar.ltd.uk.

12. Cascade Control

12.1 Output Control

The total cascade set-up will act as one single big boiler, switching on and off boilers, depending on the total load necessary to adjust and keep the flow temperature at the calculated value. When the heat demand rises, more boilers are switched on, and when heat demand falls, one or more boilers will be switched off. The boiler that was switched on last will be switched off first (see table below).

12.2 Boiler Sequence

To distribute operating hours equally over all boilers, the working sequence of the boilers will change every two hours.

Table 1: Boiler sequence example of an eight boiler cascade. In this table, a total of eight boilers (one master, seven slaves) is mentioned as an example; in practice, the maximum number in a cascade, without extra (external) control, is twelve boilers.

13. Options

To complete your cascade set-up / heating installation, you can choose from the following options:

Room Temperature Controllers

Plate Separators

Sensors

Heating circuit controller

Parameter programming

Table 2: Accessories and parts.

Figure 3: A few examples of accessories, showing RC OpenTherm room temperature controller (1 and 2), RCH E-bus room temperature controller for EBC (4 and 5), EBC 2-zone E-bus controller (10) mounted in a wall-mounted case with terminal board (11), and a wall-mounted case with terminal board for EBC (11).

Notes

This section is reserved for additional notes.