dB AM Series - User Manual

Series AM Fan Convectors
Installation, Operation & Maintenance Instructions
Dunham-Bush Ltd, Downley Road, Havant, Hants PO9 2JD
Document Ref:
023 9247 7700
info@dunham-bush.co.uk
121-000-001-D
UK:www.dunham-bush.co.uk
Global:www.dunham-bush.com
July 2021
1
INSTALLER: Please leave these instructions, heater wiring diagram & access panel keys with the user.
INTRODUCTION
This booklet provides guidance to identify, handle,
install, commission, operate and maintain
Dunham-Bush Series AM fan convectors. The
instructions apply to the standard range of 22
models shown on page 2. Please study the
instructions carefully before commencing any
installation work.
IDENTIFICATION
The fan convector serial number, model description,
figure number (size) are displayed on a label found
on the inside of the heater access panel. If specified,
a stencil reference may also be marked on the
heater on-site identification.
DESCRIPTION
Each Series AM fan convector comprises a sheet
steel casing with a lockable access panel, fan/motor
assemblies, air filter and hot water heating coil.
Single phase electric elements can be fitted instead
of a hot water coil. Heaters can be supplied for one
or two speed fan operation ; single speed units are
pre-set to low, medium or high speed, and two
speed units are pre-set to low/medium, low/high or
medium/high speeds, as ordered.
Fan control is by means of switches and/or
thermostats, listed in Accessories.
Diagram 1: Series AM Model 13 Figure 04 with left hand coil connections - *items are optional accessories

Summary

Controls

Fan Motors

Describes conventional synchronous AC motors and energy efficient EC motors for fan control.

Air Thermostats

Explains fitted and remote air thermostats for automatic temperature control and fan speed adjustment.

Low Temperature Cut-Out (LTC) Thermostat

Describes the LTC thermostat for automatic heater shutdown when water supply is low.

Switches

Commissioning Procedures

Coil Purging and System Filling

Procedure for purging air from the coil and filling the system.

LTC Thermostat Operation Check

Air Thermostat & Switch Operation

Adjusting air thermostats and checking switch functionality.

Cleaning and Maintenance

Inspection and Filter Access

Maintenance Checks

Details on coil purging, motor bearings, fuse checks, and control system verification.

Overview

1. Function Description
2. Important Technical Specifications
3. Usage Features
4. Maintenance Features

The provided manual describes the Dunham-Bush Series AM Fan Convectors, which are heating units designed for various installations.

Function Description

The Dunham-Bush Series AM fan convector is a heating device that circulates air, either heated by a hot water coil or single-phase electric elements, to warm a room. Each unit consists of a sheet steel casing, a lockable access panel, fan/motor assemblies, an air filter, and a heating coil (either hot water or electric). These units can be configured for one or two-speed fan operation. Single-speed units are pre-set to low, medium, or high speed, while two-speed units can be pre-set to low/medium, low/high, or medium/high speeds, as ordered. Fan control is managed through switches and/or thermostats, which are listed as accessories.

The fan convectors are designed to provide efficient heating by drawing in room air, passing it over the heating coil, and then discharging the warmed air back into the space. The inclusion of an air filter helps maintain air quality and protects the internal components from dust accumulation.

Important Technical Specifications

General Construction:

• Sheet steel casing
• Lockable access panel
• Fan/motor assemblies
• Air filter
• Hot water heating coil or single-phase electric elements (up to 6kW on Fig 03, 04, and 06 models)

Fan Operation:

• Fan Motors: Conventional synchronous AC motors or energy-efficient EC motors.
• EC Motor Options:
  • ECS: Speed control via an external 2-10VDC signal (e.g., from BMS).
  • ECM: Speed control via a fitted speed interface, offering single or dual fan speeds adjustable by potentiometers.
• Fan Speed Adjustment (EC Motors): Three fan speeds (low, medium, high) are available. Signal voltage can be measured across 0V and CTRL terminals.
• Fan Speed Considerations: Avoid setting fan speeds too low as this can cause stratification of heated air, reducing comfort, and with electric heating, can lead to false tripping of high-temperature safety cut-outs. All connections to the EC fan controller are safe low voltage (10VDC or less).

Heating Coil Specifications (Hot Water):

• Coil Types: WA1, WA2, WA3 (DN20 / 3/4" BSP female parallel); WA4 (22mm plain copper tails).
• Cold Test Pressure: Type M air vent: 10.5 bar g; Type A air vent: 9.0 bar g.
• Working Pressure: Both types: 7.0 bar g.
• Flow and Return: Local isolating and regulating valves are recommended. Correct flow and return positions are crucial for rated heat output.

Nominal Output and Sizes (Hot Water Models):

• Fig 03: 2.6 kW, 695 mm width
• Fig 04: 4.7 kW, 895 mm width
• Fig 06: 6.0 kW, 895 mm width
• Fig 08: 8.2 kW, 1195 mm width
• Fig 10: 9.4 kW, 1195 mm width
• Fig 12: 11.4 kW, 1495 mm width
• Fig 15: 12.7 kW, 1495 mm width

Installation Types:

• Floor Standing Models: 13, 15, 16, 17, 19, 25, 37, 41, 88. Can be mounted on 100mm, 150mm, or 200mm high plinths.
• Fixed Height Duct Models: 20, 21, 22, 60. Heights: 1700, 1900, 2100mm. Width: 230mm. Lengths: 695, 895, 1195, 1495mm.
• Adjustable Height Duct Models: 23, 92. Adjustable height: 1700 to 2300mm. Width: 230mm. Lengths: 695, 895, 1195, 1495mm.
• Ceiling Models: 28, 30, 31, 34, 38, 52, 53. Height: 253mm. Lengths: 695, 895, 1195, 1495mm.
• Wall Models: 52, 38, 53. Reversed air flow. Width: 242mm. Lengths: 695, 895, 1195, 1495mm.

Usage Features

Controls:

• Air Thermostats: Automatically switch heater on/off or change fan speed/heat output based on ambient air temperature. Can be fitted (Models 13, 15, 17, 20, 21, 23, 25 only) or remote (all models).
• Low Temperature Cut-Out (LTC) Thermostat: Operates the heater when hot water is supplied to the coil, stopping it at the end of a normal operating period.
  • Type 1 (fixed): Make circuit at 50°C±3K, break circuit 38°C±3K.
  • Type 2 (adjustable): Range 30-90°C. Requires contact with a straight pipe length of approx. 100mm for correct operation.
• Switches: Fitted (external or internal) or remote (flush or surface wall mounting) switches to control on/off, fan speed, and override thermostats. A man/off/auto switch allows fans to circulate air even when the boiler plant is shut down.
• FAI/Recirc Switch: Can be provided to open or close fresh air inlet (FAI) dampers (models 19, 22, 53, 88 with optional motorised damper).
• Special Controls: Relays, thermal controls, etc., may be incorporated and will be detailed in the wiring diagram.

Accessories:

• Plinths: 100mm, 150mm, or 200mm high plinths for floor-mounted models.
• Grilles: Remote pencil-proof grilles and fixing frames available on certain models.
• Dampers: Manual or motorised (230V actuator) dampers for fresh air inlet or recirculating air.
• Isolating Valves: Fitted on flow and return coil connections or supplied loose for pipework fitting.
• Panel Lock Indicators: Colour indicators (green for locked, red for unlocked) show the status of the access panel. Can be retro-fitted.

Maintenance Features

General Maintenance:

• Warning: Disconnect all electrical supplies and wear protective gloves due to sharp internal components.
• Inspection Frequency: Initially, inspect the air filter after 6-8 weeks, then regularly as required by operating conditions.
• Air Filter Cleaning:
  • Unlock and remove the access panel.
  • Tap out excess dust and wash in warm water (up to 40°C) with detergent.
  • Rinse and allow to dry naturally.
  • Do not use a vacuum cleaner on the filter media.
  • Filters should be replaced after approximately 20 washes.
  • Operating without a filter will clog coil fins, reducing performance.
• Annual Cleaning: Fan/motor assemblies and heater coil should be cleaned annually using an industrial vacuum cleaner to suck air through the coil in the opposite direction to normal airflow. All accessible surfaces can be wiped with a dry cloth.
• Coil Maintenance: Purge air from the coil using the manual or automatic air vent. Automatic air vents have a check valve allowing head removal without draining the system.
• Motor Maintenance: Fan motors have 'sealed for life' bearings and require no maintenance other than visual inspection.
• Fuse: A 2A anti-surge fuse is located in the mains inlet connector on the electrical connections box. A spare fuse is supplied.
• Controls: Check operation of all thermostats and switches by varying settings. A manual/off/auto switch bypasses thermostats in manual mode.
• Documentation: Leave the manual and wiring diagrams with the end user.

Identification for Spares/Service:

• The fan convector serial number, model description, and figure number (size) are on a label inside the heater access panel. A stencil reference may also be marked for on-site identification.
• When ordering spares, quote the unit type, model information, and serial number.

dB AM Series Specifications

General

Brand	dB
Model	AM Series
Category	Heater
Language	English