Danfoss BEM 4000 Boiler Energy Manager

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The Boiler Energy Manager (BEM) is an electronic controller which can be added to almost any central heating system to eliminate unnecessary boiler cycling and improve boiler seasonal efficiency.

The BEM 4000 consists of an electronic controller, an outdoor temperature sensor and a strapon flow temperature sensor. It can be used in conjunction with a room thermostat (utilized as a frost stat) and TRVs. Boiler performance is improved when the flow temperature is varied according to the outside temperature. The outside temperature sensor should be mounted on the coldest elevation of the building away from opening windows and the boiler flue.The flow sensor should be fitted within 6 inches of the boiler outlet on the flow pipe, or on low-water content boilers it can additionally be fitted between the boiler and the bypass. A cylinder thermostat should be fitted as normal. All diagrams show Danfoss programmer and thermostats, but others can be used. In all cases, if a room thermostat is to be utilized as a frost or lowlimit thermostat, connect to terminals 3 and 11.

In Figures 11.2 and 11.3 two boilers are shown – one with pump overrun and one without. Select diagram as appropriate, remembering to insert Link 2–4 when using boiler without pump overrun.

Gravity hot water pumped central heating 300x184 Danfoss BEM 4000 Boiler Energy Manager

Figure 11.1 Gravity hot water, pumped central heating

Fully pumped system with two motorized zone valves 300x169 Danfoss BEM 4000 Boiler Energy Manager

Figure 11.2 Fully pumped system with two motorized zone valves

Fully pumped system with mid position valve 300x162 Danfoss BEM 4000 Boiler Energy Manager

Figure 11.3 Fully pumped system with mid-position valve

ACL MP Programmers

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ACL MP ACL MP Programmers

(a) Fully pumped 2 x 2 port motor open/close valves links 4–9, 5–7
(b) Fully pumped 2 x 2 port spring return valves, 1 x 3-way mid-position valve, Satchell Duoflow Switchmaster Midi and Drayton Flowshare link 1–4–9 and 5–7
(c) Tower or ACL Biflo mid-position valve link 1–4–9
(d) Terminal 3 is a spare terminal

Electromechanical 24 hour Basic programmer
Clock module available as a spare.
On/off x 4
H106 x W113 x D65
Switch rating 6A

Troubleshooting Gas Burners

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As is the case with all mechanical and electrical equipment, it is recognized that occasional repair and adjustment may be necessary on any burner. Table 2-4 represents a very general list of troubles and causes that can occur with gas burners and gives some suggested remedies.

Table 2-4 Troubleshooting Gas Burners

Symptom and Possible Cause Possible Remedy
Pilot does not light.
(a) Air in gas line. (a) Clear or replace line.
(b) High or low gas pressure. (b) Check for possible gas supply problem with local gas company; replace defective burner.
(c) Blocked pilot orifice. (c) Clean orifice or replace.
(d) Flame runner improperly located. (d) Move to correct location.
Pilot goes out frequently during standby or safety switch needs frequent resetting.
(a) Restriction in pilot gas line. (a) Clear or replace line.
(b) Low gas pressure. (b) Check for possible gas supply problem first with local gas company; Replace defective burner.
(c) Blocked pilot orifice. (c) Clear blockage or replace.
d) Loose thermocouple connection on 100 percent shutoff. (d) Secure connection or replace defective thermocouple.
(e) Defective thermocouple or pilot safety switch. (e) Replace thermocouple or pilot safety switch.
(f) Poor draft connection. (f) Correct.
(g) Draft tube set into or flush with inner wall of combustion chamber. (g) Move tip of draft tube to proper location.
Pilot goes out when motor starts.
(a) Restriction in pilot gas line. (a) Remove restriction or replace line.
(b) High or low gas pressure. (b) Check for possible gas supply problem with local gas company; replace defective burner.
(c) Excessive pressure drop when main gas valve opens. (c) Check for possible gas supply problem with local gas company; test main gas valve and replace if defective.
Burner motor does not run.
(a) Burned-out fuse or tripped circuit breaker. (a) Replace fuse or reset circuit breaker. If problem continues, call an electrician.
(b) Thermostat or limit defective or improperly set. (b) Reset thermostat or limit, or replace if defective.
(c) Relay or transformer defective. (c) Replace relay or transformer.
(d) Motor burned out. (d) Replace motor or burner.
(e) Tight motor bearings from lack of oil. (e) Lubricate bearings; repair or replace damaged bearings.
(f) Improper wiring. (f) Check wiring diagram for burner and rewire correctly.
Burner motor running but no flame.
(a) Pilot out. (a) Relight pilot or replace defective pilot.
(b) Pilot safety switch needs to be reset. (b) Reset switch.
(c) Thermocouple not generating sufficient voltage. (c) Replace defective thermocouple.
(d) Very low or no gas pressure. (d) Check for possible gas supply problem with local gas company; check for obstruction in gas line and correct.
(e) Motor running too slow. (e) Replace defective motor.
Short and/or noisy burner flame.
(a) Pressure regulator set too low. (a) Change to proper setting.
(b) Air shutter open too wide. (b) Correct opening size.
(c) Too much pressure drop in gas line. (c) Check for possible gas supply problem with local gas
company; check for obstruction in gas line and correct.
(d) Vent in regulator plugged. (d) Clear vent.
(e) Defective regulator. (e) Replace regulator.
Long yellow flame.
(a) Air shutter not open enough. (a) Adjust opening.
(b) Air openings or blower wheel clogged. (b) Clear.
(c) Too much input. (c) Reduce input.
Main gas valve does not close when blower stops.
a) Defective valve. (a) Replace valve.
(b) Obstruction on valve seat. (b) Remove obstruction.

Gas Burners Safety Precautions

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The annual cleaning and inspection of gas heating equipment is important not only because it contributes to its efficient operation but also because it provides an additional safety factor.

Electrical controls should be connected on a separate switch. This enables the circuit to be broken should the equipment malfunction.

Because fuel gas is extremely volatile, it should be handled and stored with the utmost care. Propane is especially dangerous when it leaks. Because it is heavier than air, propane will accumulate at low points in a room and present an explosion hazard.

Be sure to observe the following basic safety rules when working with heating gases and gas controls:

• Always shut off the gas supply to the device when installing, modifying, or repairing it. Allow at least 5 minutes for any unburned gas to leave the area before beginning work. Remember that LPG is heavier than air and does not vent upward naturally.

• Always conduct a gas leak test after completing the installation, modification, or repair. To test for a gas leak, coat the
pipe joint, pilot gas tubing connections, and valve gasket lines with a soap-and-water solution. Then, with the main burner in operation, watch for bubbles at those points. The bubbles will indicate a gas leak, which can normally be eliminated simply by tightening joints or screws or by replacing the gasket.

• Always disconnect the power supply to prevent electrical shock or equipment damage before connecting or disconnecting any wiring.

• Change the main burner and pilot orifice(s) to meet the appliance manufacturer’ s instructions when converting a gas system from one type of gas to another.

• Always read and carefully follow the installation and operating instructions supplied with the appliance or component. Failure to follow them could result in damage or cause a hazardous condition.

• Make certain that the appliance or component is designed for your application. Check the ratings given in the instructions and on the appliance or component.

• Check the operation of the appliance or component with the manufacturer’ s instructions after installation is completed.

• Do not bend the pilot tubing at the control after the compression nut has been tightened. This could cause a gas leak at the connection.

• Never jump (or short) the valve coil terminals on 24-volt controls. Doing so could short out the valve coil or burn out the heat anticipator in the thermostat.

• Never connect millivoltage controls to line voltage or to a transformer, because doing so will burn out the valve operator or the thermostat anticipator.

• Do not remove the seals covering control inlets or outlets until you are ready to connect the piping. The seals are there to prevent dirt and other materials from getting into the gas control and interfering with its operation.

Gas Burners Venting and Ventilation

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The venting system for gas heating equipment consists of the following:

1. The chimney or smoke elimination pipe.
2. The draft diverter or draft diverter hood.

Gas-burning equipment must be vented to the outside. All pipes leading from the equipment must be fitted so that the joints are tight and free of leaks.

A draft diverter or draft hood is a wind deflector placed in the chimney to prevent downdrafts of air (i.e., air moving down the chimney from the outside) from blowing out the pilot light. Many draft diverters are designed and positioned so that the downdraft is deflected into the room containing the heating unit.

Any room containing gas heating equipment must have adequate ventilation. Provision for incoming air (i.e., air necessary for combustion) is especially important in rooms or buildings of tight construction. The minimum area requirements (in relation to each 1000 Btu/h input) for both ventilating air openings and air inlet openings can be obtained from the manufacturers of the gas-fired appliance.

Gas Piping for Conversion Burners

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Gas piping is generally wrought iron or steel with malleable iron pipe fittings. Joint compound (pipe dope) is applied sparingly to the male threads only. Make certain before applying the joint compound that it is approved for all types of gas. Never use aluminum tubing or castiron fittings on the main gas line. Soldered or sweated connections are also not recommended.

Tables 2-1 and 2-2 can be used to determine the size of pipe to use from the meter to the gas burner. The correct number of threads for any particular length of pipe is given in Table 2-3.

table 2 1 Gas Piping for Conversion Burners

table 2 2 Gas Piping for Conversion Burners

table 2 3 Gas Piping for Conversion Burners

Use pipe fittings at all turns in the gas line. Never bend or lap welded pipe because it will pinch or weaken it. Support the pipe with straps, bands, pipe hooks, or hangers (never allow one pipe to rest on another or to sag).

Pitch all horizontal pipe so that it grades toward the meter without the occurrence of sags. The piping should be protected against freezing and the accumulation of condensation.

Pipes and pipe fittings that are defective should be replaced, never repaired. Every effort must be made to eliminate any possibility of gas leakage. Gas leaks on pipes and pipe fittings should be located by spreading a soap solution over the surface. Never try to locate a gas leak with a flame. The results could be extremely hazardous.

Figure 2-11 illustrates the general configuration of the main shutoff valve, pilot shutoff valve, and riser installation for a gas conversion burner. The following suggestions are worth noting:

1. Install the main manual gas shutoff valve on the riser at least 4 ft above the floor level.
2. Install the pilot valve on the inlet side of the main manual gas shutoff valve.
3. Install a tee fitting at the bottom of the riser to catch any foreign matter in the pipe. The bottom of the tee fitting should be plugged or capped.
4. Install a ground joint union in the gas line between the burner air duct box and the tee fitting in the riser.
5. Install a pilot supply line (1?4-in OD tubing) between the pilot valve and a point located on the upper right side of the air duct box on the gas burner. This line will run parallel to the riser.

shutoff valve Gas Piping for Conversion Burners

Gas Conversion Burner Combustion Chambers

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The combustion chamber for a gas conversion burner is commonly located in the ashpit of a coal-fired boiler or furnace. Figure 2-10 illustrates the positioning of an upshot gas conversion burner. Note that the burner head port is located 1 inch (plus or minus 1?4 in) above the grate level. This is a standard measurement when installing an upshot burner in the ashpit of a furnace.

The manufacturer’ s installation instructions provided with a conversion gas burner generally include specific instructions on the preparation of the combustion chamber. The main points you should remember are as follows:

• All openings in the boiler must be sealed.
• The combustion chamber must be thoroughly cleaned.
• Heat exchanger surfaces must be protected against concentrated heat.
• All nonheat transfer surfaces must be protected.
• The combustion chamber must be designed to contain combustion, to radiate heat, and to insulate the ashpit.

upshot gas burner position Gas Conversion Burner Combustion Chambers

Gas Conversion Burners

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A gas conversion burner is used to convert heating equipment designed for coal or oil to gas fuel use (see Figure 2-8). The boiler or furnace must be properly gastight and must have adequate heating surfaces.

A characteristic of gas conversion burners is that pressure will sometimes build up in a furnace due to puffs or backfire resulting from delayed ignition and other causes. Local heating codes and regulations usually stipulate that furnace doors be held tightly closed by spring tension only (in other words, not permanently closed) in order to provide a means for relieving pressure. Figure 2-9 shows an example of a door spring that can be used for this purpose.

gas conversion burner Gas Conversion Burners

furnace doors Gas Conversion Burners

Integral-Type Gas Burners

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An integral-type gas burner assembly consists of an array of parallel burner tubes connected by a manifold pipe running at a right angle to them. The burner tubes and manifold are part of a box/drawer assembly in modern furnaces and boilers. The entire assembly can be removed from the furnace or boiler for cleaning (see Figure 2-7). Each burner tube contains a series of orifices (openings) through which the gas flows. These orifices are sized to deliver the required amount of gas flow to achieve the maximum ratings at the rated pressure listed on the appliance nameplate.

As shown in Figure 2-7, the burner manifold is connected at one end to the individual burner tubes and at its other end to the main gas valve. In other words, it functions as the bridge between the burner tubes and the main gas valve.

In many furnaces, the main burner(s) can be manually adjusted. In others, no burner adjustment is required because burner aeration has been fixed at the factory. Natural gas burner flames should be well defined (but almost transparent) and should range from light to medium blue in color. Propane burner flames often have yellowor orange-colored flame tips.

thermo pride gas control Integral Type Gas Burners