Archive for the ‘Boilers’ Category
Halsted Ace GC 47-333-15 Sequence of operation
Sequence of Operation
Control fascia contains main selector/ignition lockout reset switch, heating & hot water potentiometers, 5 function LEDs and pressure gauge.
Overheat thermostat with manual reset. Situated bottom left on the underside of boiler activating at approximately 106 ° C ± 6 ° C.
Single speed Grundfos pump (head replacement required only). Note: If pump fails this could lead to the fan venturi melting.
Primary and DHW flow switches are mounted onto the Diverter valve, both having clear plastic housing allowing the operation to be checked.
Hydraulic Diverter valve at bottom left of the boiler which is at rest in CH mode and drives to the left to DHW mode.
NOTE: When there is no demand, there is approximately 180 Vac to both connections on the fan and all connections on the APS!!
DHW Operation
- Demand for DHW.
- Diverter valve moves to the left and makes DHW flow switch (continuity).
- PCB checks primary flow switch for open circuit. If primary flow switch is closed circuit no
demand will be recognised or displayed.
- DHW light illuminates.
- PCB sends 240 Vac via the neutral wire to the pump, which runs.
- PCB checks both Central Heating (primary) and DHW NTCs are in range.
*** If either NTC is out of range DHW light goes out within 1 second of being illuminated, pump stops, boiler will not operate in either DHW or CH mode until the NTC is back in range (no lockout occurs).
- Primary flow switch goes to continuity. If primary flow switch doesn’t go to continuity within 6
seconds, sequence stops, pump ceases to run, power on light flashes (burner may ignite
within this 6 seconds).
- PCB checks APS for open circuit. If closed circuit sequence stops, pump continues to run.
- PCB sends 240 Vac to fan which runs.
- Fan operation proved by APS (closed circuit). If APS doesn’t go to closed circuit sequence
stops, fan and pump continue to run (no lockout occurs).
- PCB checks overheat stat for continuity. If open circuit fan stops, pump continues to run and
lockout light illuminates.
- PCB sends approximately 130 Vdc on grey and black wires and approximately 60 Vdc on
purple and red wires to the gas valve, which then energises.
- PCB commences spark ignition.
- Burner lights and rectification takes place within 8 seconds.
*** If flame rectification fails, the gas valve is de-energised and the lockout light illuminates.
- Gas valve modulates in conjunction with the temperature as sensed by the DHW and primary
NTCs by altering the voltage on the purple and red wires.
- End of demand, diverter valve returns to rest position, flow switch goes to open circuit.
- Fan stops, gas valve is de-energised but pump continues to run for a limited period.
CH Demand
- Demand for CH from external controls (230 Vac on X9 pin 3).
- PCB checks primary flow switch for open circuit. If primary flow switch is closed circuit no
demand will be recognised or displayed.
- PCB checks both Central Heating and DHW NTCs are in range.
*** If either NTC is out of range Central Heating light goes out within 1 second of being illuminated, pump stops, boiler will not operate in either DHW or CH mode until the NTC is back in range (no lockout occurs).
- If NTCs are in range Central Heating light illuminates.
- PCB sends 240 Vac via the neutral wire to the pump, which runs.
- Primary flow switch goes to continuity. If primary flow switch doesn’t go to continuity within 6
seconds, sequence stops, pump ceases to run, power on light flashes (burner may ignite
within this 6 seconds).
- PCB checks APS for open circuit. If closed circuit sequence stops, pump continues to run.
- PCB sends 240 Vac to fan which runs.
- Fan operation proved by APS (closed circuit). If APS doesn’t go to closed circuit sequence
stops, fan and pump continue to run (no lockout occurs).
- PCB checks overheat stat for continuity. If open circuit fan stops, pump continues to run and
lockout light illuminates.
- PCB sends approximately 130 Vdc on grey and black wires and approximately 30 to 60 Vdc
on purple and red wires to the gas valve, which then energises.
- PCB commences spark ignition.
- Burner lights and rectification takes place within 8 seconds.
*** If flame rectification fails, the gas valve is de-energised and the lockout light illuminates.
- Gas valve modulates in conjunction with the temperature as sensed by the primary NTC by
altering the voltage on the purple and red wires.
- End of demand.
- Fan stops, gas valve is de-energised but pump continues to run for a limited period.
Data
Fan: 1 Speed 230 Vac Coil Approximately 50 Ohms
Thermistors: Central Heating & Hot Water 19Kohms@ 10 ° C
Gas Valve: Honeywell Twin Solenoid (Softlight) 1 Coil Grey & Black Wires Approximately 130 Vdc Modulating Coil Purple & Red Wires Up To 60 Vdc Aps: 2 Wire, Switching At 1.5 Mbar
Ideal Classic Combi NF80 Sequence of operation
Case Removal
Upper module case – Release the one top centre securing screw and withdraw.
Boiler module case – Open the control panel door, release the four captive screws top and bottom, and lift case off the boiler (position of by-pass solenoid may interfere with case removal).
Special Features
This combi is the classic boiler (cast iron heat exchanger) with combi module above. It has a burner on/off switch. DHW pre-heat operating 24 hrs a day, but can be controlled by an external programmer if required. There is a wax capsule by-pass thermostat, on the outlet of the CH flow pipe.
Sequence of Operation: Domestic Hot Water
With no call for either DHW or CH the boiler will fire at low rate to maintain the DHW calorifier and boiler heat exchanger in a pre-heated condition. With the selector set to DHW/CH position, the burner on/off switch, switched on.
- Open a hot water draw off tap.
- The flow of water through the calorifier makes the paddle type flow switch.
- The Honeywell diverter valve remains de-energised.
- The pump starts (check by listening or viewing through the vent plug).
- Mains power is passed through the manual re-set overheat stat to the ignition PCB to start the automatic ignition cycle.Air pressure switch and PCB carry out a NO air check.
Fan starts to run, air pressure switch makes contact.
Spark commences, pilot solenoid (240 Vac) opens, pilot lights.
Flame checked by rectification circuit on PCB (spark and rectification use the same probe on this boiler).
Main solenoid (240 Vac) opens.
By-pass valve (240 Vac) opens and fires at full gas rate.
The burner may fire initially low rate but should increase to max 1-2 minutes. If there is a breakdown in this cycle check:
There is gas to the boiler and the solenoid valves are in order.
The overheat stat is in the closed position. (Try reset button first.)
The spark/rectification probe, lead, and spark gap (3-5 mm) are OK ( £ 1 coin).
The combustion chamber cover is properly sealed.
All fuses and wiring connections on the PCBs are secure.
The tubes from the air pressure switch to the fan. (Trapped, blocked, etc.)
The fan motor, or impeller is not seized or jammed.
Gas on full rate controlled by the DHW thermostat.
Sequence of Operation: Central Heating
Water is not released to the CH system until the temperature has reached 60 ° C. (This is controlled by the wax capsule thermostat.)
- External controls (clock/roomstat) call for heat.
- Diverter valve motors over to CH (no resistance at manual lever).
- The pump starts. The boiler follows the same sequence as for domestic hot water until the main flame is established (see above).
- Gas on full CH rate, controlled by CH thermostat and overheat stat. If there is a breakdown in this cycle check:
CH control thermostat, solenoids, overheat thermostat.
Wax capsule by-pass thermostat (ensure that water is leaving the boiler by checking hot water flow into the system.)
Common Faults
Flow switch can get blocked with age resulting in no hot water. Expansion vessel tube can get blocked at the tee piece.
Ideal Icos Sequence of operation
Boiler Operation (from cold)
Initial Power Up
When the main supply (230 Vac) is applied to (L3) the display will show 3. Approximately 3 seconds later the display will show 0, indicating standby mode. When the system controls are turned on (L1 to L2) the display will show c with a green flashing LED. The fan will run at ignition speed (3500 rpm) which is approximately 90% maximum CH rate. After 5 seconds the ignition will commence and 1 second later the gas valve will operate. The PCB will expect detection (ionisation) within 4 seconds. The spark will continue for the full 4 second ignition period. The green LED will be solid when detection is confirmed.
The fan will then increase to maximum speed (4140 rpm).
Note: If the PCB does not detect an ionisation current within 3 seconds the boiler will reattempt ignition. There will be a total of 3 ignition attempts and the fan will run for a post purge period of 30 seconds between each ignition attempt. If ignition is not detected, the boiler will lockout (see sheet).
The boiler will continue to fire at maximum rate until the flow temperature reaches 3 ° C below the set point. The boiler will then modulate down to suit the heating load. If the temperature rises 2 ° C above the set point the boiler will switch off. The boiler will re-ignite at 5 ° C below the modulating temperature.
Example - Boiler set point 82 ° C, boiler modulates at 79 ° C, boiler off at 84 ° C and boiler on at 74 ° C.
When the boiler switches off on temperature and the system controls are still “calling”, the green LED will flash until ignition is re-established.
Icos system
All of the above characteristics are applicable to icos system, with the inclusion of the following:
When the system controls are switched off, the pump will over-run for approximately 5 minutes and the display will show c.
Ideal Isar m30100 Sequence of operation
Boiler Operation (from cold) Initial Power Up
Note: It is essential that there is no call for CH from any of the controls (including the red link wire supplied with the boiler mains plug) during the Initial Power Up period.
When the mains supply (230 Vac) is applied to (L3) the display will show 5. Approximately 3 seconds later the display will show d and the boiler will ignite. A green LED will confirm detection and the boiler will fire at maximum rate for approximately 15 seconds. At this point the motorised valve will be in the DHW position (lever forward). This short burn time is designed to raise the temperature in the plate heat exchanger, which will allow a temperature drop when a tap is turned on.
If the boiler does not ignite on this first attempt the display will show 0 and there will be a delay of approximately 2 minutes before the boiler attempts to fire in pre-heat mode.
Pre-heat
If the temperature of the thermistor in the plate heat exchanger is allowed to drop below 35 ° C (either because of an extensive time without demand or after an Initial Power Up) the display will show t and the boiler will ignite. A green LED will confirm detection and the boiler will fire at just above minimum rate for approximately 2 minutes. At this point the motorised valve will be in the DHW position (lever forward). The boiler will then revert to standby and the display will then show 0.
DHW
When a tap is turned on, the thermistor, which is positioned in the plate heat exchanger, will experience a drop in temperature. The display will then show d and the boiler will ignite. A green LED will confirm detection and the boiler will fire at maximum rate. At this point the motorised valve will be in the DHW position (lever forward).
The fan will now modulate up or down to maintain the DHW outlet temperature (the boiler will modulate at approximately 3 ° C below the DHW set point, and will extinguish if the outlet temperature remains above the set point for more than 1 minute).
When the tap is turned off, the boiler will continue to fire until the thermistor, which is situated in the plate heat exchanger, experiences a rapid increase in temperature. The green LED will then extinguish and a 5 second pump over-run will occur. The boiler then goes to standby and the display reverts to 0.
Note: If a tap is turned on during CH operation, the boiler will not ignite in DHW mode until the return temperature is 5 ° C below the DHW set point.
Boiler Operation (from cold)
CH
When the system controls are calling for heat (L1 to L2) the display will show c with a green flashing LED. The fan will run at 90% maximum CH rate and after 5 seconds the ignition will commence, 1 second later the gas valve will operate and the PCB has 4 seconds to detect ionisation. When detection takes place the LED will be solid. At this point the motorised valve will be in the CH position (lever back).
The fan will increase to maximum rate until the flow temperature reaches 3 ° C below the CH set point. The fan will then modulate down to suit the heating load. The boiler will switch off at approximately 2 ° C above the CH set point. Ignition will take place at 5 ° C below the minimum modulating temperature.
When the system controls are switched off, the pump will over-run for approximately 5 minutes and the display will show c.
If the temperature goes above the maximum temperature, the display will show c with a flashing green LED until the temperature falls below the set point.
Note: If the PCB does not detect an ionisation current within 3 seconds the boiler will reattempt ignition. There will be a total of 3 ignition attempts and the fan will run for a post purge period of 5 seconds between each ignition attempt. If ignition is not detected, the boiler will lockout (see sheet).
Ariston EuroCombi SX 20 MFFI CE GC 47-116-02 Ignition Fault
Ariston EuroCombi SX 20 MFFICE GC 47-116-02
Boiler fails to go into ignition mode. In fact it only fires once in a while. If the boiler is fitted with a circular white air pressure switch, remove leads and check continuity between contact at 12 Noon and that at 6.00 O’clock with fan running. Replacement is a Honeywell air pressure switch.
Vokera 20/80 Flowmatic Sequnence of operation
Vokera 20/80 Flowmatic
Case Removal
Remove four screws at the base. Two horizontal towards rear. Two at the top of the Controls Fascia.
Pull bottom of case slightly forward and push case upwards to disengage top support hooks. Ease lower sides outwards and withdraw from the appliance.
Controls Fascia
The complete unit will now hinge downwards.
Sequence of Operation (Domestic Hot Water)
Only the main on/off neon switch is required to be on, the summer, constant, timed switch can be in any position.
- On this boiler the fan runs on
low speed at all times via a 560 ohms resistor to maintain the pilot.
This is brass coloured and fitted bottom RH side of combustion chamber.
This resistor will be hot. - Open a hot water draw off tap.
- The flow of mains water changes over the diverter valve and operates the
treble DHW microswitch assembly. The push rod can be seen operating
when the tap is opened (high and low voltages). - The pump starts. (Check by listening or checking at the pump vent plug.)
- The movement of water created by the pump makes the flow switch (240 Vac bottom LH side below pump).
- The fan changes to high speed and makes the pressure switch.
- Mains power is passed through the safety thermostat (auto reset, lower RH
side flow pipe) to the gas valve operator (240 Vac) which opens and
allows gas to the burner. - The modulator receives power via the DHW thermostat (Controls fascia).
Contacts open, the modulator voltage will be zero, high flame
condition. When the selected temperature is reached the stat contacts
close allowing full voltage (12.5 Vdc) to the modulator, to give a low
flame condition. (This works the opposite way round to most other
combis.) - If the DHW stat fails and the temperature of the water becomes excessive the
safety thermostat will cut the 240 Vac supply to the gas valve operator. - If for any reason the safety stat failed to operate, the overheat stat (located in
a dry pocket just below the safety stat) will operative, interrupting
the thermocouple.
Sequence of Operation (Central Heating)
External controls (roomstat) call for heat, all other CH controls on fascia calling for heat.
- Diverter valve stays in rest position.
- The pump starts. (Check by listening or checking at pump vent plug.)
- The movement of water created by the pump makes the flow switch (240 Vac bottom LH side below pump).
- The fan changes to high speed and makes the pressure switch.
- The gas valve operator (240 Vac) opens and allows gas to the burner.
- The modulator receives power via the CH thermostat (Controls fascia). With the first stage contacts open, the 12.5 Vdc is diverted through the range rating potentiometer to give a central heating high flame condition. When the preset temperature is approached the first stage contacts close, this allows the full 12.5 Vdc to the modulator. This gives a low flame condition. (This works the opposite way round to most other combis.) If the temperature continues to rise, the second stage contacts (240 Vac) will change over shutting off both gas valve operator and fan.
- The pump continues to run unless turned off by clock or roomstat.
- If the CH stat failed in an on position and the temperature continued to rise the same safety controls would operate as for the Operation of DHW Nos. 9, and 10.
Glow Worm 24 & 30 cxi down to detail
Except for differing heat output these two wall mounted boilers are otherwise visually identical. For use on sealed systems only, they can be installed without any specially provided ventilation and are suitable for high rise building installation where access to the outside wall is difficult. Horizontal or vertical flue systems can be up to 10m in length. Read the rest of this entry »
Saunier Duval Thelia 623 down to detail
Cased boiler
GC No. 47 313 11 (with clock)
GC No. 47 313 12 (without clock)
Made in France and marketed in the UK under the Hepworth Group flag, this combi is similar to the earlier SD623 boiler but has cosmetic changes to the control panel door and a printed circuit board (PCB) that features more low-voltage controls. The Thelia 623 has a fan-assisted flue that can be arranged rearward. Read the rest of this entry »
