DIY gas boiler repair. Cauldron of Pestilence

Probable errors and causes of occurrence

This article contains all possible malfunctions and options for eliminating them, as well as error codes for Mora boilers.
All information is read in the following order: code - name - possible malfunction. If you have any additional questions, please leave them in the comments to this article. The content of the article

Error code E0 - Device blocked
Error code E1 - Boiler is blocked
Error code E2 - Mora boiler stopped due to an accident
Error code E3 - Heating water temperature sensor is open
Error code E4 - Domestic water temperature sensor is not closed
Error code E5 - Failure in the security module
Possible breakdowns of Mora gas boilers that are not displayed on the screen
The device cannot gain the power required for operation
When operating, the boiler always switches to minimum power mode
The device does not work in DHW mode
The Mora wall-mounted boiler has problems with hot water supply; the working burner does not heat water for household needs or is insufficient

If you are not 100% sure what exactly the problem is and that you can solve it, immediately contact the service center to diagnose and fix the problem.

Error code E0 - Device blocked

There is no gas supply. The burner is not active. The pump is turned off.
The internal elements of the control and regulation unit are broken. Needs replacement.

Error code E1 - Boiler is blocked

Error code E1 may occur in the following cases:

The switches do not close. Due to this, gas is not supplied, the burner is inactive, and the pump is turned off.
Small amount of water in the heating system. The filter may be clogged. It needs to be cleaned.
Small amount of water in the heating system. Pump failure. Needs replacement.
There is not enough water in the heating system. The pump, instead of the recommended 2nd or 3rd stage, is installed on the first. Set the correct mode.
Presence of air pockets. It is necessary to pump water so that the recommended pressure value is established in the system. When switching heating and hot water modes, bleed off excess air. Reboot the unit.
Problems with the axis of the flow switch, it is either inactive or completely motionless. It is necessary to disassemble the switch box from the flow sensor housing. Try to free the jammed axle. If this does not work by turning the boiler on and off, push it with your finger.
The gap between the axle and the drive arm and the switch is too large. The position of the plastic arm for transmitting motion must be set correctly.
The switch is broken. Needs replacement.
The electrical connection between the switch and the control and regulation unit is broken. The chain needs to be restored. Check the wires.

Error code E2 - Mora boiler stopped due to an accident

Error code E2 may occur in the following cases:

The gas supply is interrupted. After the flame is turned off, the device tries to start again. The pump does not turn off while the device is trying to start working. Then he gets up.
The flame went out because there was no gas supply. Click the Reset button. Due to the fact that the burner is very dirty, the gas supply is difficult. In this case, partial combustion of the flame can be observed. The gas supply port needs to be cleaned.
The electrode is broken or the electrical connection line is damaged. Make a replacement.
The ignition transformer is broken or the electrical connections are damaged. Make a replacement.
Absence or partial contact in the electrical connection circuit of the ignition transformer and the control and regulation unit. Check the presence of the contact if you need to restore it.
The phase and zero in the network are mixed up. Connect the boiler correctly.
The backdraft fuse tripped due to too high a temperature rise due to leakage of combustion products. This is possible with complete or partial obstruction of the chimney. Clean the outlet pipes and chimney. To start, press the reset button.
The reverse thrust fuse is broken. Needs replacement.
The electrical connection circuit of the reverse thrust fuse is damaged. Check connection. Restore.
Lack of contact between the control unit backdraft fuse. Restore contact.
The emergency thermostat tripped because the heating water temperature exceeded the maximum permitted value.
Incorrect gas supply. Find out the reason. Eliminate.
Emergency thermostat failure. Check its operation. At 95 degrees it should open. Install a new one if necessary.
There is no electrical connection contact for the emergency thermostat. Check and fix.
Poor or no contact between the emergency thermostat and the control and regulation unit. Check and replace if necessary.
The ignition electrode is not installed correctly. Install correctly, taking into account that the distance between the end of the electrode and the plate is normally 3-4 mm.
The gas valve did not open. The result is that the flame goes out. For diagnostics, it is necessary to check the contact of the main gas valve convector in the control unit. Replace if necessary.

Error code E3 - Heating water temperature sensor is open

The device does not turn on in both modes. The gas supply to the burner is interrupted, as a result there is no flame, the pump is not turned on.
The heating water temperature sensor is broken. Needs replacement.
The sensor has no contact. Check the connection.
Problems with the electrical connection circuit of the temperature sensor. Check and fix.
There is no contact between the temperature sensor and the control and regulation unit. Contact needs to be restored.

Error code E4 - Domestic water temperature sensor is not closed

The Mora gas boiler operates in both modes. Instead of the sensor responsible for the temperature of the domestic water, the heating temperature sensor starts working. Accordingly, problems arise with regulating the required temperature in the DHW circuit.

The DHW sensor is faulty. Needs replacement.
There is no contact with the temperature sensor. Check and restore.
There is no contact in the electrical connection circuit of the temperature sensor. Check and restore.
There is no contact between the temperature sensor and the control and regulation unit. Contact needs to be restored.

Error code E5 - Failure in the security module

The unit was stopped due to an emergency. With this error, the burner turns off and the flame goes out due to a gas supply interruption. The pump runs continuously.

The emergency thermostat is triggered because the heating water temperature exceeds the maximum permissible value. This cuts off the gas supply. To eliminate it, you need to understand why the overheating occurred.
Emergency thermostat failure. It is necessary to check its operation; at temperatures below 95 degrees it should be closed. If the failure is confirmed, replacement is required.
The electrical connection circuit of the emergency thermostat is broken. Requires verification and restoration of operation.
There is no contact between the emergency thermostat and the control and regulation unit. Troubleshooting and restoration required.
Pressure switch connection missing. It is necessary to check the patency of the exhaust path for combustion products or the supply of clean air. Fix the problem.
Pressure switch broken. There is no connection to it when the fan is running. A new switch needs to be installed.
Problems in the electrical connection circuit of the pressure switch. Check and restore circuits.
There is no contact between the pressure switch and the control and regulation unit. Restore contact.
The tube connecting the pressure switch and the fan is either disconnected or damaged. It is necessary to check and install a new one if necessary. Perhaps the fan does not start working.
The engine does not work. The impeller bearing has lost its mobility.
The valve does not work due to any mechanical damage. If this problem occurs, the fan must be checked and replaced.
There is no contact in the fan electrical connection circuit. There is no set speed of rotation of the fan blades. Check and fix.
There is no contact between the fan and the control and regulation unit. To set up a contact.

Starting the boiler

The boiler is a fully automatic device. The main burner is ignited automatically by a signal from the boiler automation system from the ignition burner, which is constantly burning. The pilot burner is ignited manually. As an additional equipment, piezo ignition can be installed on the boiler.

Boiler ignition sequence

After igniting the pilot burner, continue to hold the gas valve button (approximately 5-7 seconds). Then release and make sure that the pilot burner is burning steadily;

turn the gas valve handle into operation mode. The boiler is ready for operation;

turn on the “ON/OFF” button - the button will light up. In the “Winter” mode, the main burner will light up; in the “Summer” mode, the boiler will start working if hot water is drawn off.

Possible breakdowns of Mora gas boilers that are not displayed on the screen

In addition to the error codes that the Mora heating boiler screen displays in case of malfunctions, there are breakdowns that the screen does not detect, but timely repair of the unit is still required.

The device cannot gain the power required for operation

In this case, the temperature of the water in the hot water supply or for heating does not increase to the set value.

When operating, the boiler always switches to minimum power mode

Problems in the electrical connection circuit of the modulator to the coils. Check the cable and contact in the control and regulation unit. The modulator on the coil is broken. To eliminate this problem, a complete replacement of the gas valve is required. The unit is not configured; its minimum and maximum capacities are set incorrectly. Re-adjustment of these parameters is required.

The device does not work in DHW mode

The burner does not turn on, the water does not heat up. Poor water supply for household needs.
The DHW filter is very dirty. It needs cleaning.
The differential valve is very dirty. It needs cleaning.
Water supply pressure is lower than required. To fix the problem, you need to increase the water supply pressure.
If there is sufficient water pressure for the domestic hot water supply, the three-way valve does not switch. Check the water passage between the differential valve and the three-way valve. Clean if necessary.
The 3-way valve is stuck. Try to fix the problem by turning the water supply to the hot water supply on and off. If this procedure is unsuccessful, install a new valve.
The integrity of the membrane in the hydraulic part of the three-way valve may be damaged. A new one needs to be installed.
The water supply is sufficient, the three-way valve switches from mode to mode. Check the clearance between the 3-way valve shaft, the motion transfer arm and the switch.
Perhaps it's too big. Adjustments are required.
Damage to the DHW switch. Needs replacement.
The problem is in the electrical connection between the switch and the control unit. Restore the chain.

The Mora wall-mounted boiler has problems with hot water supply; the working burner does not heat water for household needs or is insufficient

If the water supply pressure is good and the water in the taps is not heated to sufficient quantity. The problem is a heavily contaminated secondary heat exchanger. It needs cleaning.
After the heating water has heated to the required temperature, the pressure increases to two and a half bar. After this, the safety valve is activated and part of the water is discharged through it. In this case, when the water in the heating system cools, the pressure drops below the maximum permissible minimum value.
Problems with the expansion tank. There may be a violation of its tightness. And it is necessary to check the valve, and if it is damaged, install a new one. After this, you need to pump in the pressure set by the manufacturer.
The membrane in the expansion tanks is damaged. A new expansion tank needs to be installed.
The water supply pressure for household needs is so high that it increases the pressure in the heating system to two and a half bar. It is necessary to check the valve on the hydraulic unit to replenish the heating system; it may be open.
When the device operates in automatic mode, air pockets are not removed. The valve cap is too tight. Check this and unscrew it if necessary.

Heating of domestic water (standard boilers)

Boilers intended for heating can also be used to heat domestic water in the MORA storage water heater. The storage water heater is connected to the heating system, domestic water is heated with warm heating water ("WATER-WATER" system). When installing the boiler together with a storage water heater, it is necessary to use a three-way valve with an internal microswitch, as well as a room thermostat - these elements are supplied upon additional request.

Decommissioning of the boiler

Long term

Long-term decommissioning of the boiler is carried out during maintenance and repair:

close the gas and water supply taps

Short-term

leave the power cord plug in the socket

Leave the gas and water supply taps open

Any manipulations or operations with the boiler that do not meet the requirements of the “Operation Manual” are unacceptable.

Installation, commissioning, preventive inspections and troubleshooting must be carried out only by trained specialists from a service organization authorized by the manufacturer, which has the necessary state approvals and licenses. Information about all manipulations and operations with the boiler must be entered in the “Warranty Card”.

During operation, the User must periodically monitor its operation.

MORA gas boilers should not be used for purposes not specified in the “Operation Manual”.

The boiler must be turned off if work is being carried out in the room where it is installed that could change the environment (for example, working with paints, adhesives, etc.). The boiler can be turned on and used only after such work has been completed and the room has been thoroughly ventilated.

Czech-made water heating and heating equipment Mora brings warmth and comfort to the homes of many users. The devices are designed for a long service life, during which breakdowns may occur. The Mora gas boiler is prone to malfunctions, so we will outline the typical problems of the brand. You will learn how to deal with breakdowns yourself.