From this article you will find out what problems may arise in the automation of gas boilers, why it is not possible to ignite the igniter, because of which the boiler can turn off for no reason, and most importantly, we will figure out what actions must be taken to diagnose and eliminate this malfunction.
Owners of non-volatile gas boilers are probably familiar with the situation when, for some reason, they cannot ignite the boiler, or a lot of time is spent on ignition. In this case, the problem lies in the boiler automation..
Today, in domestic and imported gas equipment, the EUROSIT 630 gas valve is most often used. It is this valve that performs the functions of maintaining the set temperature of the coolant and, in the event of an emergency, completely shut off the gas supply to the burners. Further start-up of boilers with such automation is possible only manually. However, not always the cause of emergency shutdown of the boiler is a real accident.
Let’s try to understand this using the example of the Zhitomir-3 boiler. From the automation, it provides protection against loss of flame on the igniter and violation of thrust.
Note: All gas hazardous work must be carried out exclusively by representatives of specialized organizations with appropriate permits. Therefore, this article is provided for informational purposes only. Also, this article will help control the work of the wizard and, possibly, save you from the need to purchase unnecessary spare parts..
Let’s define what we will call ignition ignition. The EUROSIT 630 valve control knob allows switching the boiler into three main modes:
- temperature control (1-7).
To ignite the pilot burner (igniter), move the control knob to the “ignition” (spark) position, press it and use the piezo ignition button to ignite the pilot burner. Then the handle is held for several seconds (no more than 30) and released. The igniter should continue to burn. This is what we will call ignition ignition. If the igniter goes out, it is necessary to repeat the procedure several more times. If this does not help, you need to look for the malfunction.
At the moment of ignition of the igniter, the flame heats the thermocouple, which in turn generates an EMF (approximately 25 mV for serviceable SIT thermocouples), which is fed through the circuit of the sensor (s) of the automation to the solenoid valve.
By pressing the handle of the gas valve, we manually open the solenoid valve, supplying gas to the igniter, which, in the case of correct operation of the equipment, is held by the EMF generated by the thermocouple and remains in the open position after the handle is released. The thermocouple itself performs the function of protection against loss of flame at the igniter. The sensors in the circuit are normally closed and, when triggered, open their contacts, ensuring complete shutdown of the boiler.
Preparation for work
To carry out work to identify and eliminate problems with ignition of the igniter, we need the following tool:
- open-end wrenches No. 9, 10, 12;
- flat-head screwdriver;
To determine the cause of the malfunction, check the thermocouple circuit – the solenoid valve. First, we check the thrust sensor. In this boiler, it is located on the flue. To do this, remove two terminals from the sensor.
We close the two terminals together, they must connect tightly (for this, you can squeeze them a little with pliers).
Trying to ignite the igniter. If it was possible to do this, the cause of the malfunction is in the traction sensor. However, do not rush to change it. First, let’s check it.
Note:in this work, we dismantle the sensor in order to show the features of its installation on the boiler and the marking. It is not necessary to do this for verification..
Unscrew the two screws securing the draft sensor to the boiler flue.
Please note that the sensor is not attached close to the flue housing, but is mounted on paronite gaskets. This is necessary in order to reduce the heating of the sensor through its contact with the body, as well as to provide a gap between the hole in the gas duct and the plane of the sensor.
We examine the sensor. Its contacts must hold firmly to the case. They should be free of oxidation. Sensor rating (temperature at which the sensor contact opens) in this case 75 ° C (designation on the L75C case).
We check the thrust sensor with a tester, measuring its resistance. It should be minimal (equal to the resistance of the probes) – 1–2 Ohm. If the sensor does not ring, it is definitely necessary to replace it with a similar one (with an appropriate response temperature).
If it is possible to ring the sensor, wipe the sensor contacts and circuit terminals with alcohol, press them with pliers and dry them. We mount the sensor in place and connect it. Trying to fire up.
If the ignition was successful, the cause of the malfunction was found and eliminated.
It is imperative to check the draft after igniting the main burner. To do this, you can bring your hand to the place where the draft sensor is installed. No heat should come out of this hole. If this happens, the cause of the lack of traction must be eliminated. The sensor then responds correctly..
Attention! It is strictly forbidden to operate a boiler with a faulty chimney.!
If the ignition failed, we go further along the chain. Contacts from the draft sensor go to the traction breaker (thermocouple breaker).
We remove the terminals from the traction breaker contacts and measure the resistance of the circuit. It should be no more than 3 ohms.
If this condition is met, we perform the following actions. Using the No. 9 wrench, unscrew the thermocouple fastening nut to the traction chopper. Using the key number 12, unscrew the traction breaker by half a turn, which consists of two parts: a brass sleeve and a plastic insert.
We take out the plastic insert with contacts and unscrew the part completely.
Checking the thermocouple. We connect it directly to the solenoid valve (the place where the traction chopper was installed). We fix it with key number 9.
We fire up the igniter. If it failed to produce, the cause of the malfunction is most likely in the thermocouple. The solenoid valve rarely fails..
Let’s examine the thermocouple. In some cases, the thermocouple can be repaired. It happens that the contact of the thermocouple disappears. This is not a reason for replacement, it is enough to solder it.
It is important that the dielectric gasket is intact.
Make sure the thermocouple is properly seated in the pilot flame. The tip of the thermocouple must be immersed in the flame.
To adjust the position of the thermocouple relative to the pilot flame, loosen the nut that secures the thermocouple to the pilot burner with a key # 10. Moving the thermocouple, it is necessary to set it in the correct position and fix it with key No. 10.
To make the final verdict on replacement, you can measure the EMF generated by the thermocouple. To do this, it is necessary to ignite the igniter, and, keeping the valve handle pressed, measure the EMF between the contact of the thermocouple and its body. The optimum value should be at least 18 mV. If the thermocouple is working properly, clean the traction interrupter parts with alcohol, and also wipe the thermocouple contact. Especially if you had to solder it.
We assemble the traction interrupter in reverse order, connect a thermocouple to it. Do not crimp the parts too much. Effort must be sufficient to ensure reliable contact. We crimp the terminals with pliers and, wiping them with alcohol, try to ignite.
Performing all the above operations will surely help you troubleshoot your boiler..
Another reason for problems with ignition can be insufficient gas pressure at the igniter. This is due to a clogged nozzle. To clean it, loosen the nut securing the ignition copper tube with a wrench No. 10 and remove the jet.
Advice: you can tap the igniter lightly to make it easier to remove the jet.
We clean the hole of the nozzle of the core wire. Hole size violation is not allowed!
At the moments of the most intensive gas consumption, the pressure in the central main pipe may drop. Accordingly, the gas pressure at the pilot can also decrease. This may require adjusting the gas pressure at the pilot. Unscrew the screw securing the decorative overlay and remove it.
Adjustment is made by turning the screw on the valve. Turning it counterclockwise increases the gas pressure at the pilot..
These tips will help you sort out your boiler firing problems. In practice, the most common problems are contacts, not sensors. Therefore, if each time you ignite the igniter you have to hold the valve handle longer and longer, we advise you to simply clean the contacts and tighten the automatic terminals. In order to avoid real problems with the automatic operation, we recommend that you clean the boiler on time.