Is this a dual powered unit? ie:gas and electric.
I will need the make and model number, please.
Is the unit in a motor coach? if so what brand, please.
Ok thank you.
I do have the service manual for your unit. I will upload it for your retrival.
It will take about 15 minuets to do this.
I will be reading through the manual and then advise you where to begin. the manual will provide the instructions for you to either test the system or replace the bad part. I will need some time to study the manual so please bear with me.
What I have done is upload the manual to a file sharing site for your retrival.
Please click here to go to that site.
Once you are there click on the Free icon at the bottom left.
You will have to wait for a few seconds before you can download the file.
Once the timer has ended it will give you a download button to click on.
Click on it, and save the file to your hard drive in your desk top folder.
You will need a .pdf reader to open the file. I recommend FoxIt reader. You can download a free copy by clicking here.
Ok after reviewing the manual I believe you have a bad flame sensor. It is sending a 'flame present' signal when no flame is present.
The first thing you should do is use some steel wool to clean the sensor rod off (see electrode on page 18 for a picture of this device).
Once cleaned see if the condition still exists. If it does then you will need a DVOM (digital volt ohm meter) capable of milivolt readings.
Using the DVOM perform the test as indicated on page 20 of the manual. Please note the diffrence of the two spark units. One has two probes and the other three. If yours is the two probe type I highly recommend that you have a professional perform the test as there is a high possibility of electrical shock involved.
If it is the three probe type there is still a high possibility of shock but not as bad as the two probe type.
If the readings are not within the limits given in the manual then you need to replace the flame sensor/ spark unit.
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Best regards; The Home Smithy
The sparker is indeed coming on after the gas is being released. But it is because the first attempt by the system to light the gas has failed. The problem is that the control card is receiving the signal that there is flame present when there is not. This allows gas to flow when it shouldnt. The next attempt to fire the unit occures and the built up gas is then ignighted causing the explosion.
You need to run the tests outlined in the manual. It will show the ohm values of the unit and determin if the unit is faulty or not.
Unless the test is performed the only way to solve your problem is to start changing parts and hope you get the right one. This of course can become very costly.