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I just found out the hard way that the flame sensor for BS 36 water heaters is no longer in the inventory. I did not see one on EBAY either.
Tom
Tom
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Flame sensor for BS36
After 10 years of operation, my BS36 started shutting down after 25 seconds after startup. I keep it turned off except when I need hot water. I found out that meant the flame sensor wasn't working properly. I bridged the flame sensor cord on the PWB with a 1 meg resistor to bring the resistance down.
That lasted 4 years. Then the heater started shutting down after 25 seconds again. I tried bridging it with smaller resistors, but no luck. I finally bought a new detector from Nelson & Small.
I noticed the flame detector was a hollow plastic unit with a rubber plug in the end where the cord went in. I pried the plug out & remove the CdS cell with the wires attached. These cells go bad after a while; their operating point shifts. I replaced the CdS cell with one from Radio Shack that had similar characteristics. At the time, Radio Shack sold a package of 5 different cells, part number 276-1657. I used one that was the same size as the original. It has to be small to fit in the plastic tube. The detector I bought from Nelson & Small in Jun 2011 is still working, so I have not tried my repaired one out.
I found a notice from Hamamatsu Photonics, the original CdS cell, that they were no longer manufacturing CdS cells after Dec 2005 because of restriction of Cadmium products being imported into the EU. The original cell is a Hamamatsu S96-48-100. I have the spec sheet for this if you're interested.
NOTE: The new flame detector I bought had greater than 100 megOhm resistance when in the socket with the burner off. The resistance dropped to 60kOhm when the burner was on.
Alan
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