Hi, I can answer your question, lets handle them one at a time. Click 'accept' when you are satisfied.. or we can get another expert.
it sounds like a pilot flame sensor issue... inspect the pilot flame and how it impinges on the flame sensor rod, get back to me with what you see.
Hello again...what is happening is that there is a flame sensor rod and control, that is not sensing flame, after a few seconds it will shut the burner down. Odds are that is the problem.
The ignition obviously works..so you get ignition, but not flame sensing. Inspect the burner and locate the flame sensor rod, notice if it has any corrosion on it. or the flame for some reason is not impinging on the rod well .. let me know what the situation is.
Hello again, its electronic, not easily testable. .. slight variances can cause failure your idea to replace is good.. its not an expensive part. try reconnecting its wire connections and cleaning it off with steel wool first though.
look in you phone directory under 'air conditioning' find the Rheem, in the US thats Ferguson Plumbing and Geating Supply as a rule. *wholesaler./ distributor... take the part to them and ask for a replacement, and while you are there talk with one of their older counter men a bit about how common a failure that is.
If you need help in finding a distributor let me know the name of the nearest city over 20,000 people and I will look it up on Google for you.
to take the chill off in the meantime, 15 dollar type portable electric heaters work pretty well. one or two will do it.