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All I did was add some Great Stuff. Help!

My gas furnace won't fire up. It triggers the induced draft motor, which runs for about 20-30 seconds, and then the whole system shuts down. Up until yesterday it was working fine and I had been running it for a couple weeks now (in Minnesota). The only thing that changed was that yesterday I was going round the house and sealing up all the penetrations, and I blew some Great Stuff around the exhaust vent. I've checked the vent and no foam got in the pipe/vent, and none even came through to the inside side of the joists. It all just went behind the vinyl receptacle cover and AROUND the vent. 

There is a little condensation around the inside of the pvc pipe, but I'm not sure if this is increased from before I added the Great Stuff (I never looked that closely before).

This is a horizontal concentric termination. I'm getting error code "45"which is : low pressure switch is open. Possible issues: 

-insufficient combustion airflow

-insufficient combustion air

-improper pressure switch setting


I'm not sure how adding spray foam AROUND the exhaust changed anything. Other that scraping out all the spray foam, is there something else I should correct or look at? 


Can you guys help a single girl out??Thank you very much!


Re: All I did was add some Great Stuff. Help!

Im not sure how to delete my post, so I'm just letting everyone know that the problem has been solved. I had plugged the intake with spray foam! 

Now I fully understand how a combined exhaust works- a pipe within a pipe. Lesson learned- next time take the vinyl cover off so I can see what I'm actually doing :)

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