rollout limit tripped

[ngerrald]

hey need some help, I have a york old faithful gas unit where the rollout limit had tripped, I had the call today, it has only done it one time so far, but I just changed the gas valve out 2 weeks ago, just didnt want to miss something, I am not a DIY'er, I am a contractor

[bama 101]

You will have to register to get help around here
.....Sorry.........


I'm not a bad guy just following the rules

[tinknocker service tech]

tripping on roll out 90 percent chance cracked heat exchanger

[4l530]

So after (I assume) you reset the rollout...then what happened? Do you have any other info as to readings or anything?
A tripped rollout ain't a good sign.
How old is this thing? This rollout, its over the burners or in the collector box, or...?

[ngerrald]

what is the best way to test for a cracked heat exchanger, I read several books and still cant get a good answer?

[ngerrald]

after I reset the limit, I turned the heater on and it did not roll out, I tested the unit about 10 times, the limit is on the collector box

[4l530]

Sounds like the chimney backdrafted, if this is an old gravity draft model
Probably would be prudent to check that it's not partially blocked or something
Sometimes that kind of thing just happens, if it's excessively windy.

[24/7mechanical]

After changing the gas valve, did you check to outlet gas pressure?

[ngerrald]

yes i did check the outlet pressure, checked out...