Have a whirlpool dryer that intermittently would heat and then not, and then nothing at all. We purchased a new/used dryer off craigslist, now a Kenmore and it is doing the same thing, They both don't get HOT, have to run clothes more than 1 cycle on high heat to dry. And the 2nd seems to be heading toward the dead side like the first. The Kenmore is quite new maybe 3 years old. Our old one was > 15yrs. Both are GAS dryers. Is it possible they both have the same bad part or is it our gas supply?

The house runs on gas for the instant hot water on demand, the stove, and furnace. We have not had issues with these appliances.

we have done this, it is a short exhaust tube and exits directly thru an exterior wall. The gas line from the shut off valve in the floor to the dryer is not kinked either. Not sure what else to do. I find it ODD that 2 dryers are doing the same thing, low to intermittent heat.