Age of gas valve

Illegible model and SN on this furnace, I’m tempted to assume that this valve was manufactured 9th week of 1987 as I see numbers such as “9045” on valves, but does anyone know for certain how to determine valve age?


Hi Michael,

I would caution against using a guestimated gas valve age, as even if you are correct about that component, it is not beyond reason that it may have been replaced at some point.

If the unit is older (which it sounds like) I would report that the unit is of indeterminate age, and possibly at the end of its design life. I would also recommend that it be properly evaluated by a HVAC tech. 70’s & 80’s gas furnaces are notorious for heat exchanger cracks, inform your clients of that fact.



Thanks for the advice.

Can anyone answer the question?

8709 E15 The valve was manufactured in 1987.

Is there any information on the model number of the furnace?



Furnace was a Luxaire, no ID plate I could find - I spent several minutes looking… looked everywhere - only info was a wiring diagram on the interior of the blower compartment door which did not list a model number. The plate on Intertherm AC condenser was so sun-faded that no lettering was visible… these were* old *systems…

Furnace was badly corroded internally, and got a recommendation for replacement based on age & condition, I was just curious about the date coding on the valve which I assume is yyww as I’ve seen valves with the third and forth digits greater than twelve.