im a tech at a small company one of the senior techs have been working on this bryant 90+ gas furnace. the HSI lights up and the gas valave opens but not quick enough and statrs puttering trying to light we tryed 2 new gas valves and it does the same thing i think the HSI is not building up enough resistance to hold the gas valve open , and its getting a weak signal. any ideas. i mean what are the odds of getting 2 bad gas valves, i think its the HSI, but the senior tech thinks other wise.

 

Did he replace like for like? IOW- gas valves come in slow, standard and fast opening. Are the burners clean? How's the incoming gas pressure? It sounds like what you're saying is the burners never fully lite off? Is that accurate?

 

Did he check the continuity of the HSI?

 

What was the immediate previous history on this furnace? What were it's very first symptoms causing you to have to work on it?; like had you been doing other work on it, especially with gas lines disconencted where you simply need to purge the air out? It sounds just like you have air mixed in with the gas.

The other point I wish to make is - I don't get how the SENIOR tech would be as stubborn to pay for 2 expensive gas valves and not willing to risk taking the chance on say a $30 ignitor - even though I have to say - -I- have never ran into one that is going out in such a way where it partially works the gas valve, either.

Sounds more like air to me. And if we never hear from you again, I'd lay a bet that is what happened.

 

check your grounds.weak transformer.break out your meter....