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Honeywell pressure switch

ChrisJ
ChrisJ Member Posts: 16,715
in THE MAIN WALL
Has anyone noticed a lot of these Honeywell pressure switches failing on Luxaire/York furnaces?   Its the one that measures pressure difference between the exaust and intake on direct vent systems.



The switch I'm looking at is a model 9371-DO-HS-0010 and it has failed already in less than a year after replacing the first time.  Now, giving it a bump will get it working again for a while until it sticks again (sounds real safe, right?).

Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

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Comments

  • Timco
    Timco Member Posts: 3,040
    Is it...

    A positive or negative pressure switch? (monitors inducer or HX)



    I've found on reoccurring issues the number of elbows or length or vent was right at max.
    Just a guy running some pipes.
  • ChrisJ
    ChrisJ Member Posts: 16,715
    edited December 2012
    negative

    It says -1.00WC on it so I'm assuming thats a negative pressure switch.



    I know the exhaust and intake lines are almost identical, one has an extra 45 to offset it some. Also the lines are 1 elbow short of the recommended maximum except the intake has that extra 45 which moves it even closer to the max I guess.



    Would modifying the lines and removing any elbows possible give the switch less of a chance of failing?

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • Timco
    Timco Member Posts: 3,040
    Yes

    I would say not being 1 45* elow from max would surely help. Fieldpiece makes a sweet new pressure switch testing instrument but I don't have one yet because a failed pressure switch is uncommon. It's more likely your altitude or fittings/pipe size being near max. You can increase pipe size if fewer fittings is not possible. Use your analyzer to test negative pressure at the inducer.
    Just a guy running some pipes.
  • ChrisJ
    ChrisJ Member Posts: 16,715
    edited December 2012
    altitude

    Altitude is around 2000 feet.



    After looking at it we decided we can eliminate 4 90 deg ells and replace them with 3 45s.





    Thanks for your help, I appreciate it.

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • ChrisJ
    ChrisJ Member Posts: 16,715
    edited January 2014
    Update

    So my dad said another pressure switch failed a few days ago. He installed another new one and all is well again.



    Seems they go around a year before giving a "stuck open' error. Doing a quick search seemed to bring up a lot of pressure switch failures on York / Luxaire units but nothing specific other than a service bulletin saying they changed the switch to deal with contaminants from the silicone hoses.



    Still haven't changed the venting arrangement although I think my dad is seriously considering it now. Either that or calling his heating guy out to see if something else isn't right.

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

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