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Power Venter Questions

schieftain
schieftain Member Posts: 6
I have an oil-fired forced-air furnace with a Field Controls SWGII-5 power venter. Both are about 15 years old. We have the furnace cleaned/tuned up every year after heating season. I have a couple of questions about the pav. 1. We have white crusty powder that forms on seams of the galv pipe coming out of the furnace. The powder falls off and lays on top of the burner and in furnace. The galv pipe feels really thin, I assume this powder is from the pipe corroding from the inside. 2. There is a barometric draft in this pipe before it enters the pav, this draft reg. does not open when the pav is running. 3. The pav is running for about 6 minutes after the burner shuts off. What is the normal post-purge cycle time for these? And is that from the time the burner shuts off, or from when the fan/blower shuts off after it's final cycle? The company that we have had service the furnace every year has not said any of these things was a problem. They did mention replacing the thin pipe the next time we had the furnace serviced.

Comments

  • billtwocase
    billtwocase Member Posts: 2,385
    power vent

    The post purge is generally 3-5 min after the burner shuts down. The thin somke pipe should be replaced, and should be at least 26 gauge. The white powder, my guess, would be after the draft control only, and is common for these, and the draft control should be opening, as you can get a breech draft of negative 10-12 at least, and only a negative .02 is needed over fire. Have them decrease the post purge to about 4 min, and set the draft over fire. You will see less white crust also.
  • schieftain
    schieftain Member Posts: 6
    Power Venter Questions

    The white powder is mostly at the 90 right where the pipe comes out, and the first seam, before the draft.



    What do you men by set the draft over fire?
  • schieftain
    schieftain Member Posts: 6
    Power Venter Questions

    The white powder is mostly at the 90 right where the pipe comes out, and the first seam, before the draft.



    What do you men by set the draft over fire?
  • schieftain
    schieftain Member Posts: 6
    Power Venter Questions

    Okay I understand the draft over fire now.



    Let me ask two more questions.



    1. Is the white powder also accumulating inside the furnace anywhere?



    2. When the furance kicks on, the blower starts moving air immediately, even before the air is heated. Someone told me there should be a delay, so that the blower only kicks on after the air is heated to some degree. Is that correct in all forced-air systems?
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,692
    Depends on the controls

    On your furnace. By blower you mean for the furnace not the power venter. Some units, the blower starts from a fixed timer, others, it starts at a set temperature.

    The white powder isn't in the furnace.

    But get someone out there to correct your problems.
    steve
  • Jack
    Jack Member Posts: 1,046
    One thing to make sure of

    Is that when your "system" is being cleaned, "every couple years" that the power venter is getting the thorough cleaning treatment as well as the burner/furnace. Frequently the power venter is ignored.
  • schieftain
    schieftain Member Posts: 6
    Power Venter Questions

    Yes, we are trying to get someone to fix these things, not the people who have done it in the past. I don' think they've ever serviced the pav.



    Thanks for the feedback all. Much appreciated.
  • schieftain
    schieftain Member Posts: 6
    pv?

    I'm referring to the fan for the house air, (heated and cold returns).
  • billtwocase
    billtwocase Member Posts: 2,385
    now I'm confused

    Are we still talking power vent, or is this white accumulation at a heat supply elbow? You are now talking about the furnace blower instead of the power vent motor? 
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