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Water turned off....could autofeeder be getting confused?

Don_175
Don_175 Member Posts: 125
I went around and found any areas where steam could be escaping
last year and tightened everything up. I then reset our autofeed to 000. It is one of the VXT ones. Not sure if it is the 24v or 120v. It has been reading 000 all winter so far. We were going to be away during the cold snap so I turned off our water for the house in case we lost power etc.

I hadn't looked at the autofeed in 2-3 weeks, so last night, I was very surprised to see it reading 010 gallons (up from 000 the last time I looked). The water level looked maybe 1/2 inch below where it typically has been.

I have 2 questions.

1. What is the typical water level where the autofeed would kick in? Our water level has been very steady for months. I have a hard time believing it dropped so much as to call for water.
2. If our household water were turned off, would the autofeed in trying to run get "confused" and show it was adding more water than it did because the gallons are based on the time the valve stays open? Since water was turned off, it would calculate it was adding more water than it was? What be the time it would be calling to calculate 10 gallons?

I will now keep a close eye on it. I typically look at it once a week.
Thanks very much

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 22,912
    Where the autofeeder trips depends on the type of low water cutoff you have activating it, and where that is set on the boiler. With a float type -- MM 67 for example -- it will be about half an inch or so above where the low water cutoff shuts things down. So there is no one good answer.

    As to getting confused, yes, it will show a count for every time it tries to feed, and if it is unable to feed it will keep trying. It would appear that you got fortunate, and there were ten occasions on which it tried to feed -- but each time the boiler water level came back up and turned it off (slightly slow returns) before it tried again on that episode.

    Autofeeders are not a substitute for regularly -- preferably daily -- checking the water level in the boiler.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Don_175
    Don_175 Member Posts: 125

    Where the autofeeder trips depends on the type of low water cutoff you have activating it, and where that is set on the boiler. With a float type -- MM 67 for example -- it will be about half an inch or so above where the low water cutoff shuts things down. So there is no one good answer.

    As to getting confused, yes, it will show a count for every time it tries to feed, and if it is unable to feed it will keep trying. It would appear that you got fortunate, and there were ten occasions on which it tried to feed -- but each time the boiler water level came back up and turned it off (slightly slow returns) before it tried again on that episode.

    Autofeeders are not a substitute for regularly -- preferably daily -- checking the water level in the boiler.

    Thanks very much. We have a probe type cutoff.
  • Long Beach Ed
    Long Beach Ed Member Posts: 1,188
    edited December 2022
    Depending on the low water cutoff controlling the VXT feeder, your water level has to be low enough to shut the boiler before it feeds. If your boiler went low on water, and your water supply was turned off, the VXT could not correct the condition. It would try feeding water twice, then lock out the boiler and display "LOC" if the low water cutoff continued to show a deficiency.

    As you didn't come home to "LOC" on the display, and your water was turned off, the control probably didn't find ten gallons of water to feed the boiler.

    The VXT usually is installed to feed one gallon per minute into a small system. It does what the low water cutoff calls it to do. Assuming you have a probe-type low water cutoff, the VXT will feed a predetermined amount of water when the probe is not covered by water after a pre-determined delay.

    Here's the manual that describes how the VXT works:
    https://s3.amazonaws.com/s3.supplyhouse.com/product_files/VXT-24V-install.pdf

    During this cold spell, the boiler may have consumed the water and you may have a new problems like a failed air vent, steam or water leak. You're wise to watch it and check your radiator and main vents for blowing steam.
  • Don_175
    Don_175 Member Posts: 125

    Depending on the low water cutoff controlling the VXT feeder, your water level has to be low enough to shut the boiler before it feeds. If your boiler went low on water, and your water supply was turned off, the VXT could not correct the condition. It would try feeding water twice, then lock out the boiler and display "LOC" if the low water cutoff continued to show a deficiency.

    As you didn't come home to "LOC" on the display, and your water was turned off, the control probably didn't find ten gallons of water to feed the boiler.

    The VXT usually is installed to feed one gallon per minute into a small system. It does what the low water cutoff calls it to do. Assuming you have a probe-type low water cutoff, the VXT will feed a predetermined amount of water when the probe is not covered by water after a pre-determined delay.

    Here's the manual that describes how the VXT works:
    https://s3.amazonaws.com/s3.supplyhouse.com/product_files/VXT-24V-install.pdf

    During this cold spell, the boiler may have consumed the water and you may have a new problems like a failed air vent, steam or water leak. You're wise to watch it and check your radiator and main vents for blowing steam.

    So do you think we have some type of steam leak and the VXT is accurate? I did replace an air vent on one radiator that didn't seem to be closing, but would that be enough to cause a ten gallon deficit over 2-3 weeks?
  • Long Beach Ed
    Long Beach Ed Member Posts: 1,188
    edited December 2022
    The VXT is more likely correct and based on its display, it likely fed the water. A steam leak can boil off ten gallons in two or three weeks, depending on the pressure, size of the leak, boiler capacity and run times... There's only one way to find out:

    If you're going to be around, turn off the VXT, mark the sight gauge with a piece of tape and watch the water level. You'll know soon enough!

    If you find you are losing water, we'll help you find it.
  • Don_175
    Don_175 Member Posts: 125

    The VXT is more likely correct and based on its display, it likely fed the water. A steam leak can boil off ten gallons in two or three weeks, depending on the pressure, size of the leak, boiler capacity and run times... There's only one way to find out:

    If you're going to be around, turn off the VXT, mark the sight gauge with a piece of tape and watch the water level. You'll know soon enough!

    If you find you are losing water, we'll help you find it.

    Thanks!! I had noticed one of the radiators was red hot and the vent was audibly hissing. Despite the fact that the entire radiator was hot, the air vent was still venting. I replaced it last week and now it shuts off when hot. I'm thinking that was the culprit. But I will shut off autofeed and see if level drops.
    Long Beach Ed