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Automatic Water Feeder Install Questions on Steam Boiler


I recently had a VXT-24 automatic water feeder installed on our steam boiler and am wondering if the top ball valve in the picture should close fully 90 degrees (it won't turn anymore than shown and I don't want to force it)? I have it set up to bypass in the picture. I'm also wondering whether I should just let the auto feeder run all the time or bypass and have it run only when we're away from the house for extended periods (we're new to the system and to steam boilers as of 2 months ago).

I've also been reading some concerns of others with automatic water feeders that I wish I was educated a bit more on before I installed it. As long as I have our boiler inspected annually to check the system, are there any reasons why the automatic water feeder would overfill the boiler and thus cause water damage through the radiators? I read that the VXT-24 has a safety mechanism to prevent overfilling, but that the internal solenoid valve could still fail somehow, so am hoping the risk is pretty low. It's set on the LWCV feed setting, and the 2-minute feed delay.



  • Paul3
    Paul3 Member Posts: 19
    HO here also with a VXT-24. Specifically on your question regarding overfilling. I have seen this depending the dip-switch settings in the VXT. With LWCO time set to 30 second delay and water amount set to 1 gallon, I have found that a gallon of water will be added too often. 30 seconds is not long enough for the condensate to get back into my boiler, a gallon is added, system comes on again, water line bounces a bit, and system cuts out, more water added, and then the boiler is very full, resulting in some water thrown up into the system, some banging, and hissing. I have settled on standard 2 minute delay and fill to LWCO.
  • Fred
    Fred Member Posts: 8,542
    edited February 2018
    That upper shut-off valve should close to the stop, like the lower one. I suspect there is some solder or something preventing full closure.
    There are so many differing views of the Auto water feeder. Many are very happy with them and they can work well for several years. The issue is, when they fail, it is usually the solenoid that shuts the water supply off and the system can over fill. It may work fine at the time maintenance is done. A failure is unpredictable. I am more concerned about the feeder when away from home, for extended periods, more so than when I'm home and a problem becomes obvious very quickly, minimizing any damage. But that's just me. I took my auto water feeder off, when it failed. I tend to check my boiler every time I'm in the basement and my first indication of a problem was when I thought the gauge glass was empty. It actually was completely full. I drained about 10 gallons of water out of the boiler, thinking maybe it was some kind of fluke. Checking back an hour later, the glass was full again. I drained it again and shut the manual valve off to the feeder and problem did not reoccur. Took the feeder off and add water manually now.
    Those feeders are reliable for several years. Like anything else, you just don't know if/when it might fail.
  • Jamie Hall
    Jamie Hall Member Posts: 23,305
    As @Fred says -- there is a diversity of opinions.

    In my opinion, If -- and only if -- you are in the habit of checking the boiler water level daily (at least) and if, and only if, you have a low water cutoff independent of the one which controls the feeder, and if, and only if, you are OK with the boiler shutting down on low water on that long weekend you weren't able to check... then you're probably fine to leave it shut off.

    On the other hand... if your water is clean, and you look at the flow gauge on the meter from time to time, and you maintain whatever control is controlling the feeder, then I'd leave it on. Peace of mind.

    On the timer, though -- I'd set it to as long delay as it allows (the one in the main place I care for is set to 10 minutes). There is no harm to a longer delay, and a very short one can lead to overfilling if the returns are a little slow.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England