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Hot Water Fluctuation

kimberlyp Member Posts: 1
So we just bought a house last week, and it has an oil furnace/boiler, which heats both the house and the water. It was serviced just before we moved in, and it's working to keep the house warm just fine. The hot water is tankless, with a coil in the boiler. The hot water is sometimes hot, sometimes cold, and it has nothing to do with the amount of things using water at a time. It will fluctuate even within one shower, with it starting cold and getting warmer and then getting cold, and so on. It's not very pleasant given that it's March in NH. In my online research, I've found that the coil can get blocked, and they did install a water softener in October, so I'm wondering if this has been a problem for a while. Does anyone have any ideas? Thanks :-)


  • icesailor
    icesailor Member Posts: 7,265
    There's lots of things you can do.

    First, take photos of the boiler and post them here. Take a photo of the man boiler control that should be mounted in the center of the coil. With particular emphasis on the control settings.

    This is a common problem and an easy fix.
  • Snowmelt
    Snowmelt Member Posts: 1,416
    Could be cross plumbing at a fixture. The mixing valve can be messed up. It could be anything