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Sanco2 freezing, self caused?

H2OBandit603
H2OBandit603 Member Posts: 65
edited January 22 in Domestic Hot Water
I installed a swing check on the incoming hot water at the tank from the Sanco2 thinking to prevent thermal siphoning because the cold line would often be warm when it hadn’t been making hot water.  I believe I outsmarted myself as I had a few freeze ups, particularly an E9 error code indicating a flow problem.  The first time it didn’t seem likely that it had frozen due to milder temps,  the second and third time it was very cold, 8 F and it definitely froze and required thawing out.

Initially I assumed due to the heat pump being about the level of the top 25% of the tank that water in the heat pump would get cold, sinking and drawing hot water into the unit which would in turn get cold and keep repeating this cycle which I viewed as a source of inefficiency and likely to interfere with stratification.

My working theory is the heat pump reverses the flow through the circulator pump during freeze protection pushing hot water from the tank through the unit backwards.   I sent the manufacturer an email asking for the freeze protection protocol/order of operation to verify this but haven’t heard back,  it’s been 8 F since I removed the swing check and have had zero issues.

In your opinion did I over think the whole thing and cause the error code with my swing check that was not specified in the installation instructions?
NH well driller and pump installer, 3rd generation
What one man can do, another can do.

Comments

  • H2OBandit603
    H2OBandit603 Member Posts: 65
    *crickets*
    NH well driller and pump installer, 3rd generation
    What one man can do, another can do.
  • bjohnhy
    bjohnhy Member Posts: 9

    Did it get better with getting rid of check valve?

    What did the company say in response?

    I have a couple loops on my hot side (heat pump hot side) as to minimize the thermosiphoning effect

  • Kaos
    Kaos Member Posts: 222
    edited October 30

    My $0.02, mostly just thinking out loud.

    You are either using electricity from the heat tape to keep the pipes from freezing or heat from your buffer tank. One is COP of 1, the other is somewhere between COP 2 to 4. A hot tank is also a lot of energy, so even if power goes out, thermosyphon will continue to work for many hours but the heat tape will shut down.

    So I would not stop thermosyphon, it is your friend. Also install their anti-free valves on the outside.

    bjohnhy

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