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Combi with HWFC

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AirborneTrav
AirborneTrav Member Posts: 29
in THE MAIN WALL
Has anyone out there used a combi boiler in a hot water fan coil application? A customer of mine wants to convert to gas, and it's a vacation home that is only used some weekends, so they don't want a tank style water heater. My initial thought was a Navien NCB240, but it occured to me that if they were to take a long shower or bath, or back to back showers, there would be no hot water flowing to the fan coils. For this to occur with radiant or even baseboard isn't the end of the world, but for fan coils (which I usually set up to turn on with a heat call from the thermostat rather than a strap on aquastat) this seems like it would present an issue. The combi would save them a good amount of money on the install because they aren't paying for an indirect or separate water heater, but it might just not be the correct application here. I've thought about explaining this to them, and if they still wanted to go with the combi giving them the option to add a storage tank down the line. The Navien does have a fan coil setting on there, so some people must be doing it. Any feedback? Thanks in advance.

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  • njtommy
    njtommy Member Posts: 1,105
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    I have the exact same set up in my own home. With no problems. Navien has a set of dry contacts on the boiler to break 24volts to the fan for DHW call at the same time it's running for heating. Once call for DHW is over contacts close and fan will turn back on.

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