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Fireplace/Blowers/HVAC

Kevin Spellman | Posted in General Questions on

Zone 4 western NC build. I am installing a zero clearance wood burning fireplace, the RSF320 http://rsf-fireplaces.com/en/focus-320-woodburning-fireplace . Our great room will have a flat 17′ ceiling. The fireplace chase is essentially within conditioned space until the roofline. This particular fireplace has many options, including blowers that take same-room air in and blow out heated air, add on blowers to hook into your HVAC system, no blowers, and even a heat dump that adds a small inline fan to a duct to run heated air to another room. I had planned on using the blowers in-room and even adding the larger fan to hook up to the HVAC system. However, as I thought about it, and started thinking of my HVAC system, I came up with another route. The fireplace has a really clean look without the louvers you need when you add the internal blower fans(see photo). If you eliminate the blower fans, you need to have an air intake and two “gravity vents”(you can see them up high in the attached photo) so your chase can release heat. You can even add a little in-line fan to the intake duct to increase your flow out the top.

So, to get to the point. What would you think about having the gravity vents up high on the sides of the fireplace chase, near the ceiling, and also add a return to the HVAC system in that area. I plan on using the Carrier or Bryant variable speed heat pump units with variable speed fan coils. Supposedly, these motors use 100 watts of electricity when set to their lowest level. That way, I could circulate warm air around the house very efficiently. This would use less electricity and be far less complex than using the internal blowers and/or their central heat blower kit to circulate heat around the house.

As a bonus, I could also add one small “heat dump” duct with the small inline fan to dump into the mechanical room with the Heat Pump water heater. That would provide some ambient heat to extract in the winter.

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Kevin,
    There are a lot of variables here. Your first requirement is to comply with the manufacturer's installation instructions. Are you suggesting a deviation from those instructions? Or is your suggestion an option that the manufacturer supports?

  2. Kevin Spellman | | #2

    These are all options offered by the manufacturer.

  3. GBA Editor
    Martin Holladay | | #3

    Kevin,
    As long as you are following the manufacturer's instructions, I see no reason why you can't do as your propose.

    If this were my house, I would run the blower as little as possible, and I would use some type of meter to verify the power usage of the blower motor. Lots of blower motors use more than 100 watts, and even 100 watts is a lot if you end up leaving the blower on for most of the day.

    One of the advantages of burning wood is to reduce your utility bills, and if you end up eating your savings by running your blower motor constantly, it defeats some of the purpose of burning wood.

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