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Can I burn my Pacific Energy Insert without using the blower?

Q: Hey, guys! First let me tell that you that your website is wonderful. I have gathered so much information from you that I haven't been able to find elsewhere. Thank you for your attention to detail. Now my question:

I own a Pacific Energy Summit Insert (not purchased from you, I'm sorry to say) and am wondering if there is any risk of overheating the unit if I never use the blower. I'm also wondering if not using the blower will lower the efficiency of the unit because more heat will be transferring into the chimney. I don't seem to need the blower to move heat through my home, but I don't want to damage the insert by not using it.

Any answers will be greatly appreciated. PE should be paying you guys for disseminating much better info than they do on their website! Have a great autumn.

Sincerely,
David Fishlock

Sweepy A: Thanks for the inquiry, and for the kind words about our website! First, let's look at how a modern fireplace insert delivers heat, and the role a blower plays. The box-within-a-box design used by nearly all of today's fireplace insert manufacturers creates a convection heat exchange chamber between the firebox and the outer shell. As the firebox heats up, the outer shell reflects radiant energy back at the firebox, causing the air inside this chamber to superheat. The superheated air inside the chamber rises and flows into the room through an opening at the top, drawing replacement air in through an opening at the bottom to be heated in turn. This naturally-occuring process not only adds convection heat to the radiant energy beaming off the front surface of the insert, but helps minimize heat loss to the masonry structure behind.

Wood Firebox Diagram
Radiant Wood Firebox

    

Wood Firebox with Outer Shell
Outer Shell Added

    

Convection Airflow Diagram
Natural Air Convection

Blowers are often added to increase the flow of room air through the heat exchange chamber while creating air turbulence in the room to promote a more efficient "mix" of heated air with room air. Many manufacturers locate the blower in the bottom opening of the heat exchanger, where it impedes the natural flow of air when it isn't running. In bigger, higher output inserts, this can not only interfere with the transfer of heated air into the room whenever the blower isn't running, but also cause extreme temperature buildup in both the heat exchange chamber and the firebox, which can damage the blower or firebox components. We're betting that the origin of your concern might have been one of those manufacturers' websites or owner's manuals, which strongly caution against operating their inserts with the blowers turned off.

Convection Flow with Blower On
Blower in bottom opening-
increased airflow when on

      

Convection Flow with Blower Off
Blower off - impedes
natural airflow

You'll find no such precaution in your Pacific Summit Insert manual. This is just one of the reasons Pacific Energy has risen to the top of the woodstove marketplace in both the US and Canada in recent years, and boils down to an elegant piece of thermal design engineering. The blowers on the Summit, Neo 2.5, Alderlea T5, Pacific Super and Neo 1.6 insert models are mounted in the side openings of the heat exchange chamber, and blow heated air sideways through the heat exchange chamber, where it encounters specially designed air deflectors which direct the airflow upwards, across the top plate, and into the room through the top opening, while leaving the natural bottom-to-top air transfer channel unblocked. Thus, these models can be operated without the blower running with no fear of component damage caused by overheating.

Pacific Energy Inserts Blower Diagram
PE's Unique Blower Design
Blowers in side openings-
blow air out top opening

        

Natural Convection with Blower Off
Off-The-Grid Performance
Blower off - natural
airflow unimpeded

You also needn't be concerned about reduced heating efficiency. When the air in the exchanger is allowed to flow naturally, it enters the room at a very high temperature. When a blower is used to create more velocity through the heat exchanger, MORE air comes out FASTER, but, because the available heat from the fire is spread out over more air molecules, it also comes out proportionately COOLER. The net delivery of convected heat into the room is virtually unchanged.

Many of our customers use their PE insert blowers only when they're trying to bring a cold house up to temperature quickly: the added velocity of air through the heat exchanger causes the heated air to blend with the room air faster, and also creates turbulence in the room which promotes the flow of heated air into other rooms. As you've already discovered, once the living space has been brought up to temperature, the natural circulation of air throughout a typical house is often all that is needed to maintain that temperature. At that point, the insert's blower can be turned off with no fear of negative consequences.

 

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