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Lee Wallender

Can You Stop Window Sash Pulley Heat Loss?

By December 29, 2009

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...did you even know that window sash pulley heat loss exists?

Most older windows have sash pulleys.  Even many new windows do, too.  These are the ropes that run over the top of pulleys--one end attached to the window, other end attached to a weight.  This aids in opening the sash (the movable part of the window).

Now, place your hand over that pulley opening in the dead of winter.  You'll feel a steady draft of ice-cold air entering your house.

A fellow named Duane Miller e-mailed me recently about his Sash Pulley Air Blocker Plugs. These plugs fit into the open spaces above and below the pulley. According to the site,

The Air Blocker Plug is manufactured of a special insulation-sealant that is fabricated from a slow-expanding compressible cellular weatherization foam.

To my uneducated eyes, they look exactly like ear plugs. I mean--exactly.  I'm hoping that these Air Blocker Plugs have some difference from ear plugs that Mr. Miller can shine some light on (if he gets back to me, I'll update this post).

Would the plugs come dislodged from the movement of the pulley?  Are they meant to be removed after the winter months?  I have no idea.  In any case, I wanted to point out the tremendous energy loss resulting from those pulley holes.

Update on December 30, 2009, from Duane Miller, of AirBlocker Plug:

Slow-expansion foams are used in a variety of different products for gaskets and sealing. The foam sheets or rods are cut, sliced, diced, and punched into different shapes for different purposes. Ear plugs are certainly one of the numerous products that take advantage of this slow-expanding property, although they are usually manufactured in yellow, purple or pink.

...Much like other foams used in packing, padding, and for their thermal or acoustical properties, there is no question that they are all very similar; sometimes their properties are exactly the same. One use might make use of the cushioning properties, a different one the acoustical properties, another might utilize the thermal properties.

We've tried different slow-expanding foams and feel the foam we use has a good balance of properties for this purpose. Plus, they can be reused. The plugs insert quickly and are removed just as fast. We have found that in many homes, only a few of their windows are actually used regularly for ventilation. When the weather permits and prior to opening, the plugs would be removed for window ventilation. When winter returns, the plugs can quickly be replaced.

...I am a registered architect, 35 years in the business, and focus on sustainable solutions. This one is simple to solve, where a small cheap item can have a big cost and comfort impact.

Image:  AirBlocker


January 8, 2010 at 9:10 pm
(1) rochelle says:

Wow! they do look like ear plugs do u think someone might get it confuse.

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