Improving window energy efficiency through spring balances
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sswiat



Joined: 01 Sep 2004
Posts: 231
Location: Cambria, New York

PostPosted: Fri Jan 14, 2005 5:33 pm    Post subject: Improving window energy efficiency through spring balances Reply with quote

In assessing some double hung windows for restoration recently, the thought came to me regarding a possible cause of "drafty and cold windows".

The walls were "gutted" so all components of the window were visible. In observing the sash weight pockets it came to me that this is a non-insulated area surrounding the windows which could be a major cause of cold air convection as well possible air infiltration. Essentially, even if the walls are insulated and the window are restored in combination with a good storm window, we still have an area that is a weak spot in heat loss.

The solution being thrown out for others opinions is to remove the sash weights, cords and pulleys and fill the pockets with insulation (of course insulation that is reversible) and utilize a spring balance*.

The thought is we have improved on the overall energy efficiency of the building with minimal alteration to its window system.

I have never done this procedure before and was looking for honest feedback including pros and cons.

Thank you

* see OHJ April 2004 page 33 for info on spring balances.
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johnleeke
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Joined: 20 Aug 2004
Posts: 2972
Location: Portland, Maine, USA

PostPosted: Fri Jan 14, 2005 10:07 pm    Post subject: Reply with quote

Yep, pull out the weights and fill the pockets with insulation--it's commonly done these days.

On one project we saved the original weights and pulleys by installing thin wall metal pipes for the weights to run in and filled the pockets around the outside of the pipes with insulation. Worked pretty slick.

One of the potential problems with any insulation in the pockets (and with most weatherstripping as well) is that the air infiltration around the sash and convection within the pockets is what keeps the wood dry so it does not decay. Remember, the wood window systems have been developed over four centuries, and all this insulation and sealing up business is only with us about 50 years. I've seen some cases of 150+ year old windows where everything was sealed up real nice, and after about 8 to 15 years they were rotting out at the frame joints (lower AND upper) and sills due to moisture buildup trapped by the storms, pocket insulation and weatherstripping.

This fits my tenent that the introduction of new building technologies into older buildings often causes problems, and should only be done with great thought and careful action. Less is usually more if preservation of historic material is your goal.

If preservation of dollars spent on heating costs is your goal, there are usually other places to save many more dollars than you'll find around the windows.

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by hammer and hand great works do stand
by pen and thought best words are wrought
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DBowers



Joined: 30 Sep 2004
Posts: 40
Location: Weare, NH

PostPosted: Tue May 17, 2005 11:55 am    Post subject: Weight Pocket Insulation Reply with quote

I have several customers that are requesting this solution. I have been doing research on multiple types of insulation. I have reservations about using foams and am considering fiberglass batting not packed too tightly so that some air can circulate and moiture will not be trapped. Any comments on this solution or one that might be preferable?

Dave B
Olde Window Restorers
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jade



Joined: 11 Feb 2005
Posts: 786
Location: Hawley MA

PostPosted: Sun Aug 27, 2006 7:36 pm    Post subject: Reply with quote

i have a customer who asked that i replace the rope and pulley balances with spring balances and insulate the weight pocket...my plan is to remove and save the weights & pulleys for possible future use and install a piece of 2" rigid insulation against the exterior wall....this allows space for air circulation and at the same time keeps the drafts out.....

i have yet to use spring balances in the field and i don't exactly look forward to using them....the type i will use are the flat rolled spring tape where the housing looks similar to a rope pulley....if anyone has any tips on how to install them without them coiling out of control, please let me know....these are heavy 7' tall windows.....

thanks...
...jade
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johnleeke
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Joined: 20 Aug 2004
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PostPosted: Sun Aug 27, 2006 7:43 pm    Post subject: Reply with quote

Be very careful with coiled spring tape balances. I had one get away from me and it cut 1/3 the way through the plastic handle of my screw driver as I tried to stop it. If my finger had been there instead of the screwdriver...
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emrude



Joined: 21 Aug 2006
Posts: 17

PostPosted: Sun Aug 27, 2006 10:30 pm    Post subject: spring balances Reply with quote

I am going to be putting in my first spring balances this week. I was going to re-hang window above kitchen sink(small sash) and the pulleys were missing. I brought in a couple of pulleys but when I took off the trim to put them in there wasn't enough space to put in weights. I love remodelers. ;)
The mortise and slot where the old pulleys where will need to be cut larger for spring balance box.
I am still to figure out how to 'charge' balance--I guess that's the part you don't let the tape snap and eat your screwdriver, or fingers.
I'm lucky that this is a small sash.

Marion
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johnleeke
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PostPosted: Fri Sep 01, 2006 10:51 am    Post subject: Reply with quote

Marion writes:

I install a pair of clock spring balances Wednesday. The window was small (32" wide 40" tall) over kitchen sink. The biggest part of the job was mortising into studs that were 1/2" behind the jambs. I got to putting the sash back in, and the left balance wasn't retracting. I called the company and Dave walked me through why it would do this. I looked to be sure there was enough room in mortise. And ended up just hitting the balance on the side until it was working. Of course, I ended up cutting my finger on the very sharp tape.
The window is put together and working for the first time since the remodel--in late 1940's or early 50's. I don't like the action of the clock springs as well as 'real pulleys and weights'. Yesterday I finished the last window at this house. Except for the kitchen window they have all been broken ropes.
I am starting a project where I'm fixing broken sills, stripping, glazing, re-hanging and weatherstripping. It should be fun.
Marion

see the original post here:

http://historichomeworks.com/forum/viewtopic.php?t=606

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jade



Joined: 11 Feb 2005
Posts: 786
Location: Hawley MA

PostPosted: Fri Sep 01, 2006 9:05 pm    Post subject: Reply with quote

i'm hoping to convince my customer to continue to use the original rope and pulley balance system and here's why....the only clock tape balance i have been able to locate are zinc plated...i have found a company who will apply a brass plating to the zinc at $20 per pulley--that brings the total for the pair to $111.50 (that's my price) a bit steep i think.

these are large heavy windows and the top sash is not used....i suggested removing and storing the weight and pulley, install the rigid insulation at the outside wall and the pulley mortise then install blocks attached with brass screws to fix the top sash in place. ...

...jade
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emrude



Joined: 21 Aug 2006
Posts: 17

PostPosted: Fri Sep 08, 2006 5:50 pm    Post subject: Reply with quote

johnleeke wrote:

On one project we saved the original weights and pulleys by installing thin wall metal pipes for the weights to run in and filled the pockets around the outside of the pipes with insulation. Worked pretty slick.


John,
What happens the next time someone re-hangs window? How do they access the weights?

Marion
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johnleeke
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Joined: 20 Aug 2004
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Location: Portland, Maine, USA

PostPosted: Fri Sep 08, 2006 6:18 pm    Post subject: Reply with quote

Marion:

Good Question!

We usually do try to think of the tradespeople who will follow. In this case we cut away one half of the pipe right next to the weight pocket door in the jamb.

By the way, be sure to leave a message here:

http://historichomeworks.com/forum/viewforum.php?f=7

so we can easily refer folks to you and your good work.

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by hammer and hand great works do stand
by pen and thought best words are wrought
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