Blown-In Insulation

Dan_15

I installed a new Buderus G215 last season with indirect tank and I am not seeing the heating savings I know that big blue baby can achieve. (Although DHW efficiency is super). Part of my issue is that I have a high mass system with a lot of water to heat, but my core problem is really the tremendous heat loss in my uninsulated 1921 plaster and lath house. I am looking for some advice on the best way to blow insulation into the exterior walls. I hate the thought of punching a hole into the interior plaster/lath in each of the stud bays. My interior walls would look like swiss cheese. To my advantage, the house is old enough that the exterior walls are framed out with horizontal planks, and covered with clapboard, so I was thinking that I could access the stud bays from the outside by pulling off a couple of rows of clapboard and plank. But who knows what kind of conduits and stuff may be attached to the inside of those plank walls. Can anybody give any advice about blowing insulation into an old house? I know its not a boiler question but it critically affects my heating system!

Thanks.

Ken D.

Insulation.

There is a blown in tripolymer foam insulation that works well. Two small holes are drilled inside or out. The stuff goes in like shaving cream and surrounds and covers everything in the wall. It has a good R value and the main vehicle is water, so there is no hazardous materials to breath in. A couple of dowels for each bay and you're in business. Go to this website- www.tryfoam.com. Hope this helps.

Andrew Hagen (ALH)

Check out

the videos at Icynene.com.


In particular the "pour foam" video

-Andrew

Mark Hunt

Insulation


Increasing the thermal envelope on your home is always a great idea.

I would caution you to be sure that there are no live circuits of knob and tube wriring left in the house if there ever was any. Packing insulation around these wires is a no-no. Excessive heat can cause a fire.

Also consider that your boiler was sized according to your homes current heat loss. Adding more insulation will change all of that and your boiler may then be over-sized. Once you have made the improvements, have a heating contractor do another heat-loss with the improved thermal envelope to determine just how far apart your required heat load is from the boilers capacity. Some adjustments in control strategy may be required.

Mark H

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Jay_17

Another consideration

I faced somwhat the same dilemma, but since I ended up removing the clapboard and vinyl siding, I was able to pull some of the sheathing boards off and fill the cavities with fiberglass (and remove knob and tube!)
Another thing to consider is that your siding depends somewhat on the space behind to allow moisture to escape, I have been told that clapboard installed as it is on your house may last 100 years (if you keep it painted) but with insulation and nowhere for the moisture to go when it penetrates the clapboards it can rot prematurely. They recommend firring new clapboard away from the sheathing for just that reason.
Jay

Ron Schroeder

Oversized heating system in well insulated house

If you end up with an oversized heating system after insulation, you can just underfire the boiler. With proper controls, especially pump logic, you can down fire quite a bit without condensation problems.

My house is so well insulated that even the smallest oil boiler is way oversized if fired at its normal rate. I have been successfully firing it at less than 1/2 of it's firing rate (.25gph, yes, one quarter gallon per hour).

I currently run a wider than usual differential on the DHW indirect (40 degrees F) and cold start the boiler in the non-heating season for absolute minimum standby losses. In the winter, I keep a minimum boiler temperature of 135 degrees instead of cold starting since my basement zone needs the heat anyway.


Where it can be installed easilly, cellulose is the most cost effective insulation that can be blown in but needs larger holes than the "shaving cream" foams. Your best bet might be foam in the walls and cellulose in the attic in an older house, but, as mentioned before, some insulation is not compatable with knob and tube wiring.

Ron

jerry scharf_3

watch out for voids (which is quite hard)

Andrew,

Inynene is very difficult to retrofit without voids. You pour the slop in and you have little control over where the foam does and doesn't go. The manufacturer seems to not ackowledge this issue.

I know of one group who travels the country doing this. They use FLIR or similar infrared cameras to phtogragh each wall as the foam cures. Any cold spot are drilled and refoamed. It's neither an easy nor cheap to get this done (each camera is ~15K$ and probably don't last forever with the daily use.) If the people you talk to don't have this equipment/procedure, I'd pass... Dense pack cellulose is much more forgiving.

jerry