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blown-in insulation in a wall w/plumbing

rviger's Avatar

Join Date: Dec 2004
Posts: 89

10-09-06, 12:50 PM   #1  
blown-in insulation in a wall w/plumbing


I'm modifying ventilation in my utility room so external air feeds my boiler & potable hot water heater. I'm planning on replacing the louvred door between this room and the living area with a fire-door or something similarly heavy. I'm thinking that I want to blow (cellulose) insulation into the walls and ceiling of the utility room, as well. One of the walls contains plumbing for an adjacent bathroom. I didn't know if I needed to worry about moisture (condensation or drips) in the wall creating a nasty mold/mildew situation with any inserted insulation.

Is it okay to put insulation in like this?

Thanks for any information.

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Concretemasonry's Avatar

Join Date: Mar 2005
Posts: 6,125

10-09-06, 02:13 PM   #2  
blown-in insulation in a wall w/plumbing

Just curious - Why are insulating the wall beteween the utility room and the living space? (Wall between conditioned space and semi-conditioned space)

The amount of cold fresh air drawn in is determined by the boiler demands. There are methods to prevent siphoning the warm air out.

The money saved (if any) would be much less than the cost and trouble. The hotter your utility room is, the faster you lose heat through the wall, so the insulation gain is not what you would think. Insulation may provide a slightly cooler environment for any very sopisticated and tempermental electronics you may have on the wall to utility room.

You should not have mold problems either way since the cold air coming in will be dried out as the temperature rises. You obviously have a vent in the bathroom to handle the excess moisture from showers, etc.


rviger's Avatar

Join Date: Dec 2004
Posts: 89

10-09-06, 03:46 PM   #3  
Hi Dick,

Thanks for your response.

I'm realizing that I didn't specify that I was talking about insulating the interior walls in my original post (although you may have already figured that). This may or may not be important.

I was thinking about insulating because the boiler & hot water heater will be drawing cold air into the utility room. Although I understand that the machines will pull the same amount/rate of air into the room as is pushed up the flue by their combustion, I thought the utility room itself would be cooled by all this. My assumption is that the reduction in the long-term temperature of the room would cool the walls and eventually the neighboring (conditioned/heated) rooms.

Putting in the heavier/tighter door was what appeared to be the best tactic to keep the warm air from being siphoned from the conditioned rooms into the utility room.

I'm happy to believe that insulating simply isn't necessary. Less work! Just didn't know if this was true.


P.S. I definitely don't have any fancy stuff in the utility room. It's a late-60s hydrotherm boiler. The hot water heater is a new white-rodgers, but standard (tank) technology.

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