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DangerMouse 11-28-2011 10:27 AM

Registers in crawl space?
 
I have at least two registers/vents/openings built into the plenum in my crawl space. Is this normal? This is NOT supposed to be a 'heated' crawl space. Even when they're as closed as I can make them, they still bleed a ton of hot air down there. The only reason I can figure is I questioned their using a skinny, clear 1/4" drain hose to the kitchen sink drain. I told them that it will more than likely freeze solid the first time the temp drops below 0 since this crawl space is supposed to be sealed/insulated, but not heated.
Do you think this is their solution? Heat my crawl space?
Just wondering if registers down there are "standard"?

Thanks!

DM

gregzoll 11-28-2011 10:37 AM

Tape the joints with foil tape, and paint mastic over that. Even better, get the insulation sleeves for the vents, and insulate them after you close all the joints. The living space will actually stay warmer.

biggles 11-28-2011 11:58 AM

pull the registers and cap over with sheet metal if the duct is wrapped just add standard insulation over the patched tuck and tape it....the heated duct insualted or not will temper the crawl during heating season.if they get a quick burst of cool air in the winter just as the fan starts the heat is being pulled into the crawl in the off cycle....couple of 100watts lights will do the same keep it from freezing....:wink:

CrawlSpaceMoist 11-28-2011 09:52 PM

One issue may be a simple misunderstanding.
Most State Codes (as far as I know) require that a Sealed Crawl Space be 'conditioned'. This can be via dehumidifier or by letting hvac air into the crawl.
You may not want a heated crawl, but perhaps the hvac air is being used to control the moisture/humidity down there?

DannyT 11-29-2011 12:56 AM

I would replace the kitchen drain hose first with at least 1-1/2 pvc or abs pipe.

beenthere 11-29-2011 04:27 AM

Unless the crawlspace also has a return, seal those supplies. As they put he house into a negative pressure, and force unconditioned air to be drawn into the house, drying it out in the winter.


Not uncommon to have a single small supply and return in a sealed crawlspace. But usually only large enough to prevent a stagnation of air in the crawl.

DangerMouse 11-29-2011 04:59 AM

Quote:

Originally Posted by DangerMouse (Post 780589)
Do you think this is their solution? Heat my crawl space?
Just wondering if registers down there are "standard"?

Anyone?

Thanks!

DM

Marty S. 11-29-2011 05:31 PM

The register probably is to prevent frozen pipes.
Is the furnace gas and is it in the crawl too? If so they might be combustion air supply.

Bud Cline 11-29-2011 06:30 PM

In this area full basements are common but new additions get crawl spaces. In my case all the additions I deal with are for kitchens and bathrooms and "YES" the crawl spaces get conditioned air to keep plumbing from freezing.:)

Gary in WA 11-29-2011 08:38 PM

Post #4 nailed it; “R408.3 Unvented crawl space. Ventilation openings in under-floor spaces specified in Sections R408.1 and R408.2 shall not be required where:
1. Exposed earth is covered with a continuous Class I vapor retarder. Joints of the vapor retarder shall overlap by 6 inches (152 mm) and shall be sealed or taped. The edges of the vapor retarder shall extend at least 6 inches (152 mm) up the stem wall and shall be attached and sealed to the stem wall; and
2. One of the following is provided for the under-floor space:
2.1. Continuously operated mechanical exhaust ventilation at a rate equal to 1 cubic foot per minute (0.47 L/s) for each 50 square feet (4.7m2) of crawlspace floor area, including an air pathway to the common area (such as a duct or transfer grille), and perimeter walls insulated in accordance with Section N1102.2.9;
2.2. Conditioned air supply sized to deliver at a rate equal to 1 cubic foot per minute (0.47 L/s) for each 50 square feet (4.7 m2) of under-floor area, including a return air pathway to the common area (such as a duct or transfer grille), and perimeter walls insulated in accordance with Section N1102.2.9;
2.3. Plenum in existing structures complying with Section M1601.5, if under-floor space is used as a plenum.” From; http://publicecodes.citation.com/ico...008_par002.htm

Gary


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