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We live in a house that is approx. 1200 sq ft. and was most likely gutted and 'refactored' by the previous owner. In our laundry room, they built a 'closet' around the water heater and our HVAC unit. In this 'closet', there are two metal tubes or ducts that are circular in shape, about 8 inches in diameter, and almost four feet long. You can shine a flashlight up through it and see the wood at the top of the house.

I have a few questions about these:
What could they be (or have been) for?
Would these be causing efficiency problems?
Should they be removed and the holes filled in?

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Is it or could it have been a natural gas or propane water heater? If it is electric now any evidence of an old gas pipe, odd holes in the floor etc. – mikes Nov 26 '12 at 0:46
up vote 3 down vote accepted

Assuming your water heater is gas, those tubes are likely providing ventilation for the gas burner that heats your water. If so, they should not be filled in, they were most likely deliberately added when the water heater was boxed in.

If you DO want to close them up, replace the door on your closet with a louvered door that have the louvers permanently open.

As for efficiency - the room for the water heater is closed up - so no, the efficiency loss is minimal.

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It is gas (we just replaced it in February, actually. The bottom rusted out the old one and sat for too long doing who knows how much damage.) There is a 1/2"-5/8" gap at the bottom of the door of course, will that be of any significance? – tuespetre Nov 26 '12 at 3:05
It probably wouldn't hurt to put a threshold insulator under the door. soundproofing.org/images/door_seal_c.jpg – The Evil Greebo Nov 26 '12 at 12:42

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