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Ventilate a furnace room?

etherhuffer | Posted in Energy, Heating & Insulation on July 16, 2008 08:26am

Our furnace room is below our bedroom with a cold air return in the bedroom as well. In the summer, the room gets pretty warm and the cold air return becomes a hot air vent! Both furnace and gas water tank are in there.

Two 8 inch pipes feed air to the tight furnace room. Is it legit to put a fan in one and pull in cooler outside air faster? That should push out via the vent or other 8 incher and cool the room a little. I really don’t want to give myself CO poisoning.

www.etherhuffer.typepad.com

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Replies

  1. Clewless1 | Jul 17, 2008 02:16pm | #1

    I take it the cold air return is a ducted return? Is the water heater gas? Why does the room get warm in the summer? It sound like the two 8" ducts are combustion air ducts provided per code for the furnace and/or water heater. Where are you located?

    1. etherhuffer | Jul 17, 2008 06:13pm | #2

      We are in Seattle. The water heater is gas, the cold air return is a large duct in the bedroom that goes straight down to the furnace room. The tubes are indeed combustion air.

      The room simply accumulates heat due to the hot water tank and pilot light. In the summer, that means pretty warm. And, the exhaust pipe exits up via the bedroom wall too. http://www.etherhuffer.typepad.com

      1. peteshlagor | Jul 17, 2008 10:51pm | #3

        An energy audit.

        Get yourself one of those self proclaimed energy auditors and have him check out your place. 

        He'll come up with areas to save money that will pay for his visit.  At the same time, he'll address what you should do in that furnace room.

         

        1. etherhuffer | Jul 17, 2008 11:09pm | #4

          Not a bad idea except that I know I need a new furnace and don't want to here that. Heh.http://www.etherhuffer.typepad.com

          1. User avater
            BillHartmann | Jul 18, 2008 01:53am | #5

            Well make the new furnace a seal combustion unit and likewise a direct vent WH and get rid of the external combusiton air pipes.That is what I am going to do with mine..
            .
            A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

          2. peteshlagor | Jul 18, 2008 02:16am | #6

            You'll find your energy auditor all over Bill's suggestion.  Big time.

            So plan your project with that as the end result.  May take some time, but it's really the best way to go.

             

          3. etherhuffer | Jul 18, 2008 02:28am | #7

            So where does the combustion air come into the furnace room? I assume it feeds via a smaller pipe directly to the combustion chamber.http://www.etherhuffer.typepad.com

          4. peteshlagor | Jul 18, 2008 02:42am | #8

            A pipe within a pipe.

            The inside pipe carries the exhaust gas out, under force by a blower fan.  The same blower (or different, I suppose based upon the appliance) sucks in the combustion air thru the outside pipe.

            On the outside, there are several means of splitting the pipes.  Mine has the exhaust blowing straight out, hortizontally.  And a mushroom shaped cowl directing the incoming air from behind the exhaust outlet and preventing mixture of the exhaust and fresh air - at least enuff to provide for adequate performance of the unit.

            I've seen other installations where the pipes are not seperated and both vent near one another, but in different directions.  These can have a trap assembly built in.

            Others that know more will be along soon...

             

          5. Clewless1 | Jul 18, 2008 08:03am | #9

            I was thinking he had a standard combustion air system providing combustion air high and low into the furnace room w/out a direct connect. Standard code requirement in the Northwest. So he has two pipes plus his flue goes up through the house (apparently behind a wall adjacent the bedroom).

          6. peteshlagor | Jul 18, 2008 04:02pm | #11

            Well, we're jumping around in time here.  Bill and I are suggesting he swap out the current furnance and water heater.  Thus the discussion of the sealed vents (for combustion air and exhaust).

            Etherpuffer isn't in the mood to hear, or rather think about, a new furnance just now.

            It appears you are focusing on his current problem while we're looking beyond that.

            But we (Bill and I) are inclined to believe the return vent problem will go away with the new system.

            Iz that rite, Bill?

             

          7. User avater
            BillHartmann | Jul 18, 2008 04:35pm | #12

            "Iz that rite, Bill?"Maybe.I am not sure that I underand the problem correctly.In my case I have 2 furnaces and a WH in a utility closet. All with standing pilots.And the room is only slightly warmer than the rest of the house during the summer.And putting my hand on the WH I wouls say that it is cooler than the furnaces with only pilots going during the summer. My WH is about 12 YO and the furnaces 30. An older WH might be giving off more heat.So I wonder if something else is going on.2 things that I can think of off my head is one that the flue runs next to the return.The other is that return uses stud bays and it is not sealed at the top and it is drawing in hot attic air..
            .
            A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

      2. Clewless1 | Jul 18, 2008 08:10am | #10

        Well, then the furnace room really isn't tight, then ... i.e. open return into the room. er ... am I understanding you right? return is fully ducted to the furnace or just dumps into the furnace room?

        I don't think it will be a good idea to do the fan in the combustion air duct approach. Look for an alternative and take another look at the situation. Maybe you have a bunch of uninsulated water pipes from your water heater ... do you have a heat trap on it? The pilot light and associated heat should be small but that heat should go up the flue, not into your space.

        Insulate hot water pipe; make sure you have a heat trap. Feel your hot water pipes ... are they hot? Also turn down your water heater until your typical use pattern runs out of hot water ... then turn it back up just a bit. This will minimize your storage temp to the optimum temperature.

        I'm surprised in Seattle you have a summer overheating issue going on here. The Sealed combustion furnace would eliminate the two combustion ducts, but maybe not eliminate the problem of excess heat.

        Edited 7/18/2008 1:11 am ET by Clewless1

        1. etherhuffer | Jul 19, 2008 04:38am | #13

          Yes, I was thinking tight wrt the inside of the house. Indeed, 2 8 inch pipes to the outside for combustion.

          My cold air return in the bedroom drops into the furnace room, and is taped, but not insulated. The furnace room is therefore relying on fresh air from outside to feed the hot water tank and furnace, and exit, in theory, up the flue.

          There is enough radiant heat that the floor and wall are warmer where the flue runs. I could insulate the return duct with foil, but I am not sure that would really help.

          The furnace is so old that I should go suck up and get a new one. Any experience with hot water/furnace combos? http://www.etherhuffer.typepad.com

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