Odors in small utility room

[rich76]

I have a 1 year old bradford white nat gas water heater. It sits in a small laundry room with nat gas furance and dryer in a tight new construction property.

For the past 2 cooling seasons I notice I strange type odor (NOT rotten egg, raw gas odor) when the AC is running.

Being curious, I noticed tonight when the AC is running I put my nose up by the draft hood of the water heater and there is warmth and a slight odor of what I would relate with the pilot light. This is when the water heater is off, just pilot light. When AC is not running there is no odor or warmth when nose is placed close to draft hood.

Is it backdrafting?

There is no sooting visible on heater, no odor in living space and CO detector in living space has not sounded (I know your run of the mill nighthawk Co detectors are considered crap by the pros but still? ). The small utility room sort of stinks when AC is on, but it could be a mix of that and the stinky makeup outdoor air.

When AC off it just smells like soap (from laundry). From time to time odors acumulate in small room from makeup air... for example, drive way was paved and it reaked of blacktop for a few days in there.


Its also in a subdivision where all dimensions of utility room and equipment is the same.

Should I be concerned?

[4l530]

Originally posted by rich76
the stinky makeup outdoor air.
Why's it so stinky?
Gas being combusted doesn't always guarantee there is CO being produced...in enough quantity to set off a detector.
If you have enough make-up air coming in it's hard to believe there could be much backdraft.
Here's something you could try: Turn on your A/C. Let it run for a few minutes. Now fire the main burner on your W/H and grab ahold of the fluepipe a few inches above the draft hood. If it doesn't get good and hot, or at least pretty warm within about one minute, it's probably backdrafting. Especially if you also feel the heat rolling out from under the draft hood.
If there is an opening to the return there in the room (ie a slot you slide the filter into in the return plenum) it needs to be sealed.

[rich76]

When the W/H is heating water the flue pipe is hot as hell and its going up the pipe as far as I know. From what I describe above, is it normal when air hadler is on to bring warmth and slight odor from draft hood that isnt there when everything is idle??

[rich76]

In other words, some backdraft is normal in a utility room if say my air handler was working and someone sniffed the water heater draft hood at the same time?

[hvac_superman]

This may sound stupid but, is there a floor drain in the room? If they go dry (the trap) sewer gas starts to back up into the room. Run water down drain and presto, problem solved.

[micdundee]

when ac is not running- no odor. leaky return duct and/or loose fit on blower door.seal all and try again.

[firecontrol]

Big houses, sealed tight and small utility rooms where everything is crammed in and some burn gas. When will the deaths, low level carbon monoxide poisonings and premature equipment failures finally get enough people aware that you CAN'T do this? I just hope that the furnace is a sealed combustion unit.
Back drafting of a fuel burning appliance is never an acceptable situation. Your ductwork for your furnace and or the furnace itself is creating a negative pressure in the utility room when the blower is running. The negative pressure is pulling outside air down the water heaters venting. You're smelling the byproducts of combustion from the pilot light of the water heater. Is this good? NO! Is it safe? NO! Is it something that should be resolved? YES!
Do I get excited when I find conditions like this? YES!
No fuel burning appliance should be in the same room with your laundry.
Your dryer when it runs will probably pull more air down the water heaters venting than the furnace does and this is very dangerous because if you're running the dryer it probably means that you just ran the washer and if you just ran the washer you probably used some hot water and this means that the water heater is burning it's main burner to reheat the water in the tank and with the main burner going and polutants in the air from doing wash and drying the flame is burning poorly and producing high amounts of carbon monoxide................ get the picture?
If everything must remain in this room you really need to: The furnace must be sealed combustion certified. The water heater either needs to be replaced with a sealed combustion type or replaced with an electric unit. You should emmediately install a carbon monoxide detector in the utility room and I would also suggest one in the area just outside of the room.
No "after the fact" outside air intake or power air ventilator or gizmo is going to guarantee that you and your family will be safe in all situations.
Live long and prosper :)

[perel]

I'm familiar with the Polaris condensing water heater.. if you're not using it for radiant heating as well, the price is insane. Is there a more reasonably priced sealed combustion water heater, perhaps one that's for DHW only?

[rich76]

I had the utility CO this afternoon with their sniffer. Indeed the heater was back drafting a bit when the air handler is moving.

He measured 3-4 parts per million CO levels around the flue. He said this posed no risk, but idealy 0 is best.

Should I be concerned at this point, and how should I proceed??

I dont think demanding sealed combustion furance and heater is feasible. This property is still under warranty. There is also a fresh air duct built into the room and I am sure it passes all building codes.

Its in a new subdivision with 100's homes all with the same dimension utility room and equipment inside. I wonder if the other homes have the same occurence?

[rich76]

I apologize for multiple posting here. But to update, HVAC contractor coming out on Monday to check it out.

I am curious, besides buying all sealed combustion appliances, what can be done to fix my problem? Add another fresh air duct?

What should I address with contractor?

Should I be concerned with the low level readings at all?

I would apreicate any help you can lend.

[comfortdoc]

The fresh air ducts need to be sized correctly. There should be one near the ceiling and one near the floor. I forget the exact dimensions but I know some gas company employees here would have shut down that furnace and water heater if there was not sufficient air for combustion of all appliances in that room.

Have them make sure the A/C ducts in the utility room are sealed completely also so they are not drawing air from that room.

[Edited by comfortdoc on 08-19-2006 at 11:59 PM]

[t527ed]

sounds like you have a pretty major duct leak that is pulling the house into negative pressure when blower comes on. does ductwork run into a crawl space or attic?

[illtech]

try checking your b vent from hw heater @ furnace they make good bird nests

[rich76]

thanks for the replies. Any input is greatly apreciated so I can speak with the contractor monday with some knowledge.

The duct work runs in the attic.

My concern remains about the PPM thing.... 3 or 4 ppm in the small utility room next to draft hood on w/h. Should I be concerned?

Also providing everything is tight and no obstruction as described above... is it safe to assume everyone in the subdivision with same size room and equipment are getting the same situation?

The builder rep. described a situation where the pilots were being blown out in some of their houses. That an additional fresh duct was put in to solve problem.

The woman went on to say that she never heard of my problem ( however I was thinking, isnt it the same thing with mine and the pilots being blown out?? Not enough combustion air??)