Hot Water Heater smoking and vent has downdraft.


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Old 01-20-13, 11:19 AM
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Exclamation Hot Water Heater smoking and vent has downdraft.

I manage a restaurant with a brand new water heater. This morning we had a power outage that affected some of our systems including our hood vents. I reset those and they are working properly. About 30 minutes ago I noticed smoke coming from the top of our water heater, so I shut it off. When I did this, I felt the bottom of the vent opening and there is a cold downdraft. I am wondering if there is a reset button for the vent or another trick. I tried turning off the water heater and turning it back on but I got the same outcome, with smoke billowing out of the top. I am afraid of gas leaking out so I have not turned it back on, and all of the heating and cooling places in my area are not calling me back. Help!
 
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Old 01-20-13, 11:27 AM
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Sounds like you are getting a backdraft. Very bad. The range hoods probably exhaust a lot of air and are pulling in through the WH venting.

Is the smoke coming FROM the WH or is it being pulled down the vent from the outside?
 
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Old 01-20-13, 11:29 AM
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Looked like it was coming down through the vent.
 
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Old 01-20-13, 11:33 AM
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How is the HW heater actually vented? Directly into a chimney with its own pipe, or does it share a vent pipe with other appliances in the restaurant?

Pics would help if possible.
 
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Old 01-20-13, 11:45 AM
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Kinda thought it was being pulled down. You'll need to see if this is a power vent type WH and if the motor on the vent is working correctly. Post a model and brand and we can determine that.

I think you may find another issue such as lack of make up air when the hoods are running. What goes out has to be replaced. Do you have a fan blowing air IN to the place? Possibly that has failed or is not running.
 
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Old 01-20-13, 11:50 AM
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Pretty sure it runs on it's own pipe.

Here is a pic of the water heater and the vent above it.
 
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Old 01-20-13, 11:57 AM
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Lochinvar 194484 is the model and brand.

We had a huge windstorm last night so something could be blocking the vent and forced it closed.
 
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Old 01-20-13, 12:05 PM
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Hmmm...that's not showing up on their site.

I don't think the WH vent is blocked, since you are getting airflow/smoke down it. There may be something else that has been blocked or damaged though.
 
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Old 01-20-13, 12:10 PM
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Oops...didn't see the pic. Install looks fine, so I think you need to look at other issues as I mentioned.
 
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Old 01-20-13, 12:29 PM
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One thing you could try is to briefly shut off the cooking appliances and the exhaust fans, ensure a nearby door is open then light the water heater and see if it then vents properly.
If the water heater was started after the fans were running, cold air in the chimney may prevent flue gas from rising.

If this does work you need to keep tabs on it.
Do you have a make-up air unit and is it operating correctly.
Have any new appliances been installed recently?
It is very common in my experience for restaurants to have no or inadequate air make up.
 
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Old 01-20-13, 12:36 PM
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Normally we install a sealed combustion unit that takes air from the outside. Its the only way to go. had this issue in a local chicken restaurant. Constantly grease build up in the burner and the exhaust fans pulling air from the HWH exhaust. Always an issue in the winter. In the summer they always have a back door open so it was not noticed all the time.
 
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Old 01-20-13, 01:42 PM
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Here they routinely put a large evaporative cooler on the roof but with no water hook up. It is used strictly to add makeup air to the restaurant. As often as I have seen it done I believe it is a cheap way of complying with code. The (dry) pads acting as filters and to keep out insects.
 
 

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