Exhaust smell coming from hot water heater when it's not running

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Omar Alsweiti

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I don't know a lot about this stuff but i'll give it my best shot.

Background: We came home one day and our hotwater heater wasn't running. Plumber came out and after troubleshooting, he replaced the faulty power vent fan (broke the pilot viewing window in the process though). The hotwater heater started working again. I then turned up the hot water dial to just prior to HOT position.

Now every time we come home, the entire house smells of exhaust fumes. You get used to the smell pretty fast but I managed to find the source was coming from the hot water heater flue as expected. I called 2 different mechanics to come look. One said this is normal (insane), the other claimed that this does happen but there is an intake for our central air in the same room and that's why it's spreading through the house. So he placed metal tape over the pilot viewing window and the intake on the central air ducting.

These are my thoughts/what I've done on the matter:
1) the power vent turns on when the hot water heater turns on, and IMMEDIATELY turns off when the hot water heater turns off. So any residual fumes bellow out the top and into our basement without being vented.
2) I've done ALL youtube/google tests for backdrafting. When the vent fan is on there is no backdrafting (I've tried worst case scenario with negative pressure in the house... it still vents).
3) I've cleaned the top of the heater for any soot and will monitor for maybe intermittent back draft.
4) The heater should have sufficient air flow since it's the same setup it has been ever since we started living here (2 years).
5) After 14-16 hours of not being home (wife works too, we weren't using hot water), there are fumes throughout the house.
6) I immediately check the hot water heater when I come home everyday and this is what I find: The hot water heater is off (just the pilot is on I think?), but I hold my hand to the outside of the flue/vent and feel hot air coming on my hand. This is evidence of back drafting EXCEPT the hot water heater is off, therefore the power vent is off. Is this Normal? Does the pilot really produce that much exhaust that spreads throughout the house?
7) All in all, I have a feeling that the exhaust that's coming from our hot water heater when it's in it's standby condition (burner is not on) isn't normal.
8) Again I stress, since we've lived here for the past 2 years we have NEVER smelled exhaust coming from anywhere in our house and the only things that have changed are: Broken pilot viewing window (has metal tape over it), newly installed power vent fan, turned up the rheostat on my hot water heater for hotter water (just prior to HOT position)

I am calling a 3rd mechanical service place to have them check but I wanted to check here first as I have lost a little faith (and money) to get nothing accomplished.

Thanks for your help!
 

Omar Alsweiti

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Adding more info:
1) We have purchased 2 CO detectors and put one near the Hot water heater and the other in our living room, we have one for our bed room.
2) It is not a gas smell. The scent they put in our natural gas is no where close to this smell. This has got to be 100% exhaust.
3) This has been going on for 2 weeks, so any oil, etc. that needs to burn off has already taken it's place.

Sorry just trying to avoid the usual replies
 

Dana

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With a power vented water heater there should be no path for soot to get onto the water heater. Power vented heaters vent into a sealed (usually PVC plastic) vent pipe.

water-heater_v2.jpg
<<Power vent water heater


If it's an add-on draft inducer to an atmospheric drafted appliance it could be a code violation, or even if legal, it could also be an "orphaned water heater" situation, where there isn't enough heat going into the chimney to keep it drafting properly.

Is it vented into a masonry chimney?

If yes, what size is the chimney liner, and how tall is the chimney?

Are there any boilers or furnaces sharing the chimney? If yes, do they have separate ports in the masonry, or does the water heater vent pipe connect via a wye or tee into the vent pipe for the furnace/boiler?

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Furn-WH.jpg


An atmospheric drafted water heater will always have a convecting hot air flow out of the center flue heat exchanger, often spilling out at the draft hood (contributing to it's standby losses), even though the flue is still drafting adequately. That's not the same as backdrafting. It's not unusual to be able to feel that warm convective draft with your hand in a cold basement. But you shouldn't be able to smell gas exhaust.

A few pictures of your setup might clarify a lot.
 

WorthFlorida

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If you have a gas water heater, I assume you have a gas fired furnace. Forced air?

I would do two things. Check on the outside that the vent is clear. In cold weather critters might have decided to take up resident in the exhaust pipe blocking it. If you can, turn off the gas to the water heater when you leave for the day and when you return at the end of the day, is there any smell? If no then it is definitely the water heater.

If you have a gas fired furnace for your space heating, also check the flute and the on the outside, the exhaust vent or chimney. A possibility, have the plenum checked on the furnace. They can rust through and the fumes you're smelling could be from the furnace.
 

Master Plumber Mark

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There is a good possiblilty that if you are in a colder climate the vent could
be closed off with snow... if you can get the PVC pipe to come off the top you can use a match
to check to see if you are actually drafting properly ....

There have been stories of plumbers using
foam core PVC pipe instead fo sch40... They claim the foam core collapses inward from the heat
and about shuts off the flow through the pipe .......I have yet to see that happen...

you also have not divulged how old this heater is.....
if the unit is over 10 years old I suggest you do not throw any more money at it
and simply shit-can the unit and install a new Rheem Power vented unit....
 

Master Plumber Mark

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I agree with Mark on the 10 year point. Don't throw many at it. And he is very eloquent. :)


No Terry , I dont think I am eloquent....
but if you think so , who am I do disagree with you??


How are you doing this year terry?? Everything going ok with you??
Talking right now on the phone with some little old lady
with a flooding water heater 20 miles across town.... probably will be changing out a 75 gallon
heater in her garage tomorrow morning.... its gonna cost them big time
 

Terry

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I'm doing real well this year Mark. Sounds like you're doing well too. Christmas is always fun. We will watch the Seahawks, eat too much and then ring the bells and do Christmas. We celebrate on the 24th. It works nice because most do it on the 25th, so no conflicts that way. I'm horrible at shopping though. I prefer doing plumbing work as a gift. It's what I do best. I just dropped a new Washlet in my main bath today. The other one was ancient. Still working, but old. The new one does a pre-rinse on the bowl when you sit down.

c100-washlet-02.jpg


TOTO SW2034#01 C100 WASHLET Electronic Bidet Toilet Seat, Elongated, Cotton White
 
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Master Plumber Mark

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we seem to be doing ok this year too... got rid of all the employees last year and
we have just been kicking back and doing what ever comes in on the phone every day
If you have no employees, it seems you dont have the headaches and you dont also have
to take on extra work or god awful nasty work just to keep them busy either......the money is
basically about the same and their is no set time in the morning to start.... that is good.....

nothing pissed me off worse than to show up at the office to open the place at 7.30 only to wait around
until about 8.20 before the morons staggered into work late.... Now we just pace ourselves....
Happy days... do you realize i joined your site back in feb of 2005??
that is 11 years ago.... time has flown by extremely fast...

I remember a few people that were here from way back then and have wondered what ever happenned to them ... I sort of got the feeling they have passed on?? you can update me on a pm some time if you want

have a good x-mas


 
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Omar Alsweiti

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1) the Power Vent is located outside the house, so it draws the exhaust from the heater from outside.
2) The vent piping doesn't connect to a chimney, it literally runs through a hole in the wall to the outside fan chassis.
3) The vent piping doesn't share to any other load. It's only load is the hot water heater.
4) There is nothing blocking anything anywhere in the piping(A plumber and I took the fan and piping apart to inspect). Again, this vents normally when the burner is on. When the burner is off (just the pilot on) nothing vents and the pilot exhaust just spills out into the basement.
5) I think I have answered any questions. But if I didn't could you please specify and I will answer.
6) NEW INFO WE GATHERED: This heater is about 11 years old. The pilot is on all of the time (standing pilot hot water heater, not the electric spark ones), so all of the pilot exhaust is felt and smelled coming out the top of the hot water heater and into our basement (not the vent stack). The power vent fan will not turn on for the pilot because it's driven off of the pressure switch which is made up when the burner kicks on. So if anyone has experience with this setup I would appreciate any advice!
Setup summarized:
Standing pilot hot water heater (pilot is lit 24/7)
Power vent (vent fan located outside and draws from the inside of the house)

Our new plumber came by to take a look and agreed that what we were smelling is exhaust fumes from the pilot. He said he is going to do his research on our options but he thought of a few.
1) see if we can convert this heater to an electric spark to light the pilot heater (newer ones are like this I guess?)
2) see if we can change the vent setup to do more of a natural vent instead of power vent.
3) get a new hot water heater

THIS IS A RENTAL PROPERTY. My land lord does not want to replace the hot water heater and wants to take the cheapest route.
 

Omar Alsweiti

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Here's the power vent fan located outside the house. Again there is nothing obstructing this vent path, I might have a thought that there might be too much headloss in this setup for pilot exhaust to vent (when the fan is off). Any thoughts?
 
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Master Plumber Mark

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That unit is way older than 11 years unless someone rigged up something... They discontinued
metal pipe on power vented heaters probably back around 1993..... It will not ever work correctly...
because it is way too old to rig up pressure switches to and throw tons of time and money at....

the cheapest thing your tight assed landlord can do is just totally tear it all out then run a 220 volt
power line to that area and install a 50 gallon electric water heater..... that is it...

if push comes to shove wait a while then throw a quart of water down into the top of the heater flu pipe
and just tell them that the unit has begun leaking... THEN something will finally happen one way
or another


 

Jadnashua

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IF the vent assembly has a damper in it that only opens when the fan is running, I'd be really surprised if it is legal to use with a standing pilot heating appliance. Plus, if there's not enough vertical component in the flue assembly, it will not be able to create a draft...again, an issue. Especially if the WH turned on when the power was off...all of the exhaust would then be dumped into the building - a major health issue that could literally kill you.
 

Omar Alsweiti

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@ Master Plumber Mark- Haha thanks i'll probably have to consider that.
@jadnashua- The damper is always open, whether the fan is on or off (when we took apart the fan enclosure we saw the open damper inside the vent pipe). The hot water heater has a safety feature to shut off gas to the heater if the power vent fails to come on so hopefully that would still work (that's how we replaced the fan in the first place because we couldn't get the pilot lit)
 

FullySprinklered

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I have a growing number of clients from the subcontinent, so I have to ask. Did your mother in law just come over from the old country and take over the household cooking responsibilities?
 
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