Water Heater FVIR Sensor Chronic Issue

[paulkem]

My water heater is around 11-12 years old and I have been having issues with it for at least 7 of those years. Every so often, without much of a pattern that I have noticed, the Flammable Vapor Ignition Resistance sensor will trip and kill the pilot light. I contacted the manufacturer in 2015 (I cannot recall if this was the first time, or the first time they sent me an email) and they instructed me on how to reset the sensor and clean the filter screen on the bottom of the unit. Usually these events last a couple of days of repeated outage, clean, relight, and then it stabilizes for many months. I have had no other indicators of what may be triggering these events. I am currently going through a period of frequent outages.

I spoke to a plumber about it this summer and he said some models with FVIR are touchy and the issue is more than likely due to the space where the water heater is installed, which is a dirt floor section of my basement, near the HVAC unit. He said that if I replaced the unit, I would probably have the same issues, and then would be even more mad because I paid $800-1200 for a new unit and installation.

Over the years I have wondered if there could be a way to monitor the flame, if for no other reason than to know that it is out before I get in the shower in the morning. After an outage earlier this summer, I found a project that did exactly this. It is a light sensor that sends a message to a small matrix display, with different patterns for different light (and therefore flame) characteristics. The totally bizarre thing is that the day after installing it, I experienced an outage.

Using the monitor, I have noticed a couple of things. First, the outage appears to occur immediately after a full flame event (but not after every full flame). Also, I cannot immediately reset the "Flammable Vapor Ignition Resistance switch" until some time after it tripped and killed the flame. I guess it takes time to "reset".

This is so frustrating. I have considered replacing the unit over the years, but previously it was a matter of principle since the unit was not that old. But after what the plumber said, I do not know if that is even the best course at this time. Do I look at tankless? Is there a better pilot light design now? What other data can I gather to figure this out? I am absolutely not opposed to buying a new unit since it is getting old now, but I do not want the same thing to happen with the new one.

 

[Twowaxhack]

Dirty environment is not good for the safety systems on water heaters.

 

[Tim Whistler]

If you get a new heater, try putting it in a large water heater drain pan to keep airborne dirt/debris from fouling the FVIR.
Also, are you SURE that there's no possibility of an actual flammable vapor nearby? Varnish/stain/turpentine, whatever?
Did you ever get a NEW sensor? Or are you just clearing the old one after a few hours? Could be a faulty unit...

 

[Mitchell-DIY-Guy]

Who ever thought a dirt floor is good for any home appliance?

 

[paulkem]

To be clear, it is not actually sitting directly on the dirt. The room is a dirt floor crawlspace. It is sitting on cement blocks, next to the HVAC unit. I guess whoever built this house in 1972 (assume before FVIR sensors were a thing) thought it was a good place.

I don't think there are any vapors that would trip it. I have some latex paint stored on the other side of the crawlspace, probably 20-30 feet away. I will do a scan again just to make sure.

I have NOT tried replacing the sensor. My thought was that if it was the sensor, it would not be this sporadic, but I could be wrong I suppose. Is that what I should look into next? Keep in mind, it has been doing this on and off for at least 8 years.

This last bout is definitely the worst it has ever been. I bet I have reset and relit that thing at least 30 times this week. Pretty much any time that it burns while hot water is being used. (showers, dishwasher, etc), it will trip. From what I gather, it triggers on heat? I have brushed and vacuumed that screen on the bottom many times. I even did a smoke test yesterday and it looks to me that it is venting fine, but I can check that again this weekend too.

This morning I am actually shifting to electric if that would prevent the disappointment of having the same issues with a new unit.

Thank you all for your replies, I appreciate the input.

 

[Twowaxhack]

I’d replace the water heater. Make sure the vent piping is proper. Make sure you size the water heater for your needs. Consider relocating the water heater. Check your gas pressure.

 

[paulkem]

Relocating is not an option. The gas pressure is an interesting thought. What would that entail and what would the cause/effect be?

 

[Twowaxhack]

Relocating is not an option. The gas pressure is an interesting thought. What would that entail and what would the cause/effect be?

its tripping out because it’s getting hot. Usually that’s from lack of air, obstructed vent, flammable vapor burn. But it could be from high gas pressure. It’s worth checking.

Maybe seal the floor since you can’t relocate. Build a room around it, add air intakes from cleaner sources.

 

[breplum]

You haven't noted the brand and model. Pass it along please so we know what product you have been dealing with.
Different mfrs use different FIVR tech. A different brand and model may certainly be a good refresh in this case, as long as your basic conditions are not an ACTUAL cause of the issue.
You can also check out replacing with a new heat pump water heater and get rid of the greenhouse gas part of the equation.
I am a Navien tankless NPE A series fanboy. Installed another just yesterday.
But, that is an expenditure only for those willing to spend well over $4K

 

[Mitchell-DIY-Guy]

Who ever thought a dirt floor is good for any home appliance?

I assumed it was sitting on blocks.
Still, a dirt floor crawl space (unless encapsulated) is an inhospitable environment for anything. Good for mold, and other nefarious things.

 

[paulkem]

It is a US/Craftmaster Water Heater Company model BFG1F4040S3NOHV, purchased at Lowe's in 2009 I think.

I mean, is this a common thing for people who have their water heater in unfinished crawl spaces? Surely I cannot be the only person who has their water heater in this kind of environment, right?

 

[Twowaxhack]

It’s common for heaters installed in dirty environments have problems like your having.

 

[paulkem]

Well crap. Would gas tankless have this issue too? Is electric really my only option to be sure this is not an issue with something new?

 

[Twowaxhack]

Tankless needs good air also or it’ll shorten its life.

Electric wouldn’t be affected.

 

[paulkem]

And I guess furnances do not have the same type of setup or safety measures? My furnace is also gas and is right next to the water heater and I do not have issues with it. It is maybe 4 years old.

 

[Twowaxhack]

And I guess furnances do not have the same type of setup or safety measures? My furnace is also gas and is right next to the water heater and I do not have issues with it. It is maybe 4 years old.

It’s not good for furnaces either.

Your installation location is not good.
Period

Have a great day, I’m done with this one

 

[arctic bill]

most people do not realize that gas water heaters need ventilation . There are two components to venting. Your water heater needs to exhaust flue gases safely, and it must also draw fresh air .

 

[Mitchell-DIY-Guy]

It is a US/Craftmaster Water Heater Company model BFG1F4040S3NOHV, purchased at Lowe's in 2009 I think.

I mean, is this a common thing for people who have their water heater in unfinished crawl spaces? Surely I cannot be the only person who has their water heater in this kind of environment, right?

As a home inspector I don't often see water heaters in crawl spaces, mostly because there is generally insufficient head room. I did encounter one electric one (short and fat) in a crawl space last year, but not any gas units.

My own is in the garage, gas. Others in the 'hood have them in the garage or the (oh please no) attic. Many are electric. When any kind of appliance (which would generally be a furnace or similar) is in an unfinished crawl space, unless the dust and dirt is kept down (encapsulation) or it has a cement floor, it provides a very inhospitable environment. Doesn't mean builders don't think its ok...what do they care? They'll be long gone and then it's the homeowners issue, not theirs.

As has been pointed out you need fresh air, and a place to exhaust the fumes. If you have too high a pressure positive or negative in the crawl space you are going to affect the flame of any appliance. My furnace is in the encapsulated crawl, but it's a condensing unit with separate intake and exhaust. No issues there, and the environment is kept between 50-60% RH. Quite comfortable.

 

[paulkem]

This "crawl space" is not tiny. Perhaps this is not the best term to use. It is a large area, maybe 15x15 ish? But, it does have a dirt floor and is not "finished" in any way. It is a little humid in there, but I run a dehumidifier to help dry it out a bit. There is a vent pipe for the water heater, obviously, and it does seem to be drafting properly as far as I can tell. The intake could be an issue, as it seems kind of small in design. Relocating or encapsulating the unit are not really feasible options. I could try a bed of gravel around the unit to help keep down the dust. I have contacted a plumber to discuss options. I do think that a new gas water heater would probably work fine, and there is just something wrong with this one, or that maybe there is something wrong with the gas pressure. But, I do not think I am willing to take the risk of replacing with gas and having the same issues. From what you have all told me, it sounds like the only way to be sure there will be no issues is to go electric. I do not love the idea since it has its own drawbacks, but I just don't see any other way.

Oddly enough, today the unit has gone through 2 burns (not sure how long) and did not trip the FVIR.

 

[Mitchell-DIY-Guy]

My present crawl space is 1700 square feet. The area of the space doesn't relate to the terminology. A crawl space is any space underneath a home in which the headroom is insufficient to properly stand up in, so anything less than 7' would probably be called a crawl space.

The dirt floor or unfinished floor also doesn't make it a crawl space. There are a number of older homes in the northeast and upper midwest (ones I know about; probably in other places too) that have basements in which you can stand up in (7-9' from bottom of joists to floor) that have dirt floors. Conversely there are some crawl spaces with a small amount of headroom (2-4') that have somewhat finished floors of concrete. The photo attached is a "four-block" crawl space in central Michigan, my last home. It's very easy to control humidity, heat, and indoor air quality when you have such a space. If you control those things, the environment becomes good for appliances and bad for things like mold and vermin.

Where I came from in the NE and Midwest, regardless of basement or crawl space, or headroom, the excavation to create the home was done to make a flat, level floor. They do NOT do that around here in the SE. My present crawl space has about 5' 5" headroom in one area, and as little as 24" in others. They seem to follow the terrain, which of course saves on excavation.

When I moved into my home in December 2019 here in North Carolina, it was heating season. As soon as the a/c season started, a quick visit to the crawl space yielded what the inspectors called "a swamp". It was 98% humidity. Puddles were forming all over the "vapor barrier" (just plastic haphazardly spread over the dirt floor) as leaks from the a/c caused rampant condensation all over. The air handler for the a/c unit was sweating, too, even though it was insulated. Mold was forming on the joists. Did I mention this was a new home, and the builder said "it meets code"? Those who write the code are clueless. No reason why mold should be growing on the joists in a new home.

NOBODY likes spending money, and even less so on things they cannot see. They'll choose crown molding and quartz counters over crawl space encapsulation 99 times out of 100. I chose to encapsulate as I found living above a swamp not something I wanted. But in all my inspections, have not found a crawl space that provided a nice environment for anything except the things you don't want in a home...they are all dank, full of bugs, insects and goodness knows what else, including mold.

It should be no surprise that a large number of the encapsulation folks do this as a sideline to their main business of pest control.