Water Heater Pilot Light goes poof!

Jerry Enns

Background:
New 80 plus furnace 8 months ago
New AO Smith water heater two months ago
New Ream water heater 1 month ago (thought it was a bad water heater)
It is suspected the new furnace has more venting than before and when then furnace kicks in the venting of the furnace is creating such an up draft that it snuffs out the pilot light on his water heater since the two vents are connected.
He is thinking about going to electric now, but I think there should be an easier solution.

Kal Row

first...

is the flue really sized properly for both - taking into account the forced draft furnace? - if not, make it legal

also is the pilot really the correct size, and is the orifice really clear, and how about your gas pressure when the furnace goes on – quick test, take the flue off the water heater, if the pilot still goes out when the furnace goes on – it aint a flue problem


things to try:

a bigger draft diverter hood or an inline horizontal one

put in a forced draft gas unit - everybody make them now

or a fully condensing cpvc venting gas unit

i have seen pilot orifices drilled out one size bigger and the pilot flame diverter bent so that only the same amount of the thermocouple is in the flame, (this idea is neither good nor legal but will work if you are having gas pressure problems)

Kal Row

Dale

80 %

The 80% can be common vented with the water heater, the water heater should still go into the main vent higher or manifolded. Since the combo is now Fan+Nat the common vent or liner doesn't need to be too big, if you give us details we can be specific, but 6" liner is probably plenty big. The other common problem is gas pressure. You need a manometer on the water heater inlet and make sure it doesn't go below 4" or so when the furnace starts. Also, if the heater is new is it a FVIR model? is the air inlet clean? What is the tcouple closed circuit output? This can be solved.

Unknown

FAN + NAT problems

it seems that even when we use the charts and tables for sizing these together today we are having problems. Even when sized correctly we have pilot outage problems.

My first suggestion if it is possible is to disconnect the water heater from direct contact with the furnace flue. Is it possible to put it into the common vent above the furnace and seperated from it?

You could also be having a depressurization problem caused by the furnace running and the fan on the furnace changing the pressure in the combustion zone. Is there adequate combustion air. The fact that two different water heaters had the same problem tell me there is nothing wrong with the water heaters but something in the combustion zone.

This is new equipment so pilot orifice size should be fine however you can still check it. If this is a new FVIR water heater do not modify pilot of burner in anyway as it voids the warranty.

I would not start adding any draft hoods as this can only increase the problem. We do not need extra dilution air and in fact may need less as the fan may be causing more air to be pulled through the water heater than necessary.

Do not drill out the pilot orifice. Most of them today on new water heaters are not a hole but a special configuration to control pilot from lifting away from the thermocouple. Drilling out pilots to solve pressure problems is not a good idea. What do you do when the pressure problem is solved? You now have an orifice which is too large. Solve the pressure problem is there is one. Speaking of which with the furnace and all other equipment running you should have a minimum of 6" W.C. pressure ahead of the heating and water heating control. The pressure after the control should be what the rating plate calls for.

I would also take a set of millivolt readings on the water heater pilot. Leave the millivolt meter hooked up and watch what affect the furnace running has on millivolts. The reading should stay stable and not fluctuate. If it starts dropping then you are definitely having a problem with the furnace fan. Now run it with out the furnace and see if it remains stable. It is important to know that pilots on water heaters are regulated through the water heater control.

I would also hook up your combustion analyzer and watch for drastic changes when furnace is on versus furnace off at the water heater. Do that while at the same time watching your millivolt readings.

There are some other things you might try but I would prefer not posting them here. If you want to give me a call at 401-437-0557 I can talk to you about them.

Sweet

pilot out

Code in my neck of the woods requires 12 inchs vertical rise off H.W.H when vented common with any draft induced appliance.

Bob Harper

diagnostics

I agree with most everything Timmy said. The only thing I partially don't go with is the two separate breechings. If this combo is common vented into a properly sized liner, and it should be, you have the opportunity to manifold them. However, instead of the normal 3" off the DHW heater, increase it to a 4" then back to a 3" as it enters the stack. Use a wye fitting so the DHW heater comes in on an angle. The expansion chamber can reduce any blowback from the pre/post purge fan.

I'd do a full checklist but I'm betting on inlet gas pressure, partially clogged valve, or Combustion Appliance Zone (CAZ) depressurization.

On the inlet pressure, record the static inlet to the DHW heater, then with it firing, then with the furnace on. Note if the inlet pressure drops below spec. Now, fire the other appliances in the house and look for bottoming out. If so, you can either increase the house pressure (at the meter) or improve the gas piping. By this, I mean, size, restrictions, materials, etc. Sometimes it helps being attached to the main grid upstream of the other large hogs. Add up the total BTUs in the house and compare with the meter's CFH rating. Also look at any regulators, valves, etc. Consider getting the gas co. to install a 12.2 wci spring in the meter's regulator.

I agree with the test where you pull the vent connector off the water heater and see if it still drops out.

Test the EPU for dropout. Is this the correct thermocouple or did someone install one of those universal ones? Always use the OEM parts on gas controls.

Take a pressure reading right off the pilot tube. Replace the orifice and pilot burner as needed. Do NOT drill out orifices!

Disconnect the gas pipe from the valve and look for pipe dope, Teflon threads, rust, water, gas condensates, etc. Crack the gas line and listen for gurgling and feel for debris. I once was hit with gravel! Water is more common than you'd think. Does this piping have a proper sediment trap?

Is the duct work sealed on the furnace, esp. on the return? How about the filter slot? This should not only be foil taped but have an interlock per NFPA 54. Use duct sealing mastic only with mesh reinforcing on duct joints. Measure the room for confined space rules and assess makeup air. Provide air as needed. I use a manometer to test for depressurization in the CAZ. No more than -3 Pascals for me. Follow up with CO testing.

HTH, Bob

Mark Hunt

I bet


that the furnace is blowing the pilot out.

I have yet to see a fan assisted appliance common vented with an atmospheric appliance where the fan did not push through the atmospheric. Not ever.

Simple way to test this. Hold a match near the draft hood on the water heater and see what happens when the draft inducer on the furnace comes on. I'd bet money that this is what's happening.

Now take this one step further. There is a pressure switch on the new furnace that is supposed to keep the furnace from firing in the event that the flue gets blocked. But being common vented with that atmospheric water heater, the flue can NEVER be blocked. The chimney could collapse and that furnace will continue to run and the drfat hood on the water heater will be the new chimney.

I have heard rumors that a certain water heater manufacturer is going to forbid common venting with a fan assisted appliance.

This IS a draft issue, but it is 180 degrees the opposite way. The pilot is being blown out, NOT sucked out.



Mark H

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Unknown

I agree with Mark

I have been seeing this happen so much lately tht I am telling people not to vent fan assisted furnaces and boilers with water heaters. I know the code book says you can but remember this all the codes in the world are only right when it works if it is not working it is unsafe.

The only other thing I have tried is to give the water heater flue directly off the top of the heater about 10 to 12" of rise. another alternative is to increase the size as I believe Bob also offered, I just would not reduce it back again. Bottom line no matter what we try it has to work ALL THE TIME!!!

Kal Row

aosmith solved the blow out problem...

with their internaly domed diverter hood
(see pic)
question is - do you get more venturi effect suction when sharing with a forced draft, pluging in above it below it or do you always need and upsidedown "Y"?

Jim Davis_3

As I explain in every seminar this is one of the most dangerous installations commonly allowed today and it will continue for a while because the code(Cheap-Obstructive-Disfunctional-Enforcements)allow it. What people don't realize is that all the ones that aren't blowing out pilot are intermittently poisoning the occuppants of the building, but only under certain conditions. I have a letter from a builder in 1997 that had to buy back a new house 2 months after a pregnant woman had CO in her house(over 100ppm) because of this installation even though it only happened once. She also found out it could and would happen again. There are tens of thousands of these all over the country and those with flue liners are even more dangerous because they cause even more blow-back from the furnace down the water heater. There is a fix for the the problem that will prevent high levels of CO from being produced and the pilot from going out and even shut the equipment off if the flue plugs, which they won't do now! Everyone of my students knows the procedures, protocols and proper diagnostics to evaluate, repair and gaurantee safety.

Kal Row

you care to share - your fix...

The fix i use is to have "duct fan" in the fresh air duct feeding the boiler room, relayed off the heat demand, - so as to "fresh air" pressurize the boiler room, and to have a pressure switch with the fan to actually interlock the burner to protect against fan failure -

i was also thinking of setting up the flue tee so that the forced air device, "venturi sucks" on the natural draft device

an even bigger problem is clothes driers and exhaust fans in basements sucking the life out of the house literally

you, timmy or mark, aught to publish solutions for those who don’t get to your seminars

Unknown

kal

I have been thinking about that very thing. I do feel that I do not have all the solutions to every problem but some that I am sure I could share. The truth is it goes to the overall problem of air for combustion, combustion zone pressure problems and the attempt by manufacturers to find ways to still allow connecting equipment together that helps to see that it still gets sold and installed.

I would love to write a manual with cooperation from Jim Davis, George Lanthier and anyone else who has the willingness to share their ideas and solutions. It is however sometimes the case that it would be a better way to have everyone go to a seminar and receive first hand instruction.

I would love for Jim to share here with us exactly what he does to solve this problem or maybe one of his students would share.

Jim Davis_3

kal, I wish it was that easy. The fix will go against everything that everyone thinks they know. I have read many of those misconceptions on this post already. Mechanical combustion air is a mandatory requirement but it is only a part of the fix. Having pulled the pilots out of many new water heaters I know they are intentional mis-sided for all the wrong reasons. 75% of them are in improper positions. The conflict is which is more important, inconveniencing the customer while keeping them safe or not incoveniencing them while they are poisoned. The industry standard is the latter. Without knowing all the supportative data that has gone into the solution, most contractors say I ain't going to do that! This is a potentially life threatening situation that requires complete understanding not maybe's or could be's or try this or maybe that. Those that do not know the solution to these types of problems need to take the time to learn.

Kal Row

You’re right about the manufactures

the little dome inside many WH diverters protects against downdraft pilot blowout - they all should really be built like the pilots in the “flue-less” fireplaces (another really dangerous device) - where the slightest lack of oxygen will extinguish it

I see a lot of sealed combustion WH’s in aosmith’s new lineup – I think that the public would buy them en-mass if they were low-voltage battery backed up units that could run for weeks, after a hurricane or ice storm induced power failure

Unknown

Aw shucks Jim I guess

the only way we will find out how to help this poor guy is to have him attend your class. What would you suggest he do in the meantime?

Why all the cloak and dagger stuff just tell us what you do, inquiring minds want to know. This forum here on the Wall is for sharing what we know and I think there are a few of us here that can handle what ever you tell us.

I know I have had this problem and some of the things I have shared here on the Wall have worked but I just keep feeling frustrated when you answer a post and do not tells us what to do. You know more about this stuff than any of us and we want to learn so please help us out. You sort of leave the impression that the rest of us do not know what we are doing which is probably true but now is the time to start sharing other wise dangerous incorrect information gets given out from the rest of us who do not know. Please help us out.

Unknown

Jim I am curious

as too what you would do to relocate pilots on water heaters. I assume you are talking about pressed metal burners that have been around for about 20 years now. If you feel you can answer here I would appreciate hearing what you would do to relocate or whatever.

Do you also feel the old pilot locations on cast iron burner was incorrect?

I do not quite understand the term intentional mis-sided for all the wrong reasons and that 75% are in the wrong position.

I have my own observations about this and wonder if we are in agreement as to problems with pilots on water heaters.

Rich W

pilot

Hi Jerry, I have seen many problems like this in the last 25 years. However, we could speculate forever without all the proper information. ANY changes to the furnace room are important. Like, maybe there was no furnace room and now there is. IS there a new metal chimney liner-what size? Did you install new windows? I have seen this cause your problem a dozen times atleast.If my wife does not use the proper ingredients AND measurements, the cake will not taste right. This is a bit more important...What has changed?

Mark Hunt

I believe he said


that he now has a fan assisted furnace where an atmospheric used to be.

No chimney liner.

As I stated, I have yet to see a fan assisted appliance NOT blow through a commonly vented atmospheric appliance. Not once and I have tested hundreds.

Your questions are valid. Depressurization of the combustion appliance zone could cause issues. But.....a fan assisted appliance could handle a higher level of depressurization compared to the atmospheric which can handle almost none. BPI sets the limit at -3 pascals for an atmospheric water heater. Heck, leaky return ducting on a forced air system can do that much.

The change here was the addition of a fan assisted appliance.

Common venting FAS appliances with atmospheric should be outlawed.

Mark H

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Larry Weingarten

Perhaps...

this is a topic for the next Wetstock, where face to face discussion makes it harder to misinterpret what's said. Or maybe we need to wait for Wetheads.org to happen. Whatever, I'd LOVE to sit in at that discussion.

Perhaps we could all contribute to a technical work that Dan could sell.

Yours, Larry

Dale

Am I missing something?

Jim, the poster said these were new standing pilot natural draft water heaters, to me they MUST be FVIR technology unless some old stock was installed. I have a AO smith burner on my desk and can't think of anyone I know that would change this from as manufactured. Are you saying that you recommend moving this pilot assembly from the way it was tested and approved?

Kal Row

lets face it folks...

with higher fuel costs, and tighter emission and safety standards, the time of natural draft anything is over – the great thing is that small fuel cell technology that can run off the same gas, is getting better and cheaper by the day, so – the dream of having a fancy WH without a utility power connection will soon be only be $100 -$200 more than the current ones – maybe between fuel cells and “thermos” – we might even be able to co generate – there was at least one company at ISH BOSTON talking about that – I thought it was too much “pie in the sky” for me to lock their name in my memory – but I am reconsidering – I can even see forced draft ceramic burner stovetops – the automotive type heated oxygen sensors used for combustion feedback is getting cheaper by the day – (30 trade, 60 retail) – I personally would just love to have the chip version of “Tim McElwain” in all my combustion devices

Jim Davis_3

Besides being a nuisance problem this is potentially a health threatening situation that can not be taken lightly. Unless I know the person to whom I am making the recommendations and know they can contact me it is a rsky situation. People ask all the time about liability teaching the things that I do that go against everything the industry would like us to believe. Making sure the people have all the right information, training and tools is the only way. I would ask Glen Stanton, who attended this class earlier this year if this information should be given out randomly or if they need to know the whole story and background first. Plus the recommendations to fix this job disagree with everything posted here so far, with the exception of Mark and he won't give out the solution either for the same reason. But I will discuss the pilot situation.
1. Many ilots on water heaters prior to the new flash guard have had LP orifices-.011. Natural gas orifices are .018 to .025. The pilot flame barely hits the thermocouple, so I recommend making them the size for natural gas. Does not fix this problem by itself, just pevents another problem from being created.
2. Many pilots are rotated 45 degrees with the thermocouple under the flame which causes the flame to lift off the thermoucouple, therefore I recommend rotating the pilot upright in a better position. Still doesn't fix the problem but prevents another one.
Keeping the pilot lit only increases the chance of someone getting poisoned when unsafe conditions occur. Therefore neither of these corrections should be attempted until we can prevent the furnace from blowing down the water heater and safeties are added to shut both appliances off if the flue becomes restricted, severe downdrafts occur, uncontrolled depressurization is introduced etc. Mechanical combustion air is mandatory and the final fix is flue modification of both appliances and that is only discussed in class or one on one. I believe someone posted earlier this year if everyone had this knowledge there would be a lot less problems. Because I know this installation has caused serious injury I do not take it lightly but I also want to know it has been repaired and made 100% safe not just eliminate the nuisance.

Jim Davis_3

It was installed in a manner that was never tested or approved by the water heater manufacturer but never seems to bother anyone until it becomes a nuisance. I have helped contractors in the field modify pilots and ignitors on commercial and industrial equipment that millions of BTU's. The complaints were often intermittent explosions. The manufacturers input was it must be the installation because their equipment never malfunctions. Your choice Explosion, Modify or call someone else because we don't want the liability. We are in the wrong business if we don't want liability.

jim sokolovic

One thing not mentioned...

A fan assisted gas boiler that goes into chimney with another appliance must have the vent diameter upsized to make it a "Category I" - pressure in vent non-positive. The appropriate vent size is specified by the manufacturer, but the testing is done only at steady-state. Has the vent at this job been upsized? Or can it still create a problem on startup, even when upsized, by your experiences?

Unknown

Jim thank you

for your answer on what you do to pilots. This is something that happended when efficiency ratings and also pressed metal burners sort of came together. The orifice size thing is a definite problem on a lot of water heaters. In fact I have had two reps actually hand me larger orifices as a solution to pilot outage problems.

Now the pilot relocating thing can get real hairy as I envision the many water heaters I have seen and the many burners I have in my center. When you start relocating the pilot you have to know what you are doing. I also recommend that a pilot safety turndown test had better be done to insure proper light off.

The rest of what you do I am sure I know and I am sorry that you do not feel comforatble sharing that with us here. I do understand however why you take that stand.

We still have the problem this fellow who posted here has an in warranty water heater in a customers home which keeps going out. It does not seem we have solved his problem. It is also a good idea for you to keep an open mind that some who have offered solutions here are not guessing but have done the solutions they offer and they work. They may not accomplish all that I know you are trying to do but they do work. I am sure your comeback is that they are not safe and I understand that has to do with the FAN NAT problem itself.

As far as altering an in warranty water heater I would sure get permission from the customer and the manufacturer before doing that.

Unknown

Jim S. even

when we "upsize" we have problems with these fan assisted units. I have in some cases increased size and rise but I can tell you in many cases it does not work. I know what Jim Davis would do here but for his own reasons which I understand he will not offer them in a public forum such as this.

I will say I have in the past two years and in the past made modifications to equipment which may or may not be exactly what Jim does. I also would be careful to just arbitrarily offer that here. I go a step further maybe than Jim, I want to actually see the job before I will offer any suggestions for modifiactions. We can only go so far here on the internet.

Unknown

Jerry Evans we have not

heard from you since you posted. We sometimes get carried away here and forget the poster who still has a problem. How are you doing or have we totally confused you? Maybe Jim Davis or myself can offer you some assistance feel free to call me at 401-437-0557. Maybe Jim will share his e-mail or phone number with you. By the way what is your location?

Jerry Enns

Hi Guys

Thanks for all of your efforts on this subject. I have posted this for a friend in Beatrice, NE. I have been directing your replies to him. I need to get into contact with him.

Thank you

Jerry

jim sokolovic

Timmie, the upsize in vent diameter...

is a mandatory specified by the manufacturer. I don't know why changing the "rise" would be of relavence - we are talking about a fan assisted boiler, right?

Jerry Enns

It is not a boiler, it is a residential forced air furnace and a residential hot water heater.

Thanks

Jerry

Unknown

Jim I realize it is in

the installation manual. I am talking about things I have tried in order to overcome the pilot outage problem and back pressure caused by the fan on furnaces and boilers. Increasing size or rise is an old remedy for creating some self venting for pilots.

Jim Davis_3

Have not trained anyone in Nebraska, but I do have a wholesale company that has a branch that might provide help if it was their furnace. Otherwise have a contractor call me 800-633-7058. As long as I know a contractor has the correct information, the proper testing protocols and the proper test equipment and knows my phone number, I am confident he can fix the problem.

jim sokolovic

Whoops, it's not a boiler...

Do hot air furnaces specify upsizing the vent, then? We have fan assisted boilers with a 3" diameter vent for sidewall venting that needs to be upsized to at least 5" diameter for chimney venting.

Rich W

Hi Mark, I do agree that powered and natural draft equipment should not be mixed. It doesn’t cost much to install a spill switch at the WH draft hood to disconnect the thermocouple “just-in-case”. I think we are required to install a chimney liner- at least here in Michigan. I have seen the furnace exhaust come out of the WH vent when the chimney did not have a liner and atmospheric conditions were right. As far as the original post- I don’t think he mentioned whether there was or wasn’t a liner. I picked up a new customer last fall. I was the fifth tech. to try to solve the problem. He had a new 80% furnace installed during the summer. Then a new Water Heater when it got cold. Multiple warranty calls did not solve the problem. They replaced the WH. Still the same problem. They called a second company…they wanted to change the WH. The cust. began to get wise. How could I have three bad heaters in a row? While I was connecting my loggers, I asked about any changes in the house. Just the WH and furnace he said. Next morning, all was fine. When he got home- no hot water. When I read the loggers, I noted that the WH dropped out at 6:23AM. The furnace had not run for 30 minutes. It was discovered that both bath fans and the dryer were running at that time (they started at 6:00). With further prodding he remembered the new triple pane windows, blown-in insulation AND new furnace installed over the summer. He didn’t think this could be the problem until I showed him.
We then opened a basement window- no more problem. We installed combustion venting. Just like computers - GIGO. Knowledge (information) is power.

Rich W

> that he now has a fan assisted furnace where an

> atmospheric used to be.

>

> No chimney

> liner.

>

> As I stated, I have yet to see a fan

> assisted appliance NOT blow through a commonly

> vented atmospheric appliance. Not once and I have

> tested hundreds.

>

> Your questions are valid.

> Depressurization of the combustion appliance zone

> could cause issues. But.....a fan assisted

> appliance could handle a higher level of

> depressurization compared to the atmospheric

> which can handle almost none. BPI sets the limit

> at -3 pascals for an atmospheric water heater.

> Heck, leaky return ducting on a forced air system

> can do that much.

>

> The change here was the

> addition of a fan assisted appliance.

>

> Common

> venting FAS appliances with atmospheric should be

> outlawed.

>

> Mark H

>

> _A

> HREF="http://www.heatinghelp.com/getListed.cfm?id=

> 238&Step=30"_To Learn More About This

> Professional, Click Here to Visit Their Ad in

> "Find A Professional"_/A_

Rich W

Jim Davis_3

Because we do a CO start-up test we know that the pilot postion is correct. Have seen too many times when the pilot was not repositioned the pilot the pilot outages got worse. Most howmeowner want the problem fixed regardless. Never needed a warranty in 26 years because nothing ever failed in warranty. Hoping they will call and I can take them the rest of the way.

Mark Hunt

Hi Rich

We had a situation two years ago where a kitchen remodel caused severe back-drafting.

The new commercial sized gas oven came with a 1000cfm exhaust fan. When it ran, both the boiler and the water heater back-drafted, though the pilots did not go out.

We were also in a home recently that a young couple had just purchased. The house had hot water baseboard powered by an atmospheric gas boiler. A 40 gallon gas water heater provided the domestic. The previous homeowner installed their own central A/C system. Not one return duct to the living area, just a 20 x 25 filter grill cut into the side of the downdrop. We proved with our testing equipment that whenever the A/C system ran it was pulling combustion products into the space and pumping them into the home. There is a 2 year old boy in the home and Mom was pregnant with a second child. Add in the fact that the clothes dryer was also in the CAZ.

You are correct, you have to have your eyes open EVERY time you enter a home. Our home visits take longer than other contractors in our area, but we are also looking for potential health threats that the other guys are oblivious to. We cost more, but we do more.

Cheers!!!



Mark H

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Brian_24

I have performed the fix Jim and Mark know about many times. I will not let my other techs do it unless they have attended Jim's class. You need to know the proper way to test and make sure the modifactions are safe. JMHO.
Brian

Rich W

Hey Mark,I agree again. Customer safety should be number one. Also, nothing wrong making more for doing more.