Thermocouples on Utica Boilers

Unknown

this winter? Thermocouples that is on Utica Boilers? How long are they lasting? I am trying to determine if this is a trend or just an odd few situations. I have had about five inquires about this problem. One from a gas utility that has changed quite a few.

[Deleted User]

hi timmie

ive replaced three utica boiler t-couples this year...

Unknown

Gerry, was this

on one boiler of three different ones. What if anything did you notice about the ones you changed?

Robert O'Connor_7

$$$$$$ IT'S OK WITH ME $$$$$$$

Did my 2. Check pilot flame height & where it's making contact with it.

David_5

Alot

This has been going on for a few years for me.
The thermocouples in Uticas sit horizontally and the pilot flame is very big. I have tried pulling the thermocouples back further to let them stay cooler. It helps a little. I even called Utica and was told to turn down the pilot flame. When I comented that the smaller flame could produce delayed ignition they agreed with me. I think the horizontal position is the problem. I rarely see thermocouples fail so quickly when vertical or at slight angle. I am tempted to to try and clamp the thermocouple in a vertical position, but haven't had the time. Another option would be to change to spark ignition. These things are making me look bad, and feel frustrated. If anyone else has a suggestion I am open to new ideas.

David

David_5

to answer your question

Personally at least 3 boilers, all Utica. Not all the same size, but might have been the same model. The pilot burners were the same on all. I can usually get thermocouples to last 1 year in them. This year some are failing after 2 months.

David

Unknown

If someone could post a good picture

of the pilot assembly here on the Wall it would be appreciated. I am trying to determine if it is one particular pilot or several different ones.

David_5

One of them was

Utica M/N M-150-AGB2
S/N CD07774
Hope this helps

David

Unknown

Thanks David it does

so we can narrow it down to a particular model or models.

MIKE6

utica

our co has changed over one hundred,many yearly.this has been going on for years.the supply house says turn down the pilot or change to spark.this pilot problem and the burners getting holes in them,gas burning back in the venturi are the 3 reasons I don't like utica boilers,oh yea a group of them were mis wired from the factory last year.we were surprised to see how many installers don't check the safties on their installs.i don't know why the thermal couples go bad but the fire box seems to be hotter than most.we always check inputs.iam sure utica knows why this happens,their lips are sealed.I bet they had a million complaints over the years.
mike

ScottMP

We just contacted Tim

about this. we have one customer who we have changed thier thermocouple at least every ten months for the last three years. The last one was black and slighlty mishappen.

I think the horizontal position might be the right track.

Thanks Tim, I wish we had taken a photo of the asmb.

Scott

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[Deleted User]

i noticed that

no matter how i adjusted the pilot flame the t-couple burned bright red. but it was on seperate boilers..but i have noticed that we change alot of t-couples on utica and dunkirks...if i remember right some we adusted the pilot so we got a dull red glow and good readings (use your charts by the way).. only to have the t-couple influenced by the main burner and turned cherry red anyways..

J.C.A._3

Gerry,

The vertcal position of the flame as opposed to the horizontal position of the thermocouple seems to have a direct relation to the longetivity of the thermocouple itself.

Having the the "upshot" flow of the pilot flame, with the "side shooting" rest of the pilot would seem to me, to be a simple cost cutting measure.They made the part smaller, thereby reducing the cost to make it. In the field, WE all see that a tri flow pilot would have accomplished,#1 a smoother lightoff, and #2 a lower concentration of the pilot flame DIRECTLY ON the tip of the thermocouple.

The biggest problem I see with replacing the current model with a GOOD replacement is that a "tri-pilot" formation won't fit in the allotted space that is on the mount of the current hole of the offending appliances. It will require MODIFICATION. This will, of course, null and void the warranty, but IMHO, would solve the problem.

This isn't by any means, the first "premature failure of a thermocouple"I've seen, but it seems to happen to this particular "method of mounting a thermocouple"more than any I've seen thus far.(about 3 years working on gas fired appliances/19 years in the heating field). Thanks for the input. Chris

Unknown

I would not yet try

modifying the position of the pilot. There are safe ignition concerns when you do that. Let us be patient and see if Pete Desens gets back to me with an answer. I left a message with him today. I have tackled these problems in the past on other equipment.

One of the things I suggest is using a Johnson Controls nickel plated, high temperature corrosion resistant thermocouple. The catalog # is an K16RA. I used these for many years on Pizza ovens to withstand high temps.

There was a problem several years back on Enerjet boilers with thermocouples burning up, to the best of my knowledge they never did solve that one.

J.C.A._3

Timmie,

You , of all people, should know that I wouldn't modify anything without a factory directive or suggestion.I was just "thinking out loud", so that MAYBE the powers that be, will read this and re-think their (thermocouple) position.

Utica, in my opinion makes a wonderful product. I've never had any other problems with their equipment. I find them a great and service friendly manufacturer. I just wish that they would give up some stats and fixes for this particular problem, which seems NOT to be limited to my situation. Chris

Glenn Harrison_2

Every Utica I work on gets a 36\" Johnson Husky Thermocouple.

I have worked on a few older Utica's (10 to 20 years old) and every one has burned me with a standard Johnson thermocouple burning out within a year (usually much less). So now I put in Husky's only and turn down the pilot some and works fine.

Unknown

Glenn, have you

ever tried the nickel plated Husky?

Mark Eatherton1

T-couple failures

We deal primarily in Buderus boilers for our cast iron choice. Most of the early ones were installed with standing pilots because the spark systems were unreliable. The tide has changed. We're going through T-couples at an alarming rate. Even tried going to the Husky line. Have now started replacing them with standard spark ignition package.

They don't make 'em like they used to...

ME

Glenn Harrison_2

Can't say that I have. (nm)

.

peter desens

Honeywell recommendations for

adjusting pilots on attached MS Word Document. I pulled this from Honeywells instructons for the Q309 Thermocouple, and is a good place to start.

Worthwhile information:
Maximum hot junction temperature: 1400 F
Maximum Cold Junction temperature: 780 F
Normal operating millivolts: 26-32 MV
Minimum operating millivolts: 18 mv

----------------------

Based on the earlier postings, we are talking about the M---AGB series of boilers, i.e M100AGB. Production of these boilers was 1983-1988. The pilot was a Johnson J999, w/a Honeywell Q309 thermocouple. The pilot orifice was a Johnson 7218, w/ two .013" diameter holes through which gas flows to the pilot.

Pilot size is the number one contributing factor when concerned with thermocouple life. An overly sized pilot will cause premature thermocouple failure.

PILOT SIZE:
Pilot size is determined by two factors, 1. orifice size, and 2. incoming gas pressure.

The pilot orifice argueably could be changed, but for the sake of this discussion we will consider it a constant.

Incoming gas pressure on the contrary is a considerable variable. The lowest permissible gas pressure as stated on the boilers rating plate is 5.0 in/w.c. We know from our experience, there are occasions when incoming pressures drop to the minimum, and it is not unheard of for pressures to drop below the minimum permissible level, down to approx. 4.0 in/w.c. This is where the two hole pilot orifice is advantageos, providing enough gas flow to the pilot to satisfy the thermocouple.

When incoming gas pressures are higher, in many cases 7.0-8.0 and in some cases as high as 10.0 in/w.c. or higher, is when the flow of gas through the pilot orifice may result in a pilot flame that is to large.

TO LARGE OF PILOT FLAME:
A pilot flame that is overly large can cause thermocouple failure for two reasons, 1. overheating of the tip (hot junction), or 2. overheating of the base (cold junction) of the thermocouple. NOTE: It is the temperature difference between the cold and hot junction that creates the millivolts.

To achieve exceptable thermocouple life we want a pilot flame that is concentrated on only the tip of the thermocouple, and not to large as to overheat it. This in many cases will require an adjustment to the pilot.

If we heat only the tip of the thermocouple, and prevent overheating of it, we will prevent premature thermocouple failure.

THINGS TO CONSIDER:
Use only Honeywell Q309 or Husky thermocouples. We have found that these thermocouple provide the best life.

If the pilot flame is heating more than the tip of the thermocouple it needs to be adjusted to prevent this.

Follow Honeywells recommnedation to find the appropriate adjustment for pilot size. This should result in a mv reading of 26-32 mv.

If local gas pressures vary, a pressure regulator installed on the inlet of the gas valve will prevent fluctuation. There is no way to properly adjust a pilot if pressures vary to much. A properly adjusted pilot at low pressures, will result in an overly sized pilot at high pressures, and visa versa.

NOTE: I personally installed this model boiler in my own home. I moved 14 years later, the original thermocouple was still in the boiler. I did adjust the pilot when I installed the boiler, per boiler installation instructions.

Peter Desens
Techncial Services Manager
ECR International - Utica Boilers

Unknown

Thanks Peter for your assistance

I do have one question and that is concerning your advice on putting a pressure regulator ahead of the gas valve. There is a regulator built into the gas valve already. You can not put two regulators in series on a gas valve. Were you perhaps suggesting a regulator in the pilot line????

Bob Gagnon plumbing and heating

Marks right

i think. i suspect they are making the thermocouples cheaper so they do fail. we didn't have this problem years ago, thermocouples lasted years. now they seem to fail every year. on all boilers especially after they have already been changed once. i install uticas also and to adjust the pilot you have to screw the adjustment screw all the way down to break a seal then you can adjust it. bob

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peter desens

A requlator such as the one

> I do have one question and that is concerning

> your advice on putting a pressure regulator

> ahead of the gas valve. There is a regulator

> built into the gas valve already. You can not put

> two regulators in series on a gas valve. Were you

> perhaps suggesting a regulator in the pilot

> line????

peter desens

By regulator, I simply mean

an inline regulator, not another gas valve.

There are more and more areas that are "system regulated" as apposed to regulated at the house as was always the case years ago. Next to the gas meter was a regulator, this is not always the case today.

Regardless whether or not there is a regulator on the meter, if the inlet pressures are not being maintained at a reletively steady level, the existing requlator should be adjusted or changed, or an additional inline regulator should be added. There is simply no way a pilot can perform properly at two extremes.

BillW@honeywell

A correction is needed...

The part number is Q390A for the basic thermocouple, and Q340 A for the Premium model. Also, there is no Machieavellian conspiracy to reduce the quality of thermocouples to cut costs as some have suggested, FYI.

Glenn Harrison_2

Maybe no conspiracy at Honeywell,

but it sure seems like there is one at Johnson as every winter we seem to get a larger batch of bad standard thermocouples.

Unknown

I still do not know what you are talking about.

What pressure would be at the inlet and outlet of this regulator? What would its position be relative to other appliances in the house? This is really a new one on me if this is a low pressure system. There are not typically problems on high pressure. Peter you really have me confused with this please explain.

gas man_5

pilot outages

without a visual its' tough to trouble shoot - not sure if I've dealt with horizontal mounted thermocouples , did have luck with repeat problems (second or third visit)by sliping gasket material behind pilot burner plate and then mounting as usual , material like you see with inducer motors, or on some ignitors , I always save some scraps for this purpose - dealt with peerless on this problem also - the reason why I believe it has worked is because it prevents heat transfer to the pilot burner mounting - and prevents overheating the thermocouple - (cold junction ) I do use johnson's k15ds- thermocouples and have also tried in this situation r/s 1970-036(these are zip tips -and fit a little looser in the mounting bracket. These are the only ones that I recommended. Without knowing what adjustments you've made ,you can try the gasket material. hope it helps ! and get back to the wall - and always double ck pilot tubing for leaks at pilot burner- sometimes will lite off after you leave and heat cold junction !