Boiler Going Into Lockout

Al Corelli

Boiler has 10" flue which goes into Inducer that is rated 8-10 inch, then sizes back up to 10" and goes into a 10" double walled Metalbestos chimney.

The draft at the unit is a constant -.02 to .03 measured under the built in draft hood.

There is no condensation of flue gas that I can measure or see. The unit maintains its 20 degree delta T throughout its cycle, save for a brief 10 seconds or so at the beginning of the cycle.

Al Corelli

Boiler Going Into Lockout

I have a nagging intermittent problem with a copper boiler making hot water in a local diner.

The boiler is a Lochinvar CWN399DN.Installed five months ago.
Unit has new power venter interlocked with ignition control as per Tjerlund techs, installed last week.

Lockout problem Intermittent, once a week to twice a day, varying, has been going on since well before the replacement of the power venter.

Gas pressures are all well within specifications,7.3 incoming, 3.51 at the manifold.

Spark Ignition control (Honeywell S8610H, single 90 second trial)randomly locks out with a 6+2 code. Code refers to "no flame sense".

Draft adjusted to -.02 measured under hood.

My Quicklook tells me my micro-amps are 9.63 at startup, moving up to 10.51 to 11.01 when heated.

I originally thought the new draft inducer was causing the pilot flame to move away from the electrode/flame sensor, but it is easily seen from the flame window and the sensor is glowing red as is normal.

There is PLENTY of fresh air available to the unit.

I removed and carefully cleaned the electrode/flame sensor and watched the unit cycle four or five times. Of course it will not fail while I'm there.

Any ideas as to why it randomly goes into lockout?

Should I install a "multiple trial" ignition module?

Empire_2

Try this Al:

Check the Phasing on the incoming Voltage. Micro-Amps seem a little excessive.

Al Corelli_2

Target?

What is a good target for the micro-amps?

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Paul Rohrs_7

Any other gas-fired appliances on the line?

Do you have HI/LO gas pressure switches that may be causing lockouts? Some other appliance might not be drawing when you witness the CWN fire up. Just a thought.

I have seen this on a Laars Pennant that dealt me fits for a while.

Tech Support at Lochinvar features some of the Nations finest. I would give them a call if all else fails.

Paul

Empire_2

4 to 6 UA

That is what I was taught. Excessive readings can result from other problems that I described.'


Mike T.

Al Corelli

Gas Line

This unit shares a gas line with a 100kw Generator. But, the generator does not run when these lockouts occur.

No Hi/Lo switches. The gas valve appears to ramp up to full in about three seconds. Nothing jumps out at me as strange.

When we upgraded the service for the generator, the "utility" refused to give us more than 6" of gas (there is high pressure in the street). After petitioning repeatedly, they agreed to give us a 14" regulator. The generator requires 11" at its regulator. We kept the 7" regulator for all the ovens, stoves and roof units, so we would not have to add regulators at each point of use.

The then new CWN399 was hooked up to the 14" regulator with is own new point of use regulator. The supply pressure does not waver even when the generator excercises.


So, I guess he short answer is: We have gas.

heatguy

condensation

dont know how you have boiler set up but is there a chance you have heavy draw and are condensing flue gas

Joannie_15

Pennant

Hi, Paul.

Just an FYI, I wanted to let you know that we changed how we put the gas pressure switches on the Pennant units, to help alleviate lockouts from high gas pressure supply spikes, like the one you ran into. Seems to have worked. If you haven't seen it, and want to, let me know and I'll send you a copy of the bulletin.

Joannie

tim smith

What size of flue is it vented into

Is it the same size all the way out wall or roof or is it into a larger vertical stack?

bobbyg_5

Thanks

Mike T.
Thanks for the helpful tip there. Did you write that up? I will definitely use that for reference. I often wondered about that very issue, but couldn't find anything to refer to.

Thank you!

Unknown

Al, your microamps are a little

high which usually is an indication of a problem with the electronic control giving an occasional AC feed over into the microamp proving circuit. The electronic control in that case needs to be replaced.

I also do not think the hookup for the generator and your unit is good. Sometimes double regulation will work off each other and cause momentary pressure drops. It is tough to catch this as it does not always do it every time.

Code by the way requires the generator to be seperated from all other equipment.

Al Corelli

Double Regulation

I have a pressure transducer for my recording Fluke meter. I'll try to catch these fluctuations.

As to the boiler and generator on the same line.... Well, that's the way the "utility" had us do it. I made the "engineer" aware of the need for generator separation, but he actually had the plumbers change it over to the 14" line. Sometimes I just wanna bang my head till it bleeds, rather than deal with these "engineers" from the utility.

Rob L_3

Lochinvar Lockout

I have worked on quite a few Lochinvar over the years and a few other copper brands. Not trying to say anything bad about one brand, but they do seem to picky and have narrow window of tolerance to light off the burners.
In the past when confronted with mystery lockout that seem to occur for no good reason I have installed triple try ignition modules, or even gone as far as clipping all the male-female spade wire connections and direct wire nut them together. Not saying that will work in your case, but put in the back of your mind if you are still working on this in a few months.

All the best,
Rob L