Flame Rollout Sensor at Burner Tray

SeanW

I have a Lochnivar RBN 090 copper fin boiler. About 3 weeks ago it tripped the flame roll out switch in the middle of the night. I rest the switch and it worked for about 10 days. Then it tripped in the middle of the night again. Reset and it ran for about 10 days without a trip.



Last night it tripped 3 times.



What I know:

Flame is clean, blue and looks real nice- plenty of combustion air.

Flue is clean, plenty of flow.

Automatic damper works properly.

Startup is proper, no actual rolling at ignition.



I replaced the roll out switch today. Same problem, this time sooner.

There is no sign of heat damage to the front of the boiler. No sign of problem with venting.



System is all base boards.



Not sure what the problem can be. Any advice wold be great. I had a friend who knows boilers look at it. He says is the source of many of the knowns listed above. Another friend says I need to replace the start up controller. I don't think that is the problem and would like to avoid throwing more parts at the problem.



Thanks for your help.

JStar

RE

It only happens overnight? Here's my thought. When the temperature drops at night, the colder outdoor air will create a stronger draft than normal daytime conditions. The excess draft may be pulling more air from the draft hood, causing less air to travel through the boiler.



I wonder if there is a draft gauge is made with a "Maximum reading" option on it. Like you see on some other pressure test gauges. Then you could set it up and see if the draft changes overnight.

icesailor

Roll out:

J,

I think you are on to something but it has a different reason. I don't know what kind of ignition it has but higher draft through the boiler and any sort of delay in the ignition, will cause an over pressurization in the boiler and cause the roll out. Big problem with oil burners. With all the electronic ignitions in gas equipment, maybe you gas bags are starting to see what all us oil soot suckers have seen for years.

But this is just a thought.

Mark Eatherton

Just who you callin' a gas bag mister... :-)

I've worked on MANY of this type of boiler (copper fin tube) and the one thing they all have in common is that they get an accumulation of combustion crud on the copper heat exchanger. If you look (carefully) into the combustion chamber while the burner is on, and specifically, at the fire side of the heat exchanger, you will see a bunch of glowing embers when the boiler is under fire. This creates a reflected downward radiant energy that WILL cause the roll out switch to pop, even it no roll out is occurring. It also can significantly affect the draft through the fire box, again, compounding the problem.



Repair can be as simple as pulling the burner and servicing the fire side (wire brush and vacuum) of the system. In worst case scenarios (sooted up) the heat exchanger may have to be pulled and taken to the car wash for a good pressure washing.



In any case, you have obviously proven that it is not a defective switch, but a switch that has shown your appliance NEEDS immediate attention.

Don't ignore it, or bypass the switch, or you and your family members may go away...



And if you're not comfortable doing this kind of work, get a pro in there and have them test it (full combustion analysis) when they are done.



Make sure you have working CO detectors throughout the house.



ME

icesailor

Gas Bags & Soot Suckers:

ME,

If you noticed, this Soot Sucker is being forced to branch out into Gas Bag Land.

SeanW

Update from Last Night

Boiler made it through last night without tripping the sensor.



Some additional facts for the analysis.



I did set the operating range lower on advice of a professional. When I bought the house this summer, the boiler was set at 190 (all base boards). It would carry over close to 215 on occasion. Now it is set for to run in the 160 to 180 range.



I will investigate the theory about excessive draft tonight. Sounds interesting.



As far as the epic battle between oil and gas goes, I believe it will be a moot point in a couple of years with the billions of therms that are being developed across the country as we speak. Even you guys in the east coast will be able to buy Pennsylvania gas for a fraction of the cost of oil in the coming decade. As for me, I am located in Colorado, oil just isn't an option.

icesailor

Oil/Gas:

Have no fear, that 1%'er group of Banksters and the Wall Street Crime Family are salivating while waiting for their futures on gas reserves to go be run up by them.

If you want to stop the speculation, change the rules so that the speculators must take posession of product. That would end the markets in credit default swaps and derivitives. It would also crash the market. We 99%ers have to pay to keep the crooks and robber barons in Jet A fuel so they can fly to their vacation paradises, cool their heels in their McMansions and hire landscape crews of illegal workers to keep their grounds spiffy. And complain about our prices while they look for someone that will work on the cheap. Then complain about the quality of technical help in the USA and that schools cost too much money.

Supply and demand. Please. Like Judge Judy called her first book, "Don't pee on my leg and tell me its raining."

ColoradoDave

Burner Compartment

Sean... I was working on a Lochinvar RBL-175 a few weeks ago with a Roll-out issue.

You can check for the condescent buildup as Mark suggested, but a small folding mirror in the burner compartment can tell you easily when the boilers off, if you have buildup.  It's usually white-ish in color and usually most of it is above your pilot flame (if standing pilot).  Greenish color means you've got moisture buildup in the heat exchanger (water from a leak either in the heat exchanger or the vent), and black is soot from either ignoring the condescent buildup way too long or you're running too lean on gas mix.

Because our unit was in a crawl space, we didn't want to pull the heat exchanger, so we pulled the vent and used a plastic bag and duct tape to attach our shop vac to the vent collar.  Then using compressed air from a tank at about 5psi, we gently blew the condescent loose and sucked it out the vent.  Then blew down from the top and repeated.

Slimpickins

my method

I've used an air compressor and wire brushes both to clean copper fin heat exchangers and breathing the dust is not very good for you, even wearing a good dust mask. I pull the vent, burners and remover the diverter and top panel to access the heat exchanger. Then get a hose and rinse off the tubes being care not to get the refractory material wet, it doesn't take much water.  I use a rectangle cake pan underneath to catch most of the water along with rags. It gets it fairly clean and isn't nasty to breathe. You will need a tube of high temp mortar chalk to chalk the ends of the fins where the diverter rests, at least with theTeledyne minitherms. Then give the customer a price to provide some boiler protection.

Not a big fan of copper fin boilers for space heating BTW. People put them in because they're cheap and don't pipe them right or use any means of boiler protection.