Sealing an arcoliner

Sounds like the barometric draft regulator might need adjustment too.

Two ways:

Red RTV hi temp silicone in a caulking tube or

You can by Kao wool flat tape or round rope.

I put it on by quickly wire brushing the cast iron and spray it and the rope with 3M contact cement. Let it dry and then stick the rope on

If you have a lot of air leaking in the Co2 will be low. Draft in the flue doesn't matter much over the fire should be -.02ish. Could be leaking around the doors between the sections or into the fire box.

Take a Co2 over the fire (don't burn up the tester). If over fire is higher Co2 than at the breech you have air leaking in.

if you do it right with the silicone you can oil or wax one of the surfaces and clean the other surface and get it to stick to one surface but not the other and make a gasket that will come away with the door.

also look carefully at all of the other various seams and dampers and such and especially where the burner is mounted.

I think @EBEBRATT-Ed mentioned a type of furnace cement you could chip off and mix with water and stick back on. although that really just sounds like clay.

Even if there's no groove, small diameter kaowool rope or flat gasket. The rope can have tape adhesive but spray adhesive might be better. There's a lot of play in the hinges on those doors with not a very secure latch.

If the AF has a fixed head, you may be better off with an 80° nozzle, unless the firebox is very narrow. For that firing rate, the proper fixed head is the F3.

With the F3, if you're using a hollow (A) nozzle because the solid (B) one caused the flame to slam into the back of the firebox, you will likely get better results by switching to a larger static plate on the drawer assembly. Use the #3384:

https://www.supplyhouse.com/Beckett-3384-BECKETT-Static-Plate?srsltid=AfmBOooeVWmGGPFMO67Zi4MoH5S8mV8i9DFSrzz4Nlt0MuB_yw9q7s7v

This will create a more hollow air pattern to match the nozzle. I sometimes gain a half percentage point on my CO2 readings with zero smoke, and get a much more stable flame, with this change.

The best nozzle is the one that combustion tests the best.

#s are not too bad. Probably does have some air leaking in. You can only do so much.

Only zero smoke is acceptable. What are the chamber dimensions? What head is on the burner? That boiler is easy enough to clean. Is it clean?

I think a 429 net stack is not bad.

When I worked for the family business in the 1980s, we were replacing ten or more oil burners each week. The federal government subsidized many of these jobs for low-income homeowners.

We often retrofitted old “snowman” boilers, Arcoliner boilers, Holland furnaces, and even boilers originally designed for coal that had been sold as oil-fired units in the 1940s and 50s. Some were equipped with Arcoflame burners using the old piggyback-style burner motor and fuel pump.

Many of these boilers had air leaks between the sections. To receive payment under the government program, we had to achieve at least 80% combustion efficiency using a Bacharach wet-kit combustion kit. We developed a procedure that helped us obtain an accurate measurement.

First, we would:

1. Thoroughly clean the heat exchanger and remove as much soot as possible.
2. Install a new combustion chamber.
3. Remove the boiler jacket and seal the seams between the sections with furnace cement.
4. Install new insulation and replace the jacket.
5. Seal the boiler doors to eliminate air leakage. We would place a 1/4- to 3/8-inch bead of furnace cement around each door and carefully close it, allowing the cement to form a gasket-like seal.
6. Install a new vent connector and barometric draft regulator.

Even after completing all this careful sealing, some air leakage could still remain. A combustion-efficiency calculation assumes that all combustion air enters through the burner and that only this air is included in the flue-gas sample taken at the vent connector as shown on the left. If we had too many leaks as shown on the right the flue gas measurement was incorrect and much lower carbon-dioxide percentage.

Because that was not always possible to get an air-leak free boiler, we used a temporary testing method to determine the actual flame efficiency without dilution air from the remaining section leaks. For the test only, we operated the burner with slight positive pressure in the combustion chamber. If the boiler still had leaks, the airflow would then move outward through them instead of being drawn inward and diluting the flue-gas sample.

We accomplished this by temporarily removing the barometric draft regulator or propping it open and/or partially restricting the chimney connector. Once we obtained approximately +0.01 inches water column over-fire pressure, we performed the combustion test and recorded the actual carbon dioxide or oxygen reading and the stack temperature.

Immediately after completing the test, we restored the vent connector to its normal, unrestricted operating condition and returned the barometric draft regulator to proper operation. The final operating draft would normally be approximately –0.01 to –0.02 inches water column over the fire.

This procedure gave us a more accurate measurement of the burner’s actual flame combustion efficiency. Any air entering through small remaining leaks during normal negative-draft operation would lower the measured combustion-efficiency result, but it would not significantly change the flame inside the combustion chamber. The heat produced by that flame would still be absorbed by the boiler, with only a relatively small efficiency loss resulting from the remaining air leakage.

Government inspectors simply needed to witness an actual combustion test showing an efficiency reading of 80% or higher on the instruments and calculator before signing off on the job. Once the test was completed and the system was restored to its normal operating condition, we made sure the equipment would operate safely. Our own service technician would then sign off on the job. With both signatures in place, the U.S. Treasury checks would start rolling in.

The bottom line was that we took a system operating at 60% combustion efficiency or less, equipped with an old, wasteful burner, and made it burn less fuel while still providing all the comfort the homeowner needed. The work cost less than half as much as installing a new gas boiler and often produced similar fuel savings. At the same time, we were able to keep a fuel-oil customer from converting to gas heat.

I hope this information helps you in determining the result of your work. Your combustion numbers don't need to be as high as you think to get the lowest fuel usage

of course that many of those original materials were ACMs wasn't considered a problem then(also possibly some of the new materials you were using, it seems like a lot of products through the 90's or so they didn't remove the asbestos they just stopped mentioning it, or they made liberal use of the rule that products containing less than 1% asbestos were not ACMs). i'm pretty sure i've got asbestos gaskets in gasket sets long after they should have gone away.