HELP! guys on the Wall

tim smith

I was really hoping that one of you all might have a manual or part breakdown on old Midco Unipower A9GO 25 gas oil burner. I posted yesterday morning but no replies. This is a 2 boiler, 2 building hotel. We had to shut them down as we found 1 boiler totally sooted up and after power vac cleaned we found maintenance staff had replaced burner motors with what looks to be wrong blower motors 3450rpm c face motors. They had them running in reverse so combustion wheel was running backwards. If you swap rotation then wayyyyyy too much air in combustion chamber. They may have been 1750 motors. These are on 1940s vintage or so Kewannee firetube boilers. Burners are probably early 70s, Midco has nothing in archives to lead us to which motor and of course the hotel staff threw away old motors. Both buildings have no heat. Hoping any of you have a manual, or have a boiler with this burner in it that data could be taken from. Thanks in advance, Tim

Abracadabra

Try contacting Midco? I can't find anything on a Midco A9GO

tim smith

I noted in above that I have had them looking good portion of day yesterday for any documentation in their archives. No can find. This is last ditch effort

tim smith

Hatterasguy, problem with using an unknown spec motor on burner is the liability. If something happens and a "event" occurs, we own it.

tim smith

The big issue is that if you don't move enough air on pre and post purge, you can have build up of gas? Theoretically not,but don't ask me how I know.

tim smith

True that it is constant but if the total amount of air is incorrect being how it was designed for a specific amount of air that is unknown currently, we could have less air change in boiler than was required by burner mfr and that is where problem lies with regards to liability.

Ironman

I know this may not be what you or your customer want to hear, but: a 1940's boiler with a 1970's burner? It sounds like it may at least be time for a new burner.

Steamhead

Tim, I'd get 1725-rpm motors and try them. There were still a lot of these motors being used when your burners were made. You'll know for sure if they're right from the combustion analyzer results. And if you have proper airflow for good combustion, you'll have enough for the purge periods.

tim smith

Thanks to all on here for your input, I have already told them would help to update equipment but right now just got to figure safe way to get heat back whether with new motors if we can decide on or maybe couple used spare burners I can get. The burner replacements are time consuming and we are packed. But, I won't compromise on this. I can probably get couple C face 1725 motors and get combustion #s good. Just have to watch out what we decide to do.

Steamhead

If the test results are good, you print them out and they have a date and time stamp from the unit, that's a good indication that the unit was running properly at that point in time. We always print two copies, one for the customer and one for us, in case there is any question later.

tim smith

Thanks all, especially to Tim Mcelwain for looking through his manuals and he found a service manual for this burner which at least verified that they should be 3450 motors. Just got back from getting north bldg. running after rotating motor rotation and resetting combustion completely, the burner is on line. South bldg. still has broken blade on combustion wheel. Will have to see what we can find to replace the wheel on this. Thanks all.

Robert O'Brien

Big difference in static pressure between open and closed face motors with the identical fan

Tim McElwain

If replacement motors for standard burners are procured from a source other than MIDCO, they should conform to the following specifications: 3450 RPM, Frame 56C, end mounted open motor with ball bearings. Capacitor start and thermal overload protection if single phase.

Blowers using three-phase motors will run in either direction depending on connection of the power supply. On new installations, motor replacement or power supply disturbance, the rotation must be checked. Corrections can be made by interchanging any 2 wires of the three-phase power supply.