DF 520 maintenance before winter

Hey everyone,
So my Bro in law and sister bought a house with a DF 520 in it. Really nice shape. Going to help him fire it this winter so he can afford to eat steak every night instead of beans (by using using the oil setup ).
Anyway, before ordering coal I went and made sure the auger turned (and moved coal into the pot), all looks good. Cleared away at the end of the auger and didn't see an excess of fines or any wobbling in the auger.

Not sure the year of this, couldn't find a plate, although the manual for it looks a little older, (maybe 80's-90's) it does have a pretty large square door (which needs a gasket!) In the manual it did say DF 520-1 (digital manual anyone?)

I'm impressed with how easy the adjustment is for feed and air. I like that!

What are your common maintenance items to add?
1. Brush down and vacuum inside of boiler
2. Check chimney piping for buildup (this has run oil for at least 4 years) and check draft (what should this be set at?)
3. Check grates (done-visual)
4. New DHW gasket (seeps)
5. Oil change in gearbox and refill the slop tray for the feed paw(?)
6. Remove oil gun nozzle (anything beyond that?)

**EDIT** I notice where the drive 'shaft' is pinned to the auger/worm/screw (whatever it is!!) There are cotter pins......isn't that where the shear pin should be?

I'm sure you'll have stuff to add, thanks in advance!

Here's the link to EFM's online manuals. Look about halfway down the page... There are 3 DF520 installation and operating manuals.

https://www.efmheating.com/index.php/efm-online-manuals

Take a look at the top of this forum, stoker coal boilers, there is a permanent post by stokerman that covers a lot of Efm maintenance and repair. Scott

Looks like you have a good handle on this .

Only thing I can ad is , be sure your chimney is clear and sound . Prob install a new stove pipe . Put in a new blow off valve , and have a couple of new C/O detectors on hand before it first is fired up .

Retro_Origin wrote: ↑

Tue. Jul. 19, 2022 8:09 pm

Hey everyone,
So my Bro in law and sister bought a house with a DF 520 in it. Really nice shape. Going to help him fire it this winter so he can afford to eat steak every night instead of beans (by using using the oil setup ).
Anyway, before ordering coal I went and made sure the auger turned (and moved coal into the pot), all looks good. Cleared away at the end of the auger and didn't see an excess of fines or any wobbling in the auger.

Not sure the year of this, couldn't find a plate, although the manual for it looks a little older, (maybe 80's-90's) it does have a pretty large square door (which needs a gasket!) In the manual it did say DF 520-1 (digital manual anyone?)

I'm impressed with how easy the adjustment is for feed and air. I like that!

What are your common maintenance items to add?
1. Brush down and vacuum inside of boiler
2. Check chimney piping for buildup (this has run oil for at least 4 years) and check draft (what should this be set at?)
3. Check grates (done-visual)
4. New DHW gasket (seeps)
5. Oil change in gearbox and refill the slop tray for the feed paw(?)
6. Remove oil gun nozzle (anything beyond that?)

**EDIT** I notice where the drive 'shaft' is pinned to the auger/worm/screw (whatever it is!!) There are cotter pins......isn't that where the shear pin should be?

I'm sure you'll have stuff to add, thanks in advance!

============================================================================================================================================================================================================

The shear pins for the auger have to have a shear strength no greater than 25 PSI and no more.
It is not supposed to have cotter pins or roll pins to secure the auger to the drive mechanism.
Be sure to use nylock nuts on the shear pins to hold them in place.

Does the boiler have a Low Water Cut Off??, If not it needs to have at least one as the VERY FIRST electric control for the boiler. This insures that the stoker will have all its electric power cut off if it detects that there is no water in the steam chest.

I have a Xylem/Bell & Gossett/McDonnel & Miller RB-122-E low water cut off that is plumbed into a 3/4"tapping in my boilers steam chest.

The RB-122-E Low Water Cut Off has a conductive tab immersed in the water and it senses a low water condition that will shut the boiler off as long as it is wired as the first electric control for the stoker.

The RB-122-E has a test button to check the operation of the Low Water Cut Off that lights up with a Green LED when it is operating correctly. Pushing the test button breaks the circuit and the LED turns red indicating there is no water/insufficient water in the boiler.

If there is no spare tapping in the boiler steam chest it can be plumbed in the boilers piping as described in the owners/installers manual.

MY past experience with the digital boiler controls and the computer controlled low water cut off system has been horrid,
and that is why I tossed both hydrolevel 3250's in the circular file and returned them to the dealer and use only honeywell and McDonnel and Miller mechanical boiler controls.

You have a pretty comprehensive list already. The draft should be -0.05" at the breech (where the stove pipe connects to the base). There is a lube point at each end of the connecting rod also, and one on top of the housing above the oil pan - give those a dab of gear oil a few times per season.

Some of the blower motors have oil ports, and some are sealed. If yours has oil ports, 2 drops in each hole per season should be plenty. I use a bottle of "Zoom Spout Oil" that I got at the local hardware store for the check and drive pawl, and also the electric motor. 3-in-1 also makes a "motor oil" that works well for those areas.

lzaharis wrote: ↑

Wed. Jul. 20, 2022 9:17 am

The shear pins for the auger have to have a shear strength no greater than 25 PSI and no more.
It is not supposed to have cotter pins or roll pins to secure the auger to the drive mechanism.
Be sure to use nylock nuts on the shear pins to hold them in place.

The cotter pins connect the auger shaft to the driveshaft existing the ratchet drive. The shear pin is at the opposite end of the ratchet drive and just needs a slight bend to stay in place.

Here is a short video to help explain. Note that yours may have a newer style gearbox.

Thanks a whole lot for all the advice guys! And special thanks to Rob for making up a video for me! ( I misidentified the shear pin, now I know where to actually look!) and the zoom out oilers are awesome! Fixes everything!

Looks like the auger is about 8ft long (seems pretty long eh?) How easily should that turn with the hand crank in your opinions to be sure the worm isn't worn out and grinding fines?

Thanks Scott for the reminder about those permanent posts, had seen them before but didn't notice all the links down below! A lot of good reading!

Retro_Origin wrote: ↑

Wed. Jul. 20, 2022 6:34 pm

Looks like the auger is about 8ft long (seems pretty long eh?) How easily should that turn with the hand crank in your opinions to be sure the worm isn't worn out and grinding fines?

You should easily be able to crank that auger with one hand. If it seems hard to turn that is usually caused by one of the following:

• Feed pipe is pitted inside.

• There is a gap between the two pipes

• The auger/pot pushing is worn out

• There is too much auger exposed in the coal

There should be about 2.5 auger flights exposed in the coal. More than that will cause some grinding.

Rob R. wrote: ↑

Thu. Jul. 21, 2022 10:22 am

There should be about 2.5 auger flights exposed in the coal. More than that will cause some grinding.

Hand cranked the auger today, went a little hard, but I could turn it. also almost 5 flights exposed to the coal!! Since it's so near the ground is it sufficient to get a piece of steel pipe, cut it in half lengthways to lay over? Or does the tube actually have to extend/auger have to be cut?

This is how a doghouse should be set up if there is none.

Go to page 13 of the EFM DF520 manual and it provides you with a view of
how it should be set up with 2 1/2 auger flights exposed showing how the
tube and auger are supported by the wooden block on the floor inside the
doghouse.

download/file.php?mode=view&id=115526

Retro_Origin wrote: ↑

Tue. Aug. 02, 2022 5:33 pm

Hand cranked the auger today, went a little hard, but I could turn it. also almost 5 flights exposed to the coal!! Since it's so near the ground is it sufficient to get a piece of steel pipe, cut it in half lengthways to lay over? Or does the tube actually have to extend/auger have to be cut?

I think you could clamp something on the pipe that covered a few auger flights. If it were me I would take a good look at that bin pipe - it may need to be replaced anyway.

Rob R. wrote: ↑

Wed. Aug. 03, 2022 3:47 pm

I think you could clamp something on the pipe that covered a few auger flights. If it were me I would take a good look at that bin pipe - it may need to be replaced anyway.

I looked at the manual for reference. Today after work I stopped and removed the barrel and yes the end of the feed pipe is well shot. All crispied away, a good 5 flights exposed, maybe more underneath. Unfortunately, my sister is on the waiting list to get coal. It could show up tomorrow, and that would cover everything up. Would it be viable to make an extension for the time being? The tube looked to be 2.25" OD but not sure what the ID is, does anyone know the OD of the auger or the ID of the original tube? It would be very helpful if I could have these, I can make an extension at work with a set screw in the side to get thru till can get replacement tube. Thanks!

The tube is 2” Schedule 40 pipe. You should be able to get something locally.

https://www.engineeringtoolbox.com/ansi-steel-pip ... d_305.html

Perfect thanks Rob!!

Is there a doghouse covering the auger???

If not, it should have one; or at least place a block of wood under
the tube to support the tube and keep the auger off the floor.