No Primary Loop? KAA-2 Project Help?

 
User avatar
CoalisCoolxWarm
Member
Posts: 2323
Joined: Wed. Jan. 19, 2011 11:41 am
Location: Western PA
Stoker Coal Boiler: Keystoker KA-6
Hand Fed Coal Furnace: old Sears rebuilt, bituminous- offline as of winter 2014
Coal Size/Type: Anthracite Buckwheat
Other Heating: Oil Boiler

Post by CoalisCoolxWarm » Thu. Nov. 10, 2016 10:53 am

Looking to check with you guys before making changes to a buddy's Kaa-2 setup. I'd like opinions and cautions, etc. Want him to have the same reliable setup many of us have.

His Keystoker Kaa-2 isn't online, has outfires, doesn't heat well, etc. Typical coal boiler type stuff before it's dialed in. It's a few years old.

He has an oil boiler and isolation valves that he uses now.

His "primary loop" isn't. It goes out as 1.25" copper, has 3/4" tees for each zone (no valves, no pumps), goes through the baseboards, then returns to a pump for each zone and back to 1.25" copper return line.

There is NO CONNECTION between supply and return, except through the Four 3/4" zones/pumps. When the pumps are off, NO CIRCULATION is possible in the primary zone(!) It also doesn't have any primary loop pumps (!)

I can understand this setup in a mild climate with a cold start boiler (like oil) that tries to avoid standby losses (maybe), but not in a coal stoker setup. I don't know how it doesn't constantly overheat and pop off? Maybe it does. It hasn't been online in a few years :(

So my plan of attack is staged.

1. I found a decent spot to replace the last elbow of the 1.25" supply run and turn it in proper lengths to plumb back to the return side at the pumps. This will establish a 1.25" primary loop that permits either boiler to use it.

2. I'm planning to install a primary loop pump on the return side of each boiler, to be powered by that boiler when in service. Not a pump away, but pump to the biggest resistance. I understand the choice ;)

3. Clean up and test and adjust the Kaa-2 boiler for proper fire and control. The owner says the LWCO box keeps cutting it off. We'll fix all that. Maybe it is overheating and dropping? Regardless, we'll get on it. Going to add a Dwyer manometer and adjust the direct vent.

4. Buckwheat instead of rice? I'm thinking give him a wider range and it's been great for us in our KA-6. Same coal supplier.

5. Direct vent downsizes the 6" to a 4" stack. Bad juju for a chimney, but I can just increase the direct vent's velocity and it shouldn't matter as long as I adjust the draft with a manometer, right?

6. It's *possible* down the line to reverse the pumps and flow direction (via plumbing on the primary loop) so each zone circulator pumps towards the zone, not pulls from it. Right now they pull from it towards about 6-10" of pipe, then hits the tee into the primary loop. I'm under the impression that kills the "circulating" part of the pumping ;)

7. Possibly add more zones or replumb for split tees, depending on how the heatload calcs turn out and the baseboard he has.

8. Coal vac? But of course! LOL

The stoker adjustment is VERY DIFFERENT from my KA6. Looks like a single rod in a slot... anybody have pics and info on this setup? Would sure save time if I could learn how it adjusts.

Thanks!


 
User avatar
Rob R.
Site Moderator
Posts: 17980
Joined: Fri. Dec. 28, 2007 4:26 pm
Location: Chazy, NY
Stoker Coal Boiler: EFM 520
Hand Fed Coal Stove: Chubby Jr

Post by Rob R. » Thu. Nov. 10, 2016 11:09 am

A simple equalizing loop from the supply riser to the unused return port may take care of most of the issues. The boiler water is likely stratifying. Some dump zone tuning may be needed also.

why do you say it doesn't heat well?

 
User avatar
CoalisCoolxWarm
Member
Posts: 2323
Joined: Wed. Jan. 19, 2011 11:41 am
Location: Western PA
Stoker Coal Boiler: Keystoker KA-6
Hand Fed Coal Furnace: old Sears rebuilt, bituminous- offline as of winter 2014
Coal Size/Type: Anthracite Buckwheat
Other Heating: Oil Boiler

Post by CoalisCoolxWarm » Thu. Nov. 10, 2016 11:23 am

Rob R. wrote:A simple equalizing loop from the supply riser to the unused return port may take care of most of the issues. The boiler water is likely stratifying. Some dump zone tuning may be needed also.

why do you say it doesn't heat well?
He does have the little 1" bypass loop Keystoker suggests to temper the boiler and help with stratifying, but I doubt it is enough to overcome standby deadheading of the primary pipe.

I hadn't thought about a dump zone. Thanks, that's a good point and there is another return stub already plumbed, so I'll add a stub on the supply side to match if we need it ;)

"Doesn't heat well" - Not sure yet. They weren't satisfied with the comfort when using it and it would go out and the LWCO would shut down the boiler, they had air entrapment issues (reversed pumps would reduce the pressure in zones with air), etc. "Not reliable" would be another comment.

But I think both of those will be remedied once we get the primary loop established with pumps. Same as you, I think that is going to be our biggest difference, then tweak and tune the rest.

I gotta remember to check for air bleeders on each first elbow of the baseboards. He does have an air scoop, but without a good primary loop circulating at full volume (only when all 4 pumps are running, maybe), it would be of limited benefit at the moment.

What do you think about the pumps being on the return side of the zones? I don't "like" that idea, but is it significant enough to warrant the much larger project of reversing everything?

 
Olllotj
Member
Posts: 558
Joined: Thu. Sep. 04, 2014 10:01 am
Location: Western NY 14141
Stoker Coal Boiler: Keystoker KB-8
Coal Size/Type: Buckwheat
Other Heating: Utica Propane Hot Water

Post by Olllotj » Thu. Nov. 10, 2016 11:40 am

Keystoker says no Buckwheat coal with a direct vent. I'll bet the boiler is just dirty and not adjusted right. Timer pins, and feed screw. Maybe add a mano to the supplyhouse order.

Low water- Does each boiler have a fill valve? Maybe the fill valve (s) is stuck.
Air? High vent (s) Blocked? Proper purge options? If it's air bound it won't heat well and could trigger the low water cutoff.

Does he have a proper size expansion tank? Is it water logged?

No zone valves? So just one thermostat for the whole house?

Good luck working it out, I'm sure you'll get it.
Last edited by Olllotj on Thu. Nov. 10, 2016 12:20 pm, edited 1 time in total.

 
User avatar
McGiever
Member
Posts: 10130
Joined: Sun. May. 02, 2010 11:26 pm
Location: Junction of PA-OH-WV
Stoker Coal Boiler: AXEMAN-ANDERSON 130 "1959"
Hand Fed Coal Boiler: BUCKET A DAY water heater
Hand Fed Coal Stove: Warm Morning 414A
Coal Size/Type: PEA,NUT,STOVE /ANTHRACITE
Other Heating: Ground Source Heat Pump and some Solar

Post by McGiever » Thu. Nov. 10, 2016 12:07 pm

Plastic/nylon stoker alignment guides found in the Keystoker KAA_Series Stoker Beds should be verified too. Jacking with the power-vent fan speed can put those parts in jeopardy pretty quick allowing them to get too hot and melt which will never make or keep a proper fire. :)

 
User avatar
CoalisCoolxWarm
Member
Posts: 2323
Joined: Wed. Jan. 19, 2011 11:41 am
Location: Western PA
Stoker Coal Boiler: Keystoker KA-6
Hand Fed Coal Furnace: old Sears rebuilt, bituminous- offline as of winter 2014
Coal Size/Type: Anthracite Buckwheat
Other Heating: Oil Boiler

Post by CoalisCoolxWarm » Thu. Nov. 10, 2016 12:55 pm

Olllotj wrote:Keystoker says no Buckwheat coal with a direct vent. I'll bet the boiler is just dirty and not adjusted right. Timer pins, and feed screw. Maybe add a mano to the supplyhouse order.

Low water- Does each boiler have a fill valve? Maybe the fill valve (s) is stuck.
Air? High vent (s) Blocked? Proper purge options? If it's air bound it won't heat well and could trigger the low water cutoff.

Does he have a proper size expansion tank? Is it water logged?

No zone valves? So just one thermostat for the whole house?

Good luck working it out, I'm sure you'll get it.
Thanks for your reply.

Air bound, maybe? I don't know what there is for baseboard bleeders yet. Haven't been through the rest of the house. The basic design part was enough to get started while allowing him to heat now. He uses a woodburner in the middle of the house to supplement now.

The expansion tank is only 4.5 gallons for both the boilers. I think it should be larger for both, but only one at a time is okay?

Not sure about thermostats, but I'm pretty sure with 4 pumps he has 4 zones with Tstats. Guessing.

 
User avatar
CoalisCoolxWarm
Member
Posts: 2323
Joined: Wed. Jan. 19, 2011 11:41 am
Location: Western PA
Stoker Coal Boiler: Keystoker KA-6
Hand Fed Coal Furnace: old Sears rebuilt, bituminous- offline as of winter 2014
Coal Size/Type: Anthracite Buckwheat
Other Heating: Oil Boiler

Post by CoalisCoolxWarm » Thu. Nov. 10, 2016 1:03 pm

McGiever wrote:Plastic/nylon stoker alignment guides found in the Keystoker KAA_Series Stoker Beds should be verified too. Jacking with the power-vent fan speed can put those parts in jeopardy pretty quick allowing them to get too hot and melt which will never make or keep a proper fire. :)
I recently saw a thread showing those plastic parts and the plastic screw. Yuck.

But the long metal threaded rod...I assume it is the feed rate adjustment? It sticks in through a slot and "must do something" LOL. Anyone have a diagram or instructions for that thing?

Here's a pic of the rod
IMAG7310.jpg
.JPG | 76.4KB | IMAG7310.jpg


 
lzaharis
Member
Posts: 2366
Joined: Sun. Mar. 25, 2007 8:41 pm
Location: Ithaca, New York
Stoker Coal Boiler: Keystoker KAA-4-1 dual fuel boiler
Hand Fed Coal Boiler: former switzer CWW100-sold
Coal Size/Type: rice
Other Heating: kerosene for dual fuel Keystoker/unused

Post by lzaharis » Thu. Nov. 10, 2016 4:07 pm

We need a photo or diagram of the system WITH all the plumbing, ALL of it.

The Nylon bolts used to guide the pusher plate are screwed all the way in and there are
2 pieces of rope door gasket one on each side that is in the center with two nylon screws on either side of the 1/4" compressed rope gasket.

You can verify this by removing the hopper and looking at the stoker.

After you have removed it from the boiler- yes remove it, I will tell you why.
The KAA-2 may have coal dust and fly ash under the three firebed grates.
you can remove the squirrel cage fan and look inside and you can vacuum most of it out there but you may need to tap the base of the fire bed with a hammer to break the rest of it loose and then vacuum it out.

You also need to make sure all the air holes are open to allow the combustion air to reach the firebed.

If there is any slag on the fire bed surrounding an air hole or blocking an air hole you need to chip that away with chisel as that affects how the coal will flow across the three bed fire grate.

As long as you have the squirrel cage fan off the stoker you can also examine the fan and if it is dirty remove the fan from the motor shaft and soak it in some Dawn Dish Soap.

An ultrasonic cleaner works well too with a bit of dawn in the vat.

SO

on the left side:

two nylon screws turned all the way in
one flattened piece of rope gasket glued to the side of pusher plate
two nylon screws turned all the way in

After verifying they are not melted
you can look at the right side which has the same arrangement

2 nylon screws turned in all the way
flattened piece of rope gasket
2 nylon screws turned in all the way

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

The threaded rod is connected to the pusher plate at an angle so the Nylon cam can push the pusher plate and then pull it back so that feeds the coal into the fire bed for the KAA-2 and the KAA-4 and 4-1 K6 and K8 models.

To adjust it you need to turn it all the way in until it stops and then back it off four to five full threads to start.

The 4-5 threads backed off on the threaded rod is the actual stroke length of the pusher plate
with the cap nut on the other end when you start the stoker coal fire. The more threads turned in the longer the stroke of the coal pusher plate on the firebed which slows the rate of fuel delivery to the firebed of the AA model flat grate stoker which is three fire beds wide just like the KAA-4, KAA-4-1, and KAA-6 and KAA-6-1 units.

The fewer threads used speeds up the stroke of the pusher plate feeding more coal across the three fire beds. The threaded rods number of exposed threads stops the travel distance of the coal pusher plate in practice with the second cap nut on the end of the threaded rod and the nylon cam simply pulls and pushes the coal pusher plate for the 4-5 thread distance when firing the boiler for the first coal fire and any subsequent coal fires.

SO if you backed it off to two threads it would be working twice as fast as the four thread setting on the pusher plate with the nylon cam pulling and pushing the coal pusher plate twice as much per minute of operation and the hold fire timer would be stopping the pusher plate from operating on the KAA-2

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

Just remember that the timer on the KAA-2 operates exactly opposite of the Intermatic Timer wiring on the KAA-4 and the KAA-6 stokers. The number of timer pins stop the stoker from feeding for that set amount of time if my memory is correct from what Oliver Power told me as to how the KAA-2 operates from what I remember as it has smaller water volume.

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

Ideally an in series piping arrangement would save work, piping from the steam chest tapping
of the KAA-4-1 and piping that flow to the sump of the dinosaur juice burner with the single air scoop and bladder tank ahead of/in front of the 4 circulators on the header pipe coming off the steam chest. The four circulators pulling water from the header pipe are tee'd with either ball valves or Isolation valves to make repairs less wet and aggravating from hot water burns.

By Teeing each circulator from the header pipe you can use isolation flanges or ball valves The air scoop and bladder tank would be right before the very first circulator in the header pipe by about 2 feet at the minimum from the first circulator where it belongs to properly take advantage of the point of no pressure change with the three remaining circulators also benefiting from the placement of the air scoop and bladder tank in practice as they will operate in the same manner having a point no pressure change.

I think my description is ok after editing it.
Last edited by lzaharis on Fri. Nov. 11, 2016 10:21 am, edited 5 times in total.

 
User avatar
Rob R.
Site Moderator
Posts: 17980
Joined: Fri. Dec. 28, 2007 4:26 pm
Location: Chazy, NY
Stoker Coal Boiler: EFM 520
Hand Fed Coal Stove: Chubby Jr

Post by Rob R. » Thu. Nov. 10, 2016 4:25 pm

I do not understand why you want to add a primary pump if all of the zones require high temp. water. Can you draw a diagram of the current piping?

 
User avatar
CoalisCoolxWarm
Member
Posts: 2323
Joined: Wed. Jan. 19, 2011 11:41 am
Location: Western PA
Stoker Coal Boiler: Keystoker KA-6
Hand Fed Coal Furnace: old Sears rebuilt, bituminous- offline as of winter 2014
Coal Size/Type: Anthracite Buckwheat
Other Heating: Oil Boiler

Post by CoalisCoolxWarm » Thu. Nov. 10, 2016 9:22 pm

Great information, thanks guys!

I'm not sure series installation is the best option. Won't it reverse heat transfer up the stack of the unused oil boiler?

Why primary loop circulator?

Well, each zone is 3/4" and the primary loop is 1.25" Using just a zone circulator wouldn't move water into and BTUs out of the boiler efficiently. I could see short cycling and maybe overheating as a zone calls for lots of BTUs, so boiler is making lots of heat (takes time to deliver the BTUs to the zone), but if only one zone is running and no primary circulator, the system can't move heat out of the boiler to allow more water to be heated.

I'm probably not saying that well...

 
User avatar
McGiever
Member
Posts: 10130
Joined: Sun. May. 02, 2010 11:26 pm
Location: Junction of PA-OH-WV
Stoker Coal Boiler: AXEMAN-ANDERSON 130 "1959"
Hand Fed Coal Boiler: BUCKET A DAY water heater
Hand Fed Coal Stove: Warm Morning 414A
Coal Size/Type: PEA,NUT,STOVE /ANTHRACITE
Other Heating: Ground Source Heat Pump and some Solar

Post by McGiever » Thu. Nov. 10, 2016 9:30 pm

I was thinking the primary loop idea was to allow for the 2 individual boilers piped to service the common load(s).

Yep. a sketch will tell more. :)
Last edited by McGiever on Thu. Nov. 10, 2016 9:31 pm, edited 1 time in total.

 
User avatar
Rob R.
Site Moderator
Posts: 17980
Joined: Fri. Dec. 28, 2007 4:26 pm
Location: Chazy, NY
Stoker Coal Boiler: EFM 520
Hand Fed Coal Stove: Chubby Jr

Post by Rob R. » Thu. Nov. 10, 2016 9:31 pm

I prefer to hook the boilers up in parallel, or with two close tees and allow gravity circulation through the boilers.

You are correct that an additional circulator would increase flow through the coal boiler, but it does not change the rate that the zone can pull btus. Also, a coal boiler is nothing like an oil boiler - the output level comes up gradually, not instantly. Short cycling should not be an issue, even with multiple zones.

 
lzaharis
Member
Posts: 2366
Joined: Sun. Mar. 25, 2007 8:41 pm
Location: Ithaca, New York
Stoker Coal Boiler: Keystoker KAA-4-1 dual fuel boiler
Hand Fed Coal Boiler: former switzer CWW100-sold
Coal Size/Type: rice
Other Heating: kerosene for dual fuel Keystoker/unused

Post by lzaharis » Fri. Nov. 11, 2016 1:18 am

CoalisCoolxWarm wrote:Great information, thanks guys!

I'm not sure series installation is the best option. Won't it reverse heat transfer up the stack of the unused oil boiler?

Why primary loop circulator?

Well, each zone is 3/4" and the primary loop is 1.25" Using just a zone circulator wouldn't move water into and BTUs out of the boiler efficiently. I could see short cycling and maybe overheating as a zone calls for lots of BTUs, so boiler is making lots of heat (takes time to deliver the BTUs to the zone), but if only one zone is running and no primary circulator, the system can't move heat out of the boiler to allow more water to be heated.

I'm probably not saying that well...
===========================================================================

A couple of things;

The boiler flue pipes cannot share the same flue pipe to the chimney.
You either have two chimneys or change flue pipes to use one boiler or the other.
You said the KAA2 uses a power venter? How?

I have one circulator for my single zone heating loop of 225 feet of fin tubed baseboard and I have no trouble moving heated water from the steam chest to do the job, the poorly insulated house does not help much.

I do not have any trouble moving heat out of the KAA-4 with my single B+G NRF25(no check valve) at 12 gallons per minute(speed one) which comes off the steam chest and splits in two directions then returns to the boiler sump tapping to be reheated.

Your going to lose heat up the flue pipe from either boiler that is a given fact.
Some gas boilers have automatic exhaust dampers that have a closure method to seal the flue pipe after the firebox when the boiler is shut down. It cannot be used with a stoker or hand fed boiler.

Piping boilers in series is a matter of planning the piping runs and deciding whether you want
two separate sets of controls and circulators. The KAA-2 is complete to run the stoker the issue is the piping and circulators. If you have the room it can be done.

Side by side installation of boilers have some advantage if a common steel expansion tank with the airtrol valve and and IAS is used or a series of steel expansion tanks is used to provide the required tank volume.

When my hand fed boiler and my oil boiler were set side by side by the plumber I could not separate either boiler to use just one as a temperature balancing pump was used to heat both boilers when the hand fed was used and the exterior DHW coil housing was on top of the steam chest and the piping to the heating loop came off the DHW coil housing top tapping.

Until you go through the KAA-2 and clean it by scraping the fly ash off the walls and the steam chest, clean the stoker, clean the flue piping and the power venter you wont know much.

 
User avatar
CoalisCoolxWarm
Member
Posts: 2323
Joined: Wed. Jan. 19, 2011 11:41 am
Location: Western PA
Stoker Coal Boiler: Keystoker KA-6
Hand Fed Coal Furnace: old Sears rebuilt, bituminous- offline as of winter 2014
Coal Size/Type: Anthracite Buckwheat
Other Heating: Oil Boiler

Post by CoalisCoolxWarm » Fri. Nov. 11, 2016 11:09 am

Okay, took a bit of time, but here is the layout, with my proposed changes.
Original Boilers layout.png
.PNG | 44KB | Original Boilers layout.png
I propose to connect the deadheaded supply and return lines to create a 1.25" primary loop and add a single pump to the line, ahead of the isolation/boiler selection valves.

The electrical/electronics of a switchover/failover will be implemented in the near future. The pump would be wired to a 3 way light switch, which can be used to select either boiler.

 
User avatar
Rob R.
Site Moderator
Posts: 17980
Joined: Fri. Dec. 28, 2007 4:26 pm
Location: Chazy, NY
Stoker Coal Boiler: EFM 520
Hand Fed Coal Stove: Chubby Jr

Post by Rob R. » Fri. Nov. 11, 2016 12:37 pm

The primary pump you have added serves no benefit to the zones or oil boiler, and you still have to open/close valves to switch from one boiler to the other.

I have attached a suggested design with a circulator in the coal boiler piping. Power this circulator from the triple aquastat on the KAA-2, and connect the end switch from the zone relays to the TT terminals in the triple aquastat. This will run the circulator only on heat calls - Do not use a flow check in the circulator for the coal boiler - this will allow gravity circulation through the oil boiler. Both boilers stay warm and happy, and the additional mass will prevent the KAA-2 from overheating. In addition, you can set the oil boiler to turn on automatically if needed...without touching the ball valves.

I have setup several EFM's this way, and they all run very well.

Attachments

Robs layout.png
.PNG | 45.4KB | Robs layout.png


Post Reply

Return to “Stoker Coal Boilers Using Anthracite (Hydronic & Steam)”