Help Deciding on K6 or K8 Boiler

 
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CoalisCoolxWarm
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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 » Mon. Jan. 04, 2016 12:11 pm

Strong debate with lots of good technical info and light on the personal attacks. It's quite interesting to read about the inner "guts" and factors that go into a boiler design and rating :D

PEX in a ditch: FYI, 2" foam sheets are R10 and can easily be cut into a trench/box shape to be a thermal break from the ground, contain the piping for spray foam, can be "glued together" using spray foam, and offers some protection from rocks and stones as they heave against the pipe in cold weather (we have this problem here with very hydraulic clay and shell mix)

If it were my ditch, I'd dig it, cut strips to line the bottom of the ditch, strips for the edges, foam a little in the corners to hold it in a "U" shape, lay the insulated PEX/outer pipe assembly in the ditch, spray foam to fill the inside of the foamboard trench, lay about 6mil plastic on top with weight while the foam cures, then add a foamboard top to fit, using caulking (like you would use wood glue to assemble the top of a box) to attach it.

I'd use gravel in the bottom of the trench before anything else goes in, to help cushion any sharp rocks, and gravel all around and over when the entire assembly is done. The gravel helps with crush resistance. Cover with whatever you need for topside traffic over the ditch.

Around here, we'd probably put the piping in sch80 piping and keep it at least a foot or two deep to keep from crushing, but that's up to you.

Big Tip: Add a piece of wire in the ditch, over the trench before backfilling. Why? So years down the road a metal detector can be used to find the piping after the ground has healed.

We use gravel a lot to help with drainage and if ever digging it back up, it gives a "warning" to switch to hand shovels from the backhoe to avoid damaging the pipe/wire/whatever.

I'd bit the bullet and go with the larger piping from the boiler into the house and making my primary loop extend in there and add any secondary zoning off of it with closely spaced tees.

 
Pacowy
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Joined: Tue. Sep. 04, 2007 10:14 pm
Location: Dalton, MA
Stoker Coal Boiler: H.B. Smith 350 Mills boiler/EFM 85R stoker
Coal Size/Type: Buckwheat/anthracite

Post by Pacowy » Mon. Jan. 04, 2016 12:40 pm

Scottscoaled wrote:10 teeth times 2.5 lbs/hr of rice gives a 25 lb/hr rating. 10 teeth times 2lbs/hr of buckwheat gives it a 20 lb/hr rating. The auger fills better with rice to get the extra half pound. It is hard to get it to burn that much of either per hour. It has to have the right coal and it won't burn the coal completely. That is what Mike is saying. I don't disagree with him. I just think the same is true for the Keystoker or others in the same class for that matter.
You're getting close, but aren't quite there. It was rated at 20 lb because EFM believed that produced the max output, presumably with freeburning buck, which EFM knew had the lowest air requirements. If it really ran better on rice they had no reason to limit it to the 20 lb. in the first place. In fact, EFM routinely found across its product line that the max teeth of feed on rice needed to be restricted relative to buck. The K8 doesn't face this issue because it doesn't have to deal with the restriction on airflow imposed by rice relative to buck.

Mike

 
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EarthWindandFire
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Hot Air Coal Stoker Furnace: Leisure Line Lil' Heater.
Other Heating: Oil Furnace and Kerosene Heaters.

Post by EarthWindandFire » Mon. Jan. 04, 2016 12:47 pm

The above comments are somewhat focused on maximum output. Again, at least ten thousand posts on this board strongly and unequivocally suggest that oversizing a boiler is much preferred over the alternative. If an EFM is what the OP wants, he should consider a gently used EFM Highboy.

 
Pacowy
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Posts: 3555
Joined: Tue. Sep. 04, 2007 10:14 pm
Location: Dalton, MA
Stoker Coal Boiler: H.B. Smith 350 Mills boiler/EFM 85R stoker
Coal Size/Type: Buckwheat/anthracite

Post by Pacowy » Mon. Jan. 04, 2016 1:10 pm

Scottscoaled wrote:I'm fighting this for the simple fact you can't tell me how many pounds of coal per hour the K-8 burns to get ratings just a little higher (or lower depending on what you believe) than the 520. For all you know it could be burning 5 lbs per hour more which would make your point pointless. A Gentleman Janitor Model 63 is advertised at 200k Btu's. Yet it also has to burn 40lbs per hour to get that. EFM hasn't hid anything. It can and will burn 25lbs/hr. Maybe not efficiently on the higher end. I would think the Keystoker would suffer the same problem. It might burn how ever much coal it takes to get to it's rating but,,,, the top end efficiency suffers the same. Let's keep apples to apples.
I don't think anyone has said anything about relative efficiency until now. The guy was advised he needs the output of a K-8, and we've been discussing how the capabilities of a 520 compare to that. Efficiency is irrelevant if the 520 can't carry the load. If they both can carry the load then efficiency would be good to consider.

Mike


 
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windyhill4.2
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Posts: 6072
Joined: Fri. Nov. 22, 2013 2:17 pm
Location: Jonestown,Pa.17038
Stoker Coal Boiler: 1960 EFM520 installed in truck box
Hand Fed Coal Stove: Crane 404 with variable blower
Coal Size/Type: 404-nut, 520 rice ,anthracite for both

Post by windyhill4.2 » Mon. Jan. 04, 2016 1:14 pm

CoalisCoolxWarm wrote:Strong debate with lots of good technical info and light on the personal attacks. It's quite interesting to read about the inner "guts" and factors that go into a boiler design and rating :D

PEX in a ditch: FYI, 2" foam sheets are R10 and can easily be cut into a trench/box shape to be a thermal break from the ground, contain the piping for spray foam, can be "glued together" using spray foam, and offers some protection from rocks and stones as they heave against the pipe in cold weather (we have this problem here with very hydraulic clay and shell mix)

If it were my ditch, I'd dig it, cut strips to line the bottom of the ditch, strips for the edges, foam a little in the corners to hold it in a "U" shape, lay the insulated PEX/outer pipe assembly in the ditch, spray foam to fill the inside of the foamboard trench, lay about 6mil plastic on top with weight while the foam cures, then add a foamboard top to fit, using caulking (like you would use wood glue to assemble the top of a box) to attach it.

I'd use gravel in the bottom of the trench before anything else goes in, to help cushion any sharp rocks, and gravel all around and over when the entire assembly is done. The gravel helps with crush resistance. Cover with whatever you need for topside traffic over the ditch.

Around here, we'd probably put the piping in sch80 piping and keep it at least a foot or two deep to keep from crushing, but that's up to you.

Big Tip: Add a piece of wire in the ditch, over the trench before backfilling. Why? So years down the road a metal detector can be used to find the piping after the ground has healed.

We use gravel a lot to help with drainage and if ever digging it back up, it gives a "warning" to switch to hand shovels from the backhoe to avoid damaging the pipe/wire/whatever.

I'd bit the bullet and go with the larger piping from the boiler into the house and making my primary loop extend in there and add any secondary zoning off of it with closely spaced tees.
Lots of good advice & options,i like the foam board idea very much. We used stone dust about 12" deep under,around & over the pipe, to protect against stones & to be a "marker" during future digging.

 
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windyhill4.2
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Posts: 6072
Joined: Fri. Nov. 22, 2013 2:17 pm
Location: Jonestown,Pa.17038
Stoker Coal Boiler: 1960 EFM520 installed in truck box
Hand Fed Coal Stove: Crane 404 with variable blower
Coal Size/Type: 404-nut, 520 rice ,anthracite for both

Post by windyhill4.2 » Mon. Jan. 04, 2016 1:25 pm

With all the "debating" about which is the "better " boiler , anyone reading this thread should have sufficient info to decide if they want to have the incline grate of the Keystoker, which when pushed will make "sheet clinkers" or go with the EFM,with the underfed pot that when pushed will push some unburnt coal over the edge. As far as which unit _ k6 or k8 , best to just go with the k8 & have a bit of reserve, OR go one better & get the EFM 520 Highboy :) (I love the under fed pot best) :D

 
Pacowy
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Posts: 3555
Joined: Tue. Sep. 04, 2007 10:14 pm
Location: Dalton, MA
Stoker Coal Boiler: H.B. Smith 350 Mills boiler/EFM 85R stoker
Coal Size/Type: Buckwheat/anthracite

Post by Pacowy » Mon. Jan. 04, 2016 2:02 pm

I like Highboys and the larger heat exchange area undoubtedly pushes up efficiency and output somewhat. Not sure it would change the efficiency enough to fully offset the stoker issue but it might come close.

Mike

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