coal/oil boiler

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Old 12-09-12, 06:16 AM
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coal/oil boiler

Hello everyone, I am looking into getting a coal/oil boiler to run in parallel with my existing oil boiler. I have had some tell me that the coal boiler would not be enough btu for my house.

I have a 1200 sq ft ranch house, brick outside, insulated attic and I would assume insulated walls, built in 1959. It also has a 900 sq ft finished basement.

I did a heat loss calculation for my house, and came up with 1567 sq ft, with a heat loss around 40k btu for 15 degrees outside and 76 inside.

The boiler I am looking at is 110k btu input with around 90% efficiency but can go as low as 80% efficiency depending on how clean everything is and the quality of the coal. At 80% that is still 88k btu, that should still be plenty correct?

I used the slantfin program to do my heatloss calculation.
 
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Old 12-09-12, 08:27 AM
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Sounds like you will have more than enough.

Why do you want to burn coal?
 
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Old 12-09-12, 10:24 AM
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I too think it would be enough.

What were the qualifications of those who said it wouldn't?

Why do you want to burn coal?
He's in PA! Coal is cheap! (and fun to shovel... well at least I thought so when I was 12!)
 
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Old 12-09-12, 11:34 AM
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I know coal is cheap, but firewood can be had for free. I also hear the smoke from coal is pretty dismal. We are up to our necks in firewood here in NJ.
 
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Old 12-09-12, 12:59 PM
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I actually like the smell of coal burning... but like I said, I also enjoyed shoveling it... ok, I'm weird, but you knew that already, diddincha?

A 'proper' coal fire shouldn't generate much, if any, smoke. Stove design has a lot to do with it too, and quality (and proper size for the stove) of the coal also.

Bring yer truck, I'll GIVE you a load of firewood! Seriously!
 
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Old 12-09-12, 01:07 PM
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Bring yer truck, I'll GIVE you a load of firewood! Seriously!
I may take you up on that. It's part of my new "emergency preparedness" plan. If I get a wood rack for xmas like I asked, it may be sooner than later.
 
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Old 12-09-12, 03:01 PM
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I've worked on a lot of coal fired gravity equipment through the years. Enjoy yourself
Are you going to burn anthricite ?

A house built in 1959 may or may not have insulated walls, unless you have checked inside here and there?
 
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Old 12-10-12, 05:25 AM
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The guy who told me it wasn't was a EFM boiler salesmen, and was trying to sell me a used EFM350(go figure).

Coal is cheap in PA, much much cheaper than heating oil, electricity or propane. Wood is technically "free" If you don't account for the time cutting it, moving it, splitting it, stacking it, moving it again and finally burning it. Also not to forget the gas to pay for moving it, the gas for the chainsaws, potential hospital visits and repair costs.

I could have my entire seasons supply of coal stored in a 4x4x8 bin. I know a couple wood burners and they can't fit all their wood into an area like that.

Also with coal there is many more options, a traditional handfed stove, can even burn for upwards of 24 hrs unattended, most likely would be shaking it down and feeding twice a day, a total of 10 to 15 minutes a day.

The unit I am looking into has a 50 pound hopper and a large ash pan, based on calls for heat, could go 5 days completely unattended.

One or 2 5 gallon buckets is all I need to transport my heating material to my house.

Yes I will be burning anthracite, my plans have been kinda derailed for now, my wife doesn't want to take out a loan for it, so until I can sell my car I will be waiting and dreaming of saving money.

Boilernut, I haven't checked the walls, the attic floor is insulated, so I figured they probably would have insulated the walls then. I am going to do a heat loss calculation for uninsulated walls and see how much my loss is then, I probably will still have plenty of btu output.

I think they are insulated because of how well it holds temperature now.
 
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Old 12-10-12, 03:00 PM
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I haven't checked the walls, the attic floor is insulated, so I figured they probably would have insulated the walls then. I am going to do a heat loss calculation for uninsulated walls and see how much my loss is then, I probably will still have plenty of btu output.
While you are in the program, increase the attic insulation to at least R40 and see what you get.

I'm betting that your existing insulation is the original, and probably not more than R19, IF THAT after so many years of being compressed, etc.

You might be surprised at the difference just bulking up on attic insulation makes!

The other real biggy, especially older homes is AIR INFILTRATION. In many cases the losses from infiltration can far exceed the losses from poorly insulated wall cavities.

I don't know how good this is, but the price is right for a big boy Christmas toy... oh Santa!

Amazon.com: Black & Decker TLD100 Thermal Leak Detector: Home Improvement
 
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Old 12-11-12, 01:22 PM
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I redid everything with no attic insulation and no wall insulation and still came out to about 60k btu/hr heat loss, the boiler should have no problem at all keeping this house heated.
 
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Old 12-11-12, 01:27 PM
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Tell your wife you want this unit for Christmas...we're all pulling for you to get this unit, lol . I know you have to wait
 
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Old 12-11-12, 03:03 PM
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'nut, you talking about Andrew's coal boiler, or the thermal leak detector?

If the latter, it's on it's way... I'll start a thread about it if it's any good... or even if it's not. But maybe this isn't the right forum.
 
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Old 12-11-12, 03:11 PM
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I was talking about his boiler, I know he's excited about getting it.
 
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Old 12-11-12, 03:28 PM
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Yeah, me too! I get my cheap thrills vicariously these days... I'm happy when others are happy.

But ONLY as long as they provide plenty of high res photos to drool over.

Of course, I'm happy when I'm happy too... like I would be if I could afford that outdoor wood boiler, but that ain't gwinne happen in my lifetime I don't think.

By the way Andrew... coal needs to be stored in a dry environment. You said something about a 5 gallon pail which leads me to believe you are considering outdoor storage. You lose a large portion of it's heating value if it is allowed to absorb moisture. Dry INDOOR storage is almost a must, unless you can construct an outdoor enclosure that prevents moisture intrusion which is difficult to do! One warmer humid day after a period of cold weather will cause a lot of condensation in a coal bin.
 
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Old 12-11-12, 05:13 PM
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you planning on removing the existing oil boiler?
 
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Old 12-11-12, 08:32 PM
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I wish it was as easy as asking for it for christmas, but its not. I plan on running it in parallel with my existing boiler, I am going to powervent the existing boiler and use the chimney for the coal boiler.

I plan on building a small bin inside my basement where I can store maybe a weeks worth of coal, that should give it time to dry up before using it, outdoor storage is going to be in a 4x4x8 bin with lids. Over on the coal forums a lot of people just store their coal on piles in their driveways or in bins outside.
 
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Old 12-11-12, 08:56 PM
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lot of people just store their coal on piles in their driveways or in bins outside
I'm not saying it won't still burn of course... but the heat that is required to turn the entrapped water into vapor goes right up the chimney. Same thing with firewood... depending on the moisture content, it can be upwards of 15% less BTUs available to put into the home. Or to put it another way, you are raising the price of the coal or firewood by 15%. That's pretty substantial over the course of a heating season!

I am going to powervent the existing boiler
Be careful! There's plenty of disastrous pitfalls!
 
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Old 12-12-12, 05:58 AM
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My parents have 3 furnaces that are powervented at their business and they have had no problem with them at all. The oil burner is rarely going to be used. If I went away for an extended period of time I would probably still use coal, both my wife and my parents live very close to my house, they could take care of my coal boiler while I was gone.

Only really power venting the oil furnace so its to code, and its there in case I absolutely need it.
 
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Old 10-13-14, 01:22 PM
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Reviving an old thread here, I ended up never getting the boiler due to lack of funds, but to my joy, this year is the year, already have it ordered and waiting for it to be shipped.

Finding someone to install it has been a bit of a nightmare, either they are all to busy or don't want to even bother, I have a good understanding of plumbing, electrical and so fourth and I love to accomplish projects myself so I am going to do the install myself.

From what I understand the coal boiler will need some kind loop for temp differences. I have read through a couple things and studied some diagrams on how a solid fuel boiler should be hooked up for parallel running with an oil burner, here is the drawing I came up with for my layout.
Name:  Untitled.jpg
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I'm not sure if this is the proper way, but from what I have read this is how it should be. I will also be putting in some valves to be able to shut the coal boiler completely off from the oil if needed.
 
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Old 10-13-14, 02:36 PM
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It kind of [email protected]@ks like you have your boilers in series? lol

Re-do your drawings again and use pump symbols for pumps please!

It looks like you have a conflict with the direction of flow too!

You would be better off with a main loop and your two boilers in parallel with that...keeps the water blended and reduces thermo-shock

 

Last edited by boilernut; 10-13-14 at 03:06 PM.
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Old 10-13-14, 04:04 PM
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I modeled the drawing off the plan that is in this manual, page 17
http://leisurelinestoves.com/files/81881384.pdf

and this pictureName:  ParallelPipingLayout.jpg
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Size:  32.6 KB
 
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Old 10-15-14, 02:47 PM
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Does this model help out?
Name:  boiler hookup.jpg
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Size:  9.0 KB
 
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Old 10-16-14, 04:21 AM
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Sorry, I was in a bit of a rush yesterday and didn't have time to explain the picture.

Boiler on left is existing oil boiler, one on the right is the new boiler. Heated water leaves the oil boiler, travels up into the three zones, this line then tees off and continues to the coal boiler where it will be heated by coal. It leaves the boiler and travels up and tees, the first tee goes to the return of the oil boiler, the other tee connects onto the feed line just after it passes the zones on its way to the coal boiler, this I assume creates a mixing point.

At this point, no of this may matter. Yesterday I went to check on my sump pump(it was raining hard all day) I noticed a puddle underneath my boiler. I looked top to bottom for leaks, but couldn't find anything visible, I thought maybe it leaked in through the chimney because of how hard it had rained so I left it go.

The rain stopped late afternoon yesterday, I checked this morning and the puddle had gotten bigger. Since there was no water running into my sump today, it was quiet. I would hear gurgling ever 30 seconds or so then water running down from one of my heating zones. I suspect that I have an internal leak in my boiler, and if that is so, the old boiler will be taken out. I turned off the make up water line this morning and checked the psi, I am going to keep an eye on it and the puddle to see if the water is indeed coming from the boiler.
 
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Old 10-18-14, 07:26 AM
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Getting back to your set up there, I like the second drawing better than the 1st lol.

It looks like your oil boiler could be blended with a dedicated pump between the supply and return to short circuit and blend water since your 3 zones make a direct path back to the return.

Add a dump zone on the coal side with a reverse acting aquastat. When the system reaches 180 or above your design temp, the dump zone with a bank of radiators or a long baseboard loop would energize and lower the water temp. This protects you during the off cycle when all the zone pumps stop. Your Tarm may already be reverse acting during the off cycle. Make sure of your set up...this becomes an even bigger issue if hand firing the boiler.


I'm sure there's a lot more others out there have to add ?

 

Last edited by boilernut; 10-18-14 at 08:05 AM.
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Old 10-18-14, 10:06 AM
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Here is what I have been running. The wood/oil/coal unit is an old VanVert boiler that I've had for about 30 years. It is mostly backup for the Biasi, which has a Tekmar ODR.

I burned wood for three months last winter. Either coal or wood will drive you out of the house!


Pete
 
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Old 10-18-14, 05:12 PM
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Thanks boilernut. So by a pump between supply and return, do you mean supply of the coal burner and return of the oil burner? Or do you mean the supply of the oil burner to the return of the coal boiler? I plan on setting the dump zone to zone 3 which will be my basement, this zone will also be controlled by a thermostat to heat when needed and if the aquastat is tripped it will dump in that zone. The unit I am purchasing is a stoker type boiler so it only burns on and off and then burns when heat is called for, the aquastat, and dump zone control are all included in it.

What should I change on my model?
 
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Old 10-18-14, 06:02 PM
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In drawing #2 it looked like any zone pump could send cool water back directly to the oil boiler? Is this unit cast iron? If so I would make sure there's a short circuit so you blend some warm water back in the return line. Some boilers are short circuited from the factory.
 
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Old 10-18-14, 06:07 PM
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What exactly do you mean by short circuit? You are correct about cool water returning from any one of the three zones, but it would then be blended in to the hot water coming from the coal boiler.
 
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Old 10-18-14, 06:36 PM
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I can see the blending above your coal boiler, but not sure how it blends to the oil boiler? What would cause the return water to pass through the blending valve above the coal boiler, then turn around and return to the oil boiler?
 
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Old 10-18-14, 07:15 PM
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There will be a pump that connects the supply of the coal boiler to the return of the oil burner. This would be at the first tee of the supply. This would possibly be continuous running to keep water circulating through the loop, when heat is called for or the high temp is tripped, it will pump water to the zones while the continuous pump keeps moving water from the oil boiler side to the coal boiler side to be heated.
 
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Old 10-18-14, 07:24 PM
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Name:  boiler hookup 2.jpg
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Here is another angle with some more labels, added pump and some numbering

#1 is where heated water will be blended with slightly cooled water heading back from the oil boiler if no heat was called for.
#2 is the main supply line from the coal boiler which will be pumped to the return of the oil, call for heat with circulate this heated water throughout.
#3 is where new heated water will blend with cooled circulated water that returns from the zones
#4 is the return for the coal boiler.

Hope this clears things up.
 
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Old 10-19-14, 04:37 AM
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It seems you already have it all figured out. I didn't see the pump on your drawing I guess?
 
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Old 10-19-14, 04:57 AM
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It was my bad, I never had that other pump in, I added it so it would make more since. So this setup would work? Do you think I would need to add another expansion tank on the coal boiler side?

I had said earlier that I believed my oil boiler was leaking. Since shutting off the water 4 days ago the puddle dried up and the pressure has stayed the same. Is it possible the water make up is supplying to much pressure, possibly a faulty pressure reducer?
 
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Old 10-19-14, 12:00 PM
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Here's a simple set up with 2 boilers connected below the main loop by Ts connected close together. This works well for the most part as the blending takes place between the Ts. The 3 zones circulating create the main that the boiler loops attach to. I've found this set up to work okay, except for when the system is connected to old Rads full of rust...check valves don't like rusty systems...

This is just a sample and in no way is the correct way to install your system without factory approval.





 

Last edited by boilernut; 10-19-14 at 01:48 PM.
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Old 10-19-14, 01:23 PM
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boilernut, that makes so much more sense to me, that was the idea I had on how to connect them, but all the diagrams I saw didn't really look like that and that's why I didn't think they could be hooked together that way.

It will be pretty simple to plumb together, just leave my supply and return zone in place, and redo the plumbing to them from the two boilers, seems a lot easier than what I had in mind. I really appreciate the help.
 
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Old 10-19-14, 01:42 PM
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This is just a sample drawing I made...it's in no way approved by your boiler manufacturer. Develop your final plan and submit it to them for approval before you do anything. You can do a lot of damage by improperly installing a system such as this, eh? Definitely not for amateurs such as myself, and I sure wouldn't do this without an expert looking at it first. !!
 
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Old 10-19-14, 01:57 PM
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I will submit it to the manufactures and see what they say about it, it seems like that is the easiest and most straightforward way to plumb it.
 
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Old 10-19-14, 02:15 PM
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Make sure your plan is complete showing your equipment, valves, safety systems, controls and sensor locations. They will usually add ideas and correct any errors in your plan. You can void the warranty if you don't follow their instructions...and complete photos of the current installation...a picture is worth a thousand words!
 
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Old 10-20-14, 04:23 AM
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Somebody who has installed these specific boilers look over the plan and said it was basic, but it does work. He suggested adding valves and unions for shutdown and removal of either boiler if needed.
 
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Old 10-20-14, 05:22 AM
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I would do whatever the experts suggest, follow all the rules, size the piping correctly, most people don't have a clue as to what it's all about...that's normal, including me sometimes! lol
 
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