Replacing Oil Boiler with Indoor Wood Boiler

hot_rod

Without knowing how much leakage the home has, or the size of the room it is located in, its hard to give you an exact answer. The codes assume worse case in their 1/4 square inch per 1000 BTU/Hr appliance, both high and low vents.

When I worked in the mountains the AHJ allowed us to cut that requirement in 1/2. To lessen snow drifts in the mechanical rooms In one large lodge with heating and snowmelt boilers, several million btu/ hr. I walked in to a 2' high snow drift in the mechanical room. The AHJ allowed an "engineered" powered louver system to be installed on that job.


If you feel drafts being pulled into the home when running, from exhaust fans, door and window seals, etc, it needs more air!

Here are some ideas I have seen used to prevent the cold air from the intakes from chilling the room.
The fan in a can with insulated pipe, or dump the air into a bucket, the cold slug supposedly stops the draft?

OakLumber

leonz said:

You will have to plan on having a cold basement UNLESS you wall off the wood boiler with concrete block and place a pipe through the basement sill if there is enough open ground to pass a 4 inch pipe through and to make sure that the air inlet pipe is several feet above the ground to avoid its being plugged with snow.

How tall is this chimney? Does it have a chimney extension or chimney cap?

The chimney is about 40 feet high, 8" flue, and has a cap. It was professionally done.

The basement is finished and has floor heating throughout, which is why I wanted to tie the draft blower to a pipe going outside via the ceiling and through the wall. With my existing stove, I never had to worry about this, and once the chimney was hot there weren't any backdrafts, but this stove will be a little different because it needs bursts of combustion air, or so it appears. But the home is wide open and is quite large, so maybe I don't need to consider it for this either.

hot_rod

If you have an 8” flue going out, you need that much, and maybe much more coming into the house somehow, somewhere.

If in fact the home leaks that much, you are paying to heat all that infiltration, and the cold drafts as it makes its way to and combustion device. You mentioned a wood boiler, a wood stove, any other combustion devices? Oven, dryer, water heater?

Some  boilers have kits that allow you to pipe combustion air directly to the burner, or at least to the close to burner location m, called sealed combustion boilers sometimes.

OakLumber

Well, the stovepipe has a damper that is only open when opening the firebox. That restricts the air going up the chimney.

The house is tight, but it isn't a vacuum. Fwiw, it's an ICF construction, and there isn't any air creeping in through outlets or anything, and you don't feel any drafts even if there is a blizzard blowing outside. It has a lot of windows and doors, so adding them altogether, that's probably where the makeup air is coming in, as well as through things like bathroom fans. We don't have a range hood or a dyer, and the existing oil boiler will not be used at the same time. We'll continue using the woodstove upstairs in the livingroom, and we keep that damper closed except when it's being loaded as well.

This stove has the kit you mentioned. That's why I was considering connecting it to a pipe leading outside.

leonz

If you have not spent your money yet:

You should look at these two wood boilers;

AHS Wood Gun E110 commercial indoor model:
it can be set up as a dual fuel unit also.
www.alternateheatingsystems.com/product/indoor-wood-boiler

The AHS Wood Gun outdoor model is the E155
www. alternateheatingsystems.com/product/e155-obe/

The E155 wood gun outdoor boiler is based on the same design of the E100 indoor wood boilers with the
induced draft combustion chamber.

The Super E210 model is their indoor wood boiler for the homeowner

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www .woodboilers.com/wood-furnace-heating-indoor-wood-boiler/froling-S3-turbo-wood-boiler/

The HSTARM FROLING S3 Wood Gasification Boiler is another unit you should look at as well.

The S3 30 model is 96,000 BTU hr.
The S3 50 model is 164,000 BTU hr.

I have attached 3 HS Tarm Froling files for you to download and look at if you wish.

The Froling S3 model 30 and 50 are much more compact than the wood gun models

There is a federal tax incentive being offered now for wood boilers and Maine may have more tax incentives.

hot_rod

You will find that all the Euro built gasification units have small firebox. At least compared to the common OWF that sold in the US
The problem with large firebox designs is that the owners jam them full trying to get long burn times. But when the load gets satisfied they sit and smolder. Or over heat and boil🤣
I suspect that is the reason most are unpressurized vessels, they can boil over instead of having pressure and relief problems
But the firebox size difference tells a lot about the difference in how they burn wood across the pond compared to here.
The small firebox pretty much needs a buffer tank, but not so large to accept hours worth of excessive over heat operation

Best method I found is to build the fire size to what the weather conditions are

leonz

What Bob has stated is very true.

The Froling units have the advantage of being smaller in size and you can move the heat exchanger tube scraper arm to the opposite side of the boiler to make it easier to fit the boiler where you want it to be.

You need to have enough room at the rear of the boiler to install the flue pipe and access the combustion fan and electric motor.

The electric motor that powers the combustion fan is at the rear of the boiler out of the way and not on the floor next to the boiler like the AHS unit.

With 32 gallons of water in the S3 Turbo 30 and 50 gallons in the S3 Turbo 50 you may very well not need water storage. You could add non pressurized storage in the near term without the expense of installing pressurized storage by installing unpressurized storage with an insulated sunmax storage tank that has copper coils in it to allow heat exchange. The Sunmax tank packages have been designed to be small enough to pass through a doorway and then be installed.

Hot_water_fan

@leonz The smaller S3 turbo calls for a minimum of 400 gallons of thermal storage in that brochure you attached. 

leonz

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Hot_water_fan said:

@leonz The smaller S3 turbo calls for a minimum of 400 gallons of thermal storage in that brochure you attached. 

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1. ADDING hot water storage is an option for these units but not mandatory. It's a case of the user only wanting to fire a boiler once or twice a day to make hot water for heating and domestic hot water.

2. Many more hydronic hot water systems firing on coal, wood or wood pellets have no storage other than what is in the baseboard or radiators etc. In my case I have 54 gallons of water+- in total.

Either the Froling turbo S3 model 30(32 gallons) or model 50(50 gallons) units would work well for him as he could burn Hemlock slabwood from a lumber mill and save himself lots of work as the Froling burner design works well when using softwood fuel.

If he has room in his mechanical room for both boilers he could remove the flue pipe for the oil boiler and just use the flue pipe from the wood boiler and just reconnect the oil boiler flue pipe if he is going to be away from the home for an extended period.

If I had the amount of cast clay refractory weight in the Froling S3 model 50 for thermal mass in my old hand fed I would have burned even less wood and coal.

OakLumber

There is no room in the mechanical for a wood boiler, and I wouldn't want my wife to deal with swapping flues anyway. There is no source of slabwood since the mills sell all the biomass or use it themselves for heat and power generation. Using my own woodlot in my backyard makes the most sense.

leonz

Thanks much for the update,

If you are still intent on plumbing the boiler in series which is fine you should invest in a larger bladder tank if you are not using a steel compression tank for the point of no pressure change.

OakLumber

No, I decided to plumb it in parallel. That way, it would be a cinch to switch back to oil in case I screwed up something or there were leaks somewhere. I’ll be able to monitor the system for a while and get used to it, and then phase the oil out. Next summer, maybe I’ll put a solar hot water collector in parallel instead, and get rid of the oil completely.

hot_rod

leonz said:

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@leonz The smaller S3 turbo calls for a minimum of 400 gallons of thermal storage in that brochure you attached. 

================================================================= 1. ADDING hot water storage is an option for these units but not mandatory. It's a case of the user only wanting to fire a boiler once or twice a day to make hot water for heating and domestic hot water. 2. Many more hydronic hot water systems firing on coal, wood or wood pellets have no storage other than what is in the baseboard or radiators etc. In my case I have 54 gallons of water+- in total. Either the Froling turbo S3 model 30(32 gallons) or model 50(50 gallons) units would work well for him as he could burn Hemlock slabwood from a lumber mill and save himself lots of work as the Froling burner design works well when using softwood fuel. If he has room in his mechanical room for both boilers he could remove the flue pipe for the oil boiler and just use the flue pipe from the wood boiler and just reconnect the oil boiler flue pipe if he is going to be away from the home for an extended period. If I had the amount of cast clay refractory weight in the Froling S3 model 50 for thermal mass in my old hand fed I would have burned even less wood and coal.

I tried slab wood one season, too much bark! ended up with a lot more ash clean out.