Master BOM II

BOM:

House Water Connection

• [1] 10 pack of ¾”-1¾” hose clamps, $2
• 1” barb to ¾” NPT - amazon
• Pressure Reducer, $35
• [1] ¾”-½” NPT brass bushing - $3.5
• [1] ½” hex nip - $3.6
• ½”, 3 port diverter valve - $20, amazon
• [1] ½” NPT - ½” PEX adapter, $2
• [1] ½” PEX copper crimp ring (17 tot)

Hot Water Heater

• [1] water heater, $254
• [1] ½” NPT cross, amazon, $5
• [6] ½” galvanized plug, $1
• [13] ½” plastic PEX/NPT adapter - $0.8
• [1] ½” NPT-PEX plastic elbow, $1.5
• [1] ½” PEX insert elbow, $1
• [16] ½” PEX crimp rings, $4 (17 tot)
• [4] ½” NPT galvanized tee, $1
• [1] ½” NPT galvanized elbow, $1
• [1] ½” NPTF adapter, $3.5
• [1] ½” 3 port diverter valve, $20 amazon

Propane

• [1] 2’ gas connection line, ½” MPT-FPT - $15
• [1] ½”x2’ black pipe - $5
• [1] ½” black pipe tee - $1
• [1] ½” black pipe coupling - $1
• [1] ½” black pipe plug - $1
• [1] ½” black pipe, 5’ - $7
• [1] ⅜” flare x ½” FIP - $9
• [1] propane regulator, ⅜” flare - $21
• [1] 100 lb propane tank - $137

Electrical

• [1] breaker box - $157
• [1] 240V breaker - $15
• [6] tandem circuit breakers, 15& 20A - $16
• [1] GFCI circuit breaker, 20A - $53

Plumbing

• [2] 2” PVC elbow - $1
• [1] 2”x10’ PVC pipe - $4.5

½”

5’

2’

Master BOM

Other

• [13] Fire bricks, 4.5x9x1.25 - Stove + Door
• Aluminum screen - tree guards
• Aluminum foil tape - 25’, greenhouse
• [4] 2x4, 8’
• [2] 1x8, 8’
• [10] 1x2 furring strips, 8’
• [2] power strip 2 pack $4
• [2] packs of 4, 3x ¾” corner braces
• 5/32" x 50' Black Nylon Diamond-Braid Paracord

BOM:

Heat Exchanger

• [2] 1”x2’ black pipe - $6
• [6] 1”x18” galvanized - $6
• [8] 1”x12” black - $4
• [8] 1”x6” black - $2
• [8] 1” couplings - $2
• [15] black elbows - $2
• [15] black street elbows - $2

Hydronic Panel (does not include PEX tube)

• [3] ¾” brass cross - amazon
• [1] ¾” brass tee
• Taco 007 pump - amazon, $30 cheaper
• [2] 1” pipe union, galvanized - $6
• [1] 1”-¾” galv reducer bushing - $2
• [6] ¾”x1.5” brass nips- $4
• [1] ¾”x3” brass nip - $6
• [2] ½” brass nips - $4
• [1] P+T relief valve - $12
• [2] Pressure/Temperature gauge
• [2] ¾” PEX-¾” NPT barbs
• [1] ¾” copper NPT to ¾” PEX manifold
• [1] 4-fold, ¾” manifold for ½” PEX
• [1] ¾” copper cap
• [7] ½” PEX crimp rings
• [3] ¾” PEX crimp rings
• [1] ¾” NPT brass plug
• [4] ¾” - ½” reducers - $3.5
• [2] ¾” flanges
• [1] 3-port return PEX manifold
• [1] ½” plastic PEX plug
• [1] ½” PEX-½” NPT barb
• [1] ¾” brass check valve
• [2] ½” ball valve - $7
• [1] ¾” ball valve

¾”-½”

¾”

½”

¾”

Water System Integration with Hydronics

Bathroom

water

heater

1” tubing

½”

e

Leave 3” of slack to account for any re-plumbing in future.

Put everything on a plywood panel to facilitate mounting, screw panel directly into brick.

heater vent

To Kitchen

To Bathroom

To Stove

From Stove

Remember drain valve and stove drain integration

81” to top of heater

½”

send toilet vent outside near floor level

To Bathroom

To Kitchen

Pipe is 24” above floor

½”x2’black pipe through wall

⅜” M flare - ½” FIP

1 PSI Propane Regulator

​

1. Galvanized pipe union - $6,
2. reducer bushing- $2;
3. galvanized pipe elbow - $2
4. 3’ pipe section, ¾” - $9
5. Reliev Valve - $13
6. PEX adapter, ¾” - $2
7. [7] ¾” brass nips - $4
8. [2] ½” brass nips -

Minimum Hydronic Control Panel

Has extra hydronic takeoff for Greenhouse

Drain both for pressure and winter drain. Assumes ¾” outlet

Has a Priming Drain

Has circuit for hot water to house, which also purges air

¾” NPT - ½” PEX to house hot water

¾” NPT - ¾” PEX relief to daylight

¾”

½”

Return

Forward

Winterizing Port or T Probe

Pump is at bottom of stove for priming

Filler

Has a check valve for open system priming

Priming Port or T probe port

Sink Extension, via ¾”NPT-½” PEX elbow

Stove

½”

½”

¾”

¾-¾”

¾”

¾”

¾”

½”

Unused.

¾-½”

¾-½”

¾-½”

¾-½”

Plumbing Components, Exterior

Below-grade wooden box, on North ext. wall

North Wall

½” hydronic tube

½”-½”

1” barb to ¾” MPT does exist

¾”

3 way selector valve is the secret: allows drainage and pressure from water line in one component

½”

Open Source Hydronic Wood Stove

Marcin Jakubowski, Alec Higgins, OSE

Nov 16, 2015

Building on Open Source Hydronic Stove

See Hydronic Stove Development Template

Table of Contents

1. Overall Build Order
2. Ash compartment design
3. Calculations
4. Door Fabrication
5. Hydronic Control Panel

Breaker Box Design

¾” Brass Pipe Cross + Valve Details

Heat Exchanger

Dec 8, 2015 by MJ

Building on Open Source Hydronic Stove, and Heat Exchanger Calculations

See Hydronic Stove Development Template

left side

top side

left side

Wherever pipe bottoms out, there are about 2” to the edge of the pipe fittings for overall exchanger length dimension. The vertical part here adds 2” to what is not already accounted: so each turn adds 6” after 2 fittings are considered.

• If length of fittings is 2” on each end, then 18” pipe segments would total 22” of length - good.
• 6 galvanized at menards, $6.18 (6 in stock), black is $4.79, out of stock. Suitability of Galvanized.
• Mixing some 12”+6” sections with couplers is ok, so use whatever galvanizes is available, and rest is black sections.
• Another way is to extend stove by 6” to accept 2’ pipe, which may be desirable in the future due to sourcing constraints.
• Use 6 sections on sides, and 4 sections on top side of stove

16 turns for a 32 foot heat exchanger - 2’ per run, if 18” pipe is used. Ends add 6” per turn.

Heat Exchanger

Vertical Heat Exchanger Section (6 of 16 turns)

Dec 8, 2015 by MJ

Building on Open Source Hydronic Stove, and Heat Exchanger Calculations

See Hydronic Stove Development Template

left side

top side

left side

• Use [2] 2’, [14] 18” lengths
• [6] galvanized
• Height: 5x3.5”+2” = 19.5” - or 4” below ceiling of stove

BOM:

• [2] 1”x2’ black pipe - $6
• [14] 18” lengths:
• [6] 1”x18” galvanized - $6
• [8] 1”x12” black - $4
• [8] 1”x6” black - $2
• [8] 1” couplings - $2
• [15] black elbows - $2
• [15] black street elbows - $2
• [2] 1” pipe union - $6

​

2’

18”

1

2

3

4

5

6

Design Notes:

• Interfaces:
1. Main pressure relief to daylight
2. Air purge to daylight - at highest point for entrained air
3. Purge to daylight for initial priming, and any subsequent priming event
• [2] Pump - 1 speed - Taco 007
• General calculation - 10kBTU/1 GPM of flow at 20 degree T drop
• [2] ¾” pump flanges
• ½” pipe to PEX adapter, elbow
• 4 Branch manifold - ¾”-½” PEX - $49, cap, and ¾” NPT to copper
• 4 Branch return manifold - ¾”-½” PEX - $15
• [2] Pressure/Temperature gauge
• [2] ¾” brass tee - $8
• ¾” - 1.5” nip - $4
• Pipe to PEX - but says 140F - $3
• ½” brass ball valve, $7
• Check valve - $13
• PEX supply valve - $6

​

​

Cold water source - drains at main house drain

stove

1. ¾” brass cross - $9 amazon prime

Hydronic Panel Initial Notes- ¾”

​

• Galvanized pipe union - $6, reducer bushing- $2; galvanized pipe elbow - $2
• 3’ pipe section, ¾” - $9
• ¾” nip, 1.5” - $1
• Reliev Valve - $13
• PEX adapter, ¾” - $2

Back of Stove - Connection to Heat Exchanger

Initial Notes

Consider extra hydronic takeoff for GH

Drain both for pressure and winter drain. Assumes ¾” outlet

Must have drain for hydronic heat and hot water

Must have circuit for hot water

¾” PEX

¾” NPT - ½” PEX to house hot water

¾” NPT - ¾” PEX relief

Pump at bottom at stove to assure priming issues are addressed

House Water + Electric Connection +

Equivalent Circuits (Simplifications)

Connect Water at Pit

½”

=

1” barb

=

¾”

(5 to 1, used for water heater-hydronic hot water integration)

(3 to 1, used at water inlet to house. Saves $20 on ¾” instead of 1” pressure reducer)

(6 to 2 parts)

=

water pressure

drain

water pressure

drain

1” barb to ¾” NPT

Build Cheat Sheet

​

1. From Ash Chamber, stand up front and back, and weld in intermediate angles and 3 side body panels.
2. Cut Chimney hole
3. Weld in fire brick holder from the bottom - ¼”x2 flat?
4. Make door based on already transfer-torched pattern
5. Make heat exchanger
6. Once finished, add rope gasket between:
1. Ash and burn chambers
2. Front door assembly and burn chamber
3. Rear door and burn chamber
7. Build flue and add chimney

ash chamber

Side View

BOM SUMMATION

¼”x2”x2” angle - ironworker

• [12] 2’ long, flat frames
• [4] 1’ long, legs
• [4] 14” long, door opening
• [4] 14.75” long, door lid

⅛” Steel Sheet - exactly 1 sheet, 0 waste

1. [6] 2’x2’
2. [1] 23”x23”
3. [3] 3-¼””x2’
4. [3] 2-¾”x2’
5. [1] 6”x2’
6. [1] circle for flue, ½” bolts, ½” hole

6” Grain Spouting

• 16’ long

Expanded Metal mesh, ¼”

• [1] 23”x23”+-¼”

¾” Bolts

4. [16] nuts
5. [16] 1.5” or 2” bolts

½” steel

1. Latch
2. Door Hinges

0

cut list

14 long

14.5” long

14 long

14 long

14 long

1

1A

1B

2

3

ash

Side View

14.5” x 14.5”

14” x 14”

Door and Rear Panel Frames

1. Weld frame
2. Trace bolts, 4” away from edge and mid of the frame
3. Torch out as shown
4. Weld nuts on back
5. With nuts welded, transfer punch hole locations, and punch or torch out holes

Front Door Fabrication

Build:

7. Torch out plate on the inside of the angle
8. Weld door frame
9. Weld inner face
10. Torch 4” tube hole for air
11. Weld on 4” wide air diverter on inside
12. Fill in

Door Insulation Options:

• Shielding Insulation
• Ceramic fiber insulation
• Rock wool (1800F)
• Fiberglass insulation (1100F)

​

​

​

Lip of the ¼” angle

¼”x2”x2” angle is right outside the bolts, so inner lip of opening is 5” from edge, and opening is 14” (10” less than 24”)

7

Lip of the ¼” angle

Overall Build Order

Design Rationale:

• Experimental Modularity for a Stove Construction Set
1. Wood or pellet
2. Low pressure or steam
• Size scalability - via elongation or vertical stacking
• Initial: length-wise stackability. Extendable to height-wise scalability via removable panels
• Simplest design for hydronic heat exchanger, using 1” black pipe as a low pressure heat exchanger.
• Pipe schedule may be increased for higher pressure applications
• Uses common off-shelf parts
• Uses open source hydronics circuit

Build Order:

• Build in parallel for Extreme Manufacturing

Main Proof of Concept

1. Demonstration of dismountable, air-tight panels (such as the rear of stove for heat exchanger insertion, front for conversion to pellet stove)

Overall Build Order:

• Build 3 flat frames:
• Front and rear of stove
• Ash tray upper interface
• Cut 6 body panels, ⅛”x2’x2’, and one 23”x23” for ash tray
• Cut expanded metal mesh
• From Ash Chamber frame, build out Ash Chamber + Tray
• Take 2 stove frames and transfer-torch hole pattern for closure plates, then weld nuts on back of frames
• From Ash Chamber, stand up front and back, and weld in intermediate angles and 3 side body panels.
• Cut Chimney hole
• Weld in fire brick holder from the bottom
• Make door
• Make heat exchanger
• Once finished, add rope gasket between:
• Ash and burn chambers
• Front door assembly and burn chamber
• Rear door and burn chamber
• Build Flue and add chimney

​

​

​

burn chamber

ash chamber

Interface Frame - upper frame of ash chamber

burn chamber

ash chamber

ash chamber

Front View

Side View

BOM

BOM

• 3 flat frames:
• [12] ¼”x2”x2” angle
• ​
• Cut 6 body panels, ⅛”x2’x2’, and one 23”x23” for ash tray
• Cut expanded metal mesh
• From Ash Chamber frame, build out Ash Chamber + Tray
• Take 2 stove frames and transfer-torch hole pattern for closure plates, then weld nuts on back of frames
• From Ash Chamber, stand up front and back, and weld in intermediate angles and 3 side body panels.
• Cut Chimney hole
• Weld in fire brick holder from the bottom
• Make door
• Make heat exchanger
• Once finished, add rope gasket between:
• Ash and burn chambers
• Front door assembly and burn chamber
• Rear door and burn chamber
• Build flue and add chimney

​

​

​

burn chamber

ash chamber

Side View

BOM SUMMATION

¼”x2”x2” angle

• [12] 2’ long, flat frames
• [4] 1’ long, legs
• [4] 14” long, door opening
• [4] 14.75” long, door lid

⅛” Steel Sheet - exactly 1 sheet, 0 waste

• [6] 2’x2’
• [1] 23”x23”
• [3] 3-¼””x2’
• [3] 2-¾”x2’
• [1] 6”x2’
• ​

6” Grain Spouting

• 16’ long

Expanded Metal mesh, ¼”

• [1] 2’x2’

¾” Bolts

• [16] nuts
• [16] 1.5” or 2” bolts

½” steel

• Latch
• Door Hinges

​

​

​

Ash Chamber Design and Fabrication

Design Rationale:

• Ash tray itself serves as a smoke-tight and openable door for air intake, thereby removing the need for a door.
• Gasket rope is used to provide a seal
• Low profile (3” aperture) allows thin steel (⅛”) to be the body, without bottom frame.
• Front is reinforced with ¼”x2”x2” angle
• ¼”x2”x2” legs are added

Build Order:

• Build Interface Frame (as third frame in overall build)
• Cut ½” under
• Trim corners - 10 minue
• Weld
• Weld ¼” expanded metal mesh to underside of the frame
• Weld 3 vertical sides (except for the front) and bottom to frame
• Weld reinforcing

Overall Build Order:

• Build 3 flat frames:
• Front stove
• Rear stove
• Ash tray interface
• Cut 6 panels, 2’x2’
• Cut expanded metal mesh
• ​

​

​

​

burn chamber

ash chamber

Interface Frame - upper frame of ash chamber

1

¼”x2”x2” angle

2’x2’ footprint

top view

Corners need to to 45 degrees to build an integral frame

3

3

Sides are flat on the outside

angle is ½” under 2’ for size to end up at 2’

Issues and Goals

• Existing hydronic heating stoves are expensive. They start at $2k for the ability to run house heating on hot water. This is just the stove, not controls or distribution.
• OSE goal is a $400 for 100k BTU (enough for 2000 square feet)
• Prior art: we bought a 100k BTU stove for $5k for MicroHouse 4
• Solution: use a black pipe heat exchanger:
• Design the proper length using Heat Exchanger Calculations

​

​

Letter to builder:

​

Hello Clair,

​

We are building an open source hydronic stove. Last year we documented our build with an off-shelf hydronic stove. Please see http://opensourceecology.org/wiki/Open_Source_Hydronic_System

​

Can you review our design once we produce the new design? Do you recommend the heat exchanger made of 1" black pipe, or would you do things differently?

​

Marcin

​

Hydronic Heat Control Panel - Design Rationale

Prime design points:

• allow for proper refilling, priming, draining, and pumping, so correction from empty system or even steam-out condition is fixable immediately
• Minimize specialized parts

​

Implementation:

• Update: turns out that the control panel has been simplified sufficiently to allow for all components to be placed behind stove, as in this slide
• Pump below heat exchanger in the best case, though not co-located at control panel
• Mixing valve is relevant in our case only for tarring of heat exchanger; not relevant if continuous duty firing or gas heating
• 2nd Pressure relief - on cold side of system to prevent hot water loss. First pressure relief on hot side so it’s activated by temperature
• Have air purge double as a pressure relief? No dedicated air purge needed.
• 4.4 gallon expension tank - not needed, as in calculations
• ​

​

Heat Exchanger Calculations - Updated

QUESTION 1: Is thermal expansion significant enough to leak water through pressure relief under the assumption of incompressible fluids? Answer: No - PEX pipes expand as much as the water. Expected result: pressure relief is never activated via thermal expansion.

• 1/10000 per F coefficient of expansion for water - 600 feet of ½” pipe are (or 1% linear expansion):
• 5 gallons in 600’ of ½” PEX
• .6-1.2 gallons in 15-30’ of 1” black pipe
• Take 6 gallons of volume - expansion is only 6/10000 of a gallon - or under .2 cubic inches.
• Can expansion of water be handled by expanding PEX?
• Linear expansion of PEX is 1”/10F/100’. (p. 42 of this ) - so for 100F rise, 10” for a 100’ run - about 1% expansion.
• This indicates approximately the same expansion by volume in the tubing, thus no leaks are expected

QUESTION 2: Does empirical evidence for heat exchanger size match calculated value?

• Empirical: for 50k BTU/hr, just take ½ of the 11 square foot area of a 100k BTU/hr rated hydronic water jacket stove. Surface area of 6 square feet is thus required in a pipe-based heat exchanger
• 1” pipe - 1/3 square foot surface area per foot of length
• 1 hp = 2500 BTU/hr. BUT - a boiler horsepower is different.

• One boiler horsepower = 33k BTU/hr. This is the amount of energy necessary to produce 1 hp from a steam engine at 8% efficiency (2.5k/33k = 8%).
• Boiler horsepower = Area (sf) / 17
• Ie, 10 sf/hp for more efficient engines.
• From this figure, 17 square feet are needed for 33kBTU/hr. That’s consistent. So our pipe area should be 17-34 sf. At the higher pipe area, we can run the stove at lower heat to extract the same power.
• Stove should be ~30 ft of pipe - which is also the size for a 1-2 hp steam engine if such a retrofit is desired in the future.

Conceptual Design

• research mix valve
• manual air purge
• manifold numbers
• bom for plumbing (heat exchange is flat on 2’x2’ square, black pipe).
• valves on manifold

ash -

1x2x2’

6” chimney on top

See Heat Exchanger Calculations

left side

left side

top side

top side

firebox - 2x2x2’

left side

1’ long black pipe nip

weld a cube without a bottom from ⅛” steel

1” Street Elbow

Hydronic Stove Design Rationale

ash

left side

top side

left side

Modularity:

• Design for Extreme Manufacturing: rapid, parallel build
• Heat exchanger can be retrofitted into stove via front door
• Door can be replaced with a pellet burner attachment
• Open Source flue control
• Retrofittable with pellet burner
• Retrofittable with additional heat exchangers.
• Large bolt-on door for easy access
• Thermal design optimizes radiant heat extraction and heat retention (Fire brick)

Scalability:

• 2 or more sections can be combined front to back
• Longer heat exchanger can be used

​

2 feet long side

¾” bolt goes into ¾” nut welded to inside of shell

1.5’ long side

Flue Control

½” nut

½” bolt

⅛”x6” disk

top view

scalability

​

​

​

Gasket Rope+

Cement

fire brick

heat exchanger

Modularity

Ash Compartment

Modularity:

• Heat Exchanger - switch-out capacity, multiple heat exchangers
• Stackable body - 2’ high, multiple 2’ long secions can accept longwood. Practical length is 6’, or 3 sections
• Stackable ash compartment -
• Flue Control - DIY
• Chimney - 6” grain spouting
• Fire brick - retrofittable
• Door - retrofitable with pellet burner
• Ash tray - 2x2 foot sections, can be multiples
• Control Panel - can accept any number of circuits.

​

Control Panel

Body

Ash Compartment

Body:

• Door - can be taken off and another section can be bolted on.
• Door can have a blower or a pellet burner attachment
• Body proper is only a skin, no frame.

Design for Manufacturing

• Made from 2’x8’ strip of ⅛” mild steel

​

​

​

​

​

• Body has front and back angle frame - ¼”x2”x2” frame, allowing sections to be connected to make a larger stove:

​

​

​

​

​

​

​

​

• Gasket Rope + Cement are used for air-tightness

​

¼”x2”x2”

angle frame

Gasket

Rope

Front Flange Fabrication Detail

Front Flange:

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

Build:

• [2] Torch a front and rear plate - ⅛”x2’x2’
• cut [2] angle frames for front and rear using plate cut above as guide
• Notch the holes with torch
• Match torch for front plate
• Weld ¼”x2”x2” angle on the front
• Torch out plate on the inside of the angle

​

​

​

Ash Compartment

2” angle

2

3

1

4

5

6

⅛” plate

Blower

ordered items in red

Ash Compartment

Blower Power Supply:

• 1A, 12V - $6
• 3A, 12V - $10

Blower:

• 224 CFM, 3A, 12VDC, PWM - $12
• 146 CFM, AC
• 70 CFM, 12VDC, $8

With Cord:

• 48 CFM, AC, $18, 40dB
• 110 CFM, AC, $17, 47dBA

With Cord + Speed Control:

• 20-70 CFM - $24; noisy

Value Pack:

• 4 fans, 45 CFM, 0.2A, 2W, 3 pin, $3 each; connection; silent at 19dB
• Fan cable - $5

DC Fan Speed Control:

• 2 amp, 6 W - $9

Retrofit speed control for AC fan:

• 25A AC speed controller - $7
• With enclosure - $15

Best chimney arrangement

Pipe exits in front interfere with stove operation

Control Panel

Orientations

​

1” union

Pipe exits in front interfere with stove operation

Pipes towards back.

Easy routing to control panel.

Nonsymmetric arrangement

Link

FreeCAD download

of STEP files for elbow and pipe from McMaster-Carr