Fireplaces

How it Works Our Systems Fireplaces Fan & Coil

 

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Background and History:

 

Fireplaces were the most common means by which a house, castle, or any type of building were heated in past times.  The means of temperature control simply involves moving closer to the fireplace, the source of heat.  The method by which the heat is increased is again very rudimentary by increasing or decreasing the amount of firewood in the fireplace.  Over the years however, their role as the most dependable form of heat, has diminished. 

Fireplaces are not used for their efficiency, since far more effective means of heating exist today.  Their role has developed from that of an effective heat source to that of an aesthetic purpose.  As fireplaces have continued to develop over the years, their components, fuel types, and function have also dramatically changed.  Today, gas fireplaces have become a common component of the modern house’s living room or ‘great’ room.  Instead of dragging wood fuel across the living room, gas fireplaces can be enjoyed at the convenience of a remote control. 

 

                                   

 

 

 

 

 

     Rumford Wood Fireplace

 

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Components:

 

For a wood fireplace the core components include a

  1. Damper
  2. Throat
  3. Chimney
  4. Smoke Chamber
  5. Firebox
  6. Hearth
  7. Cap
  8. Flue

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Basic types of fireplaces:

Zero clearance - Lighter and less expensive system that can be fitted tightly within wooden framework of the building without risk of fire.
Masonry - Heavy and three times more expensive than zero clearance system. It can be completely or partially installed in the envelope of the structure.

In a gas fireplace, the same components can be used although this is not necessary.  A gas fireplace is an enclosed unit, often behind glass, whereby the gases from the flame never have the opportunity to escape into the room and are forced out by the exhaust fan.

 

Typical Wood Fireplace        Typical Gas Fireplace

related link: Gas Fire Place

Component

 

Purpose

Damper

The damper is an adjustable plate that is used to control the draft in the flue.  The exhaust gases pass this point as they exit the flue.

Throat

The part of a chimney between the firebox and the flue.

Chimney

The chimney is the structure which holds the flue, and carries the gases.  Due to the natural convection process, by which heat rises, the exhaust gases exit through this component to the outside. 

Smoke Chamber

The smoke chamber in essence is the beginning of the flue, where the smoke builds up. 

Firebox

The fire box is a where the fuel (wood) is placed, and from where the heat is radiated throughout the room

Hearth

The hearth is the floor of a fireplace, usually extending into a room and paved with brick, flagstone, or cement.

Cap

The cap is a device which is places atop the chimney and whose function is to inhibit the entrance of water and outside elements, including animals, into the smoke chamber and fireplace as a whole.

Flue

The flue is the compartment of a chimney for conveying flame and smoke to the outer air.

 

Either segmented or single throats can be used as shown below.

                                         

 

 

 

Segmented                                                         Single 

 

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Definition of System:

Our class defined a system to be “an organized set of related components working together to produce a desired result.”  Regardless of the type of fireplace, the definition of a system is met when the subsystems work together and function as a complete system.  The components, previously mentioned, cannot function individually but must function collectively in order to produce their desired result.  The desired result, creating heat, is met when all subsystems work together.

If the damper would fail, for example, the entire fireplace would fail since all subsystems are interrelated and therefore interdependent. 

 

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Typical Uses:

          The uses of fireplaces have changed and developed over the years, from being a crucial part of sustaining life, to becoming simply an ornament.  While fireplaces undoubtedly still provide heat, their uses have been limited to purely the aesthetic when economical factors are considered.  In past times they were used as the main source of heat, thereby providing several uses.  These included but were not limited to cooking, metal working, drying of clothing, and heating the house. 

 

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Limitations:

            Fireplaces are limited in several arenas.  The location in the typical house, confines the heat source to one region of the house, leaving hot and cold pockets throughout.  Although gas fireplaces can be powered by a remote control, and have no cleanup, wood fireplaces, require significant effort in starting the fire, and significant time in cleaning up the debris and by products of the fire.  When compared to other sources of heat in the modern home, fireplaces once again pale, yet their aesthetic features keep them alive. 

 

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Materials:

        The materials used within a fireplace must most definitely be of a non combustible nature.  When gas fireplace’s are constructed, the materials used are simply a light-gauge steel for the casing, a gas line, and a glass front plate.  Electronic components such as a fan can be added, but most of the materials used are simply steel and glass.  In a wood fireplace, the firebox is often constructed of any of several types of masonry.  This includes soapstone which is a very good retainer of heat, which continues to radiate heat long after the fire goes out.  The dampers, and flue are constructed of a light-gauge steel, while wrought iron is used as a form of decoration around the hearth.

 

 

 

FIREPLACE WIDTH

A

B

C

D

E

F

G

 

 

 

 

 

 

 

 

2' WIDE

24”

12”

13.5”

5,25”

24”-28”

12”

19”

2'-6" WIDE

30”

12”

13.5”

8.25”

28”-32”

12”

18”

3' WIDE

36”

14”

13.5”

11.25”

32”-38”

14”

18”

3'-6" WIDE

42”

15”

15”

13.5”

38”-42”

15”

18”

4' WIDE

48”

16”

18”

15”

42”-48”

16”

19”

4'-6" WIDE

54”

18”

18”

18”

50”

13.5”

32”

5' WIDE

60”

20”

22.5”

18.75”

48”-54”

13.5”

32”

6' WIDE

72”

24”

24”

24”

54”-60”

13.5”

32”

7' WIDE

84”

28”

28”

28”

60”

13.5”

42”

8' WIDE

96”

32”

32”

32”

60”

13.5”

42”

11' WIDE

120”

40”

40”

40”

72”

13.5”

42”

 

 

Materials and typical sizes

 

 

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Numeric Parameters:

The numeric parameters on various sizes for gas and wood fireplaces are listed below.  Efficiency ratings for a fireplace range from negative to a positive 40%.  Negative efficiency exists in old fireplaces where cold air is absorbed into the building through the chimney and although the fireplace warms its immediate vicinity, the building overall cools down. 

 http://www.rumford.com/segflyerplan.gif picture source.

 

 

Wood Fireplace Numeric Parameters

Fireplace Size

24" Wide

30" Wide

36" Wide

42" Wide

48" Wide

Smoke Chamber

8.5"x13" (clay flue) 12"x12" (metal flue)

13"x13"

13"x13"

13"x18" (clay flue) 16"x16" (metal flue)

16"x20" (clay flue) 18"x18" (metal flue)

Flue Tile

8.5"x13"

13"x13"

13"x13"

13"x18"

16"x20"

Class A Flue

8" MRF

10" MRF

12" MRF

14" MRF

16" MRF

A

24"

30"

36"

42"

48"

B

12"

12"

14"

15"

16"

C

13.5"

13.5"

13.5"

15"

18"

D

5.25"

8.25"

11.25"

13.5"

15"

E

24"-28"

28"-32"

32"-38"

38"-42"

42"-48"

F

12"

12"

14"

15"

16"

G

19"

18"

18"

18"

19"

 

Gas Fireplace Numeric Parameters

Fireplace Size

36" Wide

42" Wide

48" Wide

60" Wide

72" Wide

Throat Opening

4"x17"

4.5"x20"

5"x23"

10"x27"

10"x34"

Smoke Chamber

13"x13"

13"x18" (clay flue) 16"x16" (metal flue)

16"x20" (clay flue) 18"x18" (metal flue)

20"x20"

24"x24"

Flue Tile

13"x13"

13"x18"

16"x20"

20"x20"

24"x24"

Class A Flue

12" MFR

14" MRF

16" MRF

18" MRF

20" MRF

A

36"

42"

48"

60"

72"

B

14"

15"

16"

20"

24"

C

13.5"

15"

18"

22.5"

24"

D

11.25"

13.5"

15"

18.75"

24"

E

32"-38"

38"-42"

42"-48"

48"-54"

54"-60"

F

13.5"

13.5"

13.5"

13.5"

13.5"

G

18"

18"

19"

30"

30"

 

 

Btu output for a typical gas fireplace is in the range of 17,000 BTU/hr., while its maximum area of heat is 1,050 ft. squared.

 

 

Component Selection Chart

Fireplace Size

24" Wide

30" Wide

36" Wide

42" Wide

48" Wide

60" Wide

72" Wide

Clay Flue

8.5"x13"

13"x13"

13"x13"

13"x18"

16"x20"

20"x20"

24"x24"

Class A Flue

8" MFR

10" MFR

12" MFR

14" MFR

16" MFR

18" MFR

20" MFR

Class A Anchor Plate

8" AAP

10" AAP

12" AAP

14" AAP

16" AAP

18" AAP

20" AAP

Smoke Chamber

8.5"x13" (clay flue) 12"x12" (metal flue)

13"x13"

13"x13"

13"x18" (clay flue) 16"x16" (metal flue)

16"x20" (clay flue) 18"x18" (metal flue)

20"x20"

24"x24"

Throat

24" 1 piece

30" 1 piece

36" 1 piece

42" 1 piece

48" 1 piece

5 pcs 12" throat tile 1 coving pair

6 pcs 12" throat tile 1 coving pair

Damper

24" RSS

24" FCI

24" FCI

30" FCI

30" FCI

42" DCI

54" DCI

Firebox

65 firebrick 130 Splits

75 firebrick 150 Splits

110 firebrick 230 Splits

150 firebrick 320 Splits

170 firebrick 350 Splits

290 firebrick 590 Splits

315 firebrick 640 Splits

Heatstop Mortar

15 lbs. 30 lbs.

15 lbs. 30 lbs.

15 lbs. 30 lbs.

30 lbs. 65 lbs.

50 lbs. 80 lbs.

50 lbs. 100 lbs.

50 lbs. 100 lbs.

 

 

Wood Burning System

System Type Heating Capacity sq.ft Max Btu/Hr Overall Efficency Emissions Gr/Hr Max Burn Time hours Fire Box Volume ft^3 Fuel Capacity lbs
Masonry  1500-2500 74,300 70% 2.6 12 3.1 36
Masonry or Zero Clearance 800-1800 71,800 71.1% 2.0 9 1.8 22
Masonry or Zero Clearance 600-1200 64,200 68.0% 3.0 8 1.3 16

 

Above parameters compare selected types of wood burning fireplaces.  Masonry and zero clearance systems vary in heating capacity, but maximum energy they delivered is about 70, 000 Btu/hr.  The efficiency achieved is about 70% and it can be accomplished with different sizes of units.

 

Gas Burning System

Performance and Specifications

Zero Clearance Gas Fireplace Insert
Fuel

Variable Input (BTU/Hr.)

Steady State Efficiency

Heating Capacity Standing Pilot Room Fan Direct Vent
Natural Gas  Low 18,600   High 31,000 80% Up To 1,500 Sq. Ft. Heat even when the power's out 130 CFM Standard 3" Flex Duct Incoming & Exhaust
 Propane Low 16,000   High 31,000 80.5% Up To 1,500 Sq. Ft. Heat even when the power's out 130 CFM Standard 3" Flex Duct Incoming & Exhaust
Zero Clearance Gas Fireplace
Natural Gas Low 18,600  High 31,000

80%

Up To 1,500 Sq. Ft. Heat even when the power's out

130 CFM Standard

3" Flex Duct Incoming & Exhaust
 Propane Low 16,000  High 31,000

80.5%

Up To 1,500 Sq. Ft. Heat even when the power's out

130 CFM Standard

3" Flex Duct Incoming & Exhaust

 

Above parameters show zero clearance gas burning system having lower variable input and heating capacity than wood burning system.  However, the steady state efficiency of gas burning system is about 10% higher than wood burning systems.   Major advantage of this system is that heat is produced even when the power is out.  

Source: HVAC SYSTEMS

 

 

http://www.oldhouseweb.com/stories/Detailed/10047.shtm

Tulikivi Soapstone Wood-burning Fireplace Model KTU 1800

Description

Corner model soapstone wood-burning fireplace

Features

Soapstone exterior produces radiant heat long after the fire is out

Low emissions, creosote buildup

Outside does not get hot

Airflow controlled by ash door

Ashes removed through removable ash pan

Large viewing window

Airwash system keeps glass door clean and free of soot

Electric heating components available for back-up

External Dimensions

60 1/4" H x45 3/4" W x31 5/8" D
(rear sides measure 33")

Installation

By trained professional. Average time 2 to 4 days.

Btu Output

17,000/ hour

Max. Sq. Ft. Heated

1,050

Wood Size

4" dia., up to 16" lengths

Firebox Dimensions in inches

W: 16-1/2
D: 12-7/16

Minimum Chimney Sizes in inches

Square (rect.) 8 x 12
Round 8

Clearances in Inches to Combustible Walls
side/back

14/20

Weight in pounds

3,461

Heat Output numbers are based on a home with 8' ceilings, R-28 insulation in the walls, R-42 insulation in the ceiling, and located in Northern climate. 

Source: Fire Place

 

 

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 Heating Types:

            

Radiative heat pattern from a typical fireplace       

Gas flow through a fireplace throat

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 Construction Issues:

Masonry System:

  1. 8" of solid masonry  must separate  a fireplace from a combustible material

  2. system has to be constructed on heavy footing to support the system's heavy weight

Zero Clearance System:

  1. system has to be constructed on double floor joists 

 

 
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 Sources:

 http://www.mcnear.com/rf_comp_info.html

www.heatilator.com

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