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Watts AERCO MFC Series Pre-Installation Application Manual Download Page 33

 

MFC Series Boiler Vent and Combustion Air Guide

 

 

 

    

TAG-0080_OG

  •   

GF-148-V

    •   

  3/29/2023           

Technical Support

  

•

  (800) 526-0288  

•

  Mon-Fri, 8 am - 5 pm EST           Page 33  of 

33 

 

 Change Log:

 

Date

 

Description

 

Changed by

 

11/22/2017 

Rev D

: 

DIR 17-004

: Added optional air intake adapter figures (new section 

5.1), corrected example calculation (section 16.1), corrected figure 
numbering, added and corrected table numbering, renumbered 
sections, updated formatting per current standard. 

DIR 17

-

069:

 Updated formatting to the current standard. 

Chris Blair 

1/25/2019 

Rev E

: 

DIR 19-10

: Removed 2 optional air intake adapter from Section 5.1 

Chris Blair 

3/29/2023 

Rev F

: 

The GF number of this document is now GF-148-V. 

Chris Blair 

3/29/2023 

Rev G: 

Section 11: Updated info on who to contact for design assistance, 
and r

emoved manifold warning, as per CZ’ request 

LW 

 

    

 
 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
 

 

 

 

 

© AERCO International, Inc., 2020 

Summary of Contents for AERCO MFC Series

Page 1: ...al Power Guide TAG 0078 GF 148 G MFC Series Gas and 2 Oil Supply Guide TAG 0081 GF 148 B MFC Series Boiler Application Guide Disclaimer The information contained in this manual is subject to change without notice from AERCO International Inc AERCO makes no warranty of any kind with respect to this material including but not limited to implied warranties of merchantability and fitness for a particu...

Page 2: ...rough the MFC Series Boiler 9 5 Direct Vent Ducted Combustion Air 10 5 1 Optional Air Intake Adapters 10 6 Exhaust Vent and Combustion Air Systems 12 7 Gross Natural Draft 12 8 Acceptable Pressure Ranges 12 9 Exhaust Fans 12 10 Corrections for Altitude 13 11 Manifolded Systems 13 12 Elbow Quantity and Separation 13 13 Exhaust Muffler And Air Inlet Attenuator Guidelines 13 14 Vent and Combustion Ai...

Page 3: ...liance which requires special attention to exhaust venting and combustion air details The exhaust vent MUST be UL listed for use with Category II and IV appliances The following materials are allowed The MFC 3000 4000 5000 6000 8000 and 10000 boilers can use only AL29 4C venting materials Polypropylene PVC and CPVC are NOT allowed TABLE 1 Flue System Requirements Minimum Thickness for AL29 4C DIAM...

Page 4: ...ntal to the operation of regulators meters or related equipment Discharges should not be located in high wind wind blocked areas or corners or be located directly behind vegetation Discharges in these locations may cause the flue pressures to fluctuate and result in flame instability As a general rule designs should minimize wind effects Wall and roof penetrations should follow all applicable code...

Page 5: ...entation In equipment rooms containing other air consuming equipment including air compressors and other combustion equipment the combustion air supply system must be designed to accommodate all such equipment when all are operating simultaneously at maximum capacity Combustion air intakes must be located in areas that will not induce excessive 0 10 water column W C intake air pressure fluctuation...

Page 6: ...ditions 4 1 Combustion Air from WITHIN the Building Where combustion air will originate from within the building air must be provided to the equipment room from two permanent openings to an interior room or rooms Openings connecting indoor spaces shall be sized and located in accordance with the following Each opening shall have a minimum free area of 1 inch2 per 1 000 BTU hr 2 200 mm2 kW of total...

Page 7: ...pecified For additional details consult NFPA 54 or in Canada CSA B149 1 10 paragraphs 8 4 1 and 8 4 3 4 3 Two Permanent Openings Method USA Only Two permanent openings shall be provided one commencing within 12 inches 300 mm of the top of the enclosure and one commencing within 12 inches 300 mm of the bottom The openings shall communicate directly or by ducts with the outdoors or spaces that freel...

Page 8: ...tion Air from Outdoors Through Ventilated Attic When communicating with the outdoors through horizontal ducts each opening shall have a minimum free area of 1 inch2 per 2 000 BTU hr 1100 mm2 kW of total input rating of all appliances in the space see Figure 5 Figure 5 All Combustion Air from Outdoors through Horizontal Ducts OUTDOOR OPENINGS TO HORIZONAL AIR DUCTS ...

Page 9: ... shown in Figure 6 and shall have a minimum free area as follows 1 inch2 per 3 000 BTU hr 700 mm2 kW of the total input rating of all appliances located in the space Figure 6 All Combustion Air from Outdoors through Single Combustion Air Opening 4 5 Opening a Louver Through the MFC Series Boiler A louver can be opened using the auxiliary relay contacts part of the MFC burner controls These contact...

Page 10: ...ugh a metal or PVC duct connected between the MFC unit s and the outdoors This configuration is useful for situations in which room air is insufficient or otherwise unsuitable for combustion The minimum ducted combustion air duct sizes for the MFC boilers are as follows MFC 3000 10 inch diameter MFC 4000 12 inch diameter MFC5000 12 inch diameter MFC 6000 14 inch diameter MFC 8000 16 inch diameter ...

Page 11: ...MFC Series Boiler Vent and Combustion Air Guide TAG 0080_OG GF 148 V 3 29 2023 Technical Support 800 526 0288 Mon Fri 8 am 5 pm EST Page 11 of 33 Figure 7 Air Inlet Adapter for MFC 3000 P N 201044004 ...

Page 12: ...natural draft values for stacks at various heights above the MFC unit are presented in Table 6 in Section 19 Part 1 and Part 2 These draft values are based on an installation site at sea level Adding the gross natural draft negative to the vent and air system pressure drop positive determines if the total system will be positive pressure or negative pressure net natural draft As with most combusti...

Page 13: ...luence the system s exhaust and combustion air pressures as well as its acoustical behavior Designers should consider minimizing the quantity of elbows in the design and the use of angles less than 90 whenever possible Five or fewer elbows are recommended for individual venting connections five or fewer are recommended for common sections The minimum distance required between two elbows is five fe...

Page 14: ...6 inch dia A 1 4 inch NPT combustion test hole is provided on each unit s exhaust manifold connection A 24 inch length of straight vent is recommended downstream of the exhaust manifold The vent system should always be pitched up inch per foot of run towards the vent termination to enable condensate to drain back to the unit for disposal Low spots in the vent must be avoided Periodic inspection sh...

Page 15: ...e used for the condensate drain A base drain must be installed at the bottom of vertical common flue piping The pH level of the condensate produced by MFC Series boilers ranges between 3 0 and 3 2 The installation should be designed in accordance with local codes that specify acceptable pH limits If required any type of commercially available neutralizer may be used 16 Individually Vented Systems ...

Page 16: ... 00 ft Rain cap exit loss 1 x 8 81 8 81 ft Vent drop subtotal 54 22 ft Altitude correction 54 22 55 21 ft 0 982 CF Natural draft for 20 feet 20 F outside temperature 12 6 ft Altitude correction 12 6 x 0 982 CF 12 37 ft TOTAL VENT DROP 42 84 ft 10 INCH DIAMETER COMBUSTION AIR DUCT PRESSURE Two 90 elbows 2 x 1 88 3 76 ft 50 feet total run 50 x 0 3 15 00 ft Entrance loss 1 x 4 46 4 46 ft Combustion a...

Page 17: ...26 0288 Mon Fri 8 am 5 pm EST Page 17 of 33 17 Manifolded Ducted Combustion Air For systems using manifolded ducted combustion ductwork use the longest length of common duct and the individual branch to the furthest boiler to calculate the pressure drop Figure 8a Individual Vents Preferred Installations ...

Page 18: ...ES 1 For high wind wind blocked sites a tee may be installed at the fresh air inlet The leg of the tee connects to the combustion air intake 2 On the flue vent side a tee or exit cone velocity cone may be utilized in place of a rain cap for high wind or wind blocked sites 3 The branches of the tee can be in the horizontal or vertical direction as determined by the system designer and site conditio...

Page 19: ... be used to accomplish these connections see Figure 9a The recommended minimum individual boiler vent length before joining the common vent breech is 10 feet Figure 9a Recommended Connections to Common Vent Breeching Interconnection of groups of units must never be accomplished via a tee As shown in Figure 9b change the direction with one of the mains and then connect the second three diameters co...

Page 20: ...e vent system should always be pitched up inch per foot of run towards the vent termination see Figure 11 This will enable condensate to drain back to the unit for disposal Low spots in the vent must be avoided Inspect periodically to ensure correct drainage As shown in Figure 11 the unit at the end of the vent main must be connected via an elbow An end cap must not be used as it may cause vibrati...

Page 21: ...S HORIZ TERM EQ FT EXIT LOSS RAIN CAP EQ FT 12 24 30 0 38 3 91 3 03 7 65 14 21 14 17 85 0 18 1 96 1 52 4 13 7 67 16 13 67 0 09 1 08 0 84 2 42 4 49 18 10 80 0 05 0 64 0 50 1 51 2 81 20 8 75 0 03 0 40 0 31 0 99 1 84 Single MFC 5000 Boiler Assuming 180 F Water Temperature and 20 F Rise at Sea Level FLUE VENT IN DIA FLUE VELOCITY FT SEC STRAIGHT RUN EQ FT FOOT 90 ELBOW EQ FT 45 ELBOW EQ FT EXIT LOSS H...

Page 22: ...EXIT LOSS RAIN CAP EQ FT 16 27 33 0 33 4 33 3 38 9 68 17 98 18 21 60 0 18 2 57 2 01 6 04 11 22 20 17 49 0 11 1 61 1 26 3 97 7 36 22 14 46 0 07 1 05 0 82 2 71 5 03 24 12 15 0 04 0 71 0 55 1 91 3 55 Single MFC 10000 Boiler Assuming 180 F Water Temperature and 20 F Rise at Sea Level FLUE VENT IN DIA FLUE VELOCITY FT SEC STRAIGHT RUN EQ FT FOOT 90 ELBOW EQ FT 45 ELBOW EQ FT EXIT LOSS HORIZ TERM EQ FT ...

Page 23: ...0 21 0 23 0 24 0 25 90 Elbow 1 45 1 53 1 60 1 71 1 82 1 94 2 07 2 21 2 36 45 Elbow 1 12 1 18 1 24 1 32 1 41 1 50 1 60 1 71 1 83 Ent Loss 3 95 4 15 4 35 4 64 4 95 5 29 5 64 6 02 6 42 16 Duct Three Boilers Straight Run 0 18 0 19 0 19 0 21 0 22 0 23 0 25 0 27 0 28 90 Elbow 1 90 1 99 2 09 2 23 2 38 2 54 2 71 2 89 3 08 45 Elbow 1 49 1 56 1 64 1 74 1 86 1 99 2 12 2 26 2 41 Ent Loss 5 21 5 47 5 74 6 12 6...

Page 24: ... 16 0 17 90 Elbow 1 19 1 25 1 31 1 40 1 49 1 59 1 69 1 81 1 93 45 Elbow 0 93 0 97 1 02 1 09 1 16 1 24 1 32 1 41 1 51 Ent Loss 3 51 3 69 3 87 4 13 4 40 4 70 5 01 5 35 5 70 18 Duct Three Boilers Straight Run 0 23 0 24 0 25 0 27 0 29 0 31 0 33 0 35 0 37 90 Elbow 2 67 2 81 2 94 3 14 3 35 3 57 3 81 4 07 4 34 45 Elbow 2 09 2 19 2 30 2 45 2 61 2 79 2 98 3 18 3 39 Ent Loss 7 91 8 30 8 71 9 29 9 91 10 57 1...

Page 25: ... 7 13 41 14 31 16 Duct Two Boilers Straight Run 0 16 0 17 0 18 0 19 0 20 0 22 0 23 0 25 0 26 90 Elbow 1 86 1 95 2 05 2 19 2 33 2 49 2 65 2 83 3 02 45 Elbow 1 45 1 52 1 60 1 71 1 82 1 94 2 07 2 21 2 36 Ent Loss 5 50 5 77 6 06 6 46 6 89 7 36 7 85 8 37 8 93 18 Duct Three Boilers Straight Run 0 35 0 37 0 39 0 41 0 44 0 47 0 50 0 53 0 57 90 Elbow 4 19 4 39 4 61 4 92 5 24 5 60 5 97 6 37 6 80 45 Elbow 3 ...

Page 26: ...48 V 3 29 2023 Technical Support 800 526 0288 Mon Fri 8 am 5 pm EST Page 26 of 33 NOTES 1 Calculation assumes 1170 scfm per boiler at full fire rate 2 Units for Straight Run pressure drop values are eq ft foot 3 Units for Elbows and Ent Loss are equivalent feet item ...

Page 27: ...14 0 15 0 16 90 Elbow 1 23 1 29 1 35 1 44 1 54 1 64 1 75 1 87 1 99 45 Elbow 0 96 1 00 1 05 1 12 1 20 1 28 1 36 1 46 1 55 Ent Loss 3 80 3 98 4 18 4 46 4 76 5 08 5 42 5 78 6 16 22 Duct Three Boilers Straight Run 0 13 0 14 0 15 0 16 0 17 0 18 0 19 0 20 0 22 90 Elbow 1 80 1 89 1 99 2 12 2 26 2 41 2 57 2 75 2 93 45 Elbow 1 41 1 47 1 55 1 65 1 76 1 88 2 00 2 14 2 28 Ent Loss 5 84 6 12 6 43 6 85 7 31 7 8...

Page 28: ...90 Elbow 1 95 2 04 2 14 2 29 2 44 2 60 2 78 2 96 3 16 45 Elbow 1 52 1 59 1 67 1 78 1 90 2 03 2 16 2 31 2 46 Ent Loss 6 30 6 61 6 94 7 40 7 89 8 42 8 98 9 58 10 23 22 Duct Three Boilers Straight Run 0 31 0 33 0 35 0 37 0 39 0 42 0 45 0 48 0 51 90 Elbow 4 38 4 60 4 82 5 15 5 49 5 86 6 25 6 67 7 11 45 Elbow 3 41 3 58 3 76 4 01 4 28 4 56 4 87 5 19 5 54 Ent Loss 14 17 14 87 15 60 16 64 17 76 18 94 20 2...

Page 29: ...Elbow 3 04 3 19 3 34 3 57 3 80 4 06 4 33 4 62 4 93 45 Elbow 2 37 2 48 2 60 2 78 2 96 3 16 3 37 3 60 3 84 Ent Loss 9 82 10 30 10 81 11 53 12 30 13 13 14 01 14 94 15 94 22 Duct Three Boilers Straight Run 0 48 0 51 0 53 0 57 0 60 0 64 0 69 0 73 0 78 90 Elbow 6 83 7 17 7 52 8 02 8 56 9 13 9 74 10 39 11 09 45 Elbow 5 32 5 58 5 86 6 25 6 67 7 11 7 59 8 10 8 64 Ent Loss 22 10 23 18 24 33 25 95 27 68 29 5...

Page 30: ...3 0 367 0 321 0 275 0 229 0 183 0 138 125 0 602 0 559 0 516 0 458 0 401 0 344 0 287 0 229 0 172 150 0 722 0 670 0 619 0 550 0 481 0 413 0 344 0 275 0 206 175 0 842 0 782 0 722 0 642 0 562 0 481 0 401 0 321 0 241 200 0 963 0 894 0 825 0 734 0 642 0 550 0 458 0 367 0 275 Eq Ft STACK HEIGHT FT OUTSIDE AIR TEMPERATURE F 30 F 15 F 0 F 20 F 40 F 60 F 80 F 100 F 120 F 5 4 1 3 8 3 5 3 2 2 8 2 4 2 0 1 6 1 ...

Page 31: ... 0 321 0 275 0 229 0 183 0 138 125 0 602 0 559 0 516 0 458 0 401 0 344 0 287 0 229 0 172 150 0 722 0 670 0 619 0 550 0 481 0 413 0 344 0 275 0 206 175 0 842 0 782 0 722 0 642 0 562 0 481 0 401 0 321 0 241 200 0 963 0 894 0 825 0 734 0 642 0 550 0 458 0 367 0 275 Eq Ft STACK HEIGHT FT OUTSIDE AIR TEMPERATURE F 30 F 15 F 0 F 20 F 40 F 60 F 80 F 100 F 120 F 5 4 1 3 8 3 5 3 2 2 8 2 4 2 0 1 6 1 2 10 8 ...

Page 32: ...0 701 10000 0 688 TABLE 8 Round Duct of Identical Pressure Drop to Rectangular Duct Adjacent Side of Duct in Side of Rectangular Duct in 6 8 10 12 14 16 18 20 22 24 6 6 6 8 7 6 8 7 10 8 4 9 8 10 9 12 9 1 10 7 12 13 1 14 9 8 11 5 12 9 14 2 15 3 16 10 4 12 2 13 7 15 1 16 4 17 5 18 11 12 9 14 5 16 17 3 18 5 19 7 20 11 5 13 5 15 2 16 8 18 2 19 5 20 7 21 9 22 12 14 1 15 9 17 6 19 1 20 4 21 7 22 9 24 24...

Page 33: ...corrected figure numbering added and corrected table numbering renumbered sections updated formatting per current standard DIR 17 069 Updated formatting to the current standard Chris Blair 1 25 2019 Rev E DIR 19 10 Removed 2 optional air intake adapter from Section 5 1 Chris Blair 3 29 2023 Rev F The GF number of this document is now GF 148 V Chris Blair 3 29 2023 Rev G Section 11 Updated info on ...

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