Publisher’s version / Version de l'éditeur:
Technical Note (National Research Council of Canada. Division of Building Research), 1957-02-01
READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.
https://nrc-publications.canada.ca/eng/copyright
Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la
première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.
Questions? Contact the NRC Publications Archive team at
PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information.
NRC Publications Archive
Archives des publications du CNRC
For the publisher’s version, please access the DOI link below./ Pour consulter la version de l’éditeur, utilisez le lien DOI ci-dessous.
https://doi.org/10.4224/20355017
Access and use of this website and the material on it are subject to the Terms and Conditions set forth at Clearances Above Plenum Chambers
Ferguson, R. S.; Wilson, A. G.
https://publications-cnrc.canada.ca/fra/droits
L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.
NRC Publications Record / Notice d'Archives des publications de CNRC: https://nrc-publications.canada.ca/eng/view/object/?id=15a578b0-a3ca-46e1-8b84-9b15d6d76cab https://publications-cnrc.canada.ca/fra/voir/objet/?id=15a578b0-a3ca-46e1-8b84-9b15d6d76cab
DIVISION OF BUILDING RESEARCH
NATIONAL RESEARCH COUNCIL OF CANADA
'fECHNlICAlL
NOT FOR PUBLICATION
NOTJE
No.
219
FOR INTERNAL USE
PREPARED BY RoS. Ferguson and
A0 Grant Wilson
CHECKED BY APPROVED BY RoF.L.
"Clearances'above Plenum Cnambersr
PREPARED FOR •
D1.scussions re proposed CoSoA ..
Burning Installation Code
SUBJECT
Oil February 1, 1957
"\
ｾｴｦ
More than a year ago a request was received by the Associate
Committee on the National Building Code from the National ｾｲｭ Air
Heating and Air Conditioning Association to make revisions to Part 6 (General Services) of the National Building Code (1953) in
connection with requirements for residence-type warm-air ｨ･ｾｴｾｮｧ
units and associated ducts.. The revisions suggested were qUite
extensive and our subsequent investigations revealed that there was no one recognized standard and that the present advisory regulations
in this field were not in agreemento
The agencies which issue relevant standards are: A.CoNoB.Co
NoFoPoAo
D.BoIoUo CoSoA ..
National Building Code
Pamphlet 90B (Installation of Residence-type Warm Air Heating and
Air Conditioning Systems) also
Pamphlet 90A (Installation of other types)
also
Pamphlet 31 (Installation of Oil Burning
Equipment)
issue standards similar to N.FoPoA. issue standards similar to NoF.PoA. Proposed Standard B139 - 1956
(Installation Code for Oil Burning Equipment)
Canada test equipment9 if requested$ to manufacturerVs instructions
but not necessarily to any of these standardso
As an example of the confusion 'which now exists in this field, the differences with respect to one item only - "clearances
above plenum ｣ｨ｡ｭ｢･ｲｳｾ - are outlined belowo Three columns are
shown indicating document, type of equipment, and clearance requiredo
Significant aspects are discussed in noteso
"Clearance above Plenum Chambers" Document NoBoC. 1953 Note: N.FoP.Ao 90B (May 1955) Type of Equipment
Automatically fired mechanical
warm air furnaces with 2500Fo
temperature high limit control Until recently this was the clearance requirement given in the standards
of all the agencies in the foregoing
ｬｩｳｾ
Listed or unlisted automatically fired, forced air or gravity system,
equipped with 250oFo temperature
limit control which cannot be set higber than 250° and installed not more tban 10· above the top surface of the heat exchanger in a supply
plenum that extends at least 12ft
above the top surface of the heat
exchanger9 and Clearance
6"
1" Note:-t1sted automatically fired7 forced
air or gravity system, equipped
with limit control not conforming to 2ft
above, but that will limit outlet
air temperature to 2500 Fo
The one category in the NoBoCo (1953) be-came two categories in the new NoFoPoAo standardl' and "lis ted" equipment is
intro-ducedo If put in the NoBoCo as requested
it would ratse a matter of fundamental policyc
While this change was being considered in connection with the NoBoCol' the NoFoPoAo issued further suggested revisions to their
Standard as ｦｯｬｬｯｷｳｾ
-N.F.P.A. 1956 !Advance Reports
Pamphlet 90B
New note qualifying 1" clearance
i
added as ｦｯｬｬｯｷｳｾ
"If the limit control cannot be set higher than 250°F. but is
installed more than 10" above the top surface of the heat exchanger or is in a supply plenum that extends less
than 12ft above the top surface of
the heat exchangerp this clearance
shall not be less than 6 inches."
Note: This change really sets up a new
classifi-cation conforming to neither of the two categories in the previous 90B standard.
It also goes back to 6" (the NoB.C. clearance)
for all except the ｳｰ･｣ｬｦｩｾ type of
installation in 90B May 19530
While these standards were (and are) evolvingp the N.F.P.A.,
through another ｣ｯｭｭｩｴｴ･･ｾ published standards for installation
of oil burning equipment (NoFuP.Ao Noo 31) D.BoI.U. No. 31
June 1955
(copy of N.F.P.A.)
Forced warm air furnaces which
are equipped with approved ｴ･ｭｰ･ｲ｡ｾ
ture limit controls that cannot be set higher than 250°F.
b"
This clearance was then changed in a new advance report as ｦｯｬｬｯｷｳｾ
N.FoPoA. 1956 Advance Report s
Pamphlet 31
Automatically fired warm air furnaces equipped with approved limit controls that cannot be
set above 250QFo
New Note 2 saying "This clearance may be reduced to .1' when furnace is equipped with approved limit control that cannot be set higher
than 250oFo installed centrally
not more than 10" above the top surface of the heat exchanger in a supply plenum that extends at least 12" above the top surface of the heat exchanger"o
2"
Note:
-
This change provides a category for whicha 2ft clearance is acceptable but which
differs from the similar category in NoFoPoAo 90B in two essential points
ioeoD listing, and limit control require=
mentso If this new amendment is read
with the New Note 2 then a category is created exactly similar to the first category of Pamphlet 90Bo
ｾｾｩｬ･ all these changes were taking ｰｬ｡｣･ｾ the CoSoAo was
preparing its own standard ＨｂＱＳＹＩｾ the draft of which shows:
CoSoAo B139
March 1956
Note:
Forced air furnaces and approved gravity furnaces equipped with safety limit controls that limit
the outlet air temperature to 250oFo
This requirement bears the closest resem= blance to NoFoPoAo 90B, category 2, but there is some confusion about the words
"listed" and "approved tf o The NoFoPoAo
requires all such units to be listedg
which means something in terms of
pro-duction controlo The CoSoAo has no such
proposed requirement for forced air
furnaces but proposes that gravity furnaces be tfapproved"o
The word approved is defined as meaning
listed, or ｡ｬｴ･ｲｮ｡ｴｩｶ･ｬｹｾ acceptable to the
authority haVing jurisdictiono These are
two qu.ite different meanings for the same
word. This leads to considerable confusion
in the text on page 38 of B139 where units which are "designed for oil heating, but
not approved as an ｯｩｬｾｦｩｲ･､ unitff
, are
referred too It is inconceivable that the
authority having jurisdiction would allow
such practiceo This statement implies that
the specification condones equipment which is unacceptable to the authority having
ｪｵｲｩｳ､ｩ｣ｴｩｯｮｾ
2"
It should be appreciated that the example above refers only to clearances above plenum chambers in warm air furnaceso There are necessary clearance requirements for associated duct
5
-work and there. are many other types of furnaces. In addition,
clearances in general are only one of many requirements which
are to be found in this type of specificationo If this single
example has indicated ｴｨｾ complexity of just one item i1- B139J1
then the concern of the Associate Commi t.tee on the National Building Code over the general question of this proposed
ｳｰ･｣ｩｦｩ｣ｾｴｩｯｮ perhaps can be ｡ｰｰｲ･｣ｩ｡ｴ･､ｾ since its publication in its present form would confuse still fUrther an already complex and confused situation.
Accordingly, a meeting of representatives of all interested Canadian agencies is being suggested at which it should be possible to arrive at agreement on all such detailed requirements for Canadian useo
