Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02481493 2004-11-18
1 HEATED PLUMBING VENT
2
3
4 FIELD OF THE INVENTION:
6 [0001] The present invention relates to a vent used to vent sewer gas and
the like.
7
8 DESCRIPTION OF THE PRIOR ART
9 10002] A plumbing system typically includes a water supply system to
transfer water from a
water main to appliances within a house and a waste water system to carry
waste products to a
11 sewer or other disposal system. The waste water system includes a vent pipe
to vent gaseous
12 products and water vapour to the outside of a building.. The gaseous
products can be sewer
13 gases or other unpleasant fumes that may be noxious or hazardous if allowed
to back up within
14 the building.
[0003] It is well known to incorporate a vent pipe into a building by
extending a pipe, made
16 of a material such as acrylonitrile butadiene styrene (ABS) or polyvinyl
chloride (PVC), from the
17 waste water system to the exterior of the building. In sub-freezing
temperatures such as those
18 typically encountered in northern climates, the water vapour that escapes
the ventilation pipe
19 may condense when contacting the colder outside air, and begin to freeze
against the inner wall
of the ventilation pipe eventually completely blocking the vent pipe. With the
vent pipe blocked,
21 the gases cannot escape the plumbing system and may back up into the
building.
22 [00041 It is therefore an object of the present invention to provide a
plumbing vent which
23 obviates or mitigates at least one of the above mentioned disadvantages.
24
SUMMARY OF THE INVENTION
26 [00051 The present invention provides a vent cap comprising a pair of
nested pipes and
27 secured to one another to define a void therebetween. A heating element is
situated within the
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1 void and is capable of radiating heat for transfer from the outer surface of
the inner pipe to the
2 inner surface of the inner pipe to inhibit freezing of the water vapour in
the vent pipe.
3 [0006] Preferably, the vent cap has a cord along its axis to retain ice
axially and as a further
4 preference a bridge is extended across a lower end of said inner pipe to
inhibit downward
movement of a mass of ice.
6 [0007] In one embodiment the heating element is an electric heating element.
In another
7 embodiment the heating element is a fluid conduit that passes heated fluid
through the void.
8 [0008] To facilitate heat transfer in to the inner pipe, a metal foil is
wrapped about the outer
9 surface of the inner pipe within the void and a reflective foil is placed
around the inner wall of
the outer pipe.
11
12 BRIEF DESCRIPTION OF THE DRAWINGS
13 [0009] An embodiment of the invention will now be described by way of
example only with
14 reference to the accompanying drawings in which:
[0010] Figure 1 is a cross-sectional view of a vent installed on a building.
16 [0011] Figure 2 is a perspective view of the heated vent of Figure 1.
17 [0012] Figure 3 is a cross-sectional view of the heated vent along the line
III-III of Figure 2.
18 [0013] Figure 4 is a partial enlarged view of the cap shown in Figure 2.
19 [0014] Figure 5 is an exploded view of Figure 2 illustrating the assembly
of the heated vent.
[0015] Figure 6 is a schematic view of alternative heating element controls.
21 [0016] Figure 7 is a schematic view of a hydronic heating system as an
alternative to the
22 heating cable shown in Figure 5.
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1
2 DETAILED DESCRIPTION OF THE INVENTION
3 [0017] Referring therefore to Figure 1, a building B has a roof R. A vent
pipe installation 2
4 of a plumbing system (not shown) protrudes through the roof R of the
building B. The vent pipe
installation 2 includes a pipe 3 connected to the waste water system and a
vent cap assembly 10
6 which extends through the roof R. The vent pipe 3 is typically an ABS pipe,
however it may also
7 use other materials.
8 [0018] The details of the vent cap assembly 10 is shown in Figures 2 and 3.
The vent cap
9 assembly 10 has a cylindrical body 11 formed by an outer cylinder 12 and an
inner cylinder 13.
The cylinders 12, 13 are generally concentric and dimensioned to provide an
annular void 14
11 between them.
12 [0019] One end of the void 14 is sealed by an end cap 16 extending between
the outer
13 cylinder 12 and the inner cylinder 13. The end cap 16 has a central opening
18 coinciding with
14 the inner diameter of the inner cylinder 13 with a bridge 20 extending
across the opening 18.
[0020] The opposite end of the body 11 is sealed by a lower end cap 22 which
extends
16 between the outer cylinder 12 and inner cylinder 13 and projects downwardly
from the inner
17 cylinder 13 to provide a skirt 24 for coupling to the vent pipe 3.
18 [0021] An internal tether 28 is attached to the cap 16 at the bridge 20.
The tether 28 extends
19 along the axis of the inner cylinder 13 and is secured to a retaining disc
26 at its lower end. The
disc 26 abuts the lower end of the inner cylinder 13 within the skirt 24 and
has a central opening
21 30 with a bridge 32 extending across a diameter.
22 [0022] A heating element 40 is located in the void 14. In the embodiment
shown in figure 2
23 and 3, the heating element 40 is a self regulating electric heating cable
42, such as that available
24 from Heat-Line Corporation, Canarvon, Ontario under the trademark Paladin
I. The heating
cable 42 is wrapped spirally about the inner cylinder 13 and exits the void 14
through a strain
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1 relief aperture 44 in the lower end cap 22. The cable 42 is connected to a
power source, typically
2 an electrical outlet in the building.
3 [0023] A layer of heat conducting foil 36 is wrapped on the outer surface of
the inner
4 cylinder 13 from the lower end to the upper end and serves to distribute the
heat generated by
cable 42 uniformly into the wall of the inner cylinder 13. A liner of
reflective foil 48 is also
6 affixed to the interior surface of the outer cylinder 12 to inhibit heat
transfer through the outer
7 wall. The void 14 is vented to the atmosphere by a hole 50 in the lower end
cap 22 to maintain
8 the void 14 at an equal pressure to the interior of the building B.
9 [0024] An enlarged view of the cap 16 is shown in Figure 4. The cap 14 has
an outer sleeve
52, an inner sleeve 54 and a hole 56 for the tether 28 to pass through for
fastening. The outer
11 sleeve 52 overlies the wall of the outer cylinder 12 to allow the outer
cylinder 12 to be secured to
12 the cap 16 and the inner sleeve 54 is offset from the outer sleeve 52 such
that the smaller
13 diameter inner cylinder 13 can also be secured to the cap 16. The sleeves
52, 54 are separated
14 such that the void 14 extends to the upper end of the inner cylinder 13.
The extension of the void
14 allows the heat radiating from the heating cable 42 to rise towards the end
cap 16 thereby
16 completely surrounding the inner cylinder 13 and allowing the entire length
of the inner cylinder
17 13 to be heated, including the portion secured within the end cap 16.
18 [0025] In an exemplary method for assembling the vent cap assembly 10, the
outer cylinder
19 12 is lined with the reflective foil 38 (if applicable) and the inner
cylinder 13 is wrapped in the
conducting foil 36 (also if applicable). It is next preferable to feed the
heating cable 18 through
21 the strain relief aperture 44 in the lower end cap 22 until the majority of
the length of the heating
22 cable 42 has been fed.
23 [0026] With the majority of the length of the heating cable 42 fed through
the strain relief
24 aperture 44, it is next preferable to wrap the heating cable 42 around the
foil-wrapped inner
cylinder 13 in a substantially helical pattern to distribute the heat along
the entire exposed outer
26 surface of the inner cylinder 13. (e.g. the length of the inner cylinder 13
which is not secured
27 within the end cap 16 nor the lower end cap 22) With this arrangement, the
lower end of the
28 inner cylinder 13 can be secured to the lower end cap 22 using a suitable
adhesive such as PVC
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1 cement. The remaining length of the heating cable 42 is then pulled back
through the aperture 44
2 and the strain relief is secured.
3 [0027] The foil-lined outer cylinder 12 can then be slid over the inner
cylinder 13 and
4 secured to the larger diameter end of the lower end cap 22 using a suitable
adhesive such as PVC
cement. The tether 28 can now be fed through the lower disk 23 and
subsequently through the
6 lower end cap 22. The lower end of the tether 28 can then be fastened to the
bridge 32 of the
7 lower disk 26 using a suitable fastener 34a. The lower disk 26 can
optionally be secured to the
8 lower end of the inner cylinder 13 in which it engages the end of the inner
cylinder 13 using a
9 suitable adhesive. The unfastened end of the tether 28 can then be fed
through the inner cylinder
13 and subsequently through the hole 56 in the end cap 16. The end cap 16 can
then be secured
11 to the upper ends of both the inner cylinder 13 and the outer cylinder 12
using a suitable adhesive
12 such as PVC cement. When secured, the inner sleeve 54 of the end cap 16
will be affixed to an
13 uppermost portion of the inner cylinder 13 and the outer sleeve 52 of the
end cap 16 will be
14 affixed to an uppermost portion of the outer cylinder 12 as shown in Figure
4.
[0028] The tether 28 can now be pulled through the hole 56 until taut and
suitably trimmed
16 and fastened to the bridge 20 of the end cap 16 using a suitable fastener
34b. Once assembled,
17 the vent cap assembly 10 can be coupled with the existing pipe 3 by
securing the pipe 3 to the
18 inner wall of the skirt 24 while inserting the uppermost end of the pipe 3
into the skirt 24. The
19 uppermost end of the pipe 3 is preferably in engagement with the lower disk
26 thereby sealing
the pipe 3 to the vent cap assembly 10. The pipe 3 can be secured to the skirt
24 using a suitable
21 adhesive such as a PVC to ABS transition cement or any other adhesive
appropriate to the
22 materials used.
23 [0029] It is preferable to have the void 14 completely sealed from the pipe
3 to avoid the
24 heating cable 42 from igniting any potentially volatile gases escaping from
the plumbing system.
During assembly, the void 14 may also be filled with an insulating material if
desired to provide
26 further insulation surrounding the inner cylinder 13. Any suitable
insulating material such as
27 urethane foam can be used. The void 14 would be filled with the insulating
material after the
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1 inner cylinder 13 has been enveloped by the outer cylinder 12 and the other
elements internal to
2 the void 14 (e.g. foils and heating cable) are present within the void 14.
3 [0030] In use therefore, the vent cap assembly 10 is coupled to the pipe 3
as shown in Figure
4 2. When the heating cable 42 has not been energized, the gases originating
from the plumbing
system and travelling through the pipe 3 will proceed through the vent cap
assembly 10 as usual.
6 The openings in both the lower disk 26 and the end cap 16 allow the gases to
pass through to the
7 exterior of the building B. If the ambient temperature in the exterior of
the building B is
8 subfreezing, the gases (which tend to typically contain moisture) may begin
to condense at the
9 interface of the inner cylinder 13 and the exterior of the building B when
confronted with colder
air. This condensation will then tend to build up as is freezes towards the
centre of the opening
11 18 creating an ice blockage.
12 [0031] To remove the blockage, the heat cable 42 is connected to electrical
power through
13 the heating element 40. If a self-regulating heating cable is utilised, the
drop in ambient
14 temperature will cause the heating effect to increase. Alternatively, the
heating cable 42 may
incorporate a single pole switch 70 as shown in Figure 6. This single-pole
switch 70 allows the
16 heating cable 42 to be turned "on" or "off' manually without using any self-
regulating controls.
17 These two arrangements 16, 70 can also be combined to allow the heating
cable 42 to be
18 controlled both manually and automatically. The heating effect radiates
heat from the heating
19 cable 42. This radiated heat is simultaneously absorbed by the conductive
foil 36 and reflected
by the reflective foil 38 to distribute the heat in a substantially even
manner over the outer
21 surface of the inner cylinder 13. The inner cylinder 13 will transfer this
heat due to its
22 conductive properties from its outer surface to its inner surface thereby
applying heat to any ice
23 which has formed along its inner surface. It should be noted that the heat
is preferably
24 transferred while having the heating cable 42 sealed from the interior of
the inner cylinder 13 for
safety purposes if the gases are potentially volatile.
26 [0032] The ice will tend to melt inwards towards the tether 28 since it is
being heated
27 through the inner cylinder 13 and the tether 28 will support the ice from
falling within the inner
28 cylinder 13 and creating unpleasant noise or the ice blockage from being
lodged in an elbow of
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1 the unheated part of the plumbing system. The lower disk 26 also prevents
any large pieces of
2 ice, which may fall through the vent cap assembly 10 from entering the
unheated pipe 2. Some
3 of the heat radiated by the heating cable 42 will rise and concentrate
within the uppermost
4 portion of the void 14, which lies within the end cap 16. This portion of
the void 14 will transfer
heat through the inner sleeve 54 and the uppermost portion of the inner
cylinder 13 to melt any
6 ice forming the uppermost portion of the inner surface of the inner cylinder
13.
7 [0033] The heated vent 10 may continuously operate to prevent ice blockage
by maintaining
8 a desired temperature along the inner surface of the inner pipe. This can be
accomplished using
9 a self-regulating heat source and would ultimately prevent any gases from
backing up by
providing a continuously free passage. Alternatively, to conserve power, the
vent cap assembly
11 10 may be de-energized when ice blockage would likely not occur and re-
energized in
12 anticipation of cold weather.
13 [0034] Where a self-regulating heat source is used which can vary the heat
output based on
14 the ambient temperature, if the ambient temperature rises, the heat output
is decreased and
conversely if the ambient temperature lowers, the heat output is increased.
This is achieved
16 using a temperature sensor and suitable control electronics, which are well
known in the art.
17 [0035] It will be appreciated that the conducting foil 36 and reflective
foil 38 are preferable
18 but optional features. It will also be appreciated that the inner cylinder
13, outer cylinder 12, end
19 cap 16 and lower end cap 22 can be constructed using any material and can
be of any suitable
diameter which will satisfy the relative proportions defined herein.
Preferably, these elements
21 will be constructed using a polycarbonate material, which exhibits good
impact resistance in cold
22 weather as well as good thermal conductivity.
23 [0036] It will be appreciated that the heating cable 42 may include any
medium capable of
24 conducting heat and an electric heating cable herein described was used for
illustrative purposes
only.
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1 [0037] In an alternative embodiment, a hydronic heating cable 80 shown in
Figure 7
2 may be also be used. The hydronic heating cable 80 uses glycol heated by a
boiler 82
3 which is fed through the hydronic cable 80, constructed as a small bore tube
in a
4 continuous loop.
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