Freeze protection valve

The freeze protection valve includes a valve housing (A) which has a bore (20) through a lower wall portion (22) thereof to define a freeze drain outlet (B). A valve assembly (C) including a valve cup (50), a valving element (54), and a valve element biasing spring (56) is biased away from the valve housing lower wall portion by a valve cup spring (60). A thermal sensing assembly (D) including a thermal sensing element (82) which is disposed closely adjacent the valving element urges the valve assembly toward the lower wall portion as the temperature of fluid around the thermal element increases and allows the valve cup biasing spring to move the valving element away from the lower wall portion as the fluid around the thermal sensing element cools below a preselected temperature. In this manner, the valve assembly opens the freeze drain outlet in response to the fluid at the bottom of the valve housing adjacent the valve assembly dropping below a preselected temperature. A discharge stem (30) extends downward from the valve housing lower wall portion to provide an outlet path for fluids discharged through the freeze drain outlet. A cross bore (100) extending horizontally through the discharge stem immediately adjacent the freeze drain outlet provides an air break (E) between the freeze drain outlet and any fluids in the discharge stem bore to prevent discharged fluids which may have become contaminated from being drawn back into and mixed with the fluids in the freeze protection valve.

BACKGROUND OF THE INVENTION 
This application pertains to valves which selectively open and close in 
response to environmental conditions. More particularly, the invention 
relates to freeze protection valves which open automatically in response 
to a preselected low temperature condition. The invention finds particular 
application in freeze protection valves for solar heating systems and will 
be described with particular reference thereto. It is to be appreciated, 
however, that the invention has broader applications including freeze 
protection for sections of residential and commercial plumbing system and 
other fluid carrying or holding systems which may become exposed to 
freezing or near freezing conditions. 
Conventionally, solar water heating systems have a roof mounted collector 
panel which includes an upper header or manifold, a lower header or 
manifold, and a plurality of tubes extending between the upper and lower 
headers. In a thermosiphon type solar heater, as the water is heated by 
the sun, it rises through the tubes from the lower header toward the upper 
header. A solar heated hot water storage tank is positioned above the 
upper header, commonly on the external surface of the roof. A cold water 
feed line connects the bottom of the hot water storage tank with the lower 
header to provide a path for the coolest water in the bottom of the tank 
to flow to the solar collector unit to be heated. A warm water return path 
connects the upper header with the storage tank to allow the solar heated 
water to rise from the upper header to the top of the tank. The storage 
tank has a warm water outlet from which heated water may be withdrawn and 
an inlet for replacing the withdrawn heated water with unheated water. In 
this manner, the water is heated and circulated by the thermosiphon 
effect. 
To protect the solar water heating system from freezing, a freeze 
protection valve is connected below the lower header. When the temperature 
drops below a preselected low temperature, such as 45.degree. F., the 
freeze protection valve opens draining water from the lower header and the 
solar heating system. The removal of the coldest water at the lowest 
portion of the system draws warmer water from the upper portions of the 
system raising the temperature of the solar collector piping and the 
freeze protection valve. The warmer water is usually at least 50.degree. 
to 65.degree. F., the temperature of unheated water received from a 
residential or commercial plumbing system. Thus, the freeze protection 
valve need only open intermittently to maintain the temperature in the 
solar heating system above the exemplary temperature of 45.degree. F. 
Commonly, the prior art freeze protection valves sense the temperature of 
the fluid at their upper, inlet end which is connected below but adjacent 
the lower header. Because cold water is denser than warm water, a 
temperature gradient occurs between the freeze drain valve's upper inlet 
and lower freeze drain outlet. Under extreme cooling conditions, the 
temperature gradient across the freeze protection valve allows the lower 
portion of the valve to freeze before the upper portion senses that it 
should be opened. This freezing, of course, defeats the freeze protection 
purpose of the valve. 
Conventionally, the freeze protection valve has a nipple or fitting around 
the drain outlet for connecting the freeze protection valve with a drain 
line. Under certain conditions, a pressure differential may occur across 
the drain outlet which causes fluid in the drain line to be returned into 
the freeze protection valve and mixed with the water in the solar heating 
system. This raises the potential for the water in the drain line to 
become contaminated and for the contaminated water to be mixed with the 
potable water in the solar heating system. 
The present invention contemplates a new and improved freeze protection 
valve which inhibits the freeze protection valve from freezing adjacent 
its drain outlet and which prevents discharged water in the drain line 
from becoming mixed with the water within the freeze protection valve. 
SUMMARY OF THE INVENTION 
In accordance with a first aspect of the present invention, there is 
provided a freeze protection valve which comprises a valve housing, a 
freeze drain outlet valving means, and a thermal sensing assembly. The 
valve housing has a first wall portion defining an inlet aperture 
therethrough and a second wall portion defining a freeze drain outlet 
therethrough. The freeze drain outlet valving means selectively opens and 
closes the freeze drain outlet. The valving means is disposed adjacent the 
valve housing second wall portion. The valving means includes a biasing 
means for biasing the valving means towards the open, draining 
positioning. The thermal sensing assembly extends with increasing 
temperature and contracts with lowering temperature. The thermal sensing 
assembly includes a thermal element cup disposed closely adjacent the 
valving means, a thermal sensing element disposed in the thermal element 
cup which expands with increasing temperature and contracts with 
decreasing temperature, and a piston means operatively connected at one 
end with the thermal element and operatively connected adjacent its other 
end with the valve housing. In this manner, as a thermal element expands, 
the thermal sensing assembly urges the valving means toward the closed 
position and as the thermal element contracts the biasing means biases the 
valving means towards the open position. Thus, the freeze protection valve 
opens and closes in response to the temperature closely adjacent the 
freeze drain outlet. 
In accordance with a second aspect of the invention, there is provided a 
freeze protection valve comprising a valve housing, air break means, a 
valve means, and a thermal sensing assembly. The valve housing includes a 
first wall portion defining an inlet aperture therethrough, a bottom wall 
portion defining a freeze drain outlet therethrough, and a downward 
extending discharge stem having a longitudinal passage therethrough 
generally in vertical alignment with the freeze drain outlet. In this 
manner, fluid discharged through the freeze drain outlet falls by gravity 
into the discharge stem passage. The air break means is disposed in the 
discharge stem adjacent the freeze drain outlet to provide an air break 
between the freeze drain outlet and the discharge stem passage. The valve 
means is disposed within the valve housing adjacent the bottom wall 
portion for selectively opening and closing the freeze drain outlet. The 
thermal sensing assembly is operatively connected with the valve means and 
with the valve housing for selectively causing the valve means to open and 
close the freeze drain outlet in response to the temperature of the fluid 
within the valve housing. In this manner, fluid discharged from the freeze 
drain outlet is inhibited by the air break means from being returned 
through the valve means. 
An advantage of one aspect of the present invention is that it renders the 
freeze protection valve less susceptible to malfunctioning due to 
freezing. 
An advantage of another aspect of the present invention is that it inhibits 
contaminated drain water from being reintroduced into the fluid which is 
protected from freezing. 
Still further advantages of the present invention will become apparent upon 
reading and understanding the following detailed description of the 
preferred and alternate embodiment.

DESCRIPTION OF THE PREFERRED AND ALTERNATE EMBODIMENT 
The freeze protection valve includes a valve housing A which has a freeze 
drain outlet B through a lower wall portion. A freeze drain valve assembly 
or means C is disposed in the valve housing for selectively opening and 
closing the freeze drain outlet. A thermal energy sensing assembly or 
means D is operatively connected between the valve housing A and the 
freeze drain valve means C for causing the freeze drain outlet to be 
closed at higher temperatures and causing the freeze drain outlet to be 
opened below a preselected lower temperature. In this manner, the freeze 
protection valve blocks water or other fluid from draining from an 
associated structure when the fluid is above the preselected temperature 
and allows the fluid within the associated structure to drain when the 
temperature is below the preselected temperature. An air break means E is 
disposed adjacent the freeze drain outlet B for providing an air barrier 
between the fluid in a drain line and the fluid in the housing. The air 
prevents a pressure differential between the valve housing and the drain 
line, thus preventing siphoning of drain water into the system. 
Looking in detail to the embodiment of FIG. 1, the valve housing A includes 
an inlet or upper valve housing portion 10 and a second or lower valve 
housing portion 12 which are connected by connecting means 14. The upper 
valve housing portion terminates at a first or upper wall portion with an 
inlet fitting means 16 such as screw threads which are adapted to be 
connected with an associated structure. The upper valve housing portion 
and the inlet fitting means are hollow to define an inlet for receiving 
fluid from the associated structure. A screen 18 is disposed across the 
inlet to block particles from being carried into the valving means and the 
thermal sensing assembly to impair their operation. The lower valve 
housing portion 12 has an aperture or bore 20 through a lower valve wall 
portion 22 to define the freeze drain outlet B. An annular valve seat 24 
projects inward from the second or lower wall portion and surrounds the 
drain bore 20 of the drain valve outlet B. The drain bore has a relatively 
low length to cross-sectional area ratio and a flared bore portion 26 such 
that any ice which might form therein is readily discharged. A discharge 
stem 30 extends downward from the lower valve wall portion 22 and 
surrounds the freeze drain bore 20. The discharge stem has a longitudinal 
fluid passage 32 for providing a fluid flow path for fluids discharged 
from the freeze drain outlet. A plurality of annular barbs 34 encircle the 
discharge stem for anchoring a frictionally received drain line or hose. A 
threaded portion 36 with a maximum diameter which is less than the minimum 
diameter of the annular barbs 34 is disposed adjacent the end of the 
discharge stem. The presence of the barbs and the threaded portion enable 
the freeze protection valve to be connected with a drain line with either 
a threaded engagement or with a frictional engagement. 
The valve housing portion connecting means 14 includes a ferrule 40 which 
is crimped around the upper and lower valve body portions. An O ring 42 
provides a fluid tight seal for the joint between the upper and lower 
valve body portions. Other means for connecting the upper and lower valve 
body portions, such as mating threaded portions, solvent welds, rivets, or 
the like are also contemplated by the present invention. 
The freeze drain outlet valve means C includes a valve cup 50 which is 
interconnected with the thermal sensing assembly D such that it is urged 
toward the freeze drain outlet under increasing temperatures. The valve 
cup has a lower end 52 with a central aperture which surrounds the valve 
seat 24. The thickness of the bottom wall 52 is less than the inward 
extension of the valve seat 24 such that when the valve cup bottom wall is 
pressed firmly against the lower wall portion 22, the valve seat 24 
projects inward beyond the valve cup bottom wall. A freeze drain valving 
element 54 is disposed within the valve cup to contact valve seat 24 when 
the valve cup is in its lowermost position. A valving element spring or 
biasing means 56 extends between the thermal sensing assembly and the 
valving element 54 to bias the valving element against the valve seat with 
a preselected pressure. A valve cup spring or biasing means 60 biases the 
valve cup and the valving element 54 away from the valve seat. The valve 
cup biasing means 60 has a greater spring force than the valving element 
biasing means 56 and a lesser spring force than the expansible force of 
the thermal sensing assembly D. 
An over travel protection means 70 connects the thermal sensing assembly D 
with the upper valve housing portion 10. The over travel protection means 
allows the thermal sensing assembly to extend after the valve cup bottom 
wall 54 has engaged the valve housing bottom wall portion 26. The over 
travel protection means 70 includes an over travel spring guide 72 which 
is connected with the thermal sensing assembly to be urged upward thereby 
as it extends. An over travel protection spring 74 is disposed between the 
upper valve housing portion 10 and the over travel spring guide 72 to bias 
the over travel spring guide 72 and the thermal sensing assembly downward. 
A limit travel stop shoulder 76 limits the downward movement of the spring 
guide. The over travel protection spring 74 has a greater spring force 
than the valve cup biasing means 60. 
The thermal sensing assembly D includes a thermal element cup 80 which is 
disposed at the end of the thermal sensing assembly closest to the freeze 
drain valving element 54. A thermal sensing element 82 which expands and 
contracts with changes in its temperature is contained within the thermal 
element cup. In the preferred embodiment, the thermally expansible element 
82 is a thermally expansible wax pellet of composition well-known to those 
skilled in the art which expands with increasing temperature and contracts 
with decreasing temperature. A flexible diaphragm 84 extends across the 
open end of the thermal element cup and the corresponding surface of the 
thermal element. A piston guide 86 is disposed adjacent the diaphragm 84 
and constrains the diaphragm between the piston guide and the thermal 
element cup. The piston guide and the thermal element cup are maintained 
in a position firmly engaging the diaphragm by a clamping means 88. A 
piston assembly extends from the diaphragm 84 through an open bore defined 
by the piston guide 86. In the preferred embodiment, the piston assembly 
includes a force transmitting and amplifying means 90 which is connected 
by a polymeric spacer 92 with a rigid piston 94. The force transmitting 
means is a relatively incompressible rubber material which functions as a 
fluid. The piston guide bore expands adjacent the expansion element such 
that the rubber material functions as a fluid amplifier. The spacer 
inhibits the rubber material from flowing between the piston and the 
piston guide. As the thermal element 82 is warmed and expands, the piston 
94 and the thermal element cup 80 are urged apart. As the thermal element 
82 cools and contracts, the valve cup biasing means 60 and the over travel 
protection spring 74 urge the piston 94 and the thermal element cup 80 
toward each other. In this manner, the spring 60 functions as a thermal 
element cup biasing means to bias the thermal element cup and with it the 
attached valve cup and valve element away from the freeze drain outlet. By 
positioning the thermal element cup 80 and the thermal element, in the 
valve cup 50 and closely adjacent the valve seat 24, the thermal element 
is responsive to the temperature of the fluid adjacent the freeze drain 
outlet B. Because colder water is denser and settles toward the lowest 
point of the system and the freeze protection valve is normally disposed 
with the freeze drain outlet B at the lowest point of the system, the 
thermal element senses the temperature of the coldest water or other fluid 
in the protected fluid system. The freeze protection valve provides freeze 
protection even when there are large thermal gradients across the freeze 
protection valve. This is particularly important when the temperature 
gradient across the freeze protection valve exceeds the difference between 
the preselected drain temperature and freezing. Further, the ambient air 
temperature tends to cool most rapidly the extremes of the system, 
particularly the lowest end of the freeze protection valve. 
The air break means E includes a cross hole or bore 100 defined by the 
lower valve housing portion and which is transverse to the discharge stem 
bore 32 and is immediately adjacent the flanged bore portion 26. When the 
freeze protection valve is positioned in its normal, vertical position 
with the discharge stem bore extending vertically, the cross bore extends 
horizontally. In this manner, fluid discharged from the freeze drain flows 
by gravity past the cross bore through the discharge stem bore to a 
suitable disposal location. The cross bore provides antisiphon protection 
to prevent discharged fluids which may possibly become contaminated from 
being drawn back into the freeze protection valve. Further, the cross bore 
inhibits fluids from remaining in the discharge stem bore and the drain 
line and provides an overflow outlet if fluids should be forced up the 
discharge stem bore or the drain line or if the drain line should become 
clogged. 
In operation, the coolest water or fluid in the associated system flows 
into the lower part of the freeze protection valve. The warmth of the 
water causes the thermal element 82 to expand or contract by a 
corresponding amount. When the water is warmer than the preselected drain 
temperature, the extension of piston 94 and thermal element cup 80 
increases forcing the valve cup 50 against the lower wall portion 22 and 
the valving element 54 closes the freeze drain outlet B. When the water is 
hot enough to increase the piston and thermal element cup extension 
further, the over travel spring 74 is compressed to protect the thermal 
sensing assembly D from its internal forces. When the water cools below 
the predetermined drain temperature, the piston and thermal element cup 
extension contracts allowing the over travel spring 74 to bias the spring 
guide 72 against the stop 76. Still further contraction permits the valve 
cup biasing spring 60 to lift the valve cup 50 and with it the valving 
element 54. As the colder fluid drains from the bottom of the freeze 
protection outlet through the air break and into the drain, warmer water 
may replace it. The warmer water causes the thermal element 82 to expand 
closing the valve. In this manner, the freeze protection valve opens and 
closes intermittently. 
With reference to FIG. 2, a freeze protection valve for providing freeze 
protection to a fluid flow line is illustrated. Elements of the freeze 
protection valve of FIG. 2 which are common to the elements of the freeze 
protection valve of FIG. 1 are denoted with the same reference numeral 
followed by a prime ('). The valve housing A of the inline freeze 
protection valve includes an upper valve housing 10' and a lower valve 
portion 12' which are interconnected by bolts or other suitable connecting 
means 14'. The lower valve housing 12' defines a pair of fluid flow ports 
which are connected with tubing portions 110 and 112 to form an inlet and 
outlet for fluid flow through the lower valve housing portion. A lower 
wall portion 22' has a raised freeze drain valve seat 24' surrounding 
freeze drain outlet bore 20'. 
The freeze drain valving means C includes a valve cup 50' having a bottom 
valve cup wall portion 52' which is adapted to abut the lower valve 
housing wall portion 22'. The lower valve cup wall defines an enlarged 
aperture therein through which the valve seat 24' is receivable. The valve 
cup has an upper horizontal shoulder which engages a corresponding surface 
of the thermal sensing assembly D such that the valve cup is urged toward 
the drain outlet as the thermal sensing element expands. 
A valving element 54' and a valving element spring or biasing means 56' are 
disposed within the valve cup 50'. The valve cup bottom wall 52' is 
thinner in vertical dimension than the inward extension of the valve seat 
24'. A valve cup biasing means 60' biases the valve cup upward, away from 
the valve seat and against the thermal sensing assembly D. 
An over travel protection means 70' is disposed in the upper valve housing 
between the thermal sensing assembly and the upper valve housing 10'. The 
over travel protection means includes an over travel spring guide 72' 
which is connected with the thermal sensing assembly to be urged upward 
thereby and with an over travel protection spring 74' to be urged downward 
thereby. A stop means 76' limits the downward travel of the spring guide. 
The thermal sensing assembly D includes a thermal element cup 80' having a 
thermally expansible element 82' disposed therein. The thermal element cup 
extends downward into the valve cup 50' and is disposed closely adjacent 
the valving element 54' at the freeze drain outlet. A diaphragm 84' is 
connected between the thermal element cup 80' and a piston guide 86'. The 
piston guide 86' has a central bore in which a piston assembly including a 
resilient rubber material 90', a spacer 92', and a piston 94' are 
disposed. As the thermal element expands and contracts with changes in 
temperature, the extension or distance between the piston 94' and the 
thermal element cup 80' extends or contracts correspondingly. 
In normal operation, the fluid flowing between the inlet and outlet 110 and 
112 has a temperature well above its freezing point. If the valve is 
positioned in a cold water line, the temperature of the water is commonly 
on the order of 50.degree. to 65.degree. F. When the valve is positioned 
in a hot water line, the normal temperature of the water is commonly on 
the order of 120.degree. to 180.degree. F. When the flow of water through 
the freeze protection valve stops, the temperature of the water in the 
line and in the valve tends to approach the temperature of the ambient air 
therearound. As the water or other fluid in the freeze protection valve 
cools toward freezing, the thermal sensing element 82' contracts allowing 
the over travel spring 84' to urge the over travel spring guide 72' 
against the limit stop means 76'. Further cooling and further contraction 
of the thermal sensing element 82' reduces the length of the thermal 
sensing assembly, i.e. the distance between the thermal element cup 80' 
and the piston 94'. This allows the valve cup biasing means 60' to bias 
the valve cup 50' and with it the valve element 54' away from the valve 
seat 24'. The thermal expansion element 82' and the geometry of the system 
are selected such that the valve element 54' is lifted from the valve seat 
24' at a predetermined temperature approaching the freezing temperature of 
the fluid. In the preferred embodiment, this predetermined temperature is 
about 45.degree. F., although other temperatures may also be selected. 
The invention has been described with reference to the preferred 
embodiment. Obviously, modifications and alterations will occur to others 
upon reading and understanding the preceding detailed description of the 
preferred embodiment. It is intended that the invention be construed as 
including all such alterations and modifications which come within the 
scope of the following claims or the equivalents thereof.