GB2489425A

GB2489425A - Preventing freezing in a boiler condensate drain pipe

Info

Publication number: GB2489425A
Application number: GB1105065.5A
Authority: GB
Inventors: Simon Downie; Christopher Adey
Original assignee: Adey Holdings 2008 Ltd
Current assignee: Adey Holdings 2008 Ltd
Priority date: 2011-03-25
Filing date: 2011-03-25
Publication date: 2012-10-03
Also published as: GB201105065D0

Abstract

Alternative ways to prevent a boiler condensate drain pipe from freezing include providing ducting for selectively directing a portion of boiler exhaust gases into the drain pipe; neutralising the pH of the condensate by dosing with a soluble base; passing hot water periodically through the condensate pipe; electric heating the pipe using a wire coil; insulating the pipe by using a double wall pipe with air-gap between; inserting a flexible pipe into the drain pipe and directing condensate through the flexible pipe; passing heated air through the pipe; vibrating the pipe with a cam or an eccentric weight; and using a low friction coating on the inside of the pipe. The drain pipe temperature, base quantities, or pH can be sensed; heating be with a ceramic disc heater; and treatment be intermittent.

Description

APPARATUS AND METHOD FOR PREVENTING A CONDENSATE DRAIN

PIPE FROM FREEZING

The present invention relates to an apparatus and method for preventing a condensate drain pipe from freezing and particularly, but not exclusively, to an apparatus and method for preventing a condensate drain pipe of a domestic or commercial condensing boiler from freezing.

BACKGROUND TO THE INVENTION

Modern gas boilers are typically condensing boilers, which utilise the heat in the waste gases of combustion by condensing them, thereby achieving an improvement in efficiency of around 10%. The condensate is slightly acidic and is typically piped away from the boiler in a plastics pipe, into a drain. Usually the pipe extends through an external wall and into an external drain or soak away. Ideally the pipe should extend directly into the drain and preferably below ground. In the UK, it is recommended that the drain pipe extends 25mm below ground. The reason for this is to try and prevent freezing of the condensate in the drain pipe. Boiler condensate tends to freeze at a slightly higher temperature than, for example, water and therefore is prone to freezing in frosty conditions.

If the condensate freezes, it can block the condensate pipe causing the boiler to fail.

In very cold conditions, even if the condensate pipe is insulated, the condensate may still freeze. In some cases this can cause damage to the boiler. Furthermore, in cold conditions when the condensate is likely to freeze, the need for the boiler to operate is even greater, because without a boiler, homes and offices can be left with no other heating and can quickly become cold. This can have serious consequences if homes are without heat for some time. Usually, in a cold period, the condensate pipes of large numbers of domestic boilers freeze at the same time and there is often a shortage of service engineers to service the boilers and attend to problems caused by the condensate freezing. For example, for engineers to receive around 10,000 reported faults per day is not unusual in a frosty cold period in the UK.

It is an object of the invention to provide an apparatus and method for preventing a condensate drain pipe from freezing which reduces or substantially obviates the above mentioned problems.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided an apparatus for preventing a condensate drain pipe from freezing comprising ducting means for directing at least a proportion of boiler exhaust gases into the condensate drain pipe.

Advantageously, by diverting a small amount of warm waste gases through the condensate pipe, the temperature of the condensate pipe can be maintained above the freezing point of the condensate and the drain is kept clear. Furthermore, the movement of the gases prevents static build up of droplets prone to freezing.

Preferably the ducting includes diversion means for diverting said at least a proportion of exhaust gas flow downstream of a boiler exhaust fan.

Sensing means may be provided for detecting the temperature of the condensate drain pipe and control means for determining the amount of boiler gas to be diverted.

The diversion means may be adjustable for varying the amount of exhaust gas diverted between none and a proportion of the exhaust gas.

According to a second aspect of the invention there is provided a method of preventing a condensate drain pipe from freezing comprising passing warm boiler exhaust gases through the condensate drain pipe.

According to a third aspect of the invention there is provided an apparatus for neutralising the pH of condensate comprising containment means for containing a base, ducting means for introducing the base into the condensate trap or pipe of a condensing boiler and means for controlling the introduction of the base.

According to a fourth aspect of the invention there is provided a method of neutralising the acidity level of condensate in a boiler, comprising the steps of:

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a. providing a soluble base, and b. adding a dose of the base to the condensate, thereby neutralising the pH level of the condensate stored liquid.

Advantageously, by neutralising the pH of the condensate, the freezing point of the condensate is lowered, thus reducing the risk of the condensate pipe freezing up in cold weather.

The base may be provided in liquid or solid form and may be stored within or externally of a casing of the boiler.

The pH of the condensate may be monitored and base added as required to neutralise any acidity build up.

The monitoring and dosing may be continuous or intermittent.

According to a fifth aspect of the invention there is provided an apparatus for preventing a condensate drain pipe from freezing comprising a flow diversion fitting adapted to divert warm water to the condensate drain pipe.

Advantageously, the warm or hot water increases the heat of the flow through the condensate pipe and reduces the risk of freezing.

Preferably the flow diverter intermittently diverts warm water to the condensate drain pipe.

The flow diversion fitting may include sensing means for detecting temperature of the condensate drain pipe and control means for determining the amount and/or frequency of warm water to be diverted.

According to a sixth aspect of the invention there is provided a method of preventing a condensate drain pipe from freezing comprising passing warm water into the condensate drain pipe.

The water may be introduced intermittently in response to the temperature of at least a portion of the condensate drain pipe. In other words, the flow of water is controlled automatically.

According to a seventh aspect of the invention there is provided an apparatus for preventing a condensate drain pipe from freezing comprising an electrical heating wire coil arranged within or around the condensate drain pipe.

According to an eighth aspect of the invention there is provided a method of preventing a condensate drain pipe from freezing comprising heating the drain pipe using an electrical coil.

Advantageously, the coil can be switched on in cold weather either manually, or preferably automatically when the temperature approaches the freezing point of the condensate.

According to a ninth aspect of the invention there is provided an insulated condensate drain comprising an internal pipe and an external pipe with an air-gap therebetween, the air-gap being substantially enclosed.

Preferably the internal and external pipes extend over the full length of the condensate drain and the internal and external pipes are substantially co-axial.

The external pipe may be substantially rigid, for example, fastened to a wall, and the internal pipe may be flexible, for example, for passing through the external pipe when being installed.

According to a tenth aspect of the invention there is provided a method of insulating a condensate drain pipe comprising inserting a flexible pipe through the condensate drain pipe and directing condensate through the flexible pipe.

Preferably the respective ends of the pipes are sealed to form a sealed compartment between the pipes.

According to an eleventh aspect of the invention there is provided an apparatus for preventing a condensate drain pipe from freezing comprising a fan for introducing a flow of air into the condensate drain pipe, and a heating element, the heating element being positioned downstream of the fan for warming the air flow through the condensate pipe.

Preferably the heater is a ceramic disc heater.

According to a twelfth aspect of the invention there is provided a method of preventing a condensate drain pipe from freezing comprising introducing airflow through the condensate drain pipe using a fan, and heating the airflow.

Preferably the airflow is heated by a ceramic heater, for example, a ceramic disc heater.

According to a thirteenth aspect of the invention there is provided apparatus for vibrating a condensate drain pipe comprising a motor, an eccentric element driven by the motor, the eccentric element acting causing movement of the pipe.

By vibrating the pipe, condensate tends to be agitated and runs out of the pipe to drain. The surface tension of any drips is broken by the vibration.

The eccentric element may act against the pipe and a spring may be provided for returning the pipe in the opposite direction to the movement caused by the eccentric element.

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Alternatively, the eccentric element is connected to the pipe for causing reciprocating movement thereof According to a fourteenth aspect of the invention there is provided a method of facilitating a flow of condensate through a condensate drain pipe comprising vibrating the pipe.

Preferably vibration is initiated in response to temperatures at or below the freezing point of the condensate.

The vibration may be continuous or intermittent.

According to a fifteenth aspect of the invention there is provided apparatus for facilitating a flow of condensate through a condensate drain pipe comprising an internal coating of at least a proportion of the condensate pipe with material having a coefficient of friction of less than 0.3.

Preferably the coefficient of friction is less than 0.1, more preferably less than 0.075, more preferably less than 0.05.

Preferably the coating is Teflon.

The apparatus and methods of the invention are advantageous because they prevent or reduce ice from forming in the condensate drain of a boiler. This prevents the knock on effects of an unintended boiler shut down in cold weather. Conveniently, some of the arrangements described can be fitted to any existing condensing boiler system.

By providing airflow through the drain pipe and the condensate surface, ice seeding points are reduced through evaporation and movement on the fluid surface. By keeping droplets dynamic as they pass through the condensate pipe, eg by the flows of water, gases, warm air, vibration and low friction coating, the build up of static droplets and hence static ice is substantially prevented.

DESCRIPTION OF PREFERRED EMBODIMENT(S)

A condensing boiler is usually fitted to an external wall of a building with the exhaust flu passing through the wall. A condensate drain pipe typically extends downwardly from the underside of the boiler, through the wall and then extends down into the ground. In the UK, it is recommended that the condensate drain pipe extends below ground at least 25 mm.

In a first embodiment of the invention, ducting is taken from the exhaust flu of the boiler to the condensate drain or trap for heating the drain and ensuring a flow of gas through the drain and condensate drain pipe. The ducting is taken from the flu after the boiler fan. The flow of exhaust gases prevents the static build up of liquid droplets, which may freeze. Also, the exhaust gases are warm, thus further reducing the risk of freezing. The ducting includes a diversion means for directing or diverting at least a proportion of boiler exhaust gases into the condensate drain pipe and is controlled by a control means.

Seals may also be provided to seal the condensate drain pipe and exhaust pipe to the ducting in conventional manner. The apparatus may be retro-fitted at any time or on initial installation of the heating system. The control means can be mounted within the boiler or externally, if there is not sufficient space.

The control means is powered by the electrical supply to the boiler. A sensing means, such as a thermostat is mounted proximate the condensate drain pipe, ideally at its lower end near the outlet of the condensate drain pipe, for detecting the temperature within the condensate drain pipe. Alternatively, the thermostat can simply detect the ambient temperature around the condensate drain pipe. The control means activates the diversion means when the temperature reaches the freezing point of condensate, for example, at around degrees centigrade. The thermostat may be connected to the controller of the apparatus by hard wiring or by a wireless connection, for example, a radio frequency transmitter.

In use, when the temperature detected by the thermostat drops below a pre-determined level, the controller moves the diversion means to a position allowing boiler exhaust gases from the flu to flow into the condensate drain pipe, thus substantially preventing freezing of condensate within the pipe. The diversion ceases when the temperature raises above the freezing point of the condensate.

In another embodiment, an apparatus is provided on the boiler for neutralising the pH level of the condensate so as to raise the freezing point of the condensate and therefore make the condensate drain pipe less likely to freeze. A housing is mounted to the boiler and contains a base, such as an alkali. It will be appreciated that the housing mounted within or external of a casing of the boiler. A through duct extends from and is integrally formed with the housing. A connector is provided on the end of the duct furthest away from the housing to connect the housing of the apparatus to the condensate drain pipe of the boiler. It will be appreciated that the connector may be screw threaded and seal may be provided to prevent leakage. Furthermore, the housing may be connected to other suitable locations, such as a condensate trap.

The base used in the apparatus may be in a solid or liquid state. It will be appreciated that it may be appropriate to utilise a liquid base if the duct of the apparatus is connected directly to the condensate drain pipe to aid even mixing of the condensate to the base. If the duct connects to the condensate trap, a solid base may be use. A powered controller, mounted to the housing, is provided to control the frequency and the dosage of feeding the base into the condensate drain pipe for neutralising the condensate.

A pH detector is mounted proximate the condensate pipe for detecting the pH level of the condensate. The pH detector may be connected to the controller of the apparatus by hard wiring or by a wireless connection, for example, a radio frequency transmitter.

When the pH level of the condensate reaches a first pre-determined level of certain acidity, the control means triggers a release of base. As the condensate pH level increases and reaches a second pre-determined level, the control means ceases the release of base. The dosing of base is therefore intermittent. However, it will be appreciated that the apparatus may be set up so that the control means is activated permanently to allow continuous dosing of the base. Furthermore, the pH detector may detect the pH level either continuously or intermittently, by command from the control means.

An aperture is provided near the top of the housing for allowing the base to be topped up from time to time and a lid is provided to ensure the housing is enclosed securely when access into the housing is not required. A clear window may be provided along the length of the housing to indicate the level of base inside the housing.

Alternatively, indicator means for indicating the level of base inside the apparatus can be incorporated into the main boiler display for user's convenience.

In a third embodiment, an apparatus for diverting warm water has similar construction and features to the first embodiment described above. Rather than connecting to the exhaust flu, the inlet or ducting of this embodiment is connected to a warm water pipe, so that instead of using boiler exhaust gas to increase the temperature within the condensate drain pipe, warm water is used. The term "warm water" is intended to be interpreted as meaning water having a temperature above the freezing point of boiler condensate, for example above around 2.5°C. The wann water pipe can be a variety of pipes suitable, such as the hot pipe of the boiler.

When the temperature detected by the thermostat drops below a pre-determined level, such as below freezing, the controller enables at least a proportion of warm water to flow from the warm water pipe through the body portion of the apparatus to the condensate drain pipe. The apparatus may be set up so that flow is provided only for a pre-determined period of time to limit the warm water taken. Alternatively, once the temperature within the condensate drain pipe reaches a certain level, the controller deactivates the apparatus, for example, by closing a valve, and therefore stopping the flow of warm water into the condensate drain pipe.

In a fourth embodiment, a wire coil heated by electricity is ananged within or around the condensate drain pipe. The wire coil may be provided along substantially the whole length of the condensate drain pipe, or only part of it. A controller mounted to condensate drain pipe or to the boiler is provided to allow the heating to the wire coil to be switched on or off. A detection means, such as a thermostat similar to that described in the first embodiment, is provided to detect the temperature of the condensate drain pipe. The detection means is in communication with the controller, either by hard wiring or in remote communication. Therefore the wire coil is heated only when required, when there is a risk of condensate freezing.

In another embodiment of the invention, a flexible pipe, of smaller diameter than the diameter of the condensate pipe is passed through the condensate pipe from the condensate trap down to the other end of the condensate pipe at the drain. Typically, the condensate pipe is substantially rigid and is attached to the wall. The inner-flexible pipe connects to the condensate trap in a way that prevents condensate from entering the space between the flexible pipe and outer pipe. Outside the building, the gap between the inner pipe and the outer pipe is also sealed at the end in order to provide a cavity of air between the two pipes. This cavity of air provides insulation and helps to prevent water passing through the inner-flexible pipe from freezing in cold weather. An advantage of this system is that the inner-flexible pipe can be passed through the outer pipe, which may be existing and in position. In other words, the flexible pipe can be retrofitted through the outer pipe thus saving the need for any reinstallation.

In a further embodiment of the invention, the condensate pipe is interrupted, for example either within the boiler or externally of the boiler, and a device is fitted into the pipe run which allows the introduction of airflow through the condensate pipe.

This air flow is driven by a fan, and a heater, for example a ceramic disc heater, can be provided on the output to the fan in order to heat the air passing through the condensate pipe. A ceramic disc heater is preferred, because of its relatively large surface area with respect to the pipe, and also its efficient heating capabilities. The ceramic disc heater may be provided, for example, in a side wall of the device adjacent the outlet to the fan and if required, the passageway where the ceramic disc heater is located can be adjusted in dimensions to achieve the most effective heating of air passing through the chamber. As with the embodiment in which exhaust gasses from the boiler are passed through the condensate pipe, the droplets of condensate passing through the condensate pipe are maintained in a dynamic state, and this helps to prevent static ice formation due to the molecular surface adhesion to the pipe being reduced.

In a further embodiment of the invention, a small motor and cam device are attached to the condensate pipe in order to produce a vibration in the pipe, thereby causing droplets to fall off the wall of the pipe i.e. by breaking the surface adhesion to the pipe, and causing the droplets to continue through the pipe to the drain. The vibrator can be constructed in several ways, for example by attachment of a weight in an eccentric position on a disc of the motor. Alternatively a cam can be provided on the output to the motor which is in connection with the pipe and a return spring may be provided for returning the spring to the rest position after the cam has pushed the pipe in a particular direction. In another arrangement, an eccentric device may be attached directly to the pipe causing the vibration.

In a final embodiment of the invention, the condensate pipe may be lined or coated with a low-friction coating in order to reduce the surface adhesion of droplets of condensate passing through the pipe. Typically the surface coating will have a coefficient of friction of less than 0.3. The preferred material for the coating is Teflon which has a coefficient of friction as low as 0.04.

In all of the arrangements disclosed, it will be appreciated that they are operated most effectively automatically. In other words, a sensor for sensing the outside temperature of the condensate drain triggers the operation of the device, for example by diverting gasses through the condensate pipe, dosing the condensate with a base, passing hot water through the pipe, heating the pipe with the coil, introducing warm air through the pipe via a fan, or operation of the vibration device. It will also be appreciated that a combination of these arrangements can be utilised. For example it may be desirable to combine the features of the low-friction coating with the vibration device, thereby maximising the effects of minimising the surface adhesion to the walls of the pipe. In most severe winter conditions, it may be desirable to add a third arrangement, for example direct heating of the condensate pipe via a coil or by the flow of warn-i air or gasses or water.

It will be appreciated that by the fitting of the apparatus of the invention, freezing of condensate from domestic and commercial boilers can be prevented during periods of cold weather, thereby preventing discomfort and distress to many people at home and in work.

It is understood that variations may be made in the foregoing without departing from the scope of the invention. For example, the elements and teachings of the various illustrative embodiments may be combined in whole or in part in some or all of the illustrative embodiments. In addition, one or more of the elements and teachings of the various illustrative embodiments may be omitted, at least in part, and/or combined, at least in part, with one or more of the other elements and teachings of the various illustrative embodiments.

Although illustrative embodiments of the invention have been shown and described, a wide range of modification, changes and substitution is contemplated in the foregoing disclosure. In some instances, some features of the invention may be employed without a corresponding use of the other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.

Claims

CLAIMS1. Apparatus for preventing a condensate drain pipe from freezing comprising ducting means for directing at least a proportion of boiler exhaust gases into the condensate drain pipe.
2. Apparatus as claimed in claim 1, in which the ducting includes diversion means for diverting said at least a proportion of exhaust gas flow downstream of a boiler exhaust fan.
3. Apparatus as claimed in claim 2, in which sensing means is provided for detecting the temperature of the condensate drain pipe and control means for determining the amount of boiler gas to be diverted.
4. Apparatus as claimed in claim 3, in which the diversion means is adjustable for varying the amount of exhaust gas diverted between none and a proportion of the exhaust gas.
5. A method of preventing a condensate drain pipe from freezing comprising passing hot boiler exhaust gases through the condensate drain pipe.
6. Apparatus for neutralising the pH of condensate comprising containment means for containing a base, ducting means for introducing the base into the condensate trap or pipe of a condensing boiler and means for controlling theintroduction of the base.
7. A method of neutralising the acidity level of condensate in a boiler, comprising the steps of: a. providing a soluble base, and b. adding a dose of the base to the condensate, thereby neutralising the pH level of the condensate stored liquid.
8. A method as claimed in claim 7, in which the base is provided in liquid or solid form.
9. A method as claimed in claim 7 or claim 8, in which the base is stored within or externally of a casing of the boiler.
10. A method as claimed in any one of claims 7 to 9, in which the pH of the condensate is monitored and base added as required to neutralise any acidity build up.
11. A method as claimed in any one of claims 7 to 10, in which the monitoring and dosing is continuous or intermittent.
12. Apparatus for preventing a condensate drain pipe from freezing comprising a flow diversion fitting adapted to divert warm water to the condensate drain pipe.
13. Apparatus as claimed in claim 12, in which the flow diverter intermittently diverts warm water to the condensate drain pipe.
14. Apparatus as claimed in claim 12 or 13, in which the flow division fitting includes sensing means for detecting temperature of the condensate drain pipe and control means for determining the amount and/or frequency of warm water to be diverted.
15. A method of preventing a condensate drain pipe from freezing comprising passing warm water into the condensate drain pipe.
16. A method as claimed in claim 15, in which the water is introduced intermittently.
17. A method as claimed in claim 13, in which the water is introduced in response to the temperature of at least a portion of the condensate drain pipe.
18. Apparatus for preventing a condensate drain pipe from freezing comprising an electrical heating wire coil arranged within or around the condensate drain pipe.
19. A method of preventing a condensate drain pipe from freezing comprising heating the drain pipe using an electrical coil.
20. An insulated condensate drain comprising an internal pipe and an external pipe with an air-gap therebetween, the air-gap being substantially enclosed.
21. An insulated condensate drain as claimed in claim 20, in which the internal and external pipes extend over the full length of the condensate drain.
22. An insulated condensate drain as claimed in claim 20 and 21, in which the internal and external pipes are substantially co-axial.
23. An insulated condensate drain as claimed in any one of claims 20 to 22, in which the external pipe is substantially rigid and the internal pipe is flexible.
24. A method of insulating a condensate drain pipe comprising inserting a flexible pipe through the condensate drain pipe and directing condensate through the flexible pipe.
25. A method as claimed in claim 24, including sealing the respective ends of the pipes to form a sealed compartment between the pipes.
26. Apparatus for preventing a condensate drain pipe from freezing comprising a fan for introducing a flow of air into the condensate drain pipe, and a heating element, the heating element being positioned downstream of the fan for warming the air flow through the condensate pipe.
27. Apparatus as claimed in claim 26, in which the heater is a ceramic disc heater.
28. A method of preventing a condensate drain pipe from freezing comprising introducing airflow through the condensate drain pipe using a fan, and heating the airflow.
29. A method as claimed in claim 28 in which the airflow is heated by a ceramic heater.
30. Apparatus for vibrating a condensate drain pipe comprising a motor, an eccentric element driven by the motor, the eccentric element acting causing movement of the pipe.
31. Apparatus as claimed in claim 30, in which the eccentric element acts against the pipe.
32. Apparatus as claimed in claim 31, in which a spring is provided for returning the pipe in the opposite direction to the movement caused by the eccentric element.
33. Apparatus as claimed in claim 30, in which the eccentric element is connected to the pipe for causing reciprocating movement thereof.
34. A method of facilitating a flow of condensate through a condensate drain pipe comprising vibrating the pipe.
35. A method as claimed in claim 34, in which vibration is initiated in response to temperatures below the freezing point of the condensate.
36. A method as claimed in claim 33 or 34, in which the vibration is continuous or intermittent.
37. Apparatus for facilitating a flow of condensate through a condensate drain pipe comprising an internal coating of at least a proportion of the condensate pipe with material having a coefficient of friction of less than 0.3.
38. Apparatus as claimed in claim 37, in which the coating is Teflon.