Pressure switch for sealed room and forced draught boilers

Description

[0001] This invention refers to sealed room and forced draught domestic heating boilers (hereafter referred to simply as boilers) and the object of the invention concerns a pressure switch adapted to replace any type of faulty electro-mechanical pressure switch, during boiler repairs in domestic habitations.

[0002] It is known that all boilers of the aforesaid type are equipped with a pressure sensor in the gas flue immediately downstream of the fan, aimed at controlling correct fan function. If the measured pressure results as being lower than an established value, generally different for each type of boiler and mainly in a range between 0.30 and 1.80 mbar, the fan function is considered as faulty and the boiler is deactivated.

[0003] It is becoming increasingly more common that the deactivating device is composed of what may be defined as a digital pressure switch: an electronic pressure switch adapted to open the contacts of a relay through an appropriate electronic circuit that is generally integrated with other electronic boiler devices. In order to deactivate the boiler at a level lower than the pressure required for each boiler model, it is sufficient to set the electric signal level lower than the level at which the relay opens the contacts, by using a suitable setting means.

[0004] In the past, but also on many current boiler models, an electromechanical pressure switch was used as the deactivating device, but it was not possible to adjust the setting in a reliable and precise manner outside the production plant.

[0005] Therefore there are large numbers of models for each brand of boiler currently in use equipped with electromechanical pressure switches with a wide variety of setting levels. For example, the machine range of the company applicant for this patent must provide for at least 23 different types of pressure switch or pressure settings, and a similar variety can be estimated for other manufacturers.

[0006] This situation causes great inconvenience for the manufacturer's Technical Servicing operators who deal with the maintenance and repairs of the boilers currently in use, since they are not able to keep such a large variety of pressure switches available in their vans, and when called for an intervention, if a pressure switch replacement is necessary, the technician must return to the plant to obtain the exact switch required for that particular boiler model, because at the present moment a model with a single setting is not available. This leads to an increase in intervention time and cost.

[0007] It is just as inconvenient for the company Technical Servicing operators and their spare part warehouses to have to stock such a wide variety of switches in order to ensure the maintenance service on installed boilers, and the cost and complication involved in stock management is also considerable.

[0008] The object of this invention is to eliminate all the aforesaid problems caused by diversification of electromechanical pressure switches, also including among these different models, electromechanical switches that are identical but set at different levels.

[0009] This and other objects are attained, according to this invention, with a single universal pressure switch adapted to replace more than one type of electromechanical pressure switch that each manufacturer has used or is still currently using on various boiler models.

[0010] The characteristics of the universal pressure switch will be made clear in the following description that illustrates certain preferred embodiments, and the appended claims that form an integrated part of the same invention description.

[0011] It should be noted that it has not been considered necessary to supply appended drawings with this description since they are not needed in order to understand the concept of the invention.

[0012] The universal pressure switch is composed of a simple digital pressure switch that can be interchanged with all or the majority of the electromechanical pressure switches currently used by boiler manufacturers.

[0013] The universal pressure switch comprises:

• an electronic pressure sensor, of a type commonly known, adapted to transmit an electric signal to an appropriate electronic card, indicating the pressure measured downstream of the fan;
• a relay adapted to open the same contacts opened by microswitches on electromechanical pressure switches that are interchangeable with the universal pressure switch;
• said electronic card, in turn, is adapted to perform at least the following:
  • receive the electric signal indicating the measured pressure from said electronic pressure sensor,
  • compare said electric signal with a reference value that can be easily set by any Technical Servicing operator,
  • open the relay contacts if the electric signal that indicates the measured pressure does not attain said reference value.

[0014] Therefore, in short, the universal pressure switch acts exactly in the same manner as an electromechanical pressure switch, except for the fact that the intervention pressure level can be set by Technical Servicing personnel according to the boiler model on which it is to be mounted.

[0015] Regarding the reference value setting, this can be obtained using any recognised type of reliable and user-friendly means that can be used in the environments where Technical Servicing operators intervene, such as a trimmer for example. However, the system that is particularly useful, and therefore preferable, is composed of a set of resistors with a variety of electrical resistance, each one corresponding to the same number of reference pressure values, interchangeable and insertable in the electronic card to set the universal pressure switch at the intervention pressure required by each type of boiler.

[0016] As far as the practical possibility of mounting the universal pressure switch on each boiler is concerned, the switch should be preferably equipped with universal fixing means easily adaptable to several boiler models, and possibly all models, using a simple fixing bracket, for example.

[0017] The advantages of this invention are obvious: the spare parts necessary for the replacement of all existing pressure switches are reduced to a single universal pressure switch and a set of resistors that can be inserted in the electronic card at the appropriate moment by the Technical Servicing operator.

Claims

1. Universal pressure switch for the control of correct flue gas suction fan function on sealed room and forced draught boilers
characterised by the fact that
said switch can be used on two or more boiler models equipped with electromechanical pressure switches, being interchangeable with said pressure switches and set at the moment they are mounted by Technical Servicing operators.

2. Pressure switch according to the previous claim
characterised by the fact that
the switch comprises:

- an electronic pressure sensor adapted to transmit an electrical signal indicating the pressure measured downstream of the fan, to an appropriate electronic card;

- a relay adapted to open the same contacts that are opened by the microswitches on electromechanical pressure switches that are interchangeable with the universal pressure switch;

- said electronic card, in turn, being adapted to perform at least the following:

- receive the electric signal indicating the measured pressure from said electronic pressure sensor;

- compare said electric signal with a reference value that can be easily set by any Technical Servicing operator;

- open the relay contacts if the electric signal that indicates the measured pressure does not attain said reference value.

3. Pressure switch according to the previous claim
characterised by the fact that
the setting of said reference value can be obtained using any type of reliable and user-friendly recognised means that can be used in the environments where Technical Servicing operators intervene.

4. Pressure switch according to the previous claim
characterised by the fact that

- the said reference value setting can be obtained by simply inserting in the said electronic card a resistor indicating the reference pressure value of the boiler on which the universal pressure switch is to be mounted,

- the Technical Servicing operators being provided with a variety of resistors with different electrical resistance, each one corresponding to the same number of reference pressure values, which in turn relate to all the boiler models on which electromechanical pressure switches can be replaced by said universal pressure switch.

5. Pressure switch according to one or more of the previous claims
characterised by the fact that
the switch is equipped with universal fixing means adapted for application on several models of the boilers in question, this means being composed of a fixing bracket in particular.

6. Universal pressure switch that can be set and interchanged with electromechanical pressure switches according to the description and illustrations provided for the specific objects.