Baths – closets – sinks – and spittoons – Vapor or heat in bath
Reexamination Certificate
1998-09-17
2001-11-06
Fetsuga, Robert M. (Department: 3751)
Baths, closets, sinks, and spittoons
Vapor or heat in bath
C165S054000
Reexamination Certificate
active
06311344
ABSTRACT:
The subject of this invention is a sauna ventilation system.
The quality of the air in the sauna plays an important role in creating the ideal conditions for enjoying the steam whilst using the sauna. Control over the amount of humidity and oxygen is an important aspect in controlling the quality of the air. Moisture forming whilst the sauna is in use, which does pass to the drain, is also removed by ventilation. The sauna stove is measured according to the individual temperature and bathing conditions for each sauna. The most common temperature range while the sauna is in use is 50-120° C. It should be possible to obtain the right air condition and the desired temperature in a sufficiently short period of time. To do this, the sauna stove has to have a high power rating. This means that the peak power demand placed on the electricity production and distribution facilities arising from the simultaneous use of electric sauna stoves is large during, for example, weekend sauna times. Generally, the ventilation of the sauna and the removal of dampness has to be controlled manually, both while the sauna is in use and whilst being aired. In addition to this, the general air change in the sauna is regulated manually using ventilators to dry out the dampness created during bathing times in between sauna sessions.
Attention to safety of use and fire safety is an important matter. The sauna stove can remain switched on as a result of a malfunction in the equipment. Also, any materials close to the stove may catch fire as a result of misuse. A fire in the sauna can spread rapidly from the sauna room via the doorway or through the ventilation ducts to other areas. It is possible to control a fire situation with existing systems but these systems are independent and external to the sauna stove and are not integrated within the stove itself.
Usually the sauna is heated with a stove fuelled by electricity or wood. There are also stoves which are fuelled by gas and oil. At the same time, there are also stoves available on the market which can be heated with either wood or electricity. Electric stoves are either heat accumulator stoves, which are constantly ready for use and equipped with thermal insulation and ventilators that can be opened, or continuous heating stoves, which are the more common form of electric stove.
The continuous heating electric stove is switched on before the sauna is used and the temperature in the sauna is maintained thermostatically at the desired level while the sauna is in use. The stove operation can also be regulated with a timer or by remote control. Continuous heating stoves are more common than wood-fuelled stoves.
There are also pre-heated stoves in use which are usually heated with combustible fuel and are heated prior to using the sauna but must not be heated whilst the sauna is in use. Pre-heated stoves are further divided between those with a smoke flue and those without. A stove without a smoke flue is used with a smoke sauna.
A problem with the continuous heating electric stove is the large energy demand, especially during the early warning up stage. Ventilation in an electrically heated sauna is often minimised in order to retain the power and energy in the sauna. In particular, saunas in swimming baths and spa baths as well as in saunas kept in general sauna readiness, even 12 hours at a time, the stove is continually switched on throughout the bathing period. In these locations the efficiency of the energy consumption of the sauna is important.
The hot air in the sauna is able to absorb a greater amount of moisture than cold air. When the sauna ventilation is connected directly to, for example, the ventilation ducts of other parts of the building, the moisture condenses on the walls of the ventilation pipes as the air cools in the long ducts. When the pipes become damp the prospects for growth of mould within the air-conditioning system are increased.
A sauna ventilation system, in which the extracted air warms the incoming air by using a heat exchanger is already recognised in publication DE 2602361. This mentions a finned tube heat exchanger whose air extraction cell is connected to the front part of the air outlet duct and the air intake cell between the air inlet duct and the stove. Heat is transferred from the extracted air to the incoming air by a water circulation pipe and pump system. The cells are positioned independently but are connected together by the water circulation pipe system equipped with a heat transfer fitted with fixed or flexible connections. The air outlet channel is also equipped with a duct impeller in this publication.
The system according to publication DE 2602361 requires separate heat recovery and emission cells which are positioned awkwardly in the sauna room, water pipes between the cells, and a pump system to circulate the fluid. Water cannot stand, even temporarily, temperatures well over 100° C. in normal air pressure. In other situations the system has to be constructed in accordance with pressure resistance requirements. With low outdoor temperatures the cell after the air inlet duct can freeze with an obvious danger of water damage.
There are a number of air humidifying systems on the market. A existing system for use in sauna is the humidifier system presented in FI patent 83158, which is built into the stove and in which electricity is used to convert the water to steam in the stove with a separate unit. In the system mentioned the steam is fed along pipes from the lower part of the stove to the upper part and from there out of the stove into the sauna room. A separate water storage tank is attached to this humidifier system, from which water is drawn to be converted into steam in the vaporiser. The problems with this system are calcification and low humidifying effectiveness. In addition, the system is awkward and expensive to build in conjunction with the stove.
It is also known to locate the air humidifier system in the sauna air inlet duct. In this system water is poured from the storage tank in the upper section via the manually adjusted water tap in the pipe to a vaporiser cell made, for example from fabric, in the sauna air inlet duct below. As the air flows through the vaporiser cell in the air inlet duct to the stove air duct or directly into the sauna room it humidifies the sauna air at the same time. The problem with this system is the poor steam production due to the incoming air not being pre-heated. In addition, there are problems in regulating the humidity of the sauna air due to the lack of a control system.
There are generally on the market, various vaporiser tanks which fit in the stone cavity in the stove, the shape of which varies greatly according to the manufacturer. The latest variation in this field is a longish water tank sunk deep into the stone cavity, which is positioned upright in the stove stone cavity. The water contained in the tank is vaporised by the heating source of the stove. In this version the steam comes out of the upper section of the tank. The difficulty with this humidifier is the small quantity of water available for each use. The tank has to be refilled every 15-30 minutes. In addition the tank is difficult to place in stone cavities other than certain known types.
Various vaporiser systems which are external to the sauna room and which bring steam into the sauna room have become known amongst steam sauna systems. These systems are intended solely as steam generating systems for steam saunas and are not suitable in their present form for Finnish type saunas in which the desired temperature is in the range 50° C.-120° C. These systems are expensive to build especially for subsequent installation.
The purpose of this invention is to improve primarily the effectiveness of electrically-heated saunas, but also the ventilation of other saunas, to control the air humidity both during and after use of the sauna and to transfer heat energy from the air extracted from the sauna to the incoming air and to eliminate moisture. At the same time the stove power demand and the con
Fetsuga Robert M.
Pillsbury & Winthrop LLP
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