DIY Bastu ventilation for a bath

In order to keep a sauna or bathhouse, also called a bastu, comfortable and healthy, proper ventilation is essential. When it comes to reducing moisture and improving air quality in your sauna, do-it-yourself ventilation solutions can be both economical and efficient.

It’s not difficult to design a working ventilation system for a bastu. You don’t need a lot of technical knowledge or expensive equipment to design and install a system that meets your needs if you understand the fundamentals of moisture control and airflow.

Intake and exhaust are the two primary components of an efficient bastu ventilation system. While the exhaust eliminates hot air and extra moisture, the intake lets fresh air into the sauna. By keeping these components in balance, you can guarantee a constant airflow and avoid the accumulation of moisture, which can cause discomfort and even structural damage to the sauna.

Homemade ventilation systems for a bastu frequently make use of basic mechanical parts and natural airflow. When vents and fans are positioned carefully and moisture-resistant materials are used, your sauna will last longer and be more useful while also creating a healthier atmosphere for its users.

What kind of system is this

Given the size of the former Soviet Union and even Europe and America, it is probably hard to find someone who is unaware of the Finnish sauna. However, few are aware that dry steam also exists in Sweden. Fewer still will claim that their ventilation systems are different—the Swedes have an uncommon but highly efficient one.

Swedish for sauna is "bastu." Ventilation gets its name from this word.

We look at doable ways to set up efficient ventilation in your sauna or bathhouse in the article "DIY Bastu Ventilation for a Bath." Maintaining an environment that is safe and comfortable requires proper ventilation because it ensures enough airflow, eliminates excess heat, and reduces humidity. We’ll go over easy yet efficient ventilation solutions that you can do on your own, including selecting the best system and installation advice to guarantee peak performance. This guide will assist you in creating a healthier and more pleasurable bathing experience with enhanced air circulation and moisture control, whether you’re building a new sauna or renovating an old one.

Principle of operation

Similar to baths, saunas feature steam rooms that require ventilation. The supply and exhaust air exchange system that the Swedes invented is continuously operational because of natural air movement. The plan is as follows:

1. from outside (from the street) cold air is supplied to the bottom of the electric stove;
2. heating up from the hot metal, due to physical laws, it rises. A new portion of cold air enters in its place, resulting in excess pressure being created in the steam room;
3. through cracks in the floor and vents in the foundation (vents), cooler air is forced out. The result is a constant movement of air inside the steam room.

Let’s review the main ideas.

• The stove serves as a heat pump.
• The floor is poured, with cracks. Otherwise the idea won"t work.
• Dry steam. Therefore, after completing the bath procedures, drying the wooden elements of the sauna structure is not necessary. Here, ventilation has a different task: to create a comfortable microclimate for those taking bath procedures.

Advantages and disadvantages of Swedish-type ventilation for saunas

Depending on what it does, bastu ventilation has advantages and disadvantages of its own.

• constant ventilation of the steam room;
• uniform distribution of hot air in the upper part of the room;
• replenishment of oxygen, which is consumed during the operation of the stove and the breathing of people in the steam room;
• drying the wood if it accidentally gets wet.

• increased energy consumption.

Another benefit of the Swedish sauna mentioned in the forums is that it’s more comfortable to stay on the upper shelves of the steam room when the hot air is moving.

Ventilation diagram for a bathhouse

It is impossible to replicate the Scandinavian air exchange system in a bathhouse. Solid floors and high humidity levels interfere. Therefore, it is necessary to adapt Scandinavian ventilation to completely different operating conditions of the steam room. They decided to solve the problem as follows: cut two ventilation holes in the wall at the bottom and top. The lower one is for exchanging air during the heating of the stove and taking bath procedures, the upper one is for removing moisture to the street after finishing the wash. Time showed that the idea was not working: the walls and floor were attacked by mold. There are many reasons, but we will talk about them below.

The efforts to make the exhaust better persisted. They started using a pipe with two valves inside the steam room—one at the top and one at the bottom—instead of openings in the wall. We’ll explain what happened as a result in the content.

For what types of baths is it suitable

The ventilation principle for a bastu bath appears to work well in a Russian steam room, based on the air exchange model mentioned above. Supporters of this system think it offers a lot of benefits:

• firewood (electricity) is saved during the heating of the bath – moving, hot air warms up the steam room faster due to convection;
• during bath procedures, fresh air (or rather, oxygen) is constantly supplied to people taking a steam bath;
• due to two ventilation holes (at the top and bottom of the pipe), the microclimate in the steam room can be regulated;
• At the end of the bath procedures, the system allows you to thoroughly dry the wooden structures of the steam room: floor, walls, ceiling and shelves.

Prominent websites devoted to bath building and maintenance offer similar benefits. It is surprising, however, that some of them still encourage people to utilize the system despite acknowledging in passing that it is ineffective overall. This is extremely odd on two levels. Myths are typically propagated by companies that make products. Furthermore, it is not possible to purchase pre-made ventilation systems here.

What is actually the case? Let’s solve it together.

First paragraph: resource conservation for energy. Experts who have completely forgotten their high school physics lessons can say this. After all, regardless of the fuel type, the heater stove produces a certain amount of heat during combustion. Calories (Joules) stay in the steam room, warming the walls, floors, and air in a small area. A portion of the thermal energy is released into the street when ventilation is operating. It takes more electricity or firewood to make up for this. When firing a furnace, proponents of bastu ventilation do not list any additional benefits.

In summary, the functioning of bastu ventilation, along with other forms of air exchange during heater heating, lacks a logical reason.

Point 2: Regarding the intake of oxygen from fresh air. Even fierce proponents of bastu ventilation acknowledge that it is not ideal for bath procedures. They find this systemic behavior incomprehensible, which is why they are always trying to make things better. Thus, the only thing from the Swedish model that was kept was the name.

In actuality, the Swedish model’s ventilation principle does not apply to Russian baths during bathing procedures. The cause is the steam supply: the steam room’s drastically elevated pressure causes the cold air to flow in the opposite direction. Excess air naturally seeks escape through any gaps and fissures in order to maintain equilibrium in the pressure. This also applies to the inlet channel. The regular pouring of hot water over hot stones prevents time from being available for the restoration of the supply of cold outdoor air.

There is one more nuance here that is ignored, and many bath experts simply do not understand: the air heated by the stove does not have time to warm up to high temperatures, and therefore rises to a height of approximately 1.4-1.6 m. The laws of physics do not allow anything higher. After all, under the ceiling space the temperature is around 70 o C, and the stove manages to warm up the air flow to 45-55 o C. Therefore, you should forget about the circulation of air masses throughout the room (there will be movement, but at the bottom). And, therefore, there is no need to talk about the supply of oxygen to the shelves. By the way, several sites write about the dead zone under the ceiling space, but no conclusions are drawn.

Supporters of ventilation see this as the perfect scenario, but they forget that the supply air near the stove cannot heat up to more than 35 to 45 degrees Celsius, and if the upper one isn’t working, it can’t rise above 1.4 to 1.6 meters above the floor.

In conclusion, burst ventilation—a brief opening of the doors when someone enters or exits the steam room—is required to maintain the oxygen level in the space. It is illogical to link the strike’s benefits to the merits of switching the ventilation air.

Point 3: Those who think that the bathhouse’s microclimate can be controlled by simultaneously opening two ventilation holes ought to be reading physics textbooks in school. Why? Let’s use our fingers to illustrate. The steam room’s top and bottom have distinct air temperatures. Because it has better traction, the hotter one will rise more quickly, preventing the less heated one from leaving. Until the temperature drops, this will go on. This is equivalent to steaming and then opening a window. However, nobody opens it for some reason.

In conclusion, the Scandinavian air exchange system is not very beneficial, even though people are beating each other with brooms while they are on the shelf. In numerous instances, the microclimate is even violated due to the disruption of the horizontal air flow.

Point 4. About drying the wooden elements of the steam room. Metal has a high heat transfer coefficient. Therefore, a metal stove cools down quite quickly (2-3 times faster than a brick heater). This means that a few hours after the end of the bath procedures, ventilation will begin to work not due to excess pressure, which is typical for the Swedish model (“the pump” is turned off), but due to rarefied air – warm air goes outside, and cold air takes its place. The trouble is that the diameter of the pipe is not enough for intensive ventilation, which, by the way, is also recognized by fans of the system. As a result, mold and rot, if there is no safety net in the form of other types of ventilation.

In conclusion, a bathhouse is not a good fit for the bastu ventilation scheme. Some craftsmen are currently creating something that only slightly resembles the concept of Swedish sauna enthusiasts, and it prevents the steam room and washing area from drying out efficiently.

We provide comprehensive instructions on how to make such an air exchange for those who prefer to step on their own rake rather than learn from the mistakes of others.

Advantages and disadvantages

If the advantages and disadvantages of ventilation in a sauna are evident, then things are more complicated in a bathhouse.

• increased consumption of electricity (wood);
• lack of the required amount of fresh air during bath procedures;
• weak draft on a windless day;
• low power, which does not allow drying the wood after washing.

Materials and tools

There are two methods you can use when installing bastu ventilation for a bathhouse yourself:

• buy part of a chimney kit;
• do everything yourself.

As a result, the instruments and materials will differ.

Installation of chimney ventilation

You will require the following when buying sandwich chimney pipes:

• adapter for connecting a pipe without insulation to a sandwich pipe;
• ceiling pass-through assembly (if it is not included in the kit, then there must be a pass-through sandwich pipe);
• sealing collar with high elasticity for sealing the intersection of the pipe and the roof (master flush).
• tee for pipe – allows you to organize an exhaust from under the ceiling space;
• tee plug – closes the ventilation hole during bath procedures;
• straight sandwich pipes 1 m long;
• turbo deflector;

• clamps for fastening pipes together;
• a plug for the lower valve or a gate with a rotary valve – it performs better than its retractable counterpart;
• chainsaw – helps to cut a passage hole in the ceiling;
• Bulgarian;
• screwdriver or hammer drill;
• construction knife or scissors.

Installation instructions

The entire system is assembleable piece by piece. You’ll need the following for this:

• several galvanized metal pipes with a diameter of 110 mm (usually metal ventilation risers are used) 1.25 m long. The quantity depends on the height of the bath (3-4);

• mineral wool for insulating two pipes on the roof (preferably basalt);
• knitting wire or plastic twine for attaching the wool to the pipe;
• galvanized metal sheets to cover the insulation;
• tee with plug (for installation at the top);
• adapter from 110 to 180 mm (desirable diameter of zinc sheets covering the insulation);
• gate valve on the bottom valve;
• grille for air intake;
• metal screws;
• screwdriver;
• turbo deflector;
• Bulgarian;
• drill;
• chainsaw or electric jigsaw;
• roulette;
• pencil or chalk.

Preparatory work

Any type of ventilation, not just bastu, should be installed starting with the bathhouse’s design. You may have the idea for the project in your head, but you still need to draw up a drawing of the air exchange system—preferably by hand. Experience has shown that "by eye and based on intuition" plans to extract moist air from the steam room and laundry room are nearly never successful.

The necessity to install fresh air ventilation during the foundation pouring process explains why the preparatory work started early. Using one of the foundation vents appears to be the best course of action.

There are a few things to take into account when designing ventilation.

1. The inlet opening must be covered with a grill to prevent foreign objects or rodents from getting inside the pipe. But the protective mesh reduces the air intake area, which violates the requirements of SNiP and SP – the supply and exhaust ducts must have the same diameter (area). The way out of this situation is either to increase the diameter of the supply air duct, or to attach a nozzle to the main channel of the head with a large inlet hole.
2. The hood is installed after completion of construction work and installation of the stove – you need to cut holes in the ceiling and roof for the pipe outlet, and then seal it. In order not to perform the same work twice, ventilation is assembled before finishing work.
3. A wood-burning heater is not at all suitable for the bastu system. If it still works somehow with an electric stove, then any tricks will not work. The reason is in the ash pit. He"s cold. Therefore, the air supply under the bottom of the stove does not turn on the “heat pump”. Some bathhouse owners place a pipe with cold air next to the stove casing, in the hope that it will warm up and rise upward. But there is a small problem: below, under the stove, the air is cold. Having warmed up a little, it tends to rise higher (this is near an electric oven). At the top of the pipe, which is next to the casing, inside, the air temperature is approximately the same as outside. Therefore, due to physical laws, the movement of air flows, if at all, will be sluggish. The problem is aggravated when steam is supplied – the overturned inflow is restored much worse due to the rotation of the channel by 90 o .

Do-it-yourself bastu system installation

The detailed instructions for assembling the ventilation duct vary depending on the equipment that was purchased.

Assembly from a chimney

Although purchasing multiple sandwich chimney pipes with components will increase the cost slightly, using them will make assembly much easier. The figure below illustrates what ought to occur in the end.

Single pipes with heat protection removed, 1 and 3; Gate valve with rotary valve #2; plug-in tee #4; adapter #5; 6- sandwich pipe; 7. a lip that seals the roof; 8 is the sandwich pipe to turbo deflector adapter; 9 is the turbo deflector.

The following order is followed when performing assembly work:

1. the insulation is removed from two pipes;
2. gate is installed. There are two mounting options: from below or at the pipe connection. There is no fundamental difference where the plug will be located. If at the bottom, then it is attached to the air duct with metal screws, and the pipes themselves are inserted into each other and clamped with a clamp or taken with self-tapping screws;
3. the second pipe is shortened with a grinder so that the inlet opening of the hood is approximately 50-60 cm from the floor, and a tee is fixed on top;
4. the tee is attached with self-tapping screws;
5. a pass-through unit is inserted into the ceiling (the operation is described in detail here);
6. an adapter is mounted on the tee – an adapter from a pipe 110 mm to 180 mm (this closes the insulation from moist air);
7. a sandwich pipe is passed through the passage unit so that its end is at ceiling level and blocked by any available method;
8. single pipes are connected to the insulated part of the ventilation;
9. inside the steam room, the channel is attached to the wall using clamps;
10. a second insulated pipe is passed through the roof;
11. the pipes are fastened together using a clamp;
12. the hole in the roof is sealed with a sealant. Its edges are treated with sealant, and it itself is fastened with large self-tapping screws;
13. An adapter is installed on the ventilation head;
14. turbo deflector is attached.

The final step involves taping the seams inside the steam room and painting the pipe.

Ventilation duct assembly

It’s a little harder to assemble a hood from a set of parts. However, no particular abilities are needed. The methodical assembly procedure appears like this:

1. the gate is inserted into a pipe with a diameter of 100 or 110 mm (the second option is preferable);
2. fastened together with metal screws. Possibly "bugs". But some experts advise using simple self-tapping screws. In this case, you will have to drill holes with a drill of smaller diameter;
3. a tee with a cover is installed on the second pipe. Fastening also with self-tapping screws;
4. one of the pipes is shortened so that the lower exhaust hole is above the floor at a height of approximately 50 cm, and the tee is under the ceiling;
5. connect two mono pipes (insert into each other and fix with self-tapping screws);
6. put an adapter on the tee;
7. pass a third pipe through the ceiling and attach it to the tee;
8. the system is lifted and screwed to the wall;
9. all connections are wrapped with tape. There is immediate strengthening of the fastening and complete sealing;
10. in the attic the third pipe is connected to the fourth (the joint must be sealed with tape). The latter should be about 15 cm higher than the ridge;
11. the ventilation duct after passing through the ceiling is insulated with mineral wool. Some experts recommend fixing with glue. Easier with knitting wire or twine;
12. a pipe with a diameter of 180 mm is put on the insulation (protection from moisture) and attached to the adapter (adapter);
13. the second jacket pipe is started, after which it is connected to the first (in the attic);
14. all joints are closed again with tape;
15. the passage unit on the roof is sealed (see. higher);
16. a turbo deflector is installed through the adapter.

It’s clear that nothing is difficult. It’s true that the stove’s fresh air supply is all that remains of ventilation. What’s left is "homemade."

Errors when installing the bastu system

Many mistakes are made when installing a Swedish steam room ventilation system, which leads to the bastu appearing to function but eventually developing mold and rot. The most typical

• the hood is vented into the wall – air currents from the street block it;
• the air duct is below the roof ridge – the draft is weak, and in strong winds it can generally tip over, even with a turbo deflector;
• the pipe in the attic area is not insulated;
• on the contrary, the pipe is insulated, but already inside the steam room or covered with lining – it must be heated by hot steam;
• exhaust air is taken from under the floor or above the floor at a distance of no more than 40 cm from the surface;
• installation was carried out in a room with a solid floor (no underground ventilation);
• the exhaust pipe is smaller in size compared to the supply duct;
• air intake is carried out through a rectangular hole – the inflow is poorly restored after supplying steam.

FAQ

In the steam room’s frame bathhouse, a window was constructed. Does installing bastu ventilation become necessary?

The bastu system for a bathhouse made of any material (wood, brick, foam and gas blocks, frame) is not necessary if the steam room has a window.

How efficient is the ventilation system in the Swedish bath when a Feringer stove is installed?

This manufacturer’s stoves are all wood-burning. Due to the lack of cold air flow—bastu ventilation’s intended application is to use the stove as a heat pump, which is not the case in this situation—and as a result, the convention, bastu ventilation is incompatible with such heaters. The models with blown stones are an exception. This kind of air exchange isn’t the ideal option, though, even in this particular situation.

What kind of metal works best for the air duct?

Nearly all professionals suggest using galvanized iron. However, this isn’t the ideal choice for a steam room. Food-grade stainless steel AISI air ducts have a longer lifespan.

Which would be better to install, pipes for the hood or ducts?

A turbo deflector, a significant temperature differential between the exhaust air and the outside air, high pressure inside the bathhouse when steam is supplied, and other factors all contribute to a better draft when the air flow is twisted in a spiral pattern.

Dead zones in the corners of the box slow down the twisting process, whereas this is not the case with pipes. Consequently, the solution is obvious: just the air duct’s circular cross-section.

Can an exhaust pipe be concealed inside a frame wall?

No. The system won’t function properly. There are two causes.

1. Turning the air flow sharply slows down the thrust. And without it, exhaust air will not be able to enter the air duct.
2. The pipe must warm up inside the steam room in order to heat the air trapped inside it, increasing the draft. An air duct hidden in the wall will not heat up from the steam of the bath. As a result, the owners will get two problems: weak draft and an abundance of condensation.

Why is it that the manufacturer of Skoropark stoves recommends using a vertical air duct to vent through the ceiling, but practically all online resources advise venting ventilation through the wall?

Baths are now being taken in bastu hoods. No experience was accrued over time. As a result, a lot of self-taught individuals started, at their own peril, modifying a Swedish sauna’s ventilation system for a Russian bath. There have been attempts to breach the ceiling. but not successful. The majority of the time, the steam and the tightness of the ceiling space disappeared. Without examining the causes of depressurization, the option was left on the vine.

It was decided to use walls as a result. Articles started to surface online. And after a few years, it was discovered that while the hood appeared to be functioning, rot and mold were spreading throughout the bathhouse. The floor and walls were not dried out by the ventilation, in actuality. The locations did not take the materials out of circulation. The most likely explanation is that different people are the owners and authors of different Internet resources. The latter was merely unaware of the issues that had emerged. In an attempt to improve ventilation, builders replicated materials that had malfunctioning hoods.

Skoropark stove manufacturers called attention to the issue. Consequently, the use of a vertical pipe with a passage through the roof and ceiling was suggested. Indeed, it is not their idea. Woodson’s mediocre KuBastu system was improved.

Maintaining adequate ventilation in a sauna, also known as a bastu, is essential to keeping the interior cozy and secure while in use. You can maximize your sauna experience by using inexpensive and efficient do-it-yourself ventilation solutions.

Installing a tiny exhaust fan close to the top of the sauna room is one of the easiest ways to do this. This fan should be positioned to efficiently remove steam and hot air from the room. It can be easily controlled by connecting it to a timer switch. This aids in controlling the interior’s humidity and temperature.

It’s also crucial for the Bastu to have air circulation. Fresh air can enter the sauna more easily and stale air can exit with the installation of adjustable air vents near the ceiling and floor. This arrangement helps to maintain a healthier atmosphere in addition to improving comfort.

An alternative ventilation method for those who prefer a more natural approach is to include a small window that can be opened from outside the sauna. This is especially useful for people who appreciate the sensory experience of changing temperatures and fresh air intake because it enables manual airflow adjustment.

In the end, the ventilation system you select should complement both the layout of your sauna and your personal tastes. Ensuring sufficient ventilation, whether you choose a fan-powered system or the more conventional window method, improves the longevity and overall enjoyment of your Bastu experience.

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