Installing FTX in old house: Is it possible?

It is often possible to install FTX in an old house. However, in older buildings, the solution needs to be customised a bit more. Existing ventilation, tightness, moisture risks, chimneys, radon conditions, floor plan and possible duct routes affect both the result and the extent of the installation.

The important question is therefore not only to FTX is possible, without how system should be designed to work in that particular house. Done correctly, FTX provides better air, a more even indoor climate and lower heat losses. Done incorrectly, it can lead to noise, draughts, unbalanced pressure conditions or new moisture problems.

Quick version

What is FTX?

HRV stands for exhaust and supply air ventilation with heat recovery. The system extracts used air from bathrooms, toilets, laundry rooms and kitchens, for example, while supplying fresh filtered outdoor air to bedrooms, living rooms and other rooms where people spend long periods of time.

I The FTX unit a large part of the heat is recovered from the exhaust air before it leaves the house. The recovered heat is used to preheat the incoming supply air, both improving comfort and reducing unnecessary heat loss.

The difference with self-draught is that FTX is a mechanical and controlled system. In a self-draught house, ventilation is mainly controlled by temperature differences, wind and leaks. In an FTX system, air flows are controlled by fans, ducts, diffusers and adjustment.

When is FTX interesting in an old house?

Many older houses were built with self-draught. This could work relatively well when the house had leaky windows, warm masonry, old fireplaces and natural air leaks. But many old houses have changed over time. Windows have been replaced, the attic has been additionally insulated, the façade has been sealed and the heating system has been modernised. This can cause the original ventilation to deteriorate.

Signs of poor ventilation can be musty odour, condensation on windows, humidity problems in bathrooms, heavy air in bedrooms or a house that feels stuffy despite ventilation. In such cases, FTX can be a way to create more controlled air exchange while reducing heat loss.

FTX can be particularly interesting when:

• The house has become denser than before: For example, after window replacement, additional insulation or façade renovation.
• The self-draw works less well than it used to: It can be noticed through condensation, odours or bad air in bedrooms.
• You want to reduce heat losses: FTX recovers heat from exhaust air instead of ventilating all heated air straight out.
• There are reasonable canal routes: Attics, cellars, closets, cat attics and shafts can sometimes be used to hide ducts.
• You are planning a major renovation: It is often easier to install FTX when walls, ceilings or floors are opened anyway.
• You want filtered supply air: The supply air can be filtered before being blown into the dwelling.

When might FTX be difficult or inappropriate?

FTX is not always the best solution. In some older houses, ducting may be too extensive, especially if the house has low ceilings, small cat attics, many visible original features or cultural heritage values that should not be affected. It can also be a big mistake to start with FTX before investigating existing moisture or radon problems (read more below).

This is how the installation is usually done

1. inventory of the current ventilation of the house

Start by finding out how the house is currently ventilated. Does the house have a draught, mechanical exhaust air or already some form of supply and exhaust air? Where are the exhaust air ducts located? Are there brickwork, old ventilation ducts, wall vents or leaks that have previously been part of the air exchange?

2. check moisture, radon and tightness

Before installing a new mechanical ventilation system in an old house, it is advisable to check for moisture problems, radon risk or large air leaks. An FTX system works best when air flows can be controlled. If the house is very leaky, some of the air may be channelled away from the system, reducing both comfort and heat recovery.

3. Planning the ducting

Ducting is often the most difficult part of an older house. Ducts need to be laid to both exhaust and supply air rooms. Common solutions are to use attics, basements, closets, installation shafts or discreet cladding. The goal is short, well-insulated and service-friendly ductwork without unnecessary interference in the building's structure.

4. Choose the right unit

The unit should be sized according to the size of the house, floor plan, airflow needs and sound requirements. It also needs to be positioned so that filters can be changed and serviced easily. Common locations are attic, laundry room, technical room, basement or utility room. If the unit is placed in a cold room, ducts and connections need to be handled correctly to avoid condensation and heat loss.

5. Ducts, flues and silencers

Ducts need to be professionally installed, insulated where necessary and supplemented with silencers. Supply air diffusers are normally placed in rooms where people spend long periods of time, while exhaust air diffusers are placed in rooms where moisture and odours occur. It is also important to consider fire sealing, penetrations, condensation insulation and access for future cleaning.

6. adjust the system

Once the installation is complete, you must the ventilation is adjusted. This means that air flows are measured and balanced so that the right amount of air is supplied and removed. Adjustment is crucial to avoid draughts, noise, poor air exchange and unwanted pressure differences.

Is FTX always better than self-draught?

No, not always. A well-functioning draught system in an older house may be sufficient, especially if the house does not have moisture problems, odour problems or clear energy reasons to change. But if the draught has deteriorated after renovations, or if the house has air quality problems, FTX can be a big boost.

The important thing is not to see FTX as a standard solution for all old houses. The right solution can be FTX, mechanical exhaust air, improved self-draught, additional vents or a combination of measures. The choice should be based on the condition of the house, the layout, the tightness and how the dwelling is used.

About radon in old houses

Radon can come from the soil, building materials or domestic water. In older houses, it is therefore wise to know the radon level before changing the ventilation. An FTX system should be designed so that it does not create undesirable pressure conditions that draw more ground air into the house. In the case of known or suspected radon problems, ventilation should be planned together with an expert.

Frequently asked questions

Is it possible to install FTX in a house with a draught?

Yes, it is often possible. But the self-draught is then fully or partially replaced by a mechanical system. This requires design, ducting, adjustment and control of how the change affects the house.

Can FTX cause problems with damp in the attic?

Problems can arise if ducts are routed in cold spaces without proper insulation or if penetrations are not sealed properly. This is why condensation insulation, airtightness and professional installation are important.

Does FTX work in houses with a fireplace or tiled stove?

Yes, but the system needs to be balanced to provide the right conditions for the fireplace. In some cases, separate air supply to the fireplace is needed. Incorrect pressure conditions can cause smoke to enter or the fireplace to malfunction. For example, our units have a stove function that can create excess pressure if necessary.

How do I know if my old house is suitable for FTX?

Start with a technical review of the house. Look at existing ventilation, moisture, radon, tightness, floor plan, attic, basement and possible duct routes. A ventilation expert can then assess whether FTX is the right solution or whether a simpler measure will suffice.

Get a quote for the installation of FTX ventilation

If you want to know whether FTX is suitable for your building, the next step is to have a ventilation expert look at the conditions. A good quote should not only include the price of the unit, but also take into account ductwork, positioning of diffusers, sound attenuation, insulation, condensation management, adjustment and future service.

In order to get a more accurate quote, it is useful to prepare information on the size of the house, the number of storeys, existing ventilation, heating system, any damp or radon problems, and whether there are attics, basements, cat attics or other possible ducting routes. Pictures, floor plans and information on upcoming renovations can also make the assessment easier.

At Acetec, you can get help to think about the right ventilation solution for your house and what parts need to be included for the installation to be sustainable in the long term.