Here are our most frequently asked questions about our products and services.

If you do not find the answer to your questions here feel free to contact us directly and our professional, helpful staff will be happy to help.

Why do I need a ventilation system for my indoor pool?

Water evaporates no matter what temperature or what condition it is in, it will evaporate if left exposed.

You can reduce the amount of evaporation by covering the pool when not in use but you can not eliminate it.

If left uncovered the evaporation would produce high humidity’s in the pool hall and promote mould and corrosion of the building structure.

Why can't I just open a window?

You can but you will not get the correct amount of air that is required and you will not be able to hold the room temperature in the winter.

Can I just fit an extractor fan in the wall to ventilate the room?

You can but the air that is extracted must be replaced and it will cost a lot of money to reheat the air that is drawn into the pool from outside.

Why should I buy a Recotherm ventilation system when I can protect the structure with a couple of fans and a heater battery?

Recotherm have been building ventilation systems for indoor pools for 26 years and have refined there system so to reduce the running cost to as little as possible.

A simple off the shelf ventilation unit would not be able to offer the energy saving features of the Recotherm unit and would not be able to with stand the corrosive effects of the swimming pool atmosphere. Recotherm have units in operation that have been running for 25 years.

Do I need a three phase electrical supply?

No Recotherm have single phase units up to and including 1m3/s which is large enough to accommodate a 100 m2 domestic pool.

Can the unit be installed outside?

Yes the units can be weather proof for external use but the display panel must be sited internally or protected in a weatherproof box.

Can I site the display panel remote from the unit?

Yes the display panel can be sited up to 800m from the unit and is connected by a core telephone style cable.

Should I fit a pool cover to the pool?

A pool cover would reduce the evaporation from the pool. We would highly recommend a pool cover for domestic application where the pool is only in use for 1 to 2 hours a day. For commercial use the advantages are less clear you may wish to have the pool uncovered for aesthetic reasons or the hours of usage may be so long that the pool is only covered for a short period and getting your money back within the life of the cover may not be possible.

Can I reduce the air temperature when the pool cover is on?

Yes because the pooled the evaporation is low and therefore reducing the air temperature will have only a minor effect on the rate of evaporation. This can be linked into the Recotherm unit so that the temperature is automatically reduced when the pool cover is on.

Do I have the air temperature 1°C above the pool water temperature to avoid condensation?

No this is a myth. Condensation occurs when air is in contact with a surface that is colder than the dew point of the air. The dew point of the air is a function of the temperature and humidity of the air. You can have the air temperature 5 °C below the pool temperature as long as the dew point of the air is below the temperature of the internal surfaces.

The Recotherm unit controls the internal humidity and temperature and thus controls the dew point. With an external temperature of -1 °C and a room temperature of 30 °C a humidity of 50% will prevent condensation on a double glazed panel.

If the air temperature was 25°C then a humidity of 55% would prevent condensation on a double glazed panel.

What governs the amount of evaporation from the swimming pool?

The amount of evaporation from the pool surface is proportional to the difference in the vapour pressures of the air and the water it is also affected by the air movement above the pool and by the amount of activity in the pool i.e.A pool with high occupancy will have a higher evaporation rate than an unoccupied pool.

Can I control the pool water temperature from the Recotherm Unit?

Yes we have add capacity on the internal controller to monitor and control the temperature of the pool you will require a temperature sensor and control valve which are both available from Recotherm Ltd.

Does the unit come complete with all controls?


Will I require an extra boiler to serve the ventilation unit?

No the ventilation unit can usually be serve off the boiler that heats the pool water.

This boiler should be sized to heat the water from cold to 30 °C in either 48 or 72 hours once it has got the pool water up to temperature there is usually spare capacity to supply the ventilation unit. You may require extra capacity on a commercial project depending on the rate of back wash.

How should the supply air be distributed?

The air should be distributed in either metal or builders work ductwork and blown over the cold surfaces in the pool hall, this should mean the windows if you have any surfaces colder than the window then you should rectify the problem.

The return air can be from a single point on one of the walls. (Please note the position of the return air grille has no effect on the distribution of the air) You should avoid blowing the air directly at the pool water surface as this promotes evaporation and will make the pool occupant feel cold.

I have a spa pool will this affect the unit I select?

Yes a spa pool is at a high temperature than the pool and when in use is highly active you should let who ever is selecting the unit know that you have a spa and what size it is.

It isn’t possible to run ductwork up to my windows can I still avoid condensation?

It is possible to avoid condensation you will need specialist distribution grilles to throw the air to all corners of the room. You may also need to operate at a lower humidity because you are not covering the windows with dry warm air.

Can I run the unit from a 13 amp supply?

You can operate the VF25, VF50 and VF100 from a 13 amp supply the bigger units will require a larger supply.

Do I need to have the unit running 24 hrs/day?

Yes the unit is there to protect the building structure but if the hall is well insulated and you use a pool cover then the unit will slow down to it minimum speed and use only a small amount of electricity to power the return fan.

Do I need to have the boiler running 24 hrs/day?

Yes to avoid excessive losses from the pool and prevent condensation we need to keep the temperature in the pool 24 hrs/day. It is therefore necessary to have the hot water from the boiler available on command.

I have been told I need a heat pump dehumidifier to control condensation is this correct?

No a heat pump dehumidifier is just a different type of unit it works by recirculating the air and removing moisture in a direct expansion evaporator the heat from this process is then use to heat the air and water.

Unfortunately the dehumidification process runs on electricity which is expensive and by recirculating the air without removing the chlorine and body odour smells it give a poor atmosphere in the pool hall. The Recotherm unit will give you a better atmosphere and cost less to operate.