Heat Recovery Ventilation

Does my house need to be airtight?

Yes the more airtight and better insulated your home the higher percentage of the house air and heat can be passed through the heat exchanger; giving the best performance and a controlled ventilation system.

Do I need any wall/window vents with heat recovery ventilation?

No the disc valves of the heat recovery ventilation system becomes the ventilation opening required in building regulations for each room.

The exception to this is if you have a boiler, fire place, stove or other device consuming air from the dwelling; then you need a separate air supply to this device.

Best practice is that each stove/boiler etc has its own dedicated air supply straight to the unit.

Gas fired devices should have a permanently open vent to supply make up air to the system.

Can I have an open fire place?

Open fire places are not advised as they are inefficient and they have a lot of heat and air lost up the chimney. The amount of air and heat loss can be greatly reduced by fitting a stove or insert to the chimney to limit the air and heat lost up the chimney/flu.

This will also improve your Building Energy Rating and mean less fuel needs to be burnt.
Any stove or fire place that is not room sealed requires a dedicated air supply.

Can I use my standard cooker hood?

With heat recovery your cooker fan can’t be extracted straight outside. There are 3 options how to treat the kitchen:
1) No cooker hood and the system handles the steam and grease.
2) A standard cooker hood set on re circulate, so the grease and smells are taken out by the grease and carbon filters respectively and the steam is put back into the kitchen for the unit to extract.
3) A dummy cooker hood connected to the unit, the grease filters on the unit handle the grease and the unit extracts the steam and hot air.

Option 2 & 3 are preferable to option 1, there usually isn’t much grease in a domestic situation but it doesn’t hurt to have grease filters over the cooking area.

If you extract straight outside with the cooker hood, you are wasting energy and unbalancing the house and could cause drafts in the house. Options 2 or 3 are our recommended solutions and option 2 using the re circulating cooker hood is the most used.

What is the best type of clothes dryer to use?

Drying clothes naturally outside in good weather is the most efficient method.
With the reduced and controlled humidity within a house that comes with heat recovery ventilation then clothes should dry quicker.

If an electric clothes dryer is to be used then a condensing dryer is the preferred option as no warm air is dumped outside. A dryer that exhausts warm air to the outside means that energy is being lost and make up air is required to replace the exhausted air. The make-up air can’t be supplied by the heat recovery system.

Can I install a HRV system in my existing home?

Generally not advised as an existing home may not be as airtight or well insulated as required for the system to work at its optimum.

Also fitting ducting to an existing dwelling is destructive as ceilings and some other surfaces may have to be destroyed to run ducting to every room.

If the system is fitted as part of a comprehensive energy upgrade of the dwelling where both the insulation and air tightness are address then that is when you would consider installing the system.

Can I not just block up my wall or window vents to save energy?

No ventilation is important for both the occupants and the houses well-being. Without air exchange between inside and outside then humidity, carbon dioxide and other pollutants from furnishings etc will build up.

Ventilation is necessary to give a healthy living environment for both you and the house.

Heat recovery ventilation gives you controlled and energy efficient ventilation. The system greatly reduces your ventilation heat loss and improves air quality inside the dwelling at the same time.

What is SAP Appendix Q Eligible?

The SAP Appendix Q is a listing of all the energy efficient heat recovery ventilation units that have been independently tested in the UK.

If the unit is listed on the SAP Appendix Q website then the unit is referred to as SAP Appendix Q Eligible and your energy assessor can use the test figures to improve your BER energy rating.

Can I use flexible ducting as it is cheaper?

Simple answer is no of the majority of the installation; the majority must be rigid ducting. Rigid ducting is best practice and is required with SAP Appendix Q Eligible unit to improve the energy rating of the house.

Flexible ducting is more restrictive to airflow and can change shape over time and affect the airflows.

Rigid duct is more expensive to buy but gives better performance straight away and over time. Suitably size rigid duct will also mean the fans can run slower than with the equivalent flexible ducting and so less electricity is consumed for the same airflow.

Do I need to commission my system?

Yes the speed and airflow of the system must be set and balance to the appropriate level for your house. Without having a system commissioned then you won’t know that the system is operating at it optimum efficiency and working as designed.

The system needs to be commissioned as per TGD Part F 2009 section of the building regulations. The system needs to be commissioned using an airflow meter fitted with a cone. View Commissioning documents here.

Do I need the Pre-Heater Box to run my unit?

No you don’t need to fit the Pre-Heater box but it allows the system to keep operating during extreme cold weather where other units may shut down to protect themselves from freezing conditions.

The unit has frost protection features, but the better the system is commissioned and the better the houses air tightness and insulation levels then the system can keep going down to normal Irish conditions. The pre-heater keeps the system running in extremely cold conditions.

Do I need the external antennae?

No you should only require the external antennae where there is foil backed insulation between the unit and the occupied part of the dwelling. If you have a poor mobile phone signal inside the house then you will probably need the antennae to boost the signal quality for communicating with the unit.

Do I need the filter box?

No the unit comes with high specification F5 filters (HR400, HR200 has G3 filters) as standard.

If you are concerned about having the best filtration then yes you would opt for the larger external filter as it gives year round filtration and a longer filter clean/replacement schedule for the filter.

HR400 Heat Recovery Unit - Error Codes Explained

Please click here for manual with full explanations, operations and maintenance

The ER codes and other warnings are there to alert you possible attention required for the unit or the system. You will know if there is a problem with the system.

If your Prometeo HR400 heat recovery unit gives an ER code then the below is the explanation as to what they mean and what you should do.

First step is to clear the code by pressing the following buttons:

  • Display, – (Minus), Display, +(Plus)
  • If the code reoccurs then it means that there could be a condition that needs your attention with either the unit or the system.
  • Certain ER codes occur in the first 24 hours after turning on the unit:
    ER10, ER09, ER13.These occur occasionally as the system is learning its new environment and is completely normal.

Filter warnings:

To reset filter warnings, please turn power off to the unit. Open the unit and clean or replace the filters as per the manual.

IMPORTANT: Without turning off the power the filter indicators won’t reset.

ER Codes

ER01: By-pass or defrosting valve are blocked

ER02: Drop in airflow has been detected of the fresh air supply fan. Please check for blockages, especially around the external vent.

ER03: Drop in airflow has been detected of the extract fan. Please check for blockages, especially around the external vent.

ER04: The remote control and unit can’t communicate.
Signal is being blocked, check if foil backed insulation is present.
The batteries on the remote are getting low, replace batteries.
The unit and remote are not paired, turn power off to the unit for 3 minutes; restart and within 1 minute of starting the unit press and hold the enter button on the remote control until it beeps. This beeps means the unit and remote are paired.

ER05: The remote control is not transmitting a signal. Try Re Pairing The remote control to the base unit by removing the batteries from the remote and powering the heat recovery unit down for 5 minutes. Re-power the base unit, put fresh batteries in the remote and then press and hold the enter button on the remote down for 30 second or until you hear a long beep.

ER06: Temperature sensor in the fresh air intake is not functioning. Reset the unit as described above, if the error returns then contact the Technical department

ER07: Temperature sensor in the fresh air intake downstream from the heat exchanger is not functioning. Reset the unit as described above, if the error returns then contact the Technical department

ER08: Temperature sensor in the stale air outlet is not functioning. Reset the unit as described above, if the error returns then contact the Technical department

ER09: The relative humidity sensor is not operational or is detecting levels outside normal range. Reset the unit as described above, if the error returns then contact the Technical department
Can also occur where the condensate trap is not fitted correctly.

ER10: The carbon dioxide sensor is not operational or is detecting levels outside normal range. Reset the unit as described above, if the error returns then contact the Technical department
Can also occur where the condensate trap is not fitted correctly.

ER11: The fresh air being received is colder than the system can accept. Reset the unit as described above, if the error returns then contact the Technical department

ER12: The fresh air being received is hotter than the system can accept. Reset the unit as described above, if the error returns then contact the Technical department

ER13: The air being received from the house is lower than 9 Degrees Celsius.
The insulation on the ducting is allowing the system have a high heat loss, increase the level of insulation.
There is little or no heat from the house, the house has no active heating system.
There is a disconnected duct allowing cold air into the system.

ER14: The air being received from the house is higher than it should be.
The insulation on the ducting is allowing the system have a high heat gain from the attic, increase the level of insulation.
There is a lot of heat coming from the house.
There is a disconnected duct allowing air into the system.

Please note ER13 and ER14 are interchangeable.