Intelivent - Energy Intelligent Home Ventilation

Frequently Asked Questions

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ANSWERS

Why not just open a window? Isn’t the old fashioned way the best?

An open window doesn’t filter the incoming air or accurately control ventilation rates, and whilst it may still sometimes be necessary to leave a window ajar on a security latch at the cool end of the house in summer when cool air cannot be sourced elsewhere, it is not essential to providing a fresh air intake. An Intelivent heat recovery ventilation system is designed to be energy efficient and exchange air to:

Bring in fresh air at a rate you choose
Filter (or clean the incoming air)
Exhaust stale air, pollutants and moisture while recovering up to 97% of the heating or cooling energy
Enable excellent ventilation with security (no open windows)

An open window can’t properly do any of these things for you.

What defines a Heat Recovery Ventilation System Vs the many other ventilation systems in common use?

A true Heat Recovery Ventilation system as defined by the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE), MUST have a heat exchanger. A Heat Exchanger is a device that enables heat energy to be extracted from one air-flow and put into another air-flow. If you are quoted a Heat Recovery Ventilation system and it doesn’t have a Heat Exchanger, it may be a heat recovery ventilation system “HRV” in name only, and perform accordingly.

Can an Intelivent Heat Recovery Ventilation System retrofit to an existing attic fan system?

If your system has 200mm fans and ducting, most probably yes and lower priced kits with one fewer fan, filter and register are available for your application. If your existing system is not 200mm, most probably you would need a complete system however you would still be somewhat ahead in that the power cables would probably already be installed.

Why is a Heat Recovery Ventilation System useful?

Tight buildings reduce energy costs by keeping in heated or conditioned air. But tight buildings without adequate ventilation trap humidity and pollutants so they feel “stuffy” aggravate allergies and cause general discomfort for you and your family. Moisture damage to windows and other parts of the building shell can result from high humidity.

What purpose do Heat Recovery Ventilation Systems serve?

They provide an energy-efficient means of bringing in fresh filtered air while removing stale air. They also act as a heat transfer system and serve to reduce or eliminate condensation. Finally, they recover some solar heat energy in winter while providing cooling during the summer.

Who needs a Heat Recovery Ventilation System?

Every home (old and new) needs ventilation to bring in fresh air, remove stale air and provide moisture control.
In some places, dwellings are required by law to have a mechanical ventilation system. New Zealand is not such a place; however NZS 4303 does mandate a certain number of air changes per day which may or may not be achieved with the “open window” ventilation typical of New Zealand homes.

What is meant by thermal efficiency?

Thermal efficiency is a measure of how effectively the heat exchanger extracts heat from one airflow and puts it into another airflow. Our thermal efficiency calculations are based on the following ε-NTU method:

Do I need to remove the roof or ceiling to install the Intelivent Heat Recovery Ventilation System?

In most cases no. The heat exchanger and all other components are designed to be able to be put through a standard ceiling access.

I have a skillion/cathedral roof. Will your system work for me?

An Intelivent Heat Recovery Ventilation System will work for any application at all provided ducting can be installed that achieves the necessary air circulation, and that a source of fresh dry air can be found. There is no need for the Heat Exchanger to be installed in the ceiling cavity and in fact it is fine positioned in a cupboard or even the corner of a garage, but duct lengths must be considered as they will affect system efficiency.

Can an Intelivent Heat Recovery Ventilation System help in a leaky home situation?

The answer is a qualified yes. If your home still leaks however, an Intelivent System is not a quick fix and the problem should be properly rectified before structural damage occurs.

What if my home is not insulated?

The better a house is insulated, the more efficient a Heat Recovery Ventilation system will operate.
Ceiling insulation and draughty doors and windows should ideally be addressed prior to installing a Heat Recovery Ventilation system as the benefits of the system will be negated by the thermal losses in the house.
Exterior wall insulation and underfloor insulation are also ideal, but not necessarily as big a thermal loss as the ceiling and joinery.

Can an Intelivent Heat Recovery Ventilation System replace the heating system?

No. A Heat Recovery Ventilation system compliments rather than replaces a heating system so that fresh air is warmed, ensuring there is no discernable drop in temperature. It is compatible with woodstoves, Heat Pumps, night-store heaters, all under-floor heating systems and water heating systems with radiators.
Because an Intelivent Heat Recovery Ventilation System typically delivers dryer air, the effectiveness of heating is enhanced plus dryer air feels more comfortable and is healthier for you.

Will an Intelivent Heat Recovery Ventilation System place extra load on my existing heating? Will I need to add heating? Will I be able to eliminate some of my heating?

This depends on what your existing heating consists of, where it is located, and whether it is undersized, correctly sized, or oversized for what it is currently expected to do.
The Intelivent Heat Recovery Ventilation System works on the basis of creating airflows within the house from multiple Coldrooms to one or more Hotrooms, which are normally the lounge or living rooms which normally face north and normally contain the primary heat source, like a woodburner.

A woodburner is normally capable of producing much more heat than the room it is located in requires, and that spare capacity will mean that it should be easily capable of warming the entire house with the aid of the Intelivent system.
A Heat Pump that is oversized for the room it is located in, or some other large heat source, should like a woodburner, have spare capacity to warm the entire house with the aid of the Intelivent system.
A Central Heating system will have been sized to heat the whole house and will therefore have no trouble in maintaining heat throughout the house with an Intelivent system installed.
A Heat Pump that is correctly sized or undersized for just the room it is located in, or some other small to medium sized heat source, may struggle to produce enough heat to warm the whole house once the Intelivent system begins to distribute that heat to the coldrooms.
Numerous small heaters around your home, especially if they are oil column heaters or similar, should be replaced with a primary heat source in the hotroom if one does not already exist.
Small heaters or heat pumps located in the coldrooms that are additional to a primary heat source in the hotroom should become redundant once an Intelivent system is installed, and should be left turned off so as not to confuse the Intelivent controller which continually monitors hotroom and coldroom temperatures.

How does an Intelivent Heat Recovery Ventilation System help asthma sufferers?

Research carried out by a number of worldwide leading authorities have established a clear link between the house dust mite allergen and the development of asthma – 80% of sufferers are allergic to dust mite allergen.
Heat recovery ventilation reduces the relative humidity to a level at which the house dust mite cannot survive, thereby removing a major trigger of asthma attacks.

I’ve noticed that I tire easily and don’t seem to have much energy. Could this be related to the air I’m breathing in my home?

Potentially, yes. Air trapped inside cannot renew itself and becomes stale. Each time you breathe, you exhale CO2 and in a tightly built home, it can quickly build up to an unhealthy level. Symptoms of excess CO2 may include nagging headaches, general lethargy and grogginess.
Fresh air contains 20.9% oxygen and 0.03% Carbon dioxide where expired air is typically 16% oxygen and 4% carbon dioxide.
When CO2 levels in a room exceed only:

0.1%, the comfort of occupants is compromised.
0.35% CO2, there are long term health implications
>5% CO2 there is acute danger to health.

What about air born materials; can they affect my health too?

Absolutely. Breathing and other health disorders and allergies have variously been attributed to dust mite dander (excrement), fungal spores, pollen, off-gassing from building materials and aerosol sprays, carbon particulate from diesel engines and dust generally. The highly efficient delivery air filter provided with the Intelivent Heat Recovery Ventilation System can greatly reduce and in some cases, totally eliminate these air born pollutants.
Many illnesses are highly contagious therefore continuously removing contaminated air provides home occupants with a better chance of averting sickness.
Heat transfer systems can be useful however a major demerit of such systems is that while they transfer the heat, they also bring the moisture and odours with it. Perhaps more sinister is that should there be a fire, they will also transfer smoke. Wherever a heat transfer system is installed there MUST also be one or more smoke alarms in close proximity to the outlet.

Will an Intelivent Heat Recovery Ventilation System reduce the damp, musty smell in my home?

Yes, However please be patient and aware that it may take some days or even weeks to dry out damp floor coverings, drapes, upholstery and clothing etc.

Some suppliers of ventilation systems make claims about the efficiency of their HEPA filters and the resultant health benefits. Are these claims reasonable?

The claims relating to filter efficiency are real. The net affect on air quality however, is decidedly questionable unless every person or animal coming into your home goes through a full scrub procedure as in a hospital isolation ward or operating theatre!

I have rats/mice/starlings etc in my attic, so should I still collect air from there?

Probably not as you will likely also have unpleasant odours. In such a case, it would be advisable to draw the supply air from outside the house, however in very wet weather, the dehumidifying effectiveness of the system may be reduced as the outside air may not be as dry as the air in the ceiling cavity.

What about home security?

Home security is an every increasing concern and while two-stage catches and security stayed windows are a deterrent to home invasion, they are no match for closed and locked windows. An Intelivent Heat Recovery Ventilation System makes it possible for all windows and doors to remain closed while still providing ventilation that is actually superior to open windows.

Does the air get recycled too?

Definitely not. The prime purpose of an Intelivent Heat Recovery Ventilation System is to expel stale air

How much heat is recovered (or recycled)?

This is dependant on fan speed and humidity however the heat exchanger recovers between 80 and 97% of the available heat while also delivering solar energy from the ceiling cavity that would otherwise not be used.

What is the power consumption of an Intelivent Heat Recovery Ventilation System?

There is no definitive answer to this question as it depends on individual circumstances however in most cases, you will actually SAVE electricity. For example, the system may cost 2c/hr to run however if you currently run two dehumidifiers (~14c/hr) you may save >12c/hr. If you have a Positive Pressure Attic Fan, the power consumption of the fan may only cost 1c/hr however it could also be pushing warm air outside your home, that has cost you >$1/hr to heat! In certain circumstances, an efficient Heat Recovery Ventilation System can give back >$20 for every $1 you spend on system running costs.

You say an Intelivent Heat Recovery Ventilation System has to operate continuously. Isn’t this a waste of power?

No. It is said that hot air rises but it is more correct to say that it floats on top of cold air. It is important to ensure the air in your house is being continuously mixed as once cool air stagnates, it is difficult to get warm air to mix with it.
In addition, moisture is continuously being produced in your home from various activities and it is better to deal with the problem on a continuous basis. Finally, warm air is better able to absorb moisture than cold air and if the system were to be shut down the temperature in various rooms would quickly revert to being either too hot or too cold.
The only time that we would not recommend you keep your system running would be when setting off bug-bombs as the airflow will reduce the effectiveness of the bug-bomb, or in the case of fire when all sources of fresh air should ideally be cut-off so as not to fuel the fire however we are not suggesting that turning your system off should be a priority over escaping from a house fire.

When the air in the roof cavity is cold, won’t I be gradually losing heat, in spite of the heat exchanger?

Correct, and this is why it is vitally important to have an efficient heat exchanger along with precise control logic. There are however, a couple of other factors that must be considered besides heat loss:

The dryer air the Intelivent Heat Recovery Ventilation System delivers feels more comfortable than damp air.
Dryer air is far easier and therefore cheaper to heat (or cool) than damp air.

Is there any way that surplus heat in the roof cavity can be captured during the day and released after sunset?

We have a low-cost patent pending enhancement in the pipeline that will extract excessive heat from incoming fresh air and make it available later in the day when it can be of real benefit in maintaining the indoor temperature.

My home doesn’t leak so why do I even get damp air and how can I avoid it?

Dampness air in homes comes from a myriad of sources; some of which are controllable but most are not. They include:

Breathing
Cooking and boiling kettle
Washing (clothes, dishes)
Bathing and showering
Product of combustion from un-flued gas heaters

The average home produces about 20-25l of moisture (water) per day. This can easily be eliminated with an extraction fan but this would be most wasteful as you would also be losing warmth. An Intelivent Heat Recovery Ventilation System acts as an extraction fan but captures a very high percentage of the heat energy in the air being extracted before discharging it outside.

You recommend taking “fresh” air from the roof cavity. Is this air really fresh and why not pull it from totally outside the house?

There are four good reasons for drawing “fresh” air from the attic space:

Air drawn from the attic space tends to be 15-20% RH dryer than that taken from outside the home as some of the moisture in the air tends to condense on the underside of the roof plus the sun helps to dry it.
There is heat soak through the ceiling of even well insulated homes and it seems sensible to capture this. If down-lights are fitted, this heat soak can be quite pronounced.
When it is sunny, the roof acts as a solar collector and some solar gain will be realized while some benefit can also be had from the flue of a fire.

Air drawn from outside the house can draw in pollutants and fumes such as vehicle exhaust, barbeque smoke, etc.

Can I expect to do less dusting?

Absolutely! The bulk of the air delivered to your home will be filtered such that all pollen and 90% of all dust will be prevented from coming into your home via ventilation air. Of course you will still have people coming in and out and bringing dust and dirt in on their footwear and clothing however there will still be markedly less dusting to do when compared to the old open window method of ventilation.

Will flies be kept out too?

Definitely, along with mosquitoes, sand-flies, moths, bees, bumblebees, wasps, ants/cockroaches (unless they are breeding in your home) and even earwigs and wetas.

Will I still need a Dehumidifier?

It is highly likely that you will NOT require a Dehumidifier and will therefore not have to put up with it gurgling noises at night and the need to empty it during the day. In extreme cases where there is rising damp or leaky building issues, a dehumidifier may still be required.

What about Heat Pumps?

Heat pumps are an excellent technology and deliver $3-4 worth of energy for every $1 spent. They can however, be further enhanced by an Intelivent Heat Recovery Ventilation System in that:

A Heat Pump tends to dry out air TOO much and the Intelivent System helps to balance this provided the humidity of the outside air is in fact high enough. In extreme cases, a humidifier may be required to raise the humidity to a comfortable level.
A Heat Pump does not ventilate at all, nor can it deliver its heat throughout your home. An Intelivent Heat Recovery Ventilation System helps on both counts while also reducing the stratification of air within your home.
An Intelivent system cannot do what a Heat Pump can and vice versa however in some instances, an efficient Intelivent System can deliver up to $20 worth of energy for every $1 spent.