HRV or DVS

ive had both companies out today to discus the ventillation and heating options...

Who have you used.. whats your experience.. and pros or cons you can tell me ???


there is a lot of info on the consumer.org but im not a member

thanks in advance

OK - here is some of the info from Consumer, its a bit of a novel - and Im none the wiser on which one to get!
Can you read the comments on the website? Or do you have to be a member?

Types of system.
An automatic ventilation system is a much more effective way of reducing condensation than using a dehumidifier. And it's much more convenient than having to open and shut windows.

There are 2 main types of ventilation systems:

Positive pressure or forced air ventilation systems work by blowing drier air into your house from the roof space above the ceiling or, in some types, from outside. They suit older houses with wooden joinery better than modern houses with sealed aluminium joinery – unless windows are opened or additional vents fitted.
Positive pressure systems - These work by blowing drier air into your house from the roof space above the ceiling. They work best where there is a decent amount of space in the roof. The roof space must also be dry and reasonably warm on sunny winter days.

Positive pressure systems rely on the incoming air pushing the stale damp air out of the house through windows and doors that are not a tight fit. This means they suit older houses with wooden joinery better than modern houses with sealed aluminium joinery – unless windows are opened or trickle vents are fitted.

Most positive pressure systems claim to recover heat from the roof space. This is often possible – but not all the time. There won't be warm air up there on frosty nights and cold grey winter days. To cope with this, most systems automatically slow or even stop the airflow when the roof space temperature falls below certain levels. That means your ventilation slows down or even stops, unless there is a heater fitted.

You don't have a roof space? Some positive pressure systems – Drivaire, Moisture Master and DVS – offer units with a heater that work on outside air.

Solar-powered ventilation systems are a variation on positive pressure systems. They use the sun to heat up panels mounted on the roof or an outside wall. The panels warm the incoming air, with solar cells powering the fan. So there are no running costs with solar-powered ventilation, and you get fresh outside air that's nicely warmed up. There's also an optional cooling kit for summer ventilation.

But solar power depends on getting adequate sun, and won't suit some locations. You'll still need additional heating in the house at night – and on very cold wet days. We've found only one solar-power model suitable for a typical-sized New Zealand house, and it's quite expensive.

What to look for
Capacity
To meet building code minimum requirements for ventilation, the system needs sufficient fan capacity to move the whole volume of air in your house every three hours. All makers listed in our database offer units that can meet this requirement, with a range of models to match house sizes. If you have higher than usual ceilings or an unusually complicated house design, you may need a larger unit, and/or more outlets.

Filters
Strictly speaking, roof-space air doesn’t comply with the building code requirements. Good filtration is essential as the roof cavity can contain dust, fibreglass from batts, debris from bird nests, and other pollutants.

Most of these systems come with EU4 or G4 grade filters, which can remove 80 to 95 percent of particles down to 10 microns. Some makers of positive pressure system offer finer filters as standard; others offer this as an option.

If you know your roof space is very dusty or dirty, finer filters will prevent more of that dust from getting into your house. If you want to keep costs down by changing or cleaning your own filter, check how easy this is. Some makers won't sell you a filter; they only provide a filter-replacement service. Some filters are washable - but wash them carefully by hand, and replace them if they get torn or damaged. Driveaire says its filters can be washed up to six times. Electrostatic filters require regular washing in special solutions.

Extra outlets
Systems can be installed with either one centrally located outlet designed to push damp air out via windows and doors, or with outlets in several rooms, especially those with severe condensation problems. Larger houses will ventilate better with several outlets rather than one large one.

Controls
When set up correctly for your house, the controls should need little adjustment. That's the ideal arrangement – set and forget. It's handy to be able to do some basic things, like switching off the system in summer, from a control panel in the house. But otherwise it's easier to let the system do the work.

More expensive models let you check temperatures in the roof, the house or of incoming or outgoing air and allow adjustments to temperature cut-out settings or air flow. Others will automatically change airflow as required and even switch to summer cooling or switch on heat transfer systems at pre-set temperatures.

A basic system can provide ventilation just as effectively as one with complicated control options.

Extra features
You'll need to consider these – although they're often standard on higher specification (more expensive) models.

Most optional inline heaters are small and just designed to take the chill off the air, but some makers offer larger units that can substitute for some of your normal heating. If you want to maintain good ventilation during the colder months, we think additional heating is essential – but this will increase your running costs.
A heat-transfer feature allows the fan to take warm air from one part of the house (near a woodburner, for example) and move it to a colder part of the house.
Whether you need summer cooling depends on the design of your house and the local climate. If effective summer cooling is important, air conditioning is better than a ventilation system.
Extra ducts are added so that fresh air is drawn from outside (rather than warm air from the roof space).
Look for a model with an automatic or remotely controlled changeover feature – or you may have to send someone up into the roof space to alter the settings.
Warranties
If there's some doubt whether a positive pressure system will work in your house, make sure you get a money-back warranty. Look for a "three winter months" warranty, (not offered on most DIY systems) so you can evaluate the system's performance in more extreme conditions. Warranties are in addition to your usual protection (repair, refund, or replacement) under the Consumer Guarantees Act.

DIY
This is possible provided you're reasonably handy. You'll still have to use an electrician to make the connections to the mains or to fit a 3-pin outlet, which adds to the cost.

DIY's also the cheapest option – Bunnings offer the Comfortmaker kit for as little as $650. It's a basic one-outlet positive pressure system. Weiss and Smartvent are available through hardware stores like Mitre 10 and Placemakers, but you may have to ask your store to order one.

Some of the other makers of positive pressure units will supply systems for DIY, but they don't usually offer a winter-performance warranty if you install it yourself. And if you have to get an electrician to wire up the unit the cost savings are minimal.




Balanced pressure / heat exchanger ventilation systems extract warm damp air from living spaces and pass it through a heat-exchanger to heat up dry air which the system brings in from outside. They work best in more airtight, modern homes.
Balanced pressure systems - These extract warm damp air from living spaces, remove the heat using a heat exchanger, transfer this heat to cold dry air from outside, then pump it back into the house. A variation on this, used by Smartvent Synergy and optional from Cleanaire, draws in warmer air from roof cavities.

Balanced pressure systems can work even where there is no roof space, for example in an apartment.

To work effectively, balanced pressure systems need a relatively airtight house. So they will work best in more modern homes – unless it has lots of downlights! (See our recessed downlights report.) Old draughty Victorian villas don’t suit this style of ventilation.

Balanced pressure systems have two advantages over positive pressure systems. They run all the time, regardless of air temperature in the roof. And they can fully meet the building code's requirements for ventilation with outside air. But a properly designed balanced pressure system for your house can be quite expensive.

What to look for
Capacity
To meet building code minimum requirements for ventilation, the system needs sufficient fan capacity to move the whole volume of air in your house every three hours. All makers listed in our database offer units that can meet this requirement, with a range of models to match house sizes. If you have higher than usual ceilings or an unusually complicated house design, you may need a larger unit, and/or more outlets.

Extra outlets
Balanced pressure systems operate across the whole house, and usually have at least two outlets and two inlets inside the house. The inlets are typically located in warmer areas, and the outlets in cooler areas. Be guided by your installer on the location and number you need.

Controls
When set up correctly for your house, the controls should need little adjustment. That's the ideal arrangement – set and forget. Some of the more expensive models let you check temperatures in the roof and the house or incoming/outgoing air, and make your own adjustments to temperature cut-out settings or adjust the air flow.

A basic system can provide ventilation just as effectively as one with complicated control options.

Extra features
Balanced pressure systems make additional features like heaters and heat transfer unnecessary. They are often designed to achieve heat transfer by taking warm damp air from living areas and bringing in dry warm air to bedrooms.

If effective summer cooling is really important to you, air conditioning is better than a ventilation system – although balanced pressure systems work well in conjunction with air conditioning.
A shower boost is offered on some balanced pressure systems, and uses sensors on the hot water pipes to detect when the shower is running and switch the fan to high speed to extract the extra steamy air.
Filters
Balanced pressure systems (except Smartvent Synergy) draw in outside air. So they don't usually need filters, unless there's pollen or severe air pollution.

DIY
This is possible - provided you're reasonably handy. Balanced pressure systems are complex, but they come with comprehensive instructions. You'll still have to use an electrician to make the connections to the mains or to fit a 3-pin outlet, which adds to the cost. Usually you have to supply your own ducts and vents for DIY balanced pressure models.

DIY kits are available for Cleanaire balanced pressure systems.

Which system is best?
This depends on the design of your house, its floor area, the location, how much sun the house gets, the type of roof ... even the local climate.

Before you install any system, do some homework. We've outlined how the different designs work and some of their pros and cons which should help you decide whether your house is suitable for any of the systems available. Consider what you want to achieve against the types of system – and also look for any extra features you might need to meet your particular requirements.

For best results, a system should be designed specifically for your house and your needs. But this can be quite costly, especially if you choose a fully automated system with multiple outlets or other options.

We recommend getting quotes from several installers who are familiar with your local climate.

Our advice
Any of the three types – positive pressure, solar-powered positive pressure or balanced pressure – can be very effective. Your choice will depend on the type of house you live in, your location, and your budget.

Balanced pressure systems are the best option, if you can afford it. They'll work in almost any situation, provided they're properly matched to your house and correctly installed. There’s more choice of models since our last survey, but they are still an expensive option.

Make sure you're getting the genuine product. The HRV system implies it's a heat recovery system. But it's only able to recover what heat is in the roof space. And there will be times when there is no heat up there.
Positive pressure systems will work in any house that has a warm dry roof space, and sufficient air leaks past doors and windows. But if your roof is heavily shaded or you live in a colder part of the country, a heater will be essential for ensuring adequate airflow without cold draughts. You may also have to fit small vents to newer houses or leave windows slightly ajar on security stays to achieve sufficient air movement to fully control condensation.
Solar-powered systems will be effective anywhere that has enough sunshine – which means most parts of New Zealand. And they will always have the lowest running costs.
Always choose suppliers who are familiar with your local climate, and get at least two competitive quotes.

What about that ad on TV at the moment for 'Smartvent' ... 'eight out of ten electricians recommend'... not sure if it's worth a comparison too?

We went with DVS mostly cause they gave us a better deal, personally I don't feel there is much difference between the two systems they both operate in the same manner - its which ever suits your paticular situation.

Muz.. your a star thank you

Ball park for a 3 bedroom house is about $3k
that was with a vent in each bedroom and two in our large lounge with two fans.

thank you for your imput

I guess im just not yet convinced that the mouldy damn bedroom will completely dry out.. hmmm

i think we will go with HRV.. just feels better for some reason.
thanks everyone

Before you decide, just wanted to point out my thread about home ventilations systems that I posted last year. I put all sorts of info in it.

http://www.ohbaby.co.nz/Forum/forum_posts.asp?TID=27946

I'm really happy we went with Smartvent, and am so pleased about not having to empty a dehumidifier every morning, or waking up to condensation!

Since the time we had it installed, I have had 4 annoying phonecalls from the pushy people at HRV. I keep telling them we already went with Smartvent yet they persist in calling (although hopefully after the last one they have stopped)

we got an hrv about 3-4 years ago - and wouldn't be without it.. before HRV in our room alone we would get that little black dotty mould on the walls each winter I would wash the walls around 2 times and in the morning and night time when in bed the walls were damn to touch - like real wet.. our room is on the south side which doesn't help an din winter doesn't get any sun shining through...

Since HRV I washed the wall straight afterwards and have never done it since (for the mould reason).. its that good - we don';t get wet walls and although there is condensation on the windows first things cause of the closed curtains its cleared by lunch time.

the house is warmer cause its drier

Yes it was. All the quotes were for supply and install :)