DVS - HRV - MoistureMaster

[graemeh]

More information please?
Where from?
How much?

Hit the window with a hammer
Bunnings
$70 for a good hammer

[essence]

Wow, expensive hammer, I can get them for about $20 but then they're only used for passive window venting.

[graemeh]

That's for a good quality one that will last a lifetime (e.g. estwing).

I forgot to include "Safety Goggles - $10 from local safety gear shop or $20 from Mitre 10"

[kirschbaum]

More information please?
Where from?
How much?

They're made by Easy Air. Just google it.
They sent an installer around to measure up our windows. He came back a few days later to install them. All pretty painless really. The installer just cut out the top of the glass, secured the vent on it and glazed it all back in.
The total price for getting 8 vents installed was $1,050.
We're happy with them so far.
Once I'd decided that passive ventilation was all we needed, I looked at the options, including fitting security stays or double-tongued window latches, but neither seemed very secure, and they'll still let the bugs in.
Oh, we're in Auckland so you'd to give them a call to see if they cover your area.

[graemeh]

Only really feasible for Aluminium windows though.

Probably not something you'd want to install in a cold climate either!

[kirschbaum]

I think that depends. Older timber windows probably get enough natural air leakage anyway. The benefit of these vents is that I've got the air coming and going where I want it (at the top of the window) and I can control it. For timber frames, you'd probably want to draft seal them first. Newer timber windows are well sealed though, so they would still work well there.

As for colder climates. You still need ventilation in the deep south. If you can afford a heat exchange system, this is a great option, but if not, you're looking at either PPV or passive. Considering any free heat from the roof space is negligable, particularly the further south you go, passive vents are going to be no worse for heat loss than these forced fan systems. My vents also have a control slider, so I can reduce the opening if needed.

[muppet]

http://www.joinerydev.com/vents.htm

The average cost is around $40 to $50 per vent (priced according to length), plus a per-vent installation cost of around $50. A typical 3 bedroom home requires approximately 8 - 10 trickle vents.

[muppet]

From the above website

What about forced air (positive pressure) home ventilation systems?

Home ventilation systems such as DVS and HRV start from around double the price for a basic system, require regular maintenance and use electricity. They are no more effective than passive ventilation under normal situations but may have an advantage in the single level sheltered and shady scenario.
However, forced air systems - or domestic ventilation systems - still require the circulated air to be expelled from the home to be effective, and they generally rely on natural, uncontrolled gaps in the building envelope for this. As modern homes are built very airtight, these natural gaps will not be sufficient for the moist, stale air to be expelled. It will simply be circulated through the home.
So in many cases, installing a few strategically positioned trickle vents around the house will provide the necessary paths for the stale air to escape and will increase the effectiveness of any existing forced air home ventilation system.
Forced air home ventilation systems work by pushing air from the roof cavity down into the home. They often claim that the air in the roof cavity is fresher, drier and warmer than the outside air. The air in the roof cavity may be warmer than outside during part of the day, but at night, when the heat is needed, roof space air is almost always colder than inside, and is usually no warmer than the ambient outside air. Therefore, the forced air ventilation system is actually pumping cold air through your home.
The ability of the roof space to retain heat depends on a number of factors including the roofing materials used, time of year and daily conditions. During the winter, even with favourable weather, the roof space will generally not reach a suitable temperature until late morning or early afternoon. By early evening, the temperature in the roof has generally dropped below indoor temperatures. Also, under common winter conditions, the roof space can fall below the temperature of outside air. You can read more information on this topic in a report to EECA titled "Home Ventilation Systems Assessment"
The claim that roof space air is clean and fresh is also questionable. The roof space in a home is often rife with insects, dust and potentially rodent droppings and urine. Roof spaces are rarely cleaned and the filters supplied with these ventilation systems will not prevent all of these pollutants from making their way into your living areas.
Furthermore, the 1992 Building Code specifies that ventilation systems must comply with the New Zealand Standard 4303: Ventilation for Acceptable Indoor Air Quality. This specifies the minimum residential ventilation rate with outdoor air at approximately one complete air change every three hours to be distributed throughout the home.
Outdoor air is defined as air taken from the external atmosphere. Roof space air does not qualify as outside air.

[muppet]

Dean said

I am putting 47 of them in my rentals at the moment. We checked them all out extensively and the best brand by far is Healthaire. They actually invented the product and their system is entirely tenant proof. Turns itself on and off automatically, does NOT need setting for summer or winter and you don't need any control panels etc.
They are excellent.

Hi Dean
After three years do you any comment to make about the above systems?

[Bruzer]

Re roof space air

From the above website

Roof spaces are required to breathe in accordance with the building code. All roof spaces or cavities can breathe.
If you have a good PPVS system drawing in excess of 800 cubic meters of air per hour from the roof space, where is this air going to come from? Outside. So you have 800+ cm of air from outside, being drawn into the roof space per hour, is this old, stale dirty air as some claim. This air is then passed through a good filter such as F7 grade, to .3 micron which is smaller than the eye can see. This is then evenly distributed through out the home. We now have fresher, drier, less polluted air than what is outside on our doorsteps.

Some roof spaces are homes for rats and mice, many are not. If there is a rodent problem, have it sorted, just like you would for anything other problem.

[Bruzer]

Indoor Air Quality

From the above website

"Furthermore, the 1992 Building Code specifies that ventilation systems must comply with the New Zealand Standard 4303: Ventilation for Acceptable Indoor Air Quality"

This statement as supplied and quoted in this blog is misleading in general terms. This Code is specific to homes that have no other natural ventilation. Such as homes that under the RMA must have mechanical ventilation only then must this air be taken directly from outside. This is law however from a point of debate, refer to my comments above. It is all very interesting.

[kirschbaum]

Hi Bruzer.
I don't think I'd say this statement is any more misleading than many of the claims made by PPV companies. It is at least factual.
I read a lot of information before going with these passive vents. You are right that most homes meet the building regulations for ventilation by having enough openable windows, not by installing trickle vents or a positive pressure system.
But what this means is that installing a system sourcing air from the roof space DOES NOT help you to meet the ventilation requirements in any way.
Whereas, installing trickle vents (as they do in the UK as part of their building regulations - http://www.planningportal.gov.uk/eng...oveddocuments4) DOES contribute to your overall openable area. This would allow you to potentially reduce the number of openable windows required, which would actually result in a cost saving.
Incidentally, as Heat exchange systems also sources air from the outside, I'd suspect they can also be used to minimise the number of openable windows required.

But as you say, it's an interesting and heated debate, as shown by the number of discussions on this web site alone.

[Russiandoll]

Have just had Moisture Master installed in PPOR, and its working well - from loads of condensation one day to none the next.

Two systems installed (two separate roof spaces) + one extra outlet to allow the outlets to be in the bedrooms, rather than the hallway requiring the doors to be open overnight. $5,200 after a bit of negotiating (RRP $5800).

We went for MoistureMaster because of the inline heater - the others claimed it wasn't necessary in Auckland, but recent temperatures indicate otherwise. We couldn't see the point in taking 6 degree air from the roof and pumping it into the bedrooms all night!

cube

How did you find the inline heater? I have heard some people had increased power bills?

[Bob Kane]

How did you find the inline heater? I have heard some people had increased power bills?

Of course their power bill would increase!
They'd be using more power (to run the heater).

[Russiandoll]

Of course their power bill would increase!
They'd be using more power (to run the heater).

Sorry but I think your fanatasism may have gone to you head...yes I realise using a heater would increase their power bill...if you can in fact read, I prempted the the statement with a question..HOW DID YOU FIND IT? Leading to the assumption that it did increase their power bill...but by how much.

p.s. Thanks for your help on the free and independant forum.