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When you live your life on Twitter and Facebook, and are only friends with like minded people on Twitter and Facebook, you are not living in the real world. You are living in a narcissistic echo chamber.
My thoughts are my own and are in no way representative of my employer.
AWS Certified Solution Architect Professional, Sysop Administrator Associate, and Developer Associate
TOGAF certified enterprise architect
Professional photographer
Jeeves: PPV, or positive pressure ventilation systems, IMHO, arn't suitable for NZ climate and houses. These are the systems which take air from a ceiling cavity, and force it into the rooms. Stale air is then 'pushed' out of gaps and doors/windows to create a bit of flow through the house.
As mentioned previously, these do nothing to heat your house directly.
The problem with NZ houses is A) Damp, B) insulation.
Older houses tend to be poorly insulated. This makes them cold, and so people shut all the doors and windows to try and keep the heat in. They go about their daily business, breathing, boiling the kettle, drying clothes, having showers, doing the dishes, and cooking. All of these activies create moisture.
Because the house is shut up, all this moisture increases the relative humidity of the air inside the house. The air gets wetter, in other words.
Because of the poor insulation, a lot of interior surfaces like windows, and the inside of external walls, remain cold due to the outside temperature. This causes moisture to form on them due to condensation (Much like a cold coke can on a humid summers day). This moisture gets absorbed by these surfaces and wammo, you have mold and a cold damp house. Air that has higher relative humidity takes a lot more energy to heat as well.
Typically, during winter, the relative humidity of outside air is a lot lower than inside a house. This is where PPV comes in. It brings in this outside air (Because the roof cavity is mostly made up of outside air), and puts it inside. Because it's a bit drier - it can dry out surfaces and make it easier to heat. But of course, it's bringing in all this cold air! They rely on the intake being in the highest part of the building to try and recover some heat - which often is useless because roof cavities are so draughty.
A heat recovery system with an integrated heat exchanger is a lot more ideal. That cleanaire outfit that timmay mentioned are the best that I have found so far.
These systems suck the warm air from warm rooms like your lounge, and pass it through a heat exchanger. This exchanger takes the heat from this air and puts it into fresh air that is drawn from outside. This outside air is then pumped into bedrooms and the like. Whilst you will still lose a little heat from this process - it is considerably better than a PPV. So now you have warm, dry (Low humidty) air coming into your house - much more comfy!
Again, you will still need a heat source for this system (Fireplace/heatpump) - but they are miles better than a PPV system. Slightly more pricey - and they need a bit more room in your cavity - but certainly worth it.
Source: I'm a Data Center engineer, so have a bit of exp in air flow and humidity management.
networkn: anyone know how to get off the HRV system? We still get called about monthly despite making VERY clear in no uncertain terms we would never buy anything from them.
Common sense is not as common as you think.
jonherries: Thought I would just add, I have been planning a balanced ventilation system to replace our PPV one.
Would people recommend I put the inside air intakes in the bathroom, on the end of the clothes drier and above the oven as these are good sources of humid/hot air (I would have a few others as well).
Presumably those sources (esp. oven and drier) will hammer the filter?
networkn: anyone know how to get off the HRV system? We still get called about monthly despite making VERY clear in no uncertain terms we would never buy anything from them.
AWS Certified Solution Architect Professional, Sysop Administrator Associate, and Developer Associate
TOGAF certified enterprise architect
Professional photographer
timmmay:
Interesting question! Think about summer as well as winter, extra heat in the system in summer would be a bad thing, so it'd have to be switchable. However in winter yeah it could give you a big boost to have clothes drier exhaust and shower steam.
AWS Certified Solution Architect Professional, Sysop Administrator Associate, and Developer Associate
TOGAF certified enterprise architect
Professional photographer
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