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Amosnz
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  #827888 29-May-2013 17:20
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That is true, however if you start with an outside temp of say 10 deg you still need to heat the air so it is hotter than the ambient temp of the outlet room to feel a difference (which is likely to already be warmer than the 10 deg outside).

That's another point I didn't like about this system, the only temperature you can see is the one from the sensor in the controller.  There is another temp sensor in the control box in the roof space, but you can't see what that value is. None of the outlet rooms are monitored.

I had plans to build an arduino setup and put a sensors on a few inlets\outlets and measure the system over a period of time, but that hasn't happened yet.




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Batman
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  #827896 29-May-2013 17:38
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I had always thought of ventilation as a means of getting new fresh air or reconditioned air that gets cleaned, dehumidified and filtered not as a means of heating your house! if you want to heat your house get a heater ... right?




Involuntary autocorrect in operation on mobile device. Apologies in advance.


 
 
 
 


Amosnz
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  #827922 29-May-2013 18:13
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I'm not using it as a heater, I have a wood burner as the primary heat source, but I was looking to use the heat from that heat source more efficiently. 

My comment was meant as a real world example of a 'heat recovery ventilation' unit in action, where the heat recovery aspect doesn't work out to be as useful in some rooms. 




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Regs
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  #828022 29-May-2013 21:32
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Slumlord: Anyone got some sound insight on home ventilation? Lots of companies out there, lots of sales talk. I am comparing Sayr and Smartvent. HRV seems to expensive and pushy. Wondered if anyone could help with separating the companies, if speaking from experience. Does a fancy controller really matter? Is it all about the number of thermostats? As far as I can see they all do the same thing. Thoughts, people? PS: Don't just tell me to open a window - thanks.


Why are you looking for a 'home ventilation' system in the first place?  I assume you have a moisture problem.  If you solve the moisture problem, do you still need a home ventilation system?

Where is the moisture coming from?
- portable gas heaters?
- drying clothes on racks indoors?
- poorly vented bathrooms or kitchens?

We used to have a moisture problem, it went away when we installed a gas central heating system.  It cost a little more than the HRV/DVS but we have a constant 21degC throughout the house in the colder months...

Why did the moisture problem go away?  Mainly because we stopped using the portable gas heaters.  We still dry clothes inside.






blackjack17
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  #828027 29-May-2013 21:42
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Regs:
Slumlord: Anyone got some sound insight on home ventilation? Lots of companies out there, lots of sales talk. I am comparing Sayr and Smartvent. HRV seems to expensive and pushy. Wondered if anyone could help with separating the companies, if speaking from experience. Does a fancy controller really matter? Is it all about the number of thermostats? As far as I can see they all do the same thing. Thoughts, people? PS: Don't just tell me to open a window - thanks.


Why are you looking for a 'home ventilation' system in the first place?  I assume you have a moisture problem.  If you solve the moisture problem, do you still need a home ventilation system?

Where is the moisture coming from?
- portable gas heaters?
- drying clothes on racks indoors?
- poorly vented bathrooms or kitchens?

We used to have a moisture problem, it went away when we installed a gas central heating system.  It cost a little more than the HRV/DVS but we have a constant 21degC throughout the house in the colder months...

Why did the moisture problem go away?  Mainly because we stopped using the portable gas heaters.  We still dry clothes inside.




We rarely dry clothes inside, we never use gas heaters, always shower with a window open, hell we almost never put the heat pump on and we have condensation on most windows every morning.

It is simply a case of very good insulation and poor insulation.  

we are looking at a ventilation system  




timmmay
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  #828104 30-May-2013 07:30
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A window generally isn't sufficient for a bathroom. Have an extraction fan installed directly above the shower - a decent powerful one from a bathroom firm, not a gutless whimpy light/fan combination that does next to nothing. I used to have TWO bunnings extraction fans above my shower, and they worked ok, but not as well as one really good powerful extractor that I have now.

Like I said earlier, retrofit double glazing reduced condensation to almost nothing for me, and cost about $5000 for the whole house.

I'm not convinced a ventilation system is the best solution to your stated problem. They have benefits, but also significant downsides - pumping cold air into a house, and cutting holes in your insulation.

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  #828116 30-May-2013 08:06
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Which company charges only 5k for retrofit double glaze for a wh ole house?




Involuntary autocorrect in operation on mobile device. Apologies in advance.


 
 
 
 


timmmay
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  #828122 30-May-2013 08:24
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joker97: Which company charges only 5k for retrofit double glaze for a wh ole house?


About 5 years ago I paid around $3K (from memory) for 2/3 of my house to Magnetite. The franchise owner at the time ripped a LOT of people off, left jobs not done, but the Australian parent company mostly made it right. I'm not even sure they're operating in NZ right now.

I presume other companies are in a similar ballpark, but I could be wrong. When I was getting quotes another company was cheaper.

shall0w
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  #828259 30-May-2013 13:12
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Ah a thread I can have some input on!

We have a basic (2 outlet) DVS installed in a 60's weatherboard house, underfloor and ceiling insulation and single glazed aluminium joinery. With it on the house is nice and dry, only the master bedroom showing some signs of condensation on the joinery (only south facing bedroom). With it off the house basically leaks water on every window.

I have noticed a cold draught from it at night in the lunge so am considering switching it off at nights..

Also - we have a rental (very similar ages / setup) which had bad condensation and mould issues. We had a moisture master installed, single vent in the hallway, and it has fixed that completely tenants are stoked.

So my thoughts are PPV systems = great for fixing moisture issues in your usual poorly insulated kiwi homes but need good heating to counter the cool air they bring in.

On double glazing - we had a 2 quotes both about $7k to retrofit our place (130 sqm, only 60% alu joinery) and $3k of that was just for the sliding doors off the lounge. We decided that as we needed new curtains and they cost an extortionate amount anyway we'd by good thick thermal curtains first and re-consider double glazing at a later date if they aren't up to the task.

Niel
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  #828403 30-May-2013 17:23
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Amosnz: I didn't read the whole thread but I self installed a SmartVent Synergy (balanced ventilation) into a 80's brick\ali house last year.  The ventilation side of things works great, 1 bedroom in particular used to get significant condensation but that has reduced to 0 after installation.

The only aspect of it I'm not totally happy with is the heat transfer. Our primary heat source is in the lounge (wood burner), and that room can get up to 28 deg with it cranking.  We have a reasonably long house and the further bedroom is 15m from the intake.  Based on my research\calculations the R0.8 ducting has a heat loss of 1 deg for every 3m, and the Synergy Heat Exchanger is ~75% efficient (not quite the 'up to 90%' they advertise). I have a 6m run to the heat exchanger, then a 9m run to the furthest bedroom.  This means the air temp going into the far bedroom is (28-2)*.75-3 = ~17degrees.  In practice this isn't enough to warm up that room.  The single biggest cause of heat loss in the run is the heat exchanger (~6deg for this example) vs 5deg for the ducting (which i could insulate further).  There is no way to bypass the heat exchanger and the air directly.

TLDR; Great for ventilation, not great for heat transfer.


Heat transfer only works with a concentrated heat source, draw air from as close to the heat source as you can instead of just ambient air.  If the fire place has a flue pipe through air, then put a shield around it and draw air from that.




You can never have enough Volvos!


Hammerer
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  #828443 30-May-2013 19:21
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Niel:
Heat transfer only works with a concentrated heat source, draw air from as close to the heat source as you can instead of just ambient air.  If the fire place has a flue pipe through air, then put a shield around it and draw air from that.


Excellent point. When I was considering ducting hot air around the house I talked to a local fan company and they made precisely that point.

Their general rule of thumb was that you should have a 12-14kW heat source (medium to large wood burner, large heat pump, large gas heater) before considering pumping heated air around the house. This allows for 3-4 kW of heating for the main room, a few for transfer losses and about half for warming/heating a few rooms.

Here's two calculators to give you an idea of the heat output required for a room:
  • Based on type of room, region of NZ, level of insulation and floor area: http://www.energywise.govt.nz/how-to-be-energy-efficient/your-house/heater-sizing-calculator
  • This calculator should be more accurate but it requires more info and doesn't account for regional conditions: http://www.consumer.org.nz/reports/woodburners/what-size-woodburner
In the end, we decided to neither ventilate or transfer heat as more insulation gave the best economic return. We have a steel roof so a thick ceiling blanket made a massive difference even with the existing Batts. It reduced the interior temperature in summer - no more sweaty nights - and raised it in winter by a few degrees with no heating.

Insulation, including putting our new curtains over our old calico curtains, and no longer airing clothes inside halved the window weeping but that problem still exists.

alvin
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  #884971 26-Aug-2013 21:01
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i've been reading this thread and other similar dvs/hrv/ventilation threads the past couple of weeks.   In terms of prices, could people with these systems give a ballpark figure of how much they paid for them.  I'm just interested to have an idea before I ask for quotes.

Thanks

timmmay
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  #884981 26-Aug-2013 21:25
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Cleanaire, $3500 or so, plus installation (I'll get a builder friend to do it when I get around to ordering it). Great specs, I found the mainstream brands are either inferior or more expensive when I did the research, plus their salesmen just plain lie.

mattwnz
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  #885011 26-Aug-2013 22:17
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The components to buy these things are reasonably cheap, so there are pretty big margins in them. My parents have a ventilation system in their house which they had installed for them years ago, and it is hopeless. Their house is big with lsome skillion roofs, and I think they really only suit houses with pitched roofs with a large roof space. Not to mention that in the winter they are often pumping in cold air from the roof space, often where the fibreglass insulation is. You can feel the coldness of the air coming in.

timmmay
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  #885095 27-Aug-2013 07:19
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mattwnz: The components to buy these things are reasonably cheap, so there are pretty big margins in them. My parents have a ventilation system in their house which they had installed for them years ago, and it is hopeless. Their house is big with lsome skillion roofs, and I think they really only suit houses with pitched roofs with a large roof space. Not to mention that in the winter they are often pumping in cold air from the roof space, often where the fibreglass insulation is. You can feel the coldness of the air coming in.


Read up on the system I posted about. It doesn't use air from the ceiling cavity, it uses fresh air, passes it through filters, and then warms it with the stale air it takes from the house - in summer it cools it if the air inside the house is cooler than outside. The idea is the air quality in the ceiling cavity isn't good, and stale (warm moist) air has heat that is recovered. You can put an input in the bathroom over the shower if you want to as well, though it won't be powerful enough to get rid of all the steam. It recovers 80% of the heat that it draws out.

You can also run them on a timer, or thermostat.

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