Positive Pressure Ventilation Systems 2022

Forums › Home Workshop DIY › Positive Pressure Ventilation Systems 2022

FineWine

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#298755 13-Jul-2022 17:31

Looking at previous Topic entries, now closed, they are all a bit old now. So asking the question again but for 2022 systems.

We live in a 105m/sq (139m/sq minus walk through garage) 2000 build, brick frontage and hardy sheet the rest, with single glazing aluminium windows and full length insul curtains. Fully insulated. Has a standard sized purlin-rafter roof space with pressed tin roof covering.

edit 1: concrete pad

edit 2: have heat pumps x 2: master bedroom & lounge-dining-kitchen

This winter has been the worse for crying windows and heavy damp air since purchase in 2015.

We have looked at (quoted) double glazing. Problem is the original Wellington based manufacture has gone and there is only one company in Tauranga that has the form work for our windows so there is no competition.

So we are getting in quotes for PPV systems; HRV, DVS & SmartVent.

5 diffuses for 3 bedrooms & 2 in combined lounge-dining-kitchen.

Not looking at summer, winter or balanced kit options.

What are forums member experience, opinions etc on todays PPV systems and companies or agents, please ??

Whilst the difficult we can do immediately, the impossible takes a bit longer. However, miracles you will have to wait for.

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#2941579 13-Jul-2022 18:11

I have a PPV system that I run a few hours a day, more of a home made one than commercial. It will help a bit with wet windows, but it won't come close to solving the problem. Even with good ventilation, ducted heating, and double glazing we still get a bit of water on the windows on the coldest days - but it's a light might whereas before it was enough to saturate a towel.

If you want to address the problem more I'd go for heat recovery - not HRV the brand, the technology - so you can run it more without just pumping cold air into the house.

tweake

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#2941614 13-Jul-2022 20:11

this is a bit of a pet project for me.

first thing is that its a ventilation not a heating or home drying system. however if your not ventilating the home properly it should fix your issue. i find the systems are much better than opening windows for ventilation. as mentioned balanced ventilation is better, but you need a fairly air tight house for it to work well and is somewhat more expensive.

first thing as you have a brick wall home is do you have wooden floors? (ie a crawl space under the floor). if so, even if its only part of the house, you will need to run an external air pickup point. air inlet in the ceiling will cause problems. also if you have crawl space, put down some vapor barrier. if its all concrete floor your fine.

i see a lot of crowds going down the path of sensors, so it runs when the air is dirty etc. pointless in my option because the system should always be running.

i find the more constant the ventilation is the better (which is why balanced works so well).

things to look for, EC fans. far cheaper to run than the old style fans. also automatic summer kit. very few do a proper summer kit. i think DVS is one of the few that does. there is a new one i saw recently but can't recall the name. i find its quite important because most of the time the fans turn off because the ceiling space gets to hot, even winter. so you get very little ventilation during the day and then night time in winter it cools down so much it stops. so it doesn't run enough.

tweake

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#2941617 13-Jul-2022 20:17

another feature which is a must have is easy filter changes. mates had HRV which was a major pain to change. also try to get something with a standard filter size or filter box that can take different sizes.

timmmay

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#2941619 13-Jul-2022 20:21

I don't take air from the ceiling, in my old house it's disgusting up there. Rat droppings, insulation, 80 years of dust. I pull fresh air in from under the eaves, through a HEPA and charcoal filter, then into the house. The output is beside the ducted heating system intake which spreads fresh air around the house.

Mattnzl

281 posts

Ultimate Geek

#2941622 13-Jul-2022 20:29

80's brick/tin house with PPV system.

While it does have it uses and is worthwhile for my house, the problem is that a lot of NZ is just DAMP at this time of year.

The last few weeks have been fairly typical where I live: on/off rain, high humidity, mild temperatures. It doesn't really get cold enough to dry out the air like other colder countries get (where they actually need Humidifiers to add moisture to the air because it is so dry).

The result is that the "fresh" air from outside that the PPV is pumping in is often just as moisture laden as the air in the house. I still leave it running because it is useful for ventilating the house, providing a little extra heat on a sunny day, but as far as removing moisture goes - at this time of year it's a fail. Spring/autumn it works better, and summer quite handy for cooling the house down at night.

tweake

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#2941634 13-Jul-2022 20:48

Mattnzl:

80's brick/tin house with PPV system.

While it does have it uses and is worthwhile for my house, the problem is that a lot of NZ is just DAMP at this time of year.

The last few weeks have been fairly typical where I live: on/off rain, high humidity, mild temperatures. It doesn't really get cold enough to dry out the air like other colder countries get (where they actually need Humidifiers to add moisture to the air because it is so dry).

The result is that the "fresh" air from outside that the PPV is pumping in is often just as moisture laden as the air in the house. I still leave it running because it is useful for ventilating the house, providing a little extra heat on a sunny day, but as far as removing moisture goes - at this time of year it's a fail. Spring/autumn it works better, and summer quite handy for cooling the house down at night.

where do you live ???

while it is damp, more importantly its cold enough for heating (even here in northland) which is what lowers the inside humidity. for me 50-70% humidity inside. spring/autumn tends to be worse because its not cold enough for heating or hot enough for aircon, so +80% humidity inside is pretty common. one of the big problems with nz housing is people not heating homes properly. heat moves moisture and lack of heat gives cold surfaces for moisture to condensate on.

mattenz

190 posts

Master Geek

#2941810 14-Jul-2022 13:13

I've never read a convincing argument that PPV roofspace air is better than a heat exchanger for older homes.

Agree regarding the outside humidity being too high, 70% is pretty much universally considered unhealthy, realistically you should be down under 60%, and around 50%. To get my outside air (in Waitākere) to that right now only via heating, I'd need to get it to 26°, which doesn't seem very realistic for the whole house (and of course, I'd have to prevent other sources of water from evaporating).

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tweake

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#2941821 14-Jul-2022 13:37

mattenz:

I've never read a convincing argument that PPV roofspace air is better than a heat exchanger for older homes.

Agree regarding the outside humidity being too high, 70% is pretty much universally considered unhealthy, realistically you should be down under 60%, and around 50%. To get my outside air (in Waitākere) to that right now only via heating, I'd need to get it to 26°, which doesn't seem very realistic for the whole house (and of course, I'd have to prevent other sources of water from evaporating).

there is some articles on it. basically there is not much point having a balanced ventilation system when you have as much, or more, natural ventilation through the enclosure than you have through the ventilation system. ie there is a much, or more, air bypassing the unit than there is going through it. kinda defeats the point especially when cost comes into it.

afaik the cross over point is 5ach @50 to make it worth while.

the reality is your not really going to get humidity down to healthy levels via heating, tho today its +90% outside and 56% inside (northland). the main thing we try to do is keep it below 80% where mold starts to grow. that becomes somewhat problematic when its to warm to heat and to cool to aircon. so for the rest of the year inside humidity can be over 80% easily.

the winter mold problems (mostly in auckland/northland) come from lack of heating to keep humidity level down, which allows moist air to hit cold walls.

mattenz

190 posts

Master Geek

#2941823 14-Jul-2022 13:41

tweake:

mattenz:

I've never read a convincing argument that PPV roofspace air is better than a heat exchanger for older homes.

Agree regarding the outside humidity being too high, 70% is pretty much universally considered unhealthy, realistically you should be down under 60%, and around 50%. To get my outside air (in Waitākere) to that right now only via heating, I'd need to get it to 26°, which doesn't seem very realistic for the whole house (and of course, I'd have to prevent other sources of water from evaporating).

there is some articles on it. basically there is not much point having a balanced ventilation system when you have as much, or more, natural ventilation through the enclosure than you have through the ventilation system. ie there is a much, or more, air bypassing the unit than there is going through it. kinda defeats the point especially when cost comes into it.

afaik the cross over point is 5ach @50 to make it worth while.

Then a PPV fan is just pushing your conditioned air out, replacing it with unconditioned roofspace air, which pretty quickly becomes just outside air. May as well preheat it with the air that you've heated.

kobiak

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#2941826 14-Jul-2022 13:55

I used these guys https://www.bettervent.co.nz/ 3 years ago in AKL. They used to be way cheaper. They installed 3 outlets (installed on 3rd level bedrooms and hallway) in my 3 level townhouse (bricks and hard plastic boards, fully insulated on concrete slab with single glazed aluminium windows). I used to have running windows - I'm on 3rd winter now and don't have that issues anymore. I'd say my home never was too humid and it's less humid now.

They used arduino clone board with 12" fan with sock-on-type filter. Fully automated system (plug-in and forget. It automatically adjust air flow, there's temp sensor on the board for that reason?). A friend of mine living in the same type townhouse installed it last winter and it's different control device and box type filter.

I planned to install something smarter using the existing air vents, but never did. System is super efficient and meets all my needs anyway.

helping others at evgenyk.nz

tweake

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#2941828 14-Jul-2022 14:06

mattenz:

Then a PPV fan is just pushing your conditioned air out, replacing it with unconditioned roofspace air, which pretty quickly becomes just outside air. May as well preheat it with the air that you've heated.

your missing the point.

why bother preheating it when there is as much if not more non-preheated outdoor air coming in anyway. your only preheating a small amount of total airflow. its rather expensive equipment for very small gain.

same applies to PPV on 100 year old homes that have massive amount of wind blowing through them already.

tweake

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#2941832 14-Jul-2022 14:13

kobiak:

I used these guys https://www.bettervent.co.nz/ 3 years ago in AKL. They used to be way cheaper. They installed 3 outlets (installed on 3rd level bedrooms and hallway) in my 3 level townhouse (bricks and hard plastic boards, fully insulated on concrete slab with single glazed aluminium windows). I used to have running windows - I'm on 3rd winter now and don't have that issues anymore. I'd say my home never was too humid and it's less humid now.

They used arduino clone board with 12" fan with sock-on-type filter. Fully automated system (plug-in and forget. It automatically adjust air flow, there's temp sensor on the board for that reason?). A friend of mine living in the same type townhouse installed it last winter and it's different control device and box type filter.

I planned to install something smarter using the existing air vents, but never did. System is super efficient and meets all my needs anyway.

do you have any pics of that setup?

as per usual most crowds do not advertise what their system is, so its impossible to judge if its good or not without finding someone with one.

i'm a little wary of no control panel because most need a temp sensor inside the house. however there are a few "landlord" models around. i tend to like ones with simple controls because people tend to screw with the adjustments.

i'm not a fan of dual outlets. it makes it harder to balance well. a mate has that issue with his sayr system.

MikeAqua

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#2941833 14-Jul-2022 14:15

We put a balanced ventilation system in a ~60 year old building, including and Air-Air heat exchanger. It made a huge positive difference, made the house much more liveable.

A PPV system, I wouldn't touch with a 20 foot pole.

Mike

scuwp

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#2941843 14-Jul-2022 14:34

Love our Smart Vent system. Solved our condensation problem overnight. I wouldn't live in a house without some sort of system installed now. Just a small side-note, don't get sucked into the "positive pressure" sales pitch, they are just a fan in a box that blows air, with some smarts added. We went Smart Vent because it was cheaper, wasn't locked in to any service or maintenance, and could even install ourselves. Filters are $90 from Bunnings and take about 2 minutes to replace. We get about a year out of a filter depending on the fan speed.

Lazy is such an ugly word, I prefer to call it selective participation

mattenz

190 posts

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#2941847 14-Jul-2022 14:36

tweake:

mattenz:

Then a PPV fan is just pushing your conditioned air out, replacing it with unconditioned roofspace air, which pretty quickly becomes just outside air. May as well preheat it with the air that you've heated.

your missing the point.

why bother preheating it when there is as much if not more non-preheated outdoor air coming in anyway. your only preheating a small amount of total airflow. its rather expensive equipment for very small gain.

same applies to PPV on 100 year old homes that have massive amount of wind blowing through them already.

True, but that doesn't really answer my original question of why received wisdom indicates that you need to prefer PPV in an old house, you're just saying that they're both equally useless.

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