DIY - build your own ventilation system

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19 posts

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#1894676 3-Nov-2017 11:37

To sum up everything: the system is up and running for about half a year.
I really like the result. During the coldest days we had just a few centimeters of fog (not even water) on windows in the bedroom in the morning. All windows are clear: no water, no mold.

Almost everything was bought at the company "Smooth Air". They have all their catalog on the website with prices. I bought there: fan, heater, filters, ducting, joiners. Diffusers were from a different shop (a lot cheaper and the color we liked), air valves I got at Aliexpress.

Total price was arount $1,800 (incl GST).

I've created a module to read the temperature and humidity in the attic space, after the fan and heater inside the duct. It also controls fan speed, opens and closes air valves (to be able to control the direction of the airflow and to blow to specific rooms only).

As I can do everything with the system - I've created a few complex schedules to keep it in the way my family likes it.

deanos

18 posts

Geek

#1938374 13-Jan-2018 20:54

I would pay a bit more initially and 'go the whole hog' as you won't be disappointed by the efficiency and effectiveness of a heat exchanger. All up I paid about $4500 for my Smartvent system (DIY install) which included a inline heater plus another $500 to get some power points installed in the roof.

As with mine, I assume some heat exchangers are likely to be supplied as two or three parts so can be reassembled in the roof if your access point is limited. Would be worth checking out anyway.

As another person has said, I agree your house doesn't have to be airtight to reap the benefits of a balanced system. I have a 3 bedroom 1950's ex-state house and my balanced system has certainly reduced the crying windows, and I get to reused the heat energy in the house.

There are basic kits available in Bunnings or electrical wholesalers, but beware as you may need to put the system dead centre in the roof and have the outlets nearby due to the bare essential amount of ducting supplied. However, if you are like me and don't like ANY humming sound at night, then you may need to place away from the bedrooms which in my case required quite a bit more insulated ducting which isn't cheap.

I have the Synergy Evolve 190e which is the entry level polypropylene cased exchanger. If I was to install another system I would get a metal bodied exchanger. This is because the Smartvent 190e exchanger is difficult to open (at least once a year to clean) plus it has a condensate drain hole which Smartvent have pre-drilled in a stupid place as it is in a thin part of the polypropylene case so is not ideal if you need to disengage the drain fitting and keep a good seal over time. Also, if you are installing the unit in a vertical position the hole is not at the lowest point which isn't ideal as you can get some air lock noise.

The inline heater even at 2Kw will still only be tempering not heating. I have a 1Kw and given the capital cost of the thing I wish I had never purchased it! There is plenty of heat loss not least through the metal case which is a waste.

Hope this helps in giving you a heads up with the possible pros and cons of Smartvent, but also issues to be aware of for any installation.

jonherries

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#1938478 14-Jan-2018 09:53

Have a few questions about your balance air system:

- do you have a kitchen extractor and/or bathroom extractor as a part of the system?
- who did you buy the smart vent system from and if you don’t mind what was the price of the exchanger itself (I already have a positive pressure system).

Thanks

Jon

deanos

18 posts

Geek

#1938500 14-Jan-2018 11:34

From memory when I researched ventilation systems it was not recommended to extract from bathroom or kitchen with an HRV. In any case my kitchen has a rangehood and the bathroom has an extractor fan which is faster.
Not sure if you can just buy the heat exchanger by itself but if you ring Smartvent/Simx customer support they will be able to tell you and give you a code. If you are going from a positive pressure to balanced you will need an extra fan for the extract side of things. In the case of Smartvent these are not in their catalogue and have a special code as they have a backward curved blade which is quieter than their normal extractor fans. That's were things get a bit tricky because they are high quality 3 speed fans designed for their controller...

Electrical wholesalers like Advance or Corys don't generally stock but will order in as a cash sales.

Stan

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#1938699 14-Jan-2018 17:59

Go to an electrical wholesaler and buy a Smartvent SV04 if you want something ready made they pay around $1150+GST per unit no idea what there wholesale rate is.

jonherries

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#1938703 14-Jan-2018 18:07

Thanks @Deanos, we also have gas hot air central heating so we have two separate unconnected sets of ducts in the ceiling. Think it would be good to see if they can be integrated - have a guy coming to look at the gas in a week or so. Guessing the gas could be connected but unsure where in the cycle would be most effective?

Jon

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itlearner

19 posts

Geek

#1951340 4-Feb-2018 13:13

Hi all, had done some research and had read a lot of posts, still frustrated to find what type of ventilation system that could suit a 1940's old house.
The old house was built with brick and tiles. It has 3 bedrooms (2 of them are locate at south side), open living area, air-con in living room, and kitchen has rangehood, bathroom has extractor. It has celling and underfloor insulation. The house is hot in summer, wet in rainy day, and windows were crying in the morning in winter. SO would like to install a basic ventilation system to change theses. Hople the system will do the following:
1. get fresh air from outside not from roof space.
2. circulate the air between livin room and bedrooms.
3. switch between above 1 and 2.
4. switch the system on/off.
Have thinking of Sayr/Smart Vent, but not sure they are worth. Any suggestions please.

Aredwood

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#1951447 4-Feb-2018 15:48

@itlearner why do you want to circulate between the lounge and bedrooms?

What heating do you currently have in the bedrooms? And is it capable of maintaining a set temperature?

And does leaving the windows open get rid of the moisture? As a ventilation system will only work if you have a damp inside but dry outside problem. If the outside is also damp, a ventilation system will be a waste of time.

deanos

18 posts

Geek

#1951530 4-Feb-2018 18:01

Aredwood: @itlearner why do you want to circulate between the lounge and bedrooms?

What heating do you currently have in the bedrooms? And is it capable of maintaining a set temperature?

And does leaving the windows open get rid of the moisture? As a ventilation system will only work if you have a damp inside but dry outside problem. If the outside is also damp, a ventilation system will be a waste of time.

Not quite true. If you have a positive pressure system the intake in the roof would generally be dryer during the daytime. If you have a balanced system (heat exchanger), the temperature differencial between inside and out has a dehumidifying effect at the core

itlearner

19 posts

Geek

#1951539 4-Feb-2018 18:25

@Aredwood, want to circulate between the lounge and bedrooms because dont want to get fresh air from outside in rainy days. Dont have heating in bedrooms, but sometimes using a oil heater in winter.

itlearner

19 posts

Geek

#1951542 4-Feb-2018 18:35

@deanos, the air in the roof space is not good, hot in summer, cold in winter, damp/wet in rainy days. So dont want positive pressure system that intake in the roof.

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Starina

19 posts

Geek
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#1951577 4-Feb-2018 19:40

itlearner: @Aredwood, want to circulate between the lounge and bedrooms because dont want to get fresh air from outside in rainy days. Dont have heating in bedrooms, but sometimes using a oil heater in winter.

itlearner: @deanos, the air in the roof space is not good, hot in summer, cold in winter, damp/wet in rainy days. So dont want positive pressure system that intake in the roof.

From the ventilation point of view a better air is the air if it has less moisture in it.

1. During summer you usually don't need a ventilation system as the air is hot outside, not much moisture in it, and opening windows during the day and night is enough to keep the house dry. So, you need the intake from outside only if you want to cool your hot house during summer.

2. If you have any people in your house (not zombies), they tend to breath. When they breath - they produce a lot of moisture. You need to get rid of this moisture. So, even during the winter you need to get a drier air from the outside and blow it into your house. It's much easier to heat a drier air.

So, even if you think that conditions are not good outside, you need your ventilation running all the time. It's primary goal is to make your house drier. Heating and cooling are secondary and it will be better if you use a heatpump for it.

itlearner

19 posts

Geek

#1951602 4-Feb-2018 21:22

@Starina, got heatpulm and gas heater in the living area. So as long as isnt rainy day, fresh air from outside is fine, but if it's rainy day, prefer circulating the air between livin room and bedrooms, as the south side 2 bedrooms ard ready damp. 1 of them even more worse as nobody liveing in, at the moment (summer time) has a mini-dehumififier on 24/7, every few days got half of liter water, very frustrated.

jonherries

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#1951615 4-Feb-2018 21:48

itlearner: @Starina, got heatpulm and gas heater in the living area. So as long as isnt rainy day, fresh air from outside is fine, but if it's rainy day, prefer circulating the air between livin room and bedrooms, as the south side 2 bedrooms ard ready damp. 1 of them even more worse as nobody liveing in, at the moment (summer time) has a mini-dehumififier on 24/7, every few days got half of liter water, very frustrated.

One of the things to keep in mind with a gas heater if it isn’t flued (doesn’t have a chimney) is that burning gas creates h2o and co2. So while it makes heat it can make the house really damp... this often means that if it is raining it can still be more humid inside.

Jon

Aredwood

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#1951663 5-Feb-2018 00:30

deanos: Not quite true. If you have a positive pressure system the intake in the roof would generally be dryer during the daytime. If you have a balanced system (heat exchanger), the temperature differencial between inside and out has a dehumidifying effect at the core

How does the roof space remove moisture from the air? I get that if you heat air up, the relative humidity goes down, due to warm air being able to hold more moisture than cold air. So if there is warmth in the roof space, that can have a drying effect.

And how does the heat exchanger remove humidity? Apart from warming the incoming air?

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