Hi. I am new at this forum and, I am afraid, not as experienced as many of the current members. I hope to receive your thoughts on the 'passive' heating system supplied by a Sydney company called Ventis. There are probably other similar systems, but this is the one I came across recently at Better Homes and Gardens Show. As far as I understand the way it works is that the warmer air inside the roof cavity is sucked in by a centrifugal variable speed fan and then pumped into the rooms below through series of ducted ceiling vents. The system has a control unit that shows the temperature inside the roof cavity (e.g. 25 degrees Centigrade) and allows to choose a desired temperature for the living areas below (e.g. 20 degrees). Once the desired temp is reached, the fan would stop working. The company rep was selling it as a very efficient and simple system. But would it really be efficient for heating in my house? My house is a typical Sydney 1920-s double brick bungalow. High ceilings. Windows are not energy efficient. The house is very cold in winter. Temperature in the morning is normally 15 degrees. The front bedroom is facing south and is even colder than the rest of the house. It even gets some mould inside the built-in robe and a lot of condensation on the window. We bought the house a year ago and are slowly bringing it to a more liveable stage. Would it make sense to install this Ventis system for the entire house (the approx cost apparently 3-4K), or shall we just I replace the main bedroom window to a double glazed UPVC and get a gas heater in the living area?Can't afford both things at once. Any advise? Thank you!
Efficiency of Ventis ventilation system for heating
(16 posts) (9 voices)-
InnerWestie
MemberPosted Saturday 15 Sep 2012 @ 11:07:21 am from IP # -
alfresco24
MemberAn architect I know is now specifying this kind of tech in most of his projects. Having seen several examples of finished systems the feedback has been very positive. However the price you stated seems quite high. Is yours for like 4 or 5 inlets/outlets, or a complicated installation?
The tech is very simple so no need for gold plated components or complex control system.Posted Saturday 15 Sep 2012 @ 11:48:22 am from IP # -
ghostgum
MemberHave a read of forum topics with the tag "solar air heater", by clicking on the link near the start of this topic.
There are several suppliers of systems like this (Ventis, Solectair, HRV). I would prefer to take air from a solar air collector above the roof (Solarventi, Solamate, or make your own), than collect air from the roof cavity.
Effectiveness depends on your roof. For my light coloured colorbond roof with RFL underneath in Melbourne it would be waste of money. A dark colorbond roof, and drawing air from between the roof and RFL would work a lot better.
The money might be better spent on upgrading the insulation in the house or secondary glazing on some windows.
Posted Saturday 15 Sep 2012 @ 12:05:40 pm from IP # -
InnerWestie
MemberThanks Alfresco. The price was quoted to me was a very general ballpark for a 3 bedroom house. I would be very interested to find out of any other companies who might provide similar services to compare apples with apples.
Posted Saturday 15 Sep 2012 @ 12:06:27 pm from IP # -
Jeffbloggs
MemberWestie
What is the construction and colour of your roof? A dark roof will heat up during the day, but significantly cool at night. In the winter it will not heat at night at all and you will still need another heat source. Have you thought of installing a reverse cycle inverter air conditioner instead? Samsung sell a 8kW one for under $1000. In general, in the winter period you always need to add more energy than is available from the heat collected by the roof, so an alternative energy source is required aka gas/electricity. A heat pump (air-con) is inexpensive, has a fast response, easy to install, and will nearly always perform (so long you have power). It also uses 1/3 of the power in comparison to normal electric heaters.Posted Monday 17 Sep 2012 @ 5:56:06 am from IP # -
Jeffbloggs
MemberFireflies
Get it here and pay cash $1000: http://www.thegoodguys.com.au/warners_bay/Samsung_6.8KW_Cooling_8.0KW_Heating_Reverse_Cycle_Inverter_Split_System_AQV24NSGNWhen I bought 3x and then 4x at a later date we got a $200 pre paid visa for each from Samsung as well...so $800 each effectively after 6 weeks of waiting for the refunds!
Posted Monday 17 Sep 2012 @ 8:11:39 am from IP # -
Jeffbloggs
MemberWell the thread specifically asked for advice on cost effective heating, the Ventis ventilation system only partially fulfils that goal in my opinion, hence my recommendation to pursue the reverse cycle option instead. Very much in line with the subject in the thread, provided you accept my opinion as a valuable contribution...
Posted Monday 17 Sep 2012 @ 8:21:28 am from IP # -
InnerWestie
MemberThanks all for your posts. I have been reading the old posts about the air solar heaters. My conclusion so far is that the DIY options discussed on this forum are way above what I could do. The companies like Ventis or (more efficient) Solarventi would probably be quiet expensive. I am going to get some quotes in the next couple of months though.
JeffBlogs, thank you very much for your tips. The roof on my house is red tile. The tiles are laid directly over the roof joists (no insulation between them). We bought the house a bit over a year ago. The first night we spent here was absolutely freezing, the temp inside was 12 degrees. We bought the inverter aircon and installed it in the main living area. That helps a lot with getting the living area fairly comfortable, but only whilst the aircon is operating. The main bedroom though remains very cold. I have a feeling that the cheapest and most efficient option for me would be installing a gas heater. Obviously I won't be able to install it an the bedroom. So I am thinking of having a gas bayonet in the entrance hallway (the bedrooms are off the hallway) and ceiling fans in the bedrooms that could hopefully (?) move the warm air along.
Thanks again to all.Posted Sunday 23 Sep 2012 @ 12:03:47 pm from IP # -
Benny
Member"I have a feeling that the cheapest and most efficient option for me would be installing a gas heater."
Westie - have you done the maths on cost to verify this ? Here in WA this is not correct. Gas is 12c/unit and assuming a 100% efficent burn (ie unflued heater) the heat costs 12c/unit.
Electricity is 25c/unit but a good rev cycle aircon should have a COP of at least 4, so the heat output will cost 25/4 = 6.25c/unit.
If you can only afford 1 air con unit have you considered getting a heat transfer system - ie fan, ducting and 2 ceiling vents, to move warm air from 1 room to another - I heard a certain hardware store has them at $90.
As someone else mentioned, you can also elect to buy Green/natural power to offset at least some of the emissions from your electricity use.Posted Monday 24 Sep 2012 @ 2:29:35 am from IP # -
InnerWestie
MemberBenny. Good point. Thanks to your suggestion I spent a while talking to my energy provider to find out the price for electricity and gas consumption. That actually resulted in getting an extra 8% discount on my energy bill for the next 12 months! It appeares that we pay approx 50% of our bill on the peak tariff of approx. 27 c/KWH and another 50% on the off-peak tariff of approx 9 c/KWH. We don't have gas connection at the moment, although it is readily available on our street. The gas cost is approx 3c/MJ. Gas seems to be so much cheaper! I realise that I will be up for one-off connection cost, and for one-off gas fitters cost. So I will continue with the sums for now...
As to your suggestion about a heat transfer system, I can't imagine doing it as DYI. Plus the area my existing aircon heats in winter would only get to 18-19degrees after couple of hours (at least) of work. If I was to transfer this meager heat to the main bedroom, wouldn't
It get lost on the way?Posted Monday 24 Sep 2012 @ 5:18:00 am from IP # -
dbindoff
MemberAt 3c/Mj the thermal energy cost is 10.8c /kwh (3.6*3 to convert from Mj to Kwh), so thermal energy cost is higher for gas compared to the output from a heat pump with COP 4. (60% more in your case at 27c/kwh)
We have a heating tariff in Tassie around 16c, so far cheaper in this case.
Posted Monday 24 Sep 2012 @ 5:47:07 am from IP # -
Benny
MemberWestie - yes - if your current aircon can only just manage to get the main area to 18-19C then it won't have enough capacity to transfer any heat to the bedroom as well. The heat shouldn't get "lost" in the transfer as the ducting is insulated - just that it will reduce the temp in the main area.
If you were considering getting a higher capacity aircon to do both rooms, check the CofP - as has been shown in other threads the COP often decreases as the capacity of the unit increases and it may be better to get 2 smaller units - then they can be independently controlled too.
Bedroom heating requirements are often different to living areas. Thats why the heat transfer method can be useful - an hour before you go to bed suck the heat from the living area to the bedroom and don't put in any more heat.Posted Wednesday 26 Sep 2012 @ 2:00:56 am from IP # -
Hi Everyone,
Dave Kennedy, Founder of the Solar Thermal Association (STA). I am glad that there is discussion around alternatives to Articificial heating, cooling and ventilation occurring. I have attended ATA meetings in both Melbourne and Sydney (as a guest speaker). I'd encourage everyone to investigate the multitude of options available on the market. None of the products in the STA claim to replace traditional artificial heating and cooling but rather reduce the need on their reliance by anywhere from 30-50%. It's certainly possible to cobble together a rudimentary solar thermal air heating and cooling system using a cheap inefficient fan, and a some ducting. Speaking from experience, a sturdy, reliable, quiet, robust, energy efficient system, with great filtration and customer care back up delivering customer expectations requires considerable investment in development, testing and reinvestment in fine tuning.All of the STA members offer fantastic products, and they should be standard in every home in my opinion. Decide what you are trying to achieve. If its energy delivered into a house, then it's simple: Delta T x airflow. If quality of air is of concern then level of filtration should be considered. The type of Fan is critical no matter what what system. Fan Noise is another. Components at each stage is also important, not to mention the control system (which varies greatly). Each member of the STA has a different product to offer, and one thing is common through out- first question when listening to a self proclaimed expert is 'do you live with such a system?' If not- pass, hypothetical experts are simply not (as) credible.
Posted Monday 4 Feb 2013 @ 10:36:10 am from IP # -
TonyT
MemberThe cents/kWh costs of energy for fire-wood, gas, electricity ... are compared in a Chart posted at
http://www.ata.org.au/forums/topic/6704#post-38041Posted Monday 4 Feb 2013 @ 7:15:02 pm from IP #
