Need your advice - please help! « Alternative Technology Assn Forums

Alternative Technology Assn Forums » General

Need your advice - please help!

(32 posts) (12 voices)

Started 1 year ago by peta
Latest reply from peta

Tags:

No tags yet.

12 Next »

peta
Member

Have 2 young boys and we are a family of 4 living in Manly Queensland (SEQ).
Have natural piped gas costing me $146.00/qtr in hot water heating only. CRAZY!
Have an old Dux hot water system that runs out after 1 shower of 5 mins and is positioned at the opposite end of the house to the hot water taps. WHY?!!
Have an old lowset brick veneer house with gabel Decramastic roof facing NE and openings positioned so we miss out on most of the summer NE/SE breezes. GRRR!!
Have an aircon which is on at 8am in the morning when the temp is going to hit 30deg.
Have a home/office which is the hottest room facing W - I usually close this room of as it is sooooo increadibly hot ! Has NNW facing windows that I can get some of the Northerly breezes, and a double sliding door on the SW side.
We built in this room from the garage and although our intentions were right we unfortunately put the wall insulation around the wrong way so that it actually conducts the heat from the brickwork. (I've since found this out by reading your postings).
Have reflective batts in ceiling : for which I don't think really works that well.
http://www.qis.com.au/insulation-solutions/reflective-batts/

Have had quotes to replace current roof with Colourbond (light colour), with the whole house needing re-battening and Permastop (builders blanket), with new gutters and downpipes = 17K. AAARRRGGGHHHH !!! Before I even get to solar.

1. Does anyone know of a good roofer that will do this kind of work.
2. What is the difference between Permastop and Anticon if anything - or should I be looking at something else.
3. What is the preferred thickness / R rating should I be looking at for our location if using sisalation.
4. What kind of solar panels should I be considering for my location - I tried to understand the differences but unfortunately it just confused me more and spoke alot about frost, for which we will never get - but we would get hail.
5. What's better glass lined or stainless steel tanks - does hail affect a thermosiphon tank or evacuated tube?
6. Spit system vs thermosiphon - will my new re-battened roof take the tank?
7. What kind of inverter do I need for a 4KW grid connected system.
8. Is there a point to getting both solar hot water and a grid connected system?, or should I just aim for Solar power and use an electric hot water system?
9. Whirly birds vs vents in each end of the gabel SSE and NNW ? I'm hearing conficting stories depending on who I talk to.

I really have tried to do as much research as I can so as not to post stupid questions, in reading your contributions to other postings there are some very cluey people out there and I really need some assistance.

Posted Tuesday 17 Aug 2010 @ 1:18:48 am from IP #
LanceTurner
Key Master

Wow, that's a lot of questions, I will have to be brief, am sure other forum users will elaborate later.

1) I have no idea, but any roofer you find, ask to talk to a previous customer or three, see what their opinion is of the work done. Not always easy, but worth persuing.

2) I have no idea, anyone else got experience in this?

3) Foil insulation is just one part of the equation, you need bulk insulation as well. My preferred is polyester batts.

4) If you mean solar water heating, then in your area anything will work well. Evacuated tubes are really only advantageous in colder, cloudier climes like Melbourne. All approved systems have passed the standard hail test (ie a 25mm steel ball dropped from 1 metre)

5) Stainless steel or copper. Glass lined tanks have a sacrificial anode that has to be replaced regularly to ensure the warranty isn't invalidated. Most people never do this. Stainless tanks only need protection if your water is really low in quality with lots of salt/chlorine.

Big enough hail can damage anything, if you live in an area that sees really bad hail, a flate plate system is probably best. The type of system (ie thermosyphon or split) doesn't have an effect on the type of collector used (other than market availability). You can use both types of collectors in both systems.

6) I hate split systems, they look nice, but there are greater heat loses due to the pipe runs between the tank and collectors. There's also the problem of pump/controller failure, we have been hearing of heaps of split systems lately needing new pumps after less than 3 years, not really giving solar hot water a good name with the general public. With all systems, keep it as simple as possible. It doesn't get any simpler than thermosyphon systems.

7) Whatever you want. It has to be a grid interactive inverter of course, but there are quite a few of those, check out the inverter buyers guide from ReNew (can't recall which issue, sorry).

Grid connect solar (PV) is the last thing you do on a house. Before that you should have done solar hot water, insulation, draught proofing, shading, energy efficient lights and appliances, water efficient fittings and appliances etc etc. All of those things have a better return than PV generally. And think of it this way. What's the point of spending thousands of $ on a PV system when most of the energy it produces is wasted on inefficient lights and appliances?

9) You need forced air cooling, such as mains powered or solar powered fans. Rotary vents don't cut it, you need to replace all the air in your roof every 5-10 mins to keep roof temps down, a whirlybird or 3 simply won't do that, nor will any passive vents. Further, the hottest days can often be the stillest. The simplest solution is a decent thermostatically controlled AC fan with a switch in the home to override it in winter. Same goes for a solar fan, just connect a suitably sized panel to a decent DC fan (big computer fans, the 170mm and larger sizes can move huge amounts of air if you group them together) and the fans will run hardest when the sun is shining strongest. Of course, you can't extract air if fresh air can't get in to replace it, so you need eave vents on the opposite end of the roof so that you get airflows right across the whole length of the roof cavity.

But no matter what you use, do the calcs first, work out the volume of the roof cavity and buy a fan that can move that volume every 5 mins. Fan ratings assume no pressure on the fan outlet, so anywhere you have ducting and vent caps which produce some flow restriction you will reduce airflow. When it comes to cooling a roof, the more airflow the better, don't undersize it, it simply won't work.

Anyway, hopefully that will be useful info, just ask if you need more. It sounds like your house is a bit of a nightmare design wise, those issues need to be fixed first to reduce your energy bills, forget about PVs etc for the moment. Oh, and if it is full of halogen downlights like most houses nowadays, get rid of the suckers, they are a big part of the prob...

Posted Tuesday 17 Aug 2010 @ 1:48:28 am from IP #
peta
Member

THANKS that's absolutely great Lance !!!!!!
I knew I came to the right place

Oh and we have compact fluro down lights ;). why heat up the house anymore than already - and I checked with the local firies as to what they preferred.

... I'm trying to head in the right direction.

Where would I put the fans - in the ceiling or the end of the gabel?

Posted Tuesday 17 Aug 2010 @ 1:59:35 am from IP #
dave lawrence
Member

Re ; 2. What is the difference between Permastop and Anticon if anything - or should I be looking at something else. they are two different trade names for essentially the same product, that is reflective foil laminate coupled with bulk insulation.
if considering re roofing the house with colourbond make sure current tiedown details are specified and costed.

Posted Tuesday 17 Aug 2010 @ 2:20:18 am from IP #
peta
Member

Hi Dave - unsure what you mean re making sure current tiedown details are specified and costed. The roof is currently tied down, are you saying this may need to change?

Posted Tuesday 17 Aug 2010 @ 2:37:20 am from IP #
Tony C
Member

Hi Peta, it sounds like you need to do a lot more than a new roof, but before you do the roof you should determine if there is anything else that needs doing at the same time (wider eaves, external shade etc). No point in doing things twice.

The main problem for we QLDers is excessive heat in summer. It is more efficient, and cheaper, to prevent the house from heating up than to cool it afterwards, so external shading could be beneficial to you. Are your eaves wide enough to stop the brickwork getting direct sun in summer? If not then I would be looking into that. When I am doing Green Loans assessments it is something that I always bring up but not many homes have the right shading.

Solarventi do a nice solar powered extractor fan called 'solar whiz' which can have a thermostat connected.

Before you get solar hot water or PV systems you should get a costing analisys done to work out your payback period for each one. From my experience PV has a quicker payback period. Having said that, it appears you need to do something with your current HWS, and soon.

If it were my house I would get someone that knows what they are doing to work out a list of options, in order of effectiveness, then you can work out what fits in your budget.

Good luck,

Tony
(gold coast)

Posted Tuesday 17 Aug 2010 @ 3:22:36 am from IP #
dave lawrence
Member

if roof tied down already no worries. agree with above post re : widening eaves . i often recommend this especially if work being considered on repairs to roof.
extent of widening depends partly on roof pitch especially on low set houses.
also consider appropriate plantings to help overshadow western facade if room permits.

Posted Tuesday 17 Aug 2010 @ 3:47:45 am from IP #
peta
Member

Hi Tony, thanks for that. We did have a beautiful 4 story tall Chinese Elm that we had to cut down that shaded us beautifully in summer, but it was ripping up next doors paths and house stumps, this will be our first year without it - and I'm scared !

I didn't think of wider eaves, that would have to be considered if/when re-foofing as I'm not sure how to go about it otherwise.

Currently we're using $275.00av/qtr electricity and $ 150.00/qtr gas.

For a 340L Edwards thermosiphon all Aust made panels and S/S tank = $4520 and at a conservative 3% increase in gas costs per year it will take 7yrs - the boys will be 8 and 10.
A 3KW PV system worth $10347 from Ingenero (material sourcing unconfirmed) grid connected @ 3% increase per year also = payback 9.5yrs and a 4kw system = probably under 15.

I've got my plumber coming around to let me know what I can and cannot efficiently do as per his opinion. But yes this hot water system just has to go - it costs me $65/qtr to have the gas piped to the house. I'm not eligable for any rebates 'cause I'm already on gas, the only thing I can use are the REC's.

mmmmm Solarwhiz hey ?

Posted Tuesday 17 Aug 2010 @ 4:14:24 am from IP #
peta
Member

Hi Dave, I see your a drafter - would I need plans drawn up to increase eave size? Do I need to submit to council ?

Posted Tuesday 17 Aug 2010 @ 4:17:12 am from IP #
dave lawrence
Member

depends . different councils have different rules .
but would need to make sure works complies with BCA and timber framing code at the very least.
call your local council and ask them .
from a planning perspective one of the main considerations is distance from boundaries of new eaves.
have you considered roof mounted, thermostatically controlled sprinkler for cooling system ?

Posted Tuesday 17 Aug 2010 @ 5:39:44 am from IP #
amun-ra
Member

look at the csr edmond's solar maestro I have 2 in my house as I have cathedral ceilings so all I can hope to do is remove the hot air before it heats internal fixtures they are not cheap but will move 400+m3per hour we noticed an immediate difference in temps even the wife noticed that's a win you can diy install if you wish but best to get a plumber.

Posted Tuesday 17 Aug 2010 @ 5:52:31 am from IP #
peta
Member

Thanks Dave and amun-ra,

Dave: yes had thought of a fine mist system over our ent area also, which is on the W/SW wall, however too much in rates and don't have a tank system as by the nature of a Decramastic roof and it shedding those little pebbles - will jamb up any filtration system in a flash.

amun-ra - looks like a webber on the roof ! - but I'll look into that as well, cannot go past your comments. I am the absolute worst when it comes to coping with Qld heat even though I'm local. -

Posted Tuesday 17 Aug 2010 @ 6:23:27 am from IP #
peta
Member

aman-ra - Did a search on the maestro system and came up with this site which does not have the solar whiz - which I've ctcd today a co up at Maleny for a quote. Anyway these guys seem to have a few to choose from : http://www.gaileshardware.com.au/html/hardware_products/roofing_products/roof_ventilation.html

Dave : yes of course distance from boundary, I'll have to look back into that. Street side I don't think I can do anything, however back neigbour W/SW side I might be OK as we used to have a Oregon pergola there that of course fell to bits, but in saying that it didn't have a fixed roof either.... aahhhhhh ...all for a bit better value on our hot water..... needless to say we didn't know what we bought into when purchasing this place 9yrs ago... but it's gotta be better than moving... and I really do appreciate everybodys input and ideas, something does need to be done..

Posted Tuesday 17 Aug 2010 @ 6:51:57 am from IP #
Tony C
Member

Peta by my calculations based on your figures the solar hot water would take about 7.5 years to pay back on current usage, 3 kw PV less than 4 years, dont forget the nett feed in tariff paying you for your excess.

PM me and I can send you info on the solarwhiz.

Extended eaves is not your only option to get external shade. What about a moveable shade screen? or retractable blinds (they dont have to be canvas)? A slatted screen (at the right angle) can keep the sun out in summer and give you solar gain in winter.

Just food for thought

Tony

Posted Wednesday 18 Aug 2010 @ 3:33:30 am from IP #
peta
Member

Hi Tony,

Yes I did forget about the feed in tarrif, and your calculations are almost the same as mine when I did. I've just come back from the SolarShop and they say I can get away with a 2.9KW system with an av gen 11.4KW/Day using either Solar Frontier or Kaneka panels. So 11.4KW less the house dormant 2.5KW / day (300w x 8hrs say) = peak generation during the day ( nothing runs here but the laptop and a desk system - oh and the fridge) = say 11KW @ origins feed in tariff of .50c x 365 days = around $2000.00.
(not including the air-con in summer - but I'll mentally factor this one in).

The Solar Frontier system he quoted $8438 inc GST so that means a payback of 4.2yrs not including increases.... I'm getting excited !

The solar hot water system (as I'm on natural piped gas apparently I cannot put in an electric HWS and have it powered by solar power), so there's another $4500 from Edwards for a 340L Thermosiphon system or $ 4770 Rinnai Prestige 315L (both tanks and panels for both suppliers made in OZ). Currently paying $ 600/yr in gas = yes 7.5yrs. I think I'm getting the hang of all this now YAY !!!

Right so with the roof ventilation. Now to replace this roof is 17K. It's either the roof or the panels and SHWS - cannot do all. So am leaning towards the panels and SHWS, and ventilation. Have been looking into the Maestro as well, they're about $6-700/unit. I rang the distributor of Solarwhiz @ Maleny yesterday but he is still to get me a price as he said he'd not sold one before......

... Anyway - it's looking like the roof may have to wait, albeit in 5 yrs time the roof will probably cost 20K - but at least we'd have stopped the cash leakage to energy costs and have that in an account to pay for the roof loan in 4.2yrs !!

Yes, was awake last nite from 3.30am thinking of how to cool this place cheaply without replacing the roof just yet. Trees take to long - I have 2 yrs ago strategically planted about 3 decent Golden Canes on the W side - but a few more years yet for them to get to the required height. Extended eaves are not an option right now, but I do like your idea of a moveable shade screen.. mmmm Yes retractable blinds, but that also stops my NE breezes having them right there on the windows to the office, on the W side are mostly sliding doors.....mmmmm slatted screen yes - perfect for the office, can hang some nice plants from it, not shutting up the windows....I like it !!!

May even rip up the unshaded concrete on the W side to the house - but this is our ent area waiting for a suitable entertainment covering - which is another of my bug bears. As without covering it is absolutely lovely out there in winter with the children... and warms the house with the PM sun.

Thanks Tony very much appreciated.

Posted Wednesday 18 Aug 2010 @ 4:59:13 am from IP #
Frateco
Member

peta, I'm in Brisbane. I have an LPG storage hot water system (140L I think) sitting under my house from a reno job that has been taking up space - if you are interested to buy. Apparently you can get it converted from LPG to mains gas if you want. Knowing what a new gas HWS costs, just thinking to save some bucks for you.

Posted Thursday 19 Aug 2010 @ 1:09:31 am from IP #
peta
Member

Hi Frateco - thanks for the kind offer and thought - but have a growing family of and either need instant hot water system or 300L+ - . Thanks again!

Posted Thursday 19 Aug 2010 @ 1:22:40 am from IP #
Buzzman
Member

peta
The 170L gas storage heater offered should (just) suffice for your needs. Once you'd used the 170L it would then re-heat - gas is 'always on' unlike off-peak electric!

And it would not take long to reheat. The smaller reservoir means less time to reheat, and as hot water accumulates at top of tank where HW outlet is, even less time before you'd have enough for another shower. This is why most gas HW storage systems are much smaller than their OP electric counterparts.

170L should be enough to supply almost 4 adult size, adult length, 10min hot showers if you have 3-star (9L/min) shower head.

9L/min X 10min = 90L (of which approx half is hot, so say 45L of HW)

170L / 45L = 3.777777 showers @ 10 mins duration.

Sure, better if you had a bigger reservoir or instantanteous gas, but it would do in the short term while you figured out what else needs doing and accumulate capital with which to do it.

But check what the LPG to Mains gas conversion would cost, mmight end up not being worth it.

Posted Sunday 22 Aug 2010 @ 4:49:45 am from IP #
peta
Member

Hi Buzzman,
Just keep learning e'day I do !!!

Now it takes about 20mins for a full hot shower after the last one runs cold.
The Climate Smart man said he couldn't fit a water saving shower head to our old connections... so not sure what star we have here but would assume it is way bad.
In saying that, it's been a while since we've run out of hot water as we are trying to get out before that happens, one day I should really time it.... I'll do that tonite.
... and yes "always on".. is costing a fortune !

Makes sense and good to know about having a smaller tank on gas than the electric counter-parts - thanks for the "heads up".

We only have 2 adults and 2 under school age children so I'll go and have another look at the viability of Frateco's offer - once again thanks.

Posted Sunday 22 Aug 2010 @ 6:41:48 am from IP #
Buzzman
Member

Peta
Further thoughts.....

Idea No.1....

Measure the flow rate of your shower. You will need a bucket, a stop-watch (or a watch with a second hand), an assistant (maybe a child? partner?), and a measuring jug that has gradations of less than 100ml.

First, turn on the shower and adjust for temperature and flow rate, as though you were about to use it...
- then, while assistant watches the clock and counts you down (ready set go is enough) shove the bucket right up under the shower nozzle so you capture all the water flow
- the assistant times this for 15 secs and calls STOP
- you remove the bucket from the shower flow, hand it to your assistant, and turn off the shower.
- take the bucket of water to the kitchen and carefully and accurately measure the water captured.
- multiply this figure by 4 and you will have the litres/minute flow rate of your normal shower.

eg: If you've captured and measured 3L of water, that makes the shower head a 12L/min flow rate, or a 2-star shower head.

And any plumber who says they can't change a shower head isn't trying. Perhaps what he means to say is that you don't have high enough pressure???? Or some other issue???

Tradesman lie to save them having to explain complex issues. White lies usually!

Idea No. 2....

You say the "always on" electric HWS takes only 20mins to heat enough water for a shower? Is that right (did I understand you correctly?)

If that is so, why not (as an option) turn the damn thing off overnight and during the day when you don't ACTUALLY need to use it (like Monday - Friday when you're at work/school).

Two options: turn it on and off yourself (means going out to the meter box mid-Winter 30mins before you need a shower in the morning......) OR... fit a timer switch to the switch board so it turns on when you need it to and then off again while you don't.

I advised a social club to do this on their 'on demand' HWS and it looks like saving them about $50-80 a qtr.

Hager makes a small timer which is the same size as a standard circuit breaker, and it fits into the same-sized slot in the switchboard and is simply wired into the On/Off switch for the HWS. Doesn't replace it, just sits next to it, so can still turn off/on if needed.

It's a Hager EH010 - PM me your email addy and I'll forward the relevant docs.

We got one for my Mum's villa - she was being woken at all hours of the night by the heat pump HWS. Now it only comes on in daylight hours, and she is very happy she's getting a good nights sleep.

Not same issue as yours, but will work just the same. Might need one of the more elaborate timers if you want it to switch on/off at multiple times, but Hager have other products that do that.

Can be ordered from any electricians supplier. The EH010 was about $60, and the sparkie charged her $50 to install it. Took 15 minutes. The more elaborate switches with 7-day times and so on would not cost much more to install (same no. of wires) but would be a bit dearer to purchase.

Hope that's helpful!

Posted Wednesday 25 Aug 2010 @ 7:23:44 am from IP #
Anonymous
Unregistered

Thanks you for the post.
Hi guys, Im a newbie. Nice to join this forum.

http://moviesonlineworld.com

Posted Saturday 28 Aug 2010 @ 3:57:17 am from IP #
kathleenp980
Blocked

Thanks you for the post.

http://moviesonlineworld.com

Posted Monday 30 Aug 2010 @ 2:42:47 am from IP #
peta
Member

Hi Buzzman,

Idea # 1.
It was the "Climate Smart" man that said he couldn't retro fit our shower head without other work - for which he was not responsible for, hence would need the plumber. We need a bathroom reno anyway so I haven't pushed this issue further. Perhaps the shower head he had wouldn't fit, not "all" of them like I had assumed.

Idea #2.- very Smart !
But we have piped gas HWS not electric, and a pain to re-light the pilot light in this thing.
I like your idea of the timer though - just a shame that it's illegal here to go from piped gas to electric at all. No choice but to go Solar.

We still have the same problem, with this roof.
Got 2 more roofers coming in today to do quotes, the decramastic renovator man said he won't touch it unless we were selling in 3yrs (that's all it will look good for), and currently we cannot get anything cheaper than 17Kd doing the job properly. Colourbond, anticon, vacumme + bats.

And all I wanted was a new HWS that's not gas costing me a fortune !!

We could put the thermosiphon on the roof - but we still need to replace it in a few years, that means pulling the panels off and having them re-installed by the supplier so as not to void the warranty - so extra bucks - but we may just have to do it this way, still dissapointing as I wanted to get a 3KW system too, but again re-installation of around 1K I reckon when we do get the new roof..... (sigh).

Anyrecommendatios on a good thermosiphon supplier, I think Edwards and Solarhart both have panels and tanks (not glass) that are made here in OZ.

Posted Tuesday 31 Aug 2010 @ 2:50:39 am from IP #
Buzzman
Member

peta

Doh! Missed that vital bit about the gas HWS! But $150/qtr for HW??? How much are you using???

Seaparate question: you say "it's illegal here to go from piped gas to electric". Who says? Council? State govt?

Do they mean that you have no chiuce but to install a gas-boosted solar HWS?

Seems crazy to me.

But if true, then you're stuck with it.

But I'd be looking at what you are doing with HW first and seeing if there was any way of reducing consumption. For example, do you have showers or baths? I'm guessing you and your partner probably have showers, but do you bath the young uns? Or are they old enough to shower? How long do you spend in the shower? More than 8mins is wasteful, less than 5 superhuman.....

How's the water bill? How many kL do you get thru a qtr?

Work out where the hot water is going. With a 3-star shower head and a 10min shower that's 90L max, of which about half is HW - say 50L. Four showers is 200L of hot water per day.

With a solar HWS of only 205 or even 250L capacity, you'd run out every day, so the thing would probably auto-boost every day.

Do you use hot water in the washing machine? Or only cold? Or sometimes warm?

Does the machine take HW from the tap or does it heat the water itself?

If you're already being frugal with HW and have all the above well-covered, you will still need a decent size reservoir in your solar HWS. Maybe 315L as a minimum. That way, with care and frugality, you may be able to last two days without boosting.

Do you see what I mean? The idea of soalr HWS is that you get HW for FREE, from the sun, not from the booster, whether it's gas or electric.

If it's constantly boosting what you'll have is a 'solar boosted' gas hot water heater, not a gas-boosted solar HWS...!!!

Posted Tuesday 31 Aug 2010 @ 7:40:45 am from IP #
peta
Member

Thanks Buzzman

What we're usuing : Have not done the test yet but will get there shortly.

Was actually weighing up putting in 5kw PV system with an electric off peak HWS.
My mum's off peak bill is only $ 45.00 and she washes in HW, but no kids.
We keep the HW usage down - I don't ever wash in HW, the kids have baths to only 20-25cm, us adults get in there and then out as fast as we can, the only things I can put it down to is the shower head, so I best get to measuring that so we can calculate properly the system size we need.

http://www.dip.qld.gov.au/sustainable-housing/electric-hot-water-system-replacement.html
... cannot do full electric - was looking at putting 5KW PV system on roof and have an off peak electric HWS, $ 45.00 off peak is way better than what we're payin now.

Having said that we cannot do, but I didn't think we may even be restricted by what booster we have. I'm going to have to look into that more.

Thanks Buzzman - got some measuring to do and further research about the booster.

Posted Tuesday 31 Aug 2010 @ 9:38:06 pm from IP #
scokim
Member

What does everyone think about the difference between a simple mechanical roof ventilator like SuperWhirly or Ampelite vs a solar powered one like Solar Whiz.

Apart from the aesthetic difference, I wonder if the solar powered ones are more prone to failure due to electronics and motor.

Which does a better job of ventilation.

Posted Wednesday 1 Sep 2010 @ 12:00:00 am from IP #
rockabye
Member

One disadvantage of the solar units, that are very reliable, is they only work during sunlight hours. In a hot evening after sunset they will not be working.

Posted Wednesday 1 Sep 2010 @ 12:36:14 am from IP #
LanceTurner
Key Master

Whirlybird and the like are not very good at extracting air from a roof, and indeed they are often least effective when they are needed most, ie on hot, still days. If you want to reduce the temperature of your home in summer by ventilating the roof cavity so that it sits at a more reasonable temp, then wind powered vents won't do it, depite all the marketing hype to the contrary.

You need forced air ventilaltion, plain and simple, and indeed you need to replace all of the air in the roof every 5-10 mins. The average roof has a large air volume, so you need to do your sums and work out what ventilators will be needed, and how many, and also where to put them. And remember that to extract air out of the roof efficiently, you also have to have air inlets for fresh air to replace the hot extracted air.

Posted Wednesday 1 Sep 2010 @ 1:05:32 am from IP #
peta
Member

I've acutally looked into this one and in this string "amun-ra" says his CSR Maestro works a treat ! I am serioulsy looking at the 12V motorised version - as per Lance's comments the disadvantages of a solar powered device is at night or on a still cloudy hot humid day here in sunny Qld is still tooooo hot, particularly on our W side. The Maestro claim to run on extremely small power draw (currently something like $7.00/yr as per their advertising material). Also it has no moving parts like the others 'cause the last think I want to hear is "dink dink dink dink dink"! Whirlybirds as I understand only remove hot air moreso in the top of your roof - not way down at ceiling level to keep the heat off there, makes sense so I'm very seriously considering this Maestro device - our roof volume means we're just that little bit too much for 2 maestro's and I think I may have vents in the ceiling so they suck up the air from within the house and not just the roof space - what do you think Lance ?

Oh - and our roof quotes are down to 15.9K !... I can feel some solar coming on !

Posted Thursday 2 Sep 2010 @ 2:26:15 am from IP #
Benny
Member

Are you sure that the heat is coming in from the ceiling Peta? Do you already have good ceiling insulation ? If its hot on your West side then it could be that the heat is coming through the wall rather than the roof. I'd try to work out just where the heat is getting in before deciding where to spend any money - maybe just better insulation ?
If it is hot in the roof then maybe just a passive system will work to extract the heat by convection - I hear the ridge vents work quite well.

Posted Thursday 2 Sep 2010 @ 5:23:07 am from IP #

RSS feed for this topic

12 Next »

Reply »

You must log in to post.