Alternative Technology Assn Forums

1. 

   planck_length
   Member

   I need to order an Apricus system by tomorrow (11/02/11).

   I live in the Tweed Shire, in the Northern Rivers region of NSW.

   Our house has a good aspect (true north, no shading).

   There's usually only 2 of us in the house but we expect to get guests quite a lot and we tend to use quite a lot of hot water (long showers & baths).

   I've decided to get a 315L stainless steel mid-element tank, so the choice is between 22 and 30 tubes.

   I'm tempted to go with 30 tubes, but my local distributor said that he's heard a few reports of installations in the local area where there's been overheating in the summer, leading to banging sounds in the pipes.

   I'd like to angle the panels at 50 degrees to optimise for winter sun, and I'm hoping this will also reduce summer overheating.

   Does anyone have any advice on whether I should avoid 30 tubes?

   Thanks.

   Posted Wednesday 9 Feb 2011 @ 11:24:19 pm from IP #
2. 

   dave lawrence
   Member

   when do your guests most often come ... summer or winter ?

   Posted Wednesday 9 Feb 2011 @ 11:35:28 pm from IP #
3. 

   planck_length
   Member

   Hi Dave,

   Thanks for reading my post and following it up.

   I expect our guests to come any time except winter and stay for extended periods (e.g. at least a month). But they could even come in winter - we don't know for sure.

   Posted Wednesday 9 Feb 2011 @ 11:41:16 pm from IP #
4. 

   dave lawrence
   Member

   yes of course, impossible to say when guests will arrive.
   as for 30 vs 22 tubes , no science behind my opinion but I'd go 30 if you can afford it .

   Posted Wednesday 9 Feb 2011 @ 11:52:51 pm from IP #
5. 

   sun2steam
   Member

   The question is about your goal. Is it :
   - cost
   - convenience
   - efficiency
   - CO2 saving
   - maximizing rebates
   - noise (these banging sounds are really not that bad and happen not that often)

   The question is also how you are boosting. I have posted before that I believe boosting electrically with offpeak1 is the most cost effective way.

   We are also 2 people in one house with occasional visitors (Central Coast NSW). I decided on 30 tubes and a 400L system, no extra frame. The larger tank is more expensive. But we do have no problems with a few cloudy days. And our cost for boosting in winter (booster switched on at OP1 all the time) was less than $5!

   Posted Thursday 10 Feb 2011 @ 12:03:00 am from IP #
6. 

   mwp
   Member

   Hi,

   I increased our 10 tube system to 20 tubes and the daily water temp in Summer is often about 80degrees. There are two people in the house and I live in Melb. The tubes are angled at about 45degrees facing North. I recommend 22 tubes.

   Posted Thursday 10 Feb 2011 @ 12:07:04 am from IP #
7. 

   planck_length
   Member

   sun2steam:

   We're getting an electric booster and we plan to put it on off-peak 1. Our biggest aim is to minimise CO2 emissions and electricity usage, but not if it means creating overheating problems and noise in summer (I work from home so I'd hear it) but I have no idea what it would sound like.

   Your system is different in that your tube to tank size ratio is 0.075, whereas ours (assuming 30 tubes) would be 0.095, i.e. we could be producing around 25% more heat per unit volume, all else being equal, from our tubes, than you do from yours.

   mwp:

   What's your tank size?

   Posted Thursday 10 Feb 2011 @ 2:09:05 am from IP #
8. 

   Buzzman
   Member

   planck

   You're asking the questions in the wrong order. You say you 'have decided to get a 315L tank'.

   Sorry. Why, exactly?

   The principal purpose of utilising the sun to heat hot water is to reduce power consumption (for whatever reason).

   Ergo, you need to be sure you will not need to boost other than after many days of overcast or rain.

   So the FIRST thing you need to do is ACCURATELY determine your daily water consumption. Then multiply by how many days you get of cloud in a row, so you can be certain of enough supply.

   THEN ask what size array you need, as this is based on the size of the tank you choose.

   In your calculations, include the friends staying over.

   Let's say you have a WELS 3-star shower head = 9L/min flow rate = 90L/10min shower = 180L/bathful (roughly).

   [Calculate shower rate by measuring water flow of 'normal' heat/flow shower for 10 secs and multiply by 6 to get per min rate. Calc bath qty by measuring bucket capacity and number of buckets to fill bath]. Hot water as proportion is roughly 55-60%.

   Now multiply by number of people to use each (shower or bath).

   Then multiply by at least two (but preferably 3) so you get two days supply of HW without having to boost.

   If wanting to maximise winter sun benefit by all means get extra tubes - remember array is sized for SUMMER so as not to get too hot water (although depending on sun, cloud and elevation this can still get plurry hot as 'mwp' notes and I have found in other places).

   Build into your frame a roller blind that can be pulled down over the additional tubes in summer to reduce the sun effect and keep the temp inthe tank down to a reasonable and not scalding level (50-60degC). Or use a sheet of plywood. Or roof iron. Whatever.

   If you want to get fancy you could use a window roller shutter and a thermostat-controlled solenoid switch to operate it.

   Presume no manufacturer has done so yet as it would add appreciably to the cost of install, but when we're talking $5K for a HWS what's an extra $800 between friends?

   This solution would also work for stand-alone off-grid HWS and people who live 'off grid' as it should never need boosting.

   Provided its sized properly and you MANAGE your HW consumption (ie use less when its raining or threatening rain, for example).

   Hope that makes sense!

   Posted Thursday 10 Feb 2011 @ 3:12:19 am from IP #
9. 

   sun2steam
   Member

   Could somebody else comment on the noise of an overheating evacuated tube system?

   In my case it is really marginal. Just a bit of a rattling, gurgling noise in the middle of the day if
   a) a summer day with blue sky
   And
   b) only when a hot water tap or shower is operated.

   The noise is water boiling during the time when the system pressure is is reduced. The pressure reduction is caused by the water inflow being throttled by a 500 kPa and water leaving the system on the outlet. As soon as the taps, showers are off the noise stops.

   Posted Thursday 10 Feb 2011 @ 4:18:28 am from IP #
10. 

    Sunshine
    Member

    planck_length,
    We are a family of 3 in Brisbane and we have a 315 litre Hills Evac Tube SHWS with 30 tubes.
    Going for the 30 tubes will mean you will need to only boost on extended cloudy/rainy weather. We have only boosted once in 29 months it's been installed.
    One thing to add, there have been several people in this forum complaining of noises coming from the tank with the Apricus system. The Hills system has the same tank as the Apricus, but haven't seen anyone complain about the same noise with the Hills. The Hills has an extra PRV located in the manifold which may have something to do with the no noise issue in the Hills.
    The 22 tube system is ok, but you will boost more.

    Posted Thursday 10 Feb 2011 @ 10:21:23 am from IP #
11. 

    Solgen
    Member

    Like Sunshine, we have a Hills 315l, 30 tube system. We live in Sydney are rarely need boosting, have only used less than 100kWh in each of the last 2 years. As Sunshine mentioned we have not had any noise problems from our system either, very happy with it. Go for the 30 tubes.

    Posted Thursday 10 Feb 2011 @ 11:28:11 am from IP #
12. 

    acd
    Member

    I would like to ask a slightly different question. We have a holiday rental house in Victoria on the coast, it has no gas supply, and the hot water has been from an electric tank, overnight, or a switch to daytime if needed. the tank is outdoors. The house would be used less than 50% of the yr but when in use would have 8-12 people in it (mostly in the summer) The HWS is leaking and will need to be replaced. I am wondering if I should put in solar or is it ridiculous to have it heating water when theres nobody there to use it? Any other alternatives to the current system? Thanks for your thoughts.

    Posted Monday 8 Aug 2011 @ 12:24:19 am from IP #
13. 

    Sunshine
    Member

    acd,
    Is an instantaneous heat gas system with lpg bottles suitable?

    Posted Monday 8 Aug 2011 @ 12:52:30 am from IP #
14. 

    acd
    Member

    there is no gas inthe area, so would need to go to bottles, and I dont really want to do that because then there is another thing I need to make sure has not run out when renters come....but yes I guess it would be do-able. would you have any idea how long a bottle (size?) would last for that use? thanks

    Posted Monday 8 Aug 2011 @ 2:34:06 am from IP #
15. 

    acd
    Member

    what about a heat pump like the dux one? It must be more efficient than replacing with electric storage again?

    Posted Monday 8 Aug 2011 @ 2:46:58 am from IP #
16. 

    peter69_56
    Member

    I would go for solar evac tubes and instant bottled gas boost. The tank would generally be hot given its lack of use, and on those days where there are people there, or a number of people, the bottled gas could top it up (given its a holiday house). When there is no onje there, no gas is consumed but the HWS should remain relatively hot with lack of use.

    Posted Tuesday 18 Oct 2011 @ 5:10:40 am from IP #
17. 

    Skysolarman
    Member

    Hi planck_length , mate go for 22 tubes...don't worry about winter time you will get good savings in summer to warrant the purchase...everyone seems to think that if they buy a solar water heating system that there hot water power bill goes away...its just not true , if you set it up for winter you will get a good savings but not brilliant you then also limit its efficiency in the summer time as well...Buy a system that will suit your needs for peak summertime conditions and not for winter peak conditions , do this and you will then not have summertime overheat headaches

    Posted Tuesday 25 Oct 2011 @ 3:14:31 am from IP #

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