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Apricus Or Hills Evacuated Tube Solar HW System?

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Started 2 years ago by GJOESQ
Latest reply from micko

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JohhnyJoe
Member

I'm in Hobart and am likely to get an electric boosted AAE or Apricus system (315L SS with 30 tubes probably). I have some questions for the technical folk out there.

I think I read that mid mounted electric elements can help minimise required boost - is this so? Do either of the AAE or Apricus tanks have mid mount element options?

In Hobart I will need boost during winter, but I am looking at ways to minimise it. I am happy to have quite cool hot water. I have adjusted my current electric cylinder (which has sprung a leak) to run so low that I can just bear having a shower with hot only (in the biohazard area I suspect). I don't dismiss the hazards associated with this so I would be happy with once a week going up to 60°C, but most of the time I would probably be comfortable with 45-50°C. I have not read feedback from anyone on the SolaStat-Plus-2 controller which has controls for the electric element (Holdoff Timer, Reheat Lower, & Reheat Upper). Has anyone used this controller and these features? Does AAE have a Plus-2 version of the controller as well?

In particular in our house of morning showers, I do not want any boost coming on prior to that day's sun. Does this make sense or should I be looking at it from a total energy point of view and if, for example, I need 3kWh of electric boost a day then it won't matter when it occurs (I don't think we have timed tariffs in Hobart) - maximum energy from the sun will always be captured. Perhaps it will help on the fringes when boost is needed only on some days?

Anyone in Hobart have current pricing or comments on installers for these systems?

Thanks to those who have commented previously - excellent info.

Posted Monday 31 May 2010 @ 12:20:21 pm from IP #
gully
Member

I can tell you, if you are prepared to set it up, the AAE controller will allow you to specify a 'once a week' boost for anti-legionella, and you can also program in minimum temperatures for 3 periods during each day. Ie. let's say you get up at 7am, set 40 degree minimum for 7-9am. Then when you get home set minimum 40 degrees from 6pm - 10pm.

This way you are:
a) only boosting to 40 degrees
b) only boosting when you are home to use the hot water
c) only boosting to 60 degrees once a week, keeping legionella at bay.

Although the controller comes with these settings as options, they are not the current hot water standards (must go to 60 degrees each day if storing water).

Posted Monday 31 May 2010 @ 1:30:23 pm from IP #
swanning_it
Member

If I understand some of the ET issues, one of them is loss of water due to high temp limit of the system being reached. Wouldn't this have the same effect as "boosting" once a week to kill bacteria? Does anyone know the legionella facts? I don't, but was wondering how long does it take for it to establish (hours, days, weeks, months)? If established will a single burst of high temp destroy it? Or does it mean keeping it at bay with constant high temps (60oC and over)?

My initial thought is that most ET systems would reach well over 60oC at least once a week (even in dull weather) and from those who have given boost info in the past, it seems the boost days needed are fairly sparse which tends to indicate temps in the tank remain up.....hence no legionella (unless it can develop within hours, which I'd doubt).

Posted Monday 31 May 2010 @ 8:25:47 pm from IP #
gully
Member

This is an issue relating to solar hot water, not ET's specifically. This may seem so because ET's are much more efficient than flat plates I'm pretty such 60 degrees once a week will be safe for legionella, as this is what the 'anti-legionella' function is specifically designed for. Unfortunately it doesn't go as far to log whether that temperature has been not been reached in the last week as a pre-condition to trigger.

Posted Tuesday 1 Jun 2010 @ 12:05:38 am from IP #
Tacker
Member

Sorry to change the subject a bit, but I have still have questions regarding the overheating and associated water loss issue in SHW systems.

How much water do they lose when the tank reaches temperature, on a hot day? Some say not much as there is only a small quantity of water in the manifold.

Does having an auto air vent increase the amount of water loss by continually releasing steam from the manifold? If so why? Does the steam get replaced by water from the tank even if the pump is off?

Will the PTR valve provide the required pressure release for a solar hot water system in stagnation on a hot day, as suggested by Apricus?

What are people thoughts on cold water expansion valves, are they better as they expel pressure by releasing cold water at the inlet rather than hot, and also reduce the scale on the PTR. They also release at a lower pressure than the PTR and therefore could increase the amount of water loss ??.

What are peoples suggestions for the optimum solar hot water configuration to reduce water loss but also provide adequate pressure release for longevity of the system? (short of taking out tubes or partial shading during summer.

Posted Tuesday 1 Jun 2010 @ 12:20:37 am from IP #
swanning_it
Member

I think the partial shading has been the preferred option. From my understanding, water loss ranges from the 7 l or so in a manifold to 15 l from a tank. What I can't seem to gauge, is whether this water loss is most days, or rarely. The answer is probably somewhere in between. For the type with tank expulsion, (especially with a stainless tank and no anode) I can't see why the overflow water can't just be piped back to the main household water tank. In the situation of town water only, the cost of the lost water would be minimal, but for tank water installations, if a HWS is losing 15 l most days, that means a loss of about 5000 l each year. I have been told, you aren't permitted to pipe waste water back to a cold water tank, for the risk of raising the cold temp to a point that would support legionella. 15 l into a 35 000 l tank doesn't seem to compute with that risk though!

Posted Tuesday 1 Jun 2010 @ 1:29:33 am from IP #
Bryan Moss
Member

Hi, you can use a mid element tank in Tassie depending how many people in the house. By using a solarstat +2 the controller will automatically boost once the pump has stopped working for four hours. I would suggest if you have three or more people in the house with a 315 litre tank you might consider a bottom element tank, nothing worse than running out of hot water. On the other hand there are alot of very water conscious people who use flow restricters on showers ect, they could get away with the mid element tank, again I would exercise caution. There is an Apricus agent in Hobart, Mark Rickards of Eco Tasmania.
Hope this helps.

Posted Tuesday 1 Jun 2010 @ 1:41:12 am from IP #
gully
Member

Tacker: In an ideal environment, it would be sized and installed so that you wouldn't lose too much water out of the PTR. (ie. target for winter angle and correctly sized tank/tubes/panels for usage).

On mine i've seen it leak up to 12L / day (middle of summer).
1-2L / day is normal for me.

Yes the PTR can scale up and block, if you plumb rainwater into your hot water system this wouldn't be as much as issue.

Re: stagnation / apricus. Yes, that's what the TPR is for. If it doesn't, you'll find out about it in a bad way. Boom!

A cold water expansion valve may be better than nothing, and may lengthen the life of your PTR valve - doesn't really solve the problem of losing water though.

Hydronic heating systems use an expansion tank for this exact reason, not sure why they aren't used much for domestic hot water systems.

Posted Tuesday 1 Jun 2010 @ 4:56:51 am from IP #
bundy
Member

Hi everyone, I've read through this post with great interest. One thing I am having great difficulty with is how the Evac Tubes compare to a Flat panel system if mounted on the same roof with the same water use patterns. I am looking at a 315L , NG Boosted system in either Evac Tube or Flat panel. As Evac Tube is initially more expensive than the Old Flat panels when comparing like with like I really want to know when (or if) I will get to break even by spending the extra $$$ upfront. If it costs me $1K extra I dont want it to take 15 years ot get that back.

My other concern is whole of life costs in adding a controller and Pump as compared to the old Siphon style roof mount systems, which with less "moving" parts should have less tendancy to require repair or maintenance

Anyone have any real life input on either of these things?

Posted Thursday 17 Jun 2010 @ 6:14:49 am from IP #
kling
Member

Hi bundy, interesting that your quotes are more expensive for evac tube systems, i've had some quotes in the last month and found the 2 flat panel systems i was quoted on were about $1k more expensive than flat panel. I currently have a very old solahart flat panel siphon system, which now has a leaking tank (hence the aforementioned quotes), which has led me to consider the construction of the tank in the new system i get, might be something you should consider too, for longevity? I have lived in this house about 4 years, and had to replace a knock valve twice due to calcium buildup, but i don't think new systems have these anymore...but could be an issue whith pumps etc?

On another note, I did find a Sunergy evac tube, siphon system on ebay at a reasonable price, which I am seriuosly considering. Anyone with info/feedback on this brand? Thanks

Posted Thursday 17 Jun 2010 @ 12:00:47 pm from IP #
oldfossil
Member

Hi kling, what's knock valve? Something for water hammer?

Posted Saturday 19 Jun 2010 @ 6:57:51 am from IP #
kling
Member

Hi oldfossil. A knock valve is there to let water out in case the temperature reaches freezing. The idea is that the valve opens and because water is flowing through the panels, it can't freeze in the panels and avoids damaging them.

Posted Sunday 20 Jun 2010 @ 7:37:51 am from IP #
oldfossil
Member

Thanks for that. Never knew what they were called.

Posted Sunday 20 Jun 2010 @ 8:26:27 am from IP #
Russell Moore
Member

Knock valves are used on old style flat plate panels where the stored water is directly circulated through the panels, as opposed to newer FP ones that use gycol based fluids and a heat exchanger. My 28 year old FP turns on at 4 degrees, and my wife says "There goes my hot water for my morning shower!"

If the water was to freeze in the old syle FP heaters the expanding ice would burst the panel tubes. In fact around 1987 in Sydney when we had a very cold winter, FP panels east of a line north and south of Bankstown, where knock valves were not fitted, burst all over the place!

Posted Sunday 20 Jun 2010 @ 9:51:31 am from IP #
Jimmy
Member

Hi
I noticed a lot of discussion regarding water wastage from the PTR valve and the air remittance valve on the manifold.

I think it is a good idea when you look at buying a Evacuated Tube split system that you get a system that has a good controller which you can adjust the settings of when the circulating pump switches on and off.
Some sensors /controllers may be factory set to have a 'top out' temperature of 80 degrees Celsius but temperatures inside the tank could be higher depending on where the sensor port is located on the tank.
The right controller will allow you to configure the settings so that unnecessary load on the PTR valve is minimised by reducing top out temp to 70 degrees.
Some systems will lose a lot of water e.g. 15 L per day if the top out temp is too high.

The air remittance valve should be on the manifold. What I have noticed is there a plenty of installations around where the air remitance valve is rated to only 135 degrees Celsius. They need to be rated to 180 degrees because temperatures inside the manifold will often exceed 150 degrees if it is a good installation. Higher temperatures than what the air remittance valve can handle will cause the valve to fail and have excessive water wastage.

Hope this helps

Posted Friday 25 Jun 2010 @ 10:52:09 am from IP #
UNEVANO
Member

Hello everyone, it is sometime since I have contacted the group, although I have checked the forum a few times, just to refresh in relation to replies, I have an Apricus 30 tube, 315l SS tank, LPG boost and a Solstat 2 sensor controller.

I am asking has anyone detailed knowledge of the correct pipe insulation? I know Armacell make Armaflex solar but are there others? The reason I am asking, is that my system that was installed mid October last year had standard armaflex insulation which by Janurary this year had started to decompose, there were large gaps between joints and the installers had fastened the pipe flat on the corrogated iron so that there was a massive build up of rubbish. I did a search and found the manufacturer and was told it was not made for outside use and the installer should have used Armaflex solar. I contacted the installing company's receptionist a few times before I got to talk to someone and then emailed them photos of the deteriorating insulation and the bad installation on the roof, which then took another 2 weeks to come to fix it.

Now the problem is, they have replaced most of the old insulation (not all for some reason)with what appears to be a polyethelene insulation brand name;-Thermasmart which I have not been able to find on the Net. But all the other polyethelene insulation sites that I have found, say it is only good up to 90c, it is UV stable but it does have <2% water absorbtion over 28 days , has anyone seen the Thermasmart brand before and if so, can you list the email address or Web address please?

Another thing I noticed in listings a few months ago, was talk about the collector angle, I live in the Yarra Valley and our latitude is 37Deg something, yet I am sure my collectors would only be about 35Deg, and I remember when I was talking to the salesman he said it did not matter, "it is close enough".

I have never been 100% happy with it, even on the high 30's days, the water has never been above 80C measured at the PRV, even when the sensor at the collector showed it had "topped out" (over 147C). Back when I first mentioned somthing similar on this forum 6-8 months ago, Micko from Apricus replied and left a link to the Solstat website which turned out to be a waste of time as it didn't give the info to reprogram the controller. The gas boost runs nearly all the time, it makes me envious of those who have been able to turn their boost off, we are in a cooler area but on a bright sunny cool day, the temp still only gets to low 20's in the tank (bottom sensor).

I thought I had done all my homework before I had comitted to buy the Apricus system, but I don't know if it is the brand or the Installer which has left me so dissapointed.
The installer is an Apricus dealer that I was referred to by Apricus and is in what would be called West Gippsland.

Posted Tuesday 3 Aug 2010 @ 6:12:57 am from IP #
gully
Member

UNEVANO: Your angle is fine for your latitude, be more worried if it was 5 - 15 degrees (too low) - it doesn't have to be an exact by +-1 degree. Obviously on LPG you are paying quite a bit for the boosting when needed. I had the same problem on install with armaflex.. they just taped it up with electrical tape and go "yep, she's UV stable".

Could be a sensor issue if it's out by 60 degrees between PTR and top sensor! I've used a multimeter thermocouple to measure hot water to verify sensor measurement.

My lat is 37 deg and mine was installed at 30 deg. Last summer (feb/mar) I was getting 110+ deg C from the manifold sensor. A few days ago it got to 54 degrees (remember it's winter). Do you have a long pipe run to the roof? Any shading issues?

Do you know if the evac tubes are fitted snug all the way up into the manifold? Also check (when tubes are cold) if there has been thermal paste put on the heat pipe inside the tubes.

Can we see photos of the install? Might help.

Posted Tuesday 3 Aug 2010 @ 6:49:14 am from IP #
UNEVANO
Member

gully; so far this winter the highest temperature I have seen was about 26c. Yes I was wondering last weekend about the connections to the manifold but the tubes do appear to be sitting correctly in the cradle, but I have been reluctant to touch anything while it is still under warranty, I might have a look this weekend. The pipe length from the collectors to the storage tank is only about 5m and the height from the bottom of the tank to the collectors is about 4 - 41/2m in 1/2" copper pipe. There is some shade after about 3.30pm, but full exposure from just after sunrise, I have problems with my Internet/computer in uploading photos, I will try to take some this weekend. The other situaton with the new Insulation is that I really want to get an expert opinion on the polyethelene as to whether it will take the temps and exposure to UV, before I call the installers again.

Posted Wednesday 4 Aug 2010 @ 5:33:51 am from IP #
amun-ra
Member

Could also be one or more failed heat pipes if the vacuum is lost the heat pipe fails to transfer the heat to the header you can often feel the difference in temperature on the outside of the glass tube.Tubes even in bright sun should feel cool to the touch.Do not take the heat pipes from the tubes they can be hot enough to take the skin off your hand.

Posted Friday 6 Aug 2010 @ 6:39:00 am from IP #
UNEVANO
Member

amun-ra/gully, I checked a couple of tubes randomly last sunday and they seemed to have plenty of paste on them. I will check each tube this weekend to see what they feel like as the ones I removed last sunday were cold, also although the weather was better than expected and a bright sunny day the manifold temp only got up to 36deg before the pump started.

Posted Tuesday 10 Aug 2010 @ 11:13:00 am from IP #
gully
Member

FYI in melbourne, VIC yesterday my 1kw system generated over 4kwh and my SHW got over 55 degrees. Beautiful day!

Posted Tuesday 10 Aug 2010 @ 2:02:25 pm from IP #
hillslope
Member

Dont know if this is too late, but might be of interest to users here.
We previously installed an apricus 30/315l SS system in Vic, cold area, and generally had the electric boost turned off most of the time (2kids, 2 adults), and only needed it after 2 days of cloud. Had this system going for about 3 years.
Then we moved to a place nearby that has flat plate solar system plus wet back on wood heater, which after only 7 months is giving me the @#$%. It works fine when the wood heater is going, but spends most winter nights leaking large amounts of (tank) water - basically when the air temp hits 5 deg or less to stop frost. The ET never did this.
Now, since the house is very good passive solar and we dont need the heating for days over 12-14 deg, it is not hot enough for the solar panels to heat the water, and have to have the boost going every night, even after a 17 deg day of sunshine. House is warm, water is cold.
Now I have to decide on either gas boost or replace the panels with ET. Only problem the tank is glass lined, has internal coil and probably would not last long with ET heating so well, and replacing the tank would be very expensive. LPG too, so gas won't be cheap either.
So, if I had the choice, having used both I would never touch flat panels again - they are not efficient enough.

Posted Thursday 23 Sep 2010 @ 11:59:55 am from IP #
olfella
Member

UNEVANO, if your pump is cutting in at that temperature, I'd suggest you have either a problem with a sensor, or your sensors are incorrectly detecting the true differential between the manifold temperature & the true top tank temperature.
I had a similar problem at the onset of winter & found the uninsulated brass hot water outlet from the top of the tank, which also holds the top tank sensor, was cold relative to the real top tank temperature, unless a hot water tap was turned on to flow water through that external outlet fitting & pipe regularly. The heat loss from uninsulated fittings outside the tank insulation in winter is extrordinary. One assumes the water in the tank will keep that fitting hot, but it doesn't. I don't really think there is much heat loss to the tank water, but it does impact on the sensor reading & hence on the pump duty cycle.
I took pains to fully insulate that fitting & increased the insulation of the hot water pipe leading from the tank & the problem of excessive pump circulation was overcome. The efficiency of the overall system also increased.
Why these fittings aren't well insulated by a factory provided kit is beyond me. Plumbers might know about water flows, but seem to understand little about the issue of heat transfer & loss & its impact on electronic sensors & control systems. This is not a real problem in summer, but come winter, one ends up with the problem described.

Posted Friday 24 Sep 2010 @ 3:59:19 am from IP #
Benny
Member

Hillslope - sorry to hear of your bad experience with the flat panel SHWS, but your statement should be modified to "They are not efficient enough in very cold climates". Thats commonly stated as the big benefit of ET systems, that they are much more efficient than flat panel when the air temp is low and the FP loses a lot of heat through conduction losses.
I'm surprised though that the frost protection is venting water from the tank. Is this because its a close coupled tank ? Is there any way to vent it just from the panels without draining from the tank ? I don't have any experience with frost protection (in Perth) but I would have thought you'd only need to drain a small amount to prevent ice expansion creating leaks ?

Posted Friday 24 Sep 2010 @ 5:01:22 am from IP #
amun-ra
Member

UNEVANO the pump will start at 36 if the BOTTOM sensor is reading generally 6 deg lower than manifold sensor and turn off again when there is a 2 deg difference, factory set, heat should build and this will again start the pump at 36 untill the bottom tank sensor reads a higher temp then the pump will start at 37 and gradually bring up the tank temps this is normal. Ff you do have a top sensor it does not control the pump cycles it is there to sense top of tank to control the element if the tank does not reach 60 deg often enough

Posted Friday 24 Sep 2010 @ 11:26:25 pm from IP #
olfella
Member

amun-ra.
Your system must be completely different to my AAE/Solastat ET system then. I just went back & read both the system & controller handbooks to make sure what I posted was correct & it is. (As old techos say, when all else fails, read the handbook!)

One difference I note to UNEVANO though is, my controller uses three sensors & the pump function is controlled by the difference between the top tank sensor & the manifold sensor. The pump cuts in at a 12 degree differential & cuts out when the difference is 6 degees, but it is definitely the difference between the top tank & manifold temperature that controls that.

I can't conceive how seeking a 2 degree difference between the manifold & bottom tank/inlet temp, would ever see the pump turn off, unless the tank was full of cold water or one is triggering anti-freeze defense in really cold climates.

The other possible difference is your temperature references suggest a low pressure system, a la a swimming pool application. See Below.

Cut & Paste from the manual:
ABOUT THE PUMP SETTINGS
The SolaStat™ works by turning the pump when the difference between the temperature at the solar hot water Collector (ROOF) and the temperature in the TANK, is at a certain level. [TANK Sensor refers to the Top TANK Sensor]
The pump turns on when the difference between these two temperatures is high (i.e. the temperature at the solar hot water Collector is significantly higher than the temperature at the tank sensor (TANK).
The pump turns off again when the difference gets less (i.e. the water in the tank has been heated up.
For example, using the standard settings:
PUMP ON = 12°C [21°F] and PUMP OFF = 6°C [10°F]:
 When the solar hot water collector (ROOF) water temperature is 12°C
[21°F] higher than the TANK, the pump turns on. This transfers hot water
from the collector to the tank, and transfers cooler water from the bottom
of the tank to the collector.
 This makes the temperature in the Tank heat up; and the temperature in
the Collector on the ROOF cool down.
 When the difference in the two temperatures reduces to 6°C [10°F[, the
pump switches off, allowing the water in the collector to heat up again.

About the setting

For standard domestic hot water systems, the recommended settings are
relatively large (e.g. PUMP ON = 12°C [21°F] and PUMP OFF = 6°C [10°F].
This causes the pump to transfer hotter water over shorter periods of time.

For lower temperature systems (like swimming pools or under-floor
heating), these temperatures settings should be set lower (e.g. PUMP ON =
5°C [9°F] and PUMP OFF = 2°C [3°F]. This causes the pump to transfer more water at lower temperatures.

Posted Saturday 25 Sep 2010 @ 4:42:23 am from IP #
amun-ra
Member

Apricus 2 sensor controler wich is what unevano said he has= pump on at 8 deg higher than bottom sensor temp pump off at 2 deg higher than bottom sensor hot water returns to bottom of tank and finds its own level straight from th solarstat manual programing table page 29 there is no 3rd sensor in the apricus system

Posted Saturday 25 Sep 2010 @ 8:03:11 am from IP #
hillslope
Member

Benny - you are probably correct with the clarification. Problem is large parts of inland do suffer frost. The frost protection does not leak a large volume of water, but enough for the pump to cycle pretty frequently while trying to maintain pressure. Unfortunately, can't just drain the panels without isolating them from the tank, so no luck there. Considering flat panel systems are still being fitted in frost prone areas, and are not much cheaper than ET ones, I would still not recommend a flat panel after this.

Posted Saturday 25 Sep 2010 @ 9:41:05 am from IP #
ozelite
Member

Does anyone have any experience with passive ET systems? ie using the tank above the tubes on the roof so there is no need for all these problems with controllers and pumps?

Posted Wednesday 3 Nov 2010 @ 7:11:01 am from IP #
gav
Member

Hi Mick,
Im a newby here. I just wanted to thank you for writing your user manual from Apricus. It was very well written. The pictures were easy to follow.
I have installed both Apricus and Hills ET in the Adelaide area.
Just wandering why the bulb is offset for Apricus and with Hills it is centred.
From installation point of view the centred version is that little bit easier to fit.

Posted Sunday 21 Nov 2010 @ 1:17:52 am from IP #

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