Solar Hot Water – Evacuated Tubes – Apricus vs Hills

Posted by Benjamin Close on November 18, 2009 under Country Living | 13 Comments to Read


In building our new house we decided to install a solar hot water system. The reasons for this was simple. We have no mains electricity and only LPG bottled gas. Hence continually heating water would have cost us a lot. Solar hot water on the other hand has an upfront cost but substantially reduces the ongoing cost. Only having rain water and being in a frost region, we quickly decided on evacuated tubes rather than flat panel collectors. Not only is it safer for us (no glycol to leak into our water supply) but there is also an added benefit of better solar performance.

With the decision to use evacuated tubes made, it was now a matter of what brand. This is where the real issues began.
In Australia there is two main contenders for evaculated tube hot water system. These are Apricus and Hills. So began the investigation as to which is better. The Apricus system is significantly cheaper than the Hills. The Hills system is a ‘name brand quality’ company. A little more research finds that both companies are actually Australian (Apricus Australia) and the collectors are all imported anyway.

Not believing in hype about name brands the investigation began into the real differences of each system. It turns out there is quite a few. The below table lists the differences and a comment related to each.

Update: 20091124 – Chris Taylor Director of Apricus Australia has provided updated information to each comment – see below in red

Difference Hills Apricus Comment
Heat Exchanger/Manifold Warranty 10 Year 15 Year If a company is willing to warrant a component for 5 years more, it is probably of higher quality

Apricus is a global company with its own manufacturing operation.   It exports to more than 30 countries and has offices in the US and Europe. Hills are simply buying OEM from a Chinese company with no direct control over the manufacturing, management, working conditions adherence to labor laws, pollution control or quality control. Apricus is fully a ISO9001:2008 certified operation and audited 3 -4 times a year from 3 party auditors from Australia, Germany, USA and China.  Michael Humphreys, an Australian and the founder and CEO of Apricus is based full time in China managing the manufacturing facility.

Heat Exchanger Weld Joints 64 Welds 6 Welds Looking at both systems at a local ‘home expo’ this point is quite clear. Hills weld either side of the heat exchanger, Apricus only weld in a few places. The reason for this is probably due to the manifold setup. In the Apricus system the tube sits between two copper pipes. In the Hills there is weld joints either side of each collector. Personally, I believe less welds are stronger as you’ve not cut the original pipe in the first place!

The Apricus header was specifically designed in that way to minimise welds which are potential failure points.  The Apricus design is NOT less efficient in terms of heat transfer as we have a large head size which provides plenty of contact surface area.  The heat pipe to header connection is not a bottle-neck to the system efficiency.

Steam Relieve Valve Supplied
Caleffi 250 series
Not Supplied The steam relief valve was certainly an interesting point when comparing the differences. Hills use the Caleffi series valves (
As noted in these valves are designed to work with gycol and are not Potable (drinkable) water rated.
The other interesting point is the the maximum temperature rating of the steam valve. Max temp is 180 degrees. Pure water turns to steam at 100 degrees. However it’s under pressure in the collector. Hence in order for steam to form it must be hotter than 100 degrees. On a hot day I can understand 180 degrees being met quite easily. This as indicated in the link can melt the steam valve.

1. They are not potable water rated.
2. They will fail due to scale buildup in the fine hole.
3. They will melt as the collector can reach 190oC
4. They will dump as much as 20L per day in steam, a fact that Apricus is raising with Australian Standards as system are not allowed to dump excessive volumes of water as a means of dissipating excess heat as outlined in AS2712:2007 “no-load” clause 7.4.3 and test methodology in Appendix F.

Rubber Holder vs Plastic Holder for evacuated tube end Plastic Rubber I noticed this at a recent trade show. I do agree the plastic of the hill system will last longer. Though it’s not worth the significant cost difference. – You could even buy the boots from Hills and use them with Apricus!

Apricus uses HTV Silicone Rubber because it is FAR SUPERIOR to any plastic in terms of UV resistance.  It is a more expensive material choice than plastic, almost double the cost in fact.   I would be interested to see a third party report showing that the plastic used by Hills will last the equivalent of 10 years UV exposure without significant loss of structural strength and function

Flow Rate Limiter Supplied Not Supplied As discussed with a representative from Energymatters hills use a flow rate limiter where as Apricus do not. The rep. indicated the limiter was an important part of the system to make sure that the full efficiency was obtained from the collector. This didn’t sit well with me. Why when you have a pump moving water around would you want to slow it down? This puts pressure on the pump and makes it more likely to fail. Further investigation indicates it is due to the manifold design. The hills manifold is designed to hold 1.7l of water at a time, the apricus only 0.7l (30 tubes). Hence Hills needs the flow limiter as there’s more water to heat at any time. Apricus on the other hand is putting the same heat into less water, hence don’t need the limiter.

1. Until just the last couple of week the flow meter were NOT watermarked hence Apricus has not been allowing their use as we adhere strictly to the Australia Standards.   Now they are finally certified Apricus is investigating making them a standard part of the system.
2. It should not be used to SLOW the water but rather to allow the actual flow rate to be observed and if too slow a faster speed on the pump can be chosen (if using a 3 speed pump), Apricus would not suggest restricting the flow rate by more than 25% otherwise it is effectively wasting electricity by artificially increasing the head pressure of the solar loop and forcing the pump to run longer each day.

Circulating Pump ? Bianco three speed pump Both pumps have a 1 year warranty. The Apricus pump is stainless steel, the Hills pump is unknown.

The Apricus pump is a brass body pump, 3 speed.   The Hills would also be brass or bronze but I think single speed.  I don’t know of anybody using a SS body pump in the market.

Tank Choice Stainless Steel Stainless Steel or Glass Lined As from:

3. The tanks used in the market by Apricus are Everlast (stainless steel) or Aquamax.. Hills use Everlast tanks too. They are both made in Australia.

Stainless steel is a quality choice but more expensive. It is not suitable for all areas those as certain type of water, particularly bore, will quickly corrode stainless steel. The warranty policy of Everlast provides details of that.

Vitreous enamel (aka glass lined) tanks don’t generally last as long as SS tanks as they are protected by a sacrificial magnesium anode which corrodes instead of the steel. The problem is that hardly anybody actually replaces the anode, which you should do once every 3-4 years (depending on water quality). If you DO replace the anode the tank could last 10+ years.

Since the most likly point of failure in an evacuated tube system is the Heat Exchanger/Manifold the Apricus system does sound more promising.  This ironically is the one component that Hills don’t seem to trust as much as Apricus. Clearly indicated by the 5 year difference in warranty.

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  • john said,

    I have the apricus system. I have been involved in the sustainability industry for a couple of years now, which led me to purchase the Apricus system ovetr Hills (personal choice – both have there good and bad points) Sometimes when the pump is on there is a whistle ? There is a noise which increases in tone and then suddenly drops and lasts until the pump automatically switches off , it doesn’t normally occur first thing in the morning or even later in the afternoon and even in the middle of the day when the temperature is hot . It appears to be coming from the tank , cannot hear anything from the pump.
    I have also noted changes in water temp in the shower on a couple of occasions lately. Can anyone tell me what they think the problem may be? Im keen on sustainability and I think its a good system but I would like it to actually work properly. It was not cheap

  • Sean said,

    Hi Ben,
    Thanks for sharing your research. I’m also looking for a Solar Hot Water system. There is another company called SunTrap. Have you done any investigation about them?
    I got a quote from SunTrap which, pricewise sits between Apricus and Hills.
    The pump they use is Salmson model no: SB04-15, energy rating is 22 watt.
    They also claim their evacuated tubes are better than all others in the market.
    Would be interesting to hear other people’s view on this.

  • SolarGen said,

    Hey Sean,

    Not sure where you are located but the Solar Choice website could be a good starting point.

  • Apricus Evacuated Tube Solar Hot Water System – Post Install Review » ClearChain said,

    […] tubes were still very new to the market. Hence there was only two manufacturers: Hills and Apricus. After a bit of research, Apricus seemed like the best option due to warranty and price. So we contacted a number of Apricus […]

  • Bob said,

    We’ve had the Hills Solar for six years and it’s been problematic and costly due to a failure in the water tank and repeated failures of a valve that results in water leaking down the roof – unfortunatly for a week or more while we wait for the (poor) service dealer
    Not a product I would recommend or even consider purchasing again

  • Paul said,

    I found all the system will be heated second time in order to kill legionella. If the water in the tank has been reach to 70C but it become cool in night time,maybe 65c,gas booster still need to heat again to 70c then mix the tap water to 50 degree.

    And over heating is also a bad problem. Most time TPR valve release hot water and fill cold water to cool system.And some time, the system plus a radiator to cool but that will need pump circulation thus will also need more energy.

  • Art said,

    In response to Sean’s message above. We would not recommend Suntrap. Too many issues and problems have arisen with their systems.

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  • Diana Taylor said,

    We are extremley disapointed with the Hills endless solar hot water system and are now paying a plumber to bypass it and just put us back onto gas. It was not installed properly by the plumber organised by the company and then they denied all responsibility stating that we could have used another plumber of our choice. We then paid another plumber to fix the installation mistakes.Now several years down the track our water is currently luke warm a valve problem of some kind and we are unable to find any plumber wanting to touch the system. It has been a very expensive mistake installing Hills endless solar and would never deal with them again. Very disapointing

  • Benjamin Close said,

    I can tell you the apricus installer was just as bad:

    In regards to your comment about a valve problem. The systems are pretty simple. Tank, pump, heat exchanger (box thing on roof), tubes, steam relief valve.
    My hunch is the valve that has failed in your system is the steam relief valve. It’s one of the big difference between the hills & apricus system.
    Hill has it, apricus doesn’t… Apricus’ reasoning is:

    1. They are not potable water rated.
    2. They will fail due to scale buildup in the fine hole.
    3. They will melt as the collector can reach 190oC
    4. They will dump as much as 20L per day in steam, a fact that Apricus is raising with Australian Standards as system are not allowed to dump excessive volumes of water as a means of dissipating excess heat as outlined in AS2712:2007 “no-load” clause 7.4.3 and test methodology in Appendix F.

    If you haven’t already got that plumber out to bypass the hills system, I’d just remove the steam relief valve as it sounds like it’s the issue. A $5 part from bunning just to cap the hole would be all you need.. apricus don’t use it and the system are almost identical. I actually discussed the steam relief valve with the apricus rep. I was worried that the extra pressure (by not having one) would cause issues. The rep had a clear answer. The extra pressure causes the water to expand. This then goes back to the hot water tank which has it’s own pressure relief valves so the need for the steam relief value is not required. Only issue is you hear a little bit more noise.. (sounds a bit like a pop) when the cold water hits the hot.

    You can see the steam relief valve in:

    It’s the little white thing above/right of the word ‘hills solar’.

    A better picture of it is at:
    That diagram also has a tap right next to it.. if hills have installed the tap, just turn the tap off and see if it fixes your problem.

    To permanently remove the steam valve process would be:

    1> Early in the morning before too much sun has hit the tubes
    2> Put a blanket across the tubes (to block sun)
    3> Press & hold ‘pump’ on the controller for a good 2 minutes.. to force colder water through the system
    4> Turn off controller
    5> Remove steam relief valve & cap
    6> Turn controller back on, run pump, check for leaks
    7> Remove blanket

    The other thing we did was remove the hot water tempering valve. This limits the temperature of the water to 50 degrees… that just wasn’t hot enough for us. Officially it’s required by law to prevent scaulding (as the water in the tank can get well over 60 degrees). But when your washing the dishes, 50 degrees is just cold. (See:
    You can see a picture of the tempering valve at: (ours had an orange cap)
    We just make sure we turn the cold on first then slowly add hot… and rather than the government being over protective of our kids burning themselves, just teach the kids not to touch the hot water. (In summer the water can get VERY hot).

    Hope that helps and good luck which ever way you go.

  • Diana Taylor said,

    Thankyou so much for your advice we have removed the valve now have fantastic hot water.Despite now enjoying great hot water I wouldn’t advise anyone to touch Hills once they sell you the product they are not interested in any customer service we ound them uncareing and rude even in the warranty period.

  • Andy said,

    Hi, I am Andy from china solar water heater company, Apricus solar collector is good, but our company solar collector can compete with them. if anyone interested in our collector please contact with me. solarandy(at)wksolardotcom.

  • Solar Power Adelaide said,

    Nowadays solar panels become a necessary of life its important is being exist in those country where electricity problems facing daily mostly is tough in summer season.

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