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Author Topic: Nova Solar Water Heating  (Read 6032 times)

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Offline dacker

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Nova Solar Water Heating
« on: February 01, 2011, 10:20:06 AM »
Hi there,

Just been reading the posts with interest as I had a guy from Nova Energy come over bragging about the solar water heating. I thought installing a solar water heating panel would be a good investment for when we sell up but not so sure now.

We installed a new fire place with wetback and 180L water cylinder just under 2 years ago and I was told they can retrofit it using our existing hot water cylinder.

Question: "How efficient will our wetback be or more so what effect will it have on our cylinder and wetback".

Any help would be greatly appreciated.

Linkback: https://www.plumbers.nz/solar-heating-and-heat-pumps/9/nova-solar-water-heating/575/

Offline Plumber

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Re: Nova Solar Water Heating
« Reply #1 on: February 01, 2011, 11:39:09 PM »
Hi Dacker,

Just a few questions on your existing system. How far away is the wetback from your HWC. Also if possible can you tell me how much time is between every thermo siphon? Also please share what HWC you have at the moment.

thanks Plumber
Please note that the advice I am giving is only my opinion and not necessarily a fact.  Please refer to our terms and conditions.

Offline dacker

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Re: Nova Solar Water Heating
« Reply #2 on: February 02, 2011, 04:01:21 PM »
Hi Plumber

We have a 180L Rheem Low Pressure HWC and this is situated straight through the wall from our wetback. As for the "time between every thermo siphon", your plumbing technical know how has eluded me lol.

I have included 2 photos of my cylinder and you can see the copper piping which goes through the wall into our lounge.

Offline Plumber

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Re: Nova Solar Water Heating
« Reply #3 on: February 05, 2011, 02:54:56 PM »
Hi Dacker, looking at the pictures it seams they have retrofitted your HWC with the wetback. The wrong tempering valve has been used and doesn't cope with High temp output (wetback is an uncontrolled heatsource) this could harm your family, existing plumbing and tapware.
I also hope they insulated the pipe everywhere else. In my question I was referring to how often do you hear the water circulating when your wetback is up and running? Have you tried switching off the power to the HWC and timing how long it takes to heat your water when the Wetback is running?

Personally I would say NO don't add anything else to your existing HWC. Its to small and not designed for this purpose. Solar will heat the 135 Liters in very short time and for the rest of the day your pressure relief valve will discharge water to protect your system. This leads to a quicker deterioration of your valves and HWC. you will also get a higher waterbill due to overflow. If you want solar and wish to save on power there is no point unless you get a HWC that is designed for this purpose. They same cylinder can also be used wetback. 

Please let me know if you have any other questions.

Offline dacker

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Re: Nova Solar Water Heating
« Reply #4 on: February 07, 2011, 03:53:14 PM »
Hi Plumber

Thank you for your input and I see a trip to my local plumber who installed our wetback to ask the hard questions are on the cards which is a shame because they came highly recommended by half the town lol.

Now to get rid of the sales rep >:D from Nova

Offline newguy

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Re: Nova Solar Water Heating
« Reply #5 on: July 26, 2012, 06:47:50 PM »
Several months after I had lost a job to Nova Energy I got the opportunity to go back to site and look at the installation. Months before the client rang me and explained they were 5K cheaper and there was no way I could compete! This was an indirect system on a 600L tank, it involved an expansion tank, pump station, glycol and the whole works + panels!

I should have followed up to make sure they were quoting apples for apples, as far as the owner is concerned he was getting an indirect solar heating system that was 5K cheaper. So when I got back to site what I found was that they simply connected the domestic water to the coil. there is nothing preventing the heated water back siphoning into the main domestic water supply when the pump is off. Additionally they installed 2 ball valves one on the flow and one on the return, whats going to happen when someone isolates both? the only relief I could identify was the cold water expansion on the water main.

Have a look at pictures, would be very interested to get your thoughts on it.         

Offline 07442

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Re: Nova Solar Water Heating
« Reply #6 on: July 26, 2012, 09:20:00 PM »
My initial thought... Something bad is going to happen to that installation and possibly the owners of it..

Offline gordyplum

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Re: Nova Solar Water Heating
« Reply #7 on: July 27, 2012, 09:19:06 PM »
Hi newguy, that effort in pic 1 don't look like a cold water expansion to me, so your explanition could get even worse! Not suprising they could undercut your price so much. I wonder if they will care to defend themselves in this forum, or maybe the board will see the item and act!!!!!!!!!

Offline newguy

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Re: Nova Solar Water Heating
« Reply #8 on: July 28, 2012, 09:59:20 AM »
Thanks for the feedback guys. Sorry I probably should have explained the pictures. The 15mm line is the one going to the T on the Cylinder inlet, its the main water feed to the coil. This is simply to show the direct connection. The CWE is to the left on the 25mm water main but is not in the picture and was existing prior to the install.

My question is, should a RPZ not be on that water feed? Should the water feed be connected to the coil the way it is? This system also does not have any form of reducing valve on the Solar Inlet and is getting over 500 KPA of pressure from the commercial buildings water main up to the panels. How can this be efficient? (also no heat trap on the return and no CWE on the direct feed to HWC only relying on TPR) Are you even allowed to install such a semi closed loop system where fresh cold water is pushed through the heat exchanger. Then use a relief valve on the roof (about 25 meters away)? I looked in AS/NZS 2712 and could not find any references.

If you look at the pump its a standard sized Wilo, can they do 13 meters of head and will it provide 30L/h.m of collector area for 600L as per 2712? I would love to install a flow meter just as an experiment! Would really like to know if this installation in legal. One thing is for sure, legal or not this system wont be saving this guy any money on power absolute waste of time!  :(

Offline integrated

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Re: Nova Solar Water Heating
« Reply #9 on: July 29, 2012, 11:20:52 PM »
heat trap not required as it has non-return valve fitted to return line

if the system is not in area prone to frost then it does not require glycol therefore no problem with potable water as transfer medium - even if it is installed in area prone to frost it doesnt necessarily need glycol as long as the controller has frost protection function

in my opinion it does not require a rpz but should have a nrv fitted between draw-off and cross-connection (rpz's are used far too often and are massive overkill in most cases - they are only required where cross-connection is likely to cause death) additionally should also be reduced in pressure to 100-150kPa and a pressure relief installed on the flow pipe within hwc cupboard or there-abouts (nothing wrong with relief valve on roof as ideally it would be installed as close as practicable to the heat source-just needs to be protected from damage and frost)

not sure how they would set-up or commission the system without some sort of flow reading....

the system WILL still work and WILL be saving money but will never be as efficient as it can or could be - it is a cheap and nasty looking install - is it controlled with a TDC?


generally speaking - WE GET WHAT WE PAY FOR!!





Offline o2b007

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Re: Nova Solar Water Heating
« Reply #10 on: October 04, 2012, 03:10:17 PM »
Back on topic I did a combo system for a guy who works for eeca with solar and wetback to put it simple the solar does little in winter allowing the wetback to do its job when you need it where during summer your not using fire so there for your solar is doing your hot water heating the main thing you need to think about is the design of your system and weather its worth the money you will be spending to achieve this. I have had no dealings with Nova nor there designs but to achieve a well balanced system is very simple.


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