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Is my solar geyser potentially underperforming


SvenA
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Hi all

 

So I have a evt 18 retrofit to my 150l kwikot. Yesterday we had a max of 23 degrees at a uv index peaking at 6/10. When I checked in the morning it was Luke warm, come 17h00, the water was not hot at all. Maybe went up a few degrees.

It has heated up in these conditions before, yes it's a little colder in the mornings, but for 4 months now I have had to switch on my geyser. 

 

Is there a potential fault? In the picture attached, the item in the black box that looks like the thing in your toilet, that was previously leaking but they put a ball valve to stop that. 

Screenshot_20200816-073857_Drive.jpg

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I can hear the circulation pump going, when I felt the pipe by the pump I can feel water moving through it, but the pipe by the tubes and the Pipe feeding the other side of the geyser don't have the same pressure when I feel it. Is the pipe with the pump attached to the geyser the water going to the tubes or returning to the geyser

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15 minutes ago, SvenA said:

It has heated up in these conditions before,

I have installed 15 tube collectors a few weeks back in Bloem when it was freezing cold. The first two days the element wasn't even connected and we reached 70degC in the geyser before 14H00 every day. So I think yours are under performing. 

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On 2020/08/16 at 8:07 AM, SvenA said:

Then it's the water returning to the geyser where the problem lies, water is fed to tubes, just not returning like it should. It's still under warranty so uber solar should fix it.

please keep us posted on what the issue/outcome was.

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Tip, check the pump every 6 months. They like to "kalk" up inside. We got this problem in our estate where we got solar geysers. It's easy to clean them. 

The other thing that you need to check, if you temp don't go up but the pump is running, then there is air bubble in the top side of the geyser. What you do is, open the high pressure over run valve en start the pump, it will help to get the air out of the pannel and the geyser. I had this problem when my mains burst. Twise in one week. 

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7 hours ago, Gerlach said:

Tip, check the pump every 6 months. They like to "kalk" up inside. We got this problem in our estate where we got solar geysers. It's easy to clean them.

How do you clean it? Just loosen it and then flush? 

Also I see you mention starting the pump to get the air out, is there a way to manually start it? 

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You close the small tap between the geyser and pump that go's to the pannel. Then you unscrew the pump between the fittings and take it off and take thr pump apart. I got one of thr geyser wise setups. 

To run the pump manually i usually take the cable out of the geyserwise controller at the pump. I made up a cable to connect to that to start the pump then. 

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So they replaced the motor, but I still don't have the temps I am expecting. I have done as was suggested by running the valve and trying to Remove the air bubble, run it three times now and nothing. I do notice when I open it, that the water is cold. There is a small leak by the orange pipe which leads outside for the water to escape attached to the valve, and this is cold. 

 

Any ideas?

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The owner of uber solar called me after a medium review on hello Peter. It wasn't the the most pleasant conversation I had but they are going to look at the system, so either it's nothing and just to cold to heat up, or there is a bigger issue going on. 

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@SvenA  I am surprised that an installer would cover part of the evacuated tubes with a photovoltaic solar panel. That reduces the heat collection capability of the system. Just to clarify, water does not flow through the evacuated tubes but only through the metal manifold at the top into which they plug. Also UV light does not heat anything, infrared light does. You may want to Google evacuated tube water heaters for relevant information.

A simple test to determine if water flows through the heater would be to shut of the input feed from the municipal supply at the geyser. Then disconnect the connecting pipe from the heater at the top of the geyser and start the pump. If water flows all is fine, otherwise you have an air lock or other blockage.

On my own similar system I added a Geyserwise to control the pump and added a 15AH 12V sealed lead acid battery. This was done to make the system totally independent of mains power except for the heating element. More importantly, if your pump is powered by the solar panel directly, it will start pumping as soon as the solar panel produces enough power. At that time the sun does not yet supply enough heat for the evacuated tubes to heat the water. So you end up pumping colder water from the bottom of the geyser to the top and thus cooling down the water at the top from where hot water is fed to your house. That was my experience prior to installing the Geyserwise and it was confirmed by my first home made controller which measured temperatures at the top and bottom of the geyser. The Geyserwise has automated heating with electricity and can be set to do that at convenient times to suit your lifestyle. Mine goes on at 04:00 and 17:00 in winter and not at all in summer. It will only use mains power if the water is not above the minimum programmed temperature. It also incorporates a battery charger to charge the battery from the solar panel. There may well be other suitable controllers available. 

If and when your installer turns up, insist that they mount the solar panel at a location where it does not cover the evacuated tubes and demonstrate proper water flow by using my suggested simple test. There appears to be no insulation on the pipe running around your collector. If that is a feed pipe to or from the collector, you are losing a great deal of heat and you should demand that insulation is added. 

 

 

Edited by ebrsa
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8 hours ago, ebrsa said:

Geyserwise to control the pump

The installer suggested I don't get one due to, in his view, they have a 50 percent failure rate. My only reason for this query is that I have had to turn on my geyser everyday for 5 months now.  I used to have to do it once in a while, then the cistern started overflowing, and that was the last time I had hot water from it. Since then the pump has been replaced. The installer says I need to add 12 more tubes to expect more results but as Jaco said, he gets performance from a 15 tube he installed around a month ago

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2 hours ago, SvenA said:

The installer suggested I don't get one due to, in his view, they have a 50 percent failure rate. My only reason for this query is that I have had to turn on my geyser everyday for 5 months now.  I used to have to do it once in a while, then the cistern started overflowing, and that was the last time I had hot water from it. Since then the pump has been replaced. The installer says I need to add 12 more tubes to expect more results but as Jaco said, he gets performance from a 15 tube he installed around a month ago

Lots of Geyserwise installations out there, mine included for around 4 years. If there was a 50% failure rate I doubt there would be that many installed.

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@SvenA  I would not have much confidence in the views of an installer that covers part of the evacuated tubes with a photovoltaic solar panel. My Geyserwise has been working flawlessly for about 2 years now. But there are other brands available although I don't know what features they offer.

My heater has 12 tubes but it is only my wife and I in the house. Thus far my geyser electricity consumption, measured by an Owl meter, amounts to about 350KWh for the year. At present the Geyserwise turns on the heater at 04:00 and off not later than 05:00 as my electricity supply, controlled by ICC-Pi, then turns to battery/solar power which I don't want to use for water heating considering the 2000W load of the geyser. Mostly the mains to the geyser stays on for less than 30 minutes. 

Did your installer cover the pipes to and from the solar heater with insulation. If not you will be losing a great deal of heat and the system will have low efficiency. I ask because the uninsulated pipe on your photo raises suspicion that other pipes to and from the solar heater are probably also not insulated. 

 

Edited by ebrsa
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7 hours ago, ebrsa said:

Did your installer cover the pipes to and from the solar heater with insulation

There is a foam around the pipes leading in and out of the manifold, but not around the pipes in the ceiling itself. I have asked @Jaco de Jongh to quote me on a SR81, perhaps he can check out the installation next time he is around and we can take it from there. Its only me and the wife as well 

 

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Sven

Something to check:-

Is your water and electricity bill drastically higher than previous months ?

We did a repair job at a retirement village with 2x 200 litre geysers in parallel and they had NO hot water.

Checked all the usual - solar controller working; pump working(this case an AC pump); no air lock etc etc.

After much investigation we found that there was a big leak in the geysers hot water pipe underground that was not physically visible. So the water never stayed in the geysers long enough to get heated by solar and also the heating elements were on for half the day as backup heating. Fixed leak and problem solved.

Needless to say, their water and electricity bill was substantially higher than normal. Also the old folk did not have hot water....

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7 minutes ago, GreenMan said:

Is your water and electricity bill drastically higher than previous months ?

I have been on a prepaid meter for years already so no major increase in electricity bill, as for the water bill, we did have a small leak just after the meter about 2 weeks ago, which turned into a big leak when the plumber put his spade through the pipe before the meter, which lead to three days of no water as joburg water had to repair it now, and they replaced the meter and it was reconnected, but otherwise I don't see any major jump in the costs of water. And considering the timeframe we talking here(5 months now), it doesn't appear to be that. It could just boil down to a below par installation combined with a issue in the manifold section

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