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Daisy Chain Geyser Idea.

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Hi Guys!

I've got an older 200L geyser in the roof and have decided to get a newer 150L 3Kw to go easier on my solar during the day.
An Idea I had was to feed the old geyser into the new geyser purely to use the ambient temp in the roof so that the water feeding into the new geyser isn't as cold.

Not sure if it's viable though, but I will have the piping done so I can cut out the old geyser if required for any reason. Just wanted to see if it's a worthy idea!


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1 hour ago, JustinSchoeman said:

There is a guy on the other forum who did something similar, except he heats the 'old' geyser with excess solar once his battery is charged.

I am not sure how much ambient heating will get you, as geysers tend to be fairly well insulated.

That's true, it's a pretty old square geyser and I think it's losing a lot of heat overnight. 
I've ordered a Geyserwise kit, and I could probably use it to check how that temp differs to the tap water temp, especially in winter.

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The concept of geysers in series is an excellent one.

My thinking is to use excess PV solar during the day to heat the first geyser.

First geyser then feeds the second geyser.

Second geyser can then have a smaller element, say 1kw or 2kw for a 150L instead of 3kW and take power from inverter/battery combo.

Given that my hot water heating consumes about 30% of daily electricity then using excess PV solar to heat the first geyser is an alternative to adding more battery capacity.

Geysers are cheaper than batteries. At this stage I've not researched the best value for money methodology to feed excess solar into the geyser though.

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I also have a 200 & 150 in series with 24 EV tubes. No AC elements, backup is Heat pump feeding both as well. The solar portion doesn't produce high (+45°C) enough temps, as i need +12 more tubes. But the HP gives me warm enough water to shower in 5min. Busy with Sunsynk install, and will run HP during Sunlight hours to max temp before sundown, should have enough (enough) hot water for morning showers as well. 

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Thanks Guys,

Got the plumber to do the install, I'll test how much the temps between tap and ambient geyser differ, and if it's isn't a major difference, I can always add a small 1kw element to the old geyser that can be used with excess solar.

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Geysers are generally well insulated, even the old types so you are not going to get much heat transfer from the ambient to the geyser. 

I would definitely add an element in there even if it can get to say 40 degrees without an element. I would then heat the thing once a week to 65 degrees. Legionella bacteria would otherwise love that environment. 

I have a 150l geyser that came with the house. Its out on a flat roof and is still going strong. Added a geyserwise to it that only turns it on at midday and heats it to 65 degrees it also comes on if water temp drops below 50. I then added a thermosyphon evacuated tube system with a 200l geyser that then feeds into the 150l. I have since connected a 2kw element in the 200l for winter when the evacuated tubes don’t do much. I then heat this to 80 degrees. So in essence I have 350l of hot water. The 150l hardly ever comes on other than at midday. 

Depending on your solar setup and how much of excess power you have, I would connect the 200l as well, and heat it as much as possible. Hot water heater with solar power and stored for evening use results in massive savings. 

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