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!

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.

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.

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.

I daisy-chained two 150l at my previous place in a solar setup. Water from both geysers would flow through the solar collector, but only the last geyser (which fed the house) had an element connected to it. 

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. 

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.

On 2021/04/11 at 10:35 AM, Rooney Hat said:

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.

I’m curious of how this worked out for you, did you test the system with any results?

I did something similar but have put my two geysers in parallel, I have my old normal electric 150ltr geyser in the ceiling that I kept just as a spare and installed a HP evacuated tube 200ltr geyser on the roof about 2years ago. For the two years I have been using only the EV solar geyser and have switched off and drained the spare old geyser, but about May this year I had a small problem on the EV geyser controller that prevented me from using the element so I decided to re-instate the spare geyser in ceiling I opened it’s valves and switched on the element I also just left the EV tube geyser to carry on as normal, so-that I could see how it will work. Well it changed my mind on thinking geysers need to be in series only, as I have not had a day with anybody complaining about cold water since May. I have fixed my EV solar controller in the meantime but hardly used it. I now power the old geyser in the ceiling mostly with excess solar PV and because the two geysers both feed my taps at the same time the geysers seem to maintain higher temperatures at all times and need less heating. 

I think I will add a circulation pump now for the summer to circulate hot water through the two geysers it should assist in keeping the EV tube geyser more under control due to their extreme efficiency in summer when they tend to blow out hot water when temperatures can go over 89degrees. 

Damn, that's pretty interesting. Would not expected the parallel to work as it should mix the temps, but I guess that you're halving the drain, so it will be essentially like having a 350L geyser. The circulation pump idea should also do a great job in summer and will likely eliminate the need to run the electric geyser, especially at temps that high.

I was using the my 150L as my main with a 3kw element and the unpowered 200L 4kw as the feed, but was running out of hot water too quickly during the first bit of winter. 
So I decided to try changing my solar timings and temps, I turn on the 4KW element at 12 till 1pm at 60 degrees, then have my 3kw on from 1pm to 3pm at and again from 4am to 6am with the thermostat set to 50 degrees. It made a massive difference immediately. 
I only have 7kwh of battery power at night, and people need hot water in the morning, but after this change there is hot water nearly all the time, and the geyser only takes about 15mins to heat to 50 degrees at 4am, saving me battery power.

I had to get an extra 2 panels to accommodate the extra load during the day, as I also have a 100L 2kw geyser in the cottage that I power from 10:30 to 12. So I am maximizing my solar currently and have ordered another 2 panels just so I can also get my batteries up to 100% before 5pm.

15 hours ago, Gerrie said:

I’m curious of how this worked out for you, did you test the system with any results?

I did something similar but have put my two geysers in parallel, I have my old normal electric 150ltr geyser in the ceiling that I kept just as a spare and installed a HP evacuated tube 200ltr geyser on the roof about 2years ago. For the two years I have been using only the EV solar geyser and have switched off and drained the spare old geyser, but about May this year I had a small problem on the EV geyser controller that prevented me from using the element so I decided to re-instate the spare geyser in ceiling I opened it’s valves and switched on the element I also just left the EV tube geyser to carry on as normal, so-that I could see how it will work. Well it changed my mind on thinking geysers need to be in series only, as I have not had a day with anybody complaining about cold water since May. I have fixed my EV solar controller in the meantime but hardly used it. I now power the old geyser in the ceiling mostly with excess solar PV and because the two geysers both feed my taps at the same time the geysers seem to maintain higher temperatures at all times and need less heating. 

I think I will add a circulation pump now for the summer to circulate hot water through the two geysers it should assist in keeping the EV tube geyser more under control due to their extreme efficiency in summer when they tend to blow out hot water when temperatures can go over 89degrees. 

Not so sure about having it in parallel like that.

I have this almost exact setup except is in series, the solar geyser on the roof preheats water and feeds into my 200ltr electric geyser in the roof.

Installed a sensor in the solar geyser to record the temperature. 

 

We now have almost endless hot water 🙂 

I have a 2kw element in my 200ltr electric geyser which I heat up during the day to make sure we have at least 200ltr of hot water.

 

I have a flow in node red using Ewelink smart breaker switches to switch my geysers on and then switch them off when the thermostat kicks out and switch the next one on.

Works very well and all my water is usually heated up by 13:00 and stops my inverter from getting overloaded.

16 minutes ago, Sc00bs said:

I have a flow in node red using Ewelink smart breaker switches to switch my geysers on and then switch them off when the thermostat kicks out and switch the next one on.

Works very well and all my water is usually heated up by 13:00 and stops my inverter from getting overloaded.

What software/system do you use to control all of this?

53 minutes ago, Rooney Hat said:

Would not expected the parallel to work as it should mix the temps

It does mix and send hot water from the electric geyser in the ceiling to the evacuated geyser on top of the roof especially during the night, it took me a while to realize this because after everyone showered at night my EV geyser on roof would be say 44degrees and without giving it any power during the night it would sometimes be higher the next morning like 50degrees thats when I realized the hot circulation is happening. Unfortunately I cannot see the temperature of the geyser in the ceiling but would expect it to be slightly colder when it has not been powered for a couple of hours.

 

1 hour ago, Rooney Hat said:

there is hot water nearly all the time, and the geyser only takes about 15mins to heat to 50 degrees at 4am, saving me battery power.

Your first geyser in line seem to make the difference and is key for longer periods of hot water, I might change my system to series but for now I’m still experimenting with the parallel setup and am just wondering where to fit the circulation pump.

41 minutes ago, Sc00bs said:

Not so sure about having it in parallel like that.

It was never my intention to run it in parallel like the but when I installed the solar geyser I did not want to remove the old geyser but rather keep it as a spare, as I thought removing a perfectly good geyser would be a waste.

49 minutes ago, grant.cpt said:

What software/system do you use to control all of this?

I use Home Assistant with Node Red/InfluxDB & Grafana, links up to my Sunsynk 8kw inverter and gets all the production data from there. 

I use the solar power prediction in Home Assistant to make a decision at to what flows to run every morning at the start of the routine as I have a Node Red flow for low solar power days and one for high solar power days (pool etc) 

There are some instructions as to how to do it on the forum but have been thinking of doing a video guide 🙂 

36 minutes ago, Gerrie said:

It was never my intention to run it in parallel like the but when I installed the solar geyser I did not want to remove the old geyser but rather keep it as a spare, as I thought removing a perfectly good geyser would be a waste.

I was running out of how water and decide to connect up my old geyser again so I can add that as well, eventually decided to pre-heat the water using the solar and feed that into my old 200ltr electric, works very well as we have loads of hot water now. 

On 2021/08/29 at 1:23 PM, Sc00bs said:

I use Home Assistant with Node Red/InfluxDB & Grafana, links up to my Sunsynk 8kw inverter and gets all the production data from there. 

I use the solar power prediction in Home Assistant to make a decision at to what flows to run every morning at the start of the routine as I have a Node Red flow for low solar power days and one for high solar power days (pool etc) 

There are some instructions as to how to do it on the forum but have been thinking of doing a video guide 🙂 

Thank you! Def need to look at this. As I'm not fully utilizing the free energy from the sun at the moment