October 20, 20223 yr Hi, I am looking at ways to get around geyser not using my batteries in the morning to heat up. I have a 200l geyser with a 2kW PTC element. I use my solar system to heat the geyser during the day to 70deg. this gives enough water for evening bath and dish washer. The problem is in the morning. the geyser on at 2am-5am. this will deplete my battery bank and use eskom. I need one more battery to go fully offgrid. just that i want to use this window of they geyser breaking wisely. today my geyser is leaking and i must replace it tomorrow morning with insurance. Option: get a 300l geyser. use a bigger storage capacity and store hot water during the day. Question: is a 2kW element sufficient? What is the max geyser capacity i can push this to. Alternatively what other methods can you suggest. BTW. i dont want to add more batteries, and im not going to add a gas geyser. ill be moving next year and dont plan on investing into the current house.
October 20, 20223 yr 9 minutes ago, KB - Kabelo said: Hi, I am looking at ways to get around geyser not using my batteries in the morning to heat up. I have a 200l geyser with a 2kW PTC element. I use my solar system to heat the geyser during the day to 70deg. this gives enough water for evening bath and dish washer. The problem is in the morning. the geyser on at 2am-5am. this will deplete my battery bank and use eskom. I need one more battery to go fully offgrid. just that i want to use this window of they geyser breaking wisely. today my geyser is leaking and i must replace it tomorrow morning with insurance. Option: get a 300l geyser. use a bigger storage capacity and store hot water during the day. Question: is a 2kW element sufficient? What is the max geyser capacity i can push this to. Alternatively what other methods can you suggest. BTW. i dont want to add more batteries, and im not going to add a gas geyser. ill be moving next year and dont plan on investing into the current house. Without knowing what inverter you have does not make it easy to help. Why can't you just use the grid for the 2h to 5h slot for the next few months before you move. Not sure that one can get a 300L geyser. Due to prices 2 x 150L are normally used.
October 20, 20223 yr Author Sorry man, its growatt inverter and doesnt have many cool features like the one you mention
October 20, 20223 yr 2 X 150l geysers in series would partially solve the problem. i.e. the hot water used in the evening will be replenished with hot water from the second geyser. The two geysers can be heated during the day sequentially. I have a 150l with 3kW element and even when my water is down to 30C it takes max 1:30 to get it to the max Geyserwise temp of 65C. So I could easily heat a second geyser to that temp too. All dependent on the size of the Inverter and panels obviously and of course the solar irradiance on the day. Today my geyser was at 31C and you can see the 3kW element starting at 08:58 and switching off at 10:20. So I could have heated another one from 10:20 to 11:50.
October 20, 20223 yr Author that sound like a good option, i have 2x 5kW Growatts SPF. so i can play with the element config. im not well versed on plumbing. so with two geysers in series, do you need an element for each geyser?
October 20, 20223 yr 3 minutes ago, KB - Kabelo said: that sound like a good option, i have 2x 5kW Growatts SPF. so i can play with the element config. im not well versed on plumbing. so with two geysers in series, do you need an element for each geyser? definitely. Each geyser needs it's own element, else only one will heat. Your water supply to your taps will be lets say from Geyser 1. Geyser 2 then feeds Geyser 1 with hot water. Geyser 2 will be refilled with the municipal water feed just like you have now with a single geyser.
October 20, 20223 yr Author okay, that changes the picture a bit. why cant i just use one 300l geyser and use single 3kw element. i pdont want to pull 6kw. and always heat geyser between 12-2pm when all the morning work is out and battery are fully charged i still have other power needs during the day. i push the system to 80% usage. pool pump, geyser, AC, i do most oven cooking during the day, waching and iron.
October 20, 20223 yr Of course you can use a 300l geyser. Problem is when you use it in the evening it is replenished with cold water which reduces your overnight temp till morning a lot more than refilling it with already hot water. As said, your elements should be timed to run sequentially, i.e. as soon as Geyser 1 is at max temp, only then does Geyser 2 element start. Your own available solar power will determine if you can or can't do it. Alternatively consider a gas geyser for the mornings fed from your 300L geyser that you have set your mind on Edited October 20, 20223 yr by zsde
October 20, 20223 yr Author ill see what the plumber can do tomorrow when they replace the geyser. QQ: the plumber that did my geyser conversion mentioned he did a Thermosiphon. wont that solve the mixing problem. unless its a fancy term that doesnt work. but he that caters for cold water mixing.
October 21, 20223 yr 70 seg? If you're always adding in cold water then turn your thermostat down. That will reduce the run time. But to make the most of any solar solution you have to fit your routine to sun availability.
October 21, 20223 yr Hi @KB - Kabelo What sort of heat loss are you getting from the geyser overnight? Geysers are regulated by SANS 151 (SANS – South African National Standards) and are usually pretty well insulated. According to specifications you should loose 8 to 10 degrees C over a 24 hour period (depending on ambient temperature) If you are loosing significantly more than that you may be loosing heat from your geyser through the hot water pipes connected to the geyser overnight cooling your geyser down. A thermosyphon can be formed on the geyser here cold water from the pipes (heavier) is slowly circulated with hot water from the geyser (lighter) cooling the water in the geyser down. The effect can often be reduced by insulating the hot water pipes leading from the geyser. You can check if this is happening by feeling how hot the pipe is coming out of the geyser after an extended time of non-hot water use in the house to see how much heat you are loosing through the pipes. There is an interesting study on heat loss from geysers in South Africa that can be downloaded from https://www.savingenergy.org.za/wp-content/uploads/2019/05/Report_GeyserStudy_Final-Report-27-November-2014.pdf
October 21, 20223 yr Author Thanks @Sc00bs and @Bobster., so I have insulated the pipes. i am not having heat loss overnight. The wife and kids deplete the hot water reserve from night bath. Then morning I have to use batteries then when they deplete i move to eskom to heat up the water. Say about 2am-5am for morning baths. My option now to increase the water storage = geyser to 300l.
October 21, 20223 yr 24 minutes ago, KB - Kabelo said: Thanks @Sc00bs and @Bobster., so I have insulated the pipes. i am not having heat loss overnight. The wife and kids deplete the hot water reserve from night bath. Then morning I have to use batteries then when they deplete i move to eskom to heat up the water. Say about 2am-5am for morning baths. My option now to increase the water storage = geyser to 300l. Keep this figure in mind. To heat 300L from 20 to 60 degrees will need 14kwh. This is not the measured temp but the whole 300L. 3kW element will take 4hrs40min to achieve the 40 degree increase. Edited October 21, 20223 yr by Scorp007
October 22, 20223 yr Is this not something that can be solved by powering your geyser through a timer and an automatic transfer switch?
October 22, 20223 yr 12 hours ago, KB - Kabelo said: Thanks @Sc00bs and @Bobster., so I have insulated the pipes. i am not having heat loss overnight. The wife and kids deplete the hot water reserve from night bath. Then morning I have to use batteries then when they deplete i move to eskom to heat up the water. Say about 2am-5am for morning baths. My option now to increase the water storage = geyser to 300l. Further on the practical side. Trusses are normally spaced about 760mm apart. A 300L geyser might not fit between the truss spacing even after the roof tiles are removed.
October 22, 20223 yr Author Fair enough, I shall do a like for like replacement on the geyser and look at other ways I save the battery utilisation in the morning. i need to investigate a DIY automation on growat to switch from SBU to SUB priority without manually attending to the inverter.
October 22, 20223 yr 23 minutes ago, KB - Kabelo said: Fair enough, I shall do a like for like replacement on the geyser and look at other ways I save the battery utilisation in the morning. i need to investigate a DIY automation on growat to switch from SBU to SUB priority without manually attending to the inverter. You can do that using parameter 50 on your inverter, you will be able to set the time to switch it on and off. I've never tried but according with the manual that will do it for you.
October 23, 20223 yr Hi @KB - Kabelo I had a similar problem to yours, we kept on running out of hot water because of "excess" hot water usage by the family (2 x teenagers and a wife will do that) 🙂 I switched to a 200ltr solar geyser but we kept on running out of hot water. I still had my 200ltr standard geyser in the roof so I plumbed my solar geyser to feed into my standard 200ltr geyser. We have never run out of hot water since I did this as the water being fed into the regular 200ltr geyser is being preheated by the solar geyser. We essentially have 400ltr's of hot water now. The heat exchange solar geysers are a good option as the whole geyser is not pressurised which keeps the cost down and increases reliability. It is essentially a low pressure geyser with a copper coiled pipe going through it cold water gets fed in one end of the pipe and comes out the other side hot. The other advantage is that you do not get a lot of calcium build up in the geyser as the only water going into the geyser is to top it up occasionally. I purchased mine from Apollo solar and it was half the price of a regular high pressure solar geyser and has been working for the last 12 years without any issues. https://apollotechnology.co.za/copper-collier-system/
October 23, 20223 yr 3 hours ago, Sc00bs said: Hi @KB - Kabelo I had a similar problem to yours, we kept on running out of hot water because of "excess" hot water usage by the family (2 x teenagers and a wife will do that) 🙂 I switched to a 200ltr solar geyser but we kept on running out of hot water. I still had my 200ltr standard geyser in the roof so I plumbed my solar geyser to feed into my standard 200ltr geyser. We have never run out of hot water since I did this as the water being fed into the regular 200ltr geyser is being preheated by the solar geyser. We essentially have 400ltr's of hot water now. The heat exchange solar geysers are a good option as the whole geyser is not pressurised which keeps the cost down and increases reliability. It is essentially a low pressure geyser with a copper coiled pipe going through it cold water gets fed in one end of the pipe and comes out the other side hot. The other advantage is that you do not get a lot of calcium build up in the geyser as the only water going into the geyser is to top it up occasionally. I purchased mine from Apollo solar and it was half the price of a regular high pressure solar geyser and has been working for the last 12 years without any issues. https://apollotechnology.co.za/copper-collier-system/ My neighbor has one of those, he is very happy with it, even with his extended family.
October 25, 20223 yr Author Update on my side: So insurance replaced the Geyser for a like for like. I am exploring parameter 50 on the Growat without them being temperamental. If this work then life is all good. @Sc00bs, unfortunately i dont have any north facing roof area for a geyser. i'll have to manipulate the growat to be functional. If not then i can justify an upgrade to deye and get the time of use settings
October 25, 20223 yr Author On 2022/10/22 at 11:26 AM, Antonio de Sa said: You can do that using parameter 50 on your inverter, you will be able to set the time to switch it on and off. I've never tried but according with the manual that will do it for you. im exploring that option thanks. i have not seen anyone use it. testing will be done tomorrow
October 26, 20223 yr On 2022/10/20 at 8:35 PM, KB - Kabelo said: Alternatively what other methods can you suggest Just my 2c worth since you have an existing solar system: Heat Pump only uses +-860w to heat up your water and store it in the existing geyser with element disconnected/bypassed Edited October 26, 20223 yr by SYC
October 26, 20223 yr 16 hours ago, KB - Kabelo said: im exploring that option thanks. i have not seen anyone use it. testing will be done tomorrow I have used it, it might come on an hour earlier or later you just have to adjust it up or down.
October 26, 20223 yr On 2022/10/23 at 11:26 AM, YellowTapemeasure said: My neighbor has one of those, he is very happy with it, even with his extended family. This looks amazing!
October 26, 20223 yr On 2022/10/23 at 8:24 AM, Sc00bs said: Hi @KB - Kabelo I had a similar problem to yours, we kept on running out of hot water because of "excess" hot water usage by the family (2 x teenagers and a wife will do that) 🙂 I switched to a 200ltr solar geyser but we kept on running out of hot water. I still had my 200ltr standard geyser in the roof so I plumbed my solar geyser to feed into my standard 200ltr geyser. We have never run out of hot water since I did this as the water being fed into the regular 200ltr geyser is being preheated by the solar geyser. We essentially have 400ltr's of hot water now. The heat exchange solar geysers are a good option as the whole geyser is not pressurised which keeps the cost down and increases reliability. It is essentially a low pressure geyser with a copper coiled pipe going through it cold water gets fed in one end of the pipe and comes out the other side hot. The other advantage is that you do not get a lot of calcium build up in the geyser as the only water going into the geyser is to top it up occasionally. I purchased mine from Apollo solar and it was half the price of a regular high pressure solar geyser and has been working for the last 12 years without any issues. https://apollotechnology.co.za/copper-collier-system/ Great suggestion. Also ensure the extra geyser is also well insulated in order to maintain that ambient temperature and if it's in the roof, the trapped heat during the hot days should help to maintain the heat.
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