Browse Forums Eco Living 1 Apr 01, 2016 12:25 pm Hi There, I am looking to upgrade our solar hot water system and wondering if anyone has any advice on what would be better/ more efficient A heat pump v's solar. Also looking to see what would be more cost effective in terms of upfront cost v's life time cost. Here are the two i am looking at: http://www.saveenergysavemoney.com.au/product-listing/heating-cooling/hot-water-systems/solar.aspx or http://www.saveenergysavemoney.com.au/product-details/heating-cooling/hot-water-systems/heat-pump/odysseo2.aspx Ideally i the system with the least amount of maintenance, i understand heat pump hot water systems can actually require a lot of upkeep over time and that solar systems tend to spring leaks making them less efficient. Thanks, Sam Re: Heat Pump hot Water v's Solar Hot Water System 2Apr 01, 2016 3:00 pm A couple of good sites to ask this question would be; Alternative Technology Association forums, http://www.ata.org.au/forums/ and Whirlpool's Greentech forums, https://forums.whirlpool.net.au/forum/143 I don't have any experience with either solar thermal or heat pumps. But I do like the sound of heat pumps powered by solar PV throughout the day. Although solar thermal is more efficient than solar PV, it can be a bit of a nightmare in some situations. Sometimes requiring lots of boosting in cold climates in winter, to avoid cold showers for large families. Also once water is heated any additional solar energy is just wasted. With solar PV, once water is heated additional electricity produced can be used for many, many applications, from air con & heating, to washing & fridges. For this reason I'd prefer to save roof space for solar PV. Due to the cost of solar thermal & heat pumps, many people are advocating installing medium to large solar PV systems, & using normal electric domestic hot water systems. The element must be reduced in size, so that the consumption of the hot water system will not be larger than the amount of electricity produced by the solar PV system at any one time. As for maintenance of heat pumps. I haven't heard of the brand you mentioned, but I'm no expert. I'd be very careful, & study up on this. It sounds like the quality of heat pumps varied dramatically across brands. Rheem & Dux seem to be very, very poor. While Sanden seem to be the best reviewed. Siddons & Stiebel Eltron also get good reviews. Hydrotherm seems to get good reviews for a cheaper unit. Along with the quality of the products, I believe the noise they produce also varies substantially. Not sure if all of these things have changed recently, as much of this info is quite old. Some brands, like Siddons, also have bolt on units. These can be bolted on to a normal hot water tank. Seems like a good idea, as often the tank is the first thing to pack up, when it corrodes through. From memory, I think that was one of the problems with Dux, the tank would corrode through, & the whole system would need replacing. With the Siddons, you'd just replace the tank. Whirlpool has many threads on all these heat pumps, & solar thermal. Best of luck. Re: Heat Pump hot Water v's Solar Hot Water System 3Apr 01, 2016 3:42 pm Great advice from ddarroch, for what it's worth we went hydrotherm heat pump and 5.2 PV. We're an all electric house running induction cooktop in place of gas. Loving the whole set up, even with 6c feed in tariff last power bill $83, we completely covered our power requirement with solar credit it's the supply charge causing the bill. Roll on battery storage competition then we're going off grid! Heat pump is under house, PVs north facing. Oh hydrotherm is quiet, some heat pumps can be loud. Can't help with solar hot water comparison. Custom build Northern NSW viewtopic.php?f=31&t=72217 Re: Heat Pump hot Water v's Solar Hot Water System 4Apr 01, 2016 5:30 pm Great thanks, I knew it wasn't going to be a quick process, we have a 6kW PV solar system already on the house however 3 kids and a pool seems to drain it easily i am hoping that adding a solar hot water system will be the final addition to free us of electricity bills. I'll check out the other forums and go from there. Re: Heat Pump hot Water v's Solar Hot Water System 5Apr 02, 2016 9:07 pm We have a Sandan heat pump hot water system and PV system. Very happy with how it is working so far. It was installed about 12 months ago. Can't comment on solar hot water though. Re: Heat Pump hot Water v's Solar Hot Water System 6Apr 03, 2016 9:59 am dolphinblu We have a Sandan heat pump hot water system and PV system. Very happy with how it is working so far. It was installed about 12 months ago. Can't comment on solar hot water though. I have had solar hot water systems for many years. I have a 2 panel system that provides free hot water for 7 months of the year and reduced energy cost for the rest of the year. A large family would require a 3 panel system. My electric booster element is connected to off peak "K" tariff which is half the cost of the normal tariff. The hot water tank has a sacrificial anode to protect it from corrosion. The only maintenance cost is replacing this anode every 5 years. My first solar hot water system lasted 20 years. I only replaced it when it started to leak. The leaks were in the fittings and connections to the hot water system, not in the actual tank. One down side of a solar hot water system is if the house is un-occuppied for extended periods of time (especially during summer). I.E. a holiday house. In this situation the water will start overheat and the system will dump water to cool the remaining water in the tank down. Note that the water coming out of a solar hot water system can be very hot so copper hot water pipes must be used, not plastic, at least up to the thermostatic mixing valve. Note heat pumps when operated in mild to warm conditions have a coefficient of performance greater than about 2.5 This means that under these conditions they make 2 to 3 times more hot water than the energy they use. However heat pumps do not perform well in very cold conditions as their coefficient of performance reduces as the outside temperature drops. In areas subject to frequent frosts or near to below freezing conditions heat pumps do not perform very well. Re: Heat Pump hot Water v's Solar Hot Water System 8Apr 11, 2016 9:35 am One of the issues with heat pump hot water is that the heat pump is part of the tank system, so any failures requires the replacement of everything. Evacuated Tube systems work the best, and we only had to boost once last year, and that was only for the one day when the tank cooled down (we isolated the power from the boost, so we know when the boost was needed). Our system is an Apricus 315l 30 tube with electric boost, and we're in South East Queensland, which makes it easier to go without boosting it. Heat pump systems don't work as well when you are in the cooler climates too. Owner Building at Jimboomba Woods in Logan City Qld. Blog : http://bandlnewhomebuild.blogspot.com H1 thread : viewtopic.php?f=38&t=68283 . Re: Heat Pump hot Water v's Solar Hot Water System 9Apr 11, 2016 2:47 pm bpratt One of the issues with heat pump hot water is that the heat pump is part of the tank system, so any failures requires the replacement of everything. Evacuated Tube systems work the best, and we only had to boost once last year, and that was only for the one day when the tank cooled down (we isolated the power from the boost, so we know when the boost was needed). Our system is an Apricus 315l 30 tube with electric boost, and we're in South East Queensland, which makes it easier to go without boosting it. Heat pump systems don't work as well when you are in the cooler climates too. You can also get bolt-on heat pump models, which bolt on to a normal hot water storage tank. For Queensland solar thermal seems to be the best, requiring very little boosting if appropriately sized. However, for southern latitudes, although heat pumps do operate less efficiently, the general consensus seems to be that in dollar terms they out perform solar thermal. In cool climates, solar thermal may require plenty of expensive boosting, particularly in winter. As for the two types of solar thermal, in cooler climates evac tubes out perform flat plates substantially, while in hotter climates there isn't too much between the two different styles. Re: Heat Pump hot Water v's Solar Hot Water System 10Apr 15, 2016 6:49 am Solar hot water, especially in a sunny climate like most of Australia, is an absolute no brainer in my view. It is by far the most efficient way to use solar energy and you get a zero-maintenance energy battery (i.e. the hot water tank) as well. We have a Solahart 320L rooftop solar unit, with a 1.8kW electric backup element with thermostat control. About a year ago I turned the HWS circuit breaker off as an experiment. It's still off to this day and we have never not had steaming hot water. Building Services Engineer Renovating our 1960's modernist home in Brisbane https://forum.homeone.com.au/viewtopic.php?f=53&t=82091 Re: Heat Pump hot Water v's Solar Hot Water System 11May 26, 2016 2:40 pm Great posts - we are about to build and had planned to not use gas at all. Just trying to pick which system we should go for but leaning towards heat pump - based in Gold Coast Re: Heat Pump hot Water v's Solar Hot Water System 12May 26, 2016 2:40 pm Does anyone have a recommendation on brands? Re: Heat Pump hot Water v's Solar Hot Water System 13Jun 29, 2016 7:16 pm bpratt One of the issues with heat pump hot water is that the heat pump is part of the tank system, so any failures requires the replacement of everything. Evacuated Tube systems work the best, and we only had to boost once last year, and that was only for the one day when the tank cooled down (we isolated the power from the boost, so we know when the boost was needed). Our system is an Apricus 315l 30 tube with electric boost, and we're in South East Queensland, which makes it easier to go without boosting it. Heat pump systems don't work as well when you are in the cooler climates too. Our heat pumps are located beside the tank. In the same way an air conditioner motor is located on a concrete base outside the house. Re: Heat Pump hot Water v's Solar Hot Water System 14Jul 05, 2016 3:48 pm dolphinblu Our heat pumps are located beside the tank. In the same way an air conditioner motor is located on a concrete base outside the house. That's a good way to have, the heat pump being separate from the tank... the issue with some is that if the heat pump fails, the entire system has to be replaced. Owner Building at Jimboomba Woods in Logan City Qld. Blog : http://bandlnewhomebuild.blogspot.com H1 thread : viewtopic.php?f=38&t=68283 . Re: Heat Pump hot Water v's Solar Hot Water System 15Jul 05, 2016 5:16 pm releigh1980 Does anyone have a recommendation on brands? Check the forum I listed above, https://forums.whirlpool.net.au/forum/143 I've heard Sanden & Siddons are supposed to be good, though I have no first hand experience. Rheem, Dux were supposed to be bad I think, from old threads though. Re: Heat Pump hot Water v's Solar Hot Water System 16Jul 05, 2016 5:17 pm ddarroch releigh1980 Does anyone have a recommendation on brands? Check the forum I listed above, https://forums.whirlpool.net.au/forum/143 I've heard Sanden & Siddons are supposed to be good, though I have no first hand experience. Rheem, Dux were supposed to be bad I think, from old threads though. Re: Heat Pump hot Water v's Solar Hot Water System 17Jul 07, 2016 8:26 pm We have Sanden heat pumps. Purchased from a company in Melbourne. Re: Heat Pump hot Water v's Solar Hot Water System 18May 25, 2020 4:11 pm TraceyWayne Great advice from ddarroch, for what it's worth we went hydrotherm heat pump and 5.2 PV. We're an all electric house running induction cooktop in place of gas. Loving the whole set up, even with 6c feed in tariff last power bill $83, we completely covered our power requirement with solar credit it's the supply charge causing the bill. Roll on battery storage competition then we're going off grid! Heat pump is under house, PVs north facing. Oh hydrotherm is quiet, some heat pumps can be loud. Can't help with solar hot water comparison. Hi Tracey, Planning for a heat pump myself. It's been sometime now, how is the hydrotherm holding up? Re: Heat Pump hot Water v's Solar Hot Water System 19Jul 19, 2020 9:02 pm We had a Sanden for 7 years at previous house, and have moved and are planning to get another one. It draws 1000W for 2-3 hours for 2 people (one of who has long showers) and was at least 90% powered from Solar PV all year as opposed to Solar Thermal which needs expensive boosting. If you are planning to get off gas, then it is a no brainer in my opionion. IT also means that roof space is producing useful energy all day, not just when you need hot water. the sun master is the solar heating to "warm" the water in the tank the S26 is your hot water system which will heat the water (25 degrees?) so with both turned on you… 2 14074 instantaneous is three phase and draws heaps of current, the efficiency comes from not storing it so you don’t lose heat to the environment. The problem is it is not… 5 1350 |