Myatix Posted October 29, 2022 Share Posted October 29, 2022 (edited) Hi All, I am planning on installing a Vaillant aroTherm Plus 7kw and want to also use the My PV AC-Thor solar PV diverter to control a 3rd party immersion heater. Does anyone know if Vaillant’s uniStor 300l (20235274) cylinder immersion heater can be changed for a 3rd party immersion heater to be used together with Solar PV? Or do I need to find an alternative cylinder for the arotherm plus ASHP? Thanks! Edited October 29, 2022 by Myatix Link to comment Share on other sites More sharing options...
PeterW Posted October 29, 2022 Share Posted October 29, 2022 Vaillant immersion is a standard immersion so not sure why you would want to change it ..? Never seen the AC-Thor in the flesh but it’s nearly double the price of the market leaders and all for a nice colour screen … what is taking you down that route ..? Link to comment Share on other sites More sharing options...
Myatix Posted October 29, 2022 Author Share Posted October 29, 2022 I have an SMA Home Manager which is a smart meter for my solar inverter that also acts as a smart device the AC-Thor integrates directly with the home manager. That’s the main reason Link to comment Share on other sites More sharing options...
HughF Posted October 30, 2022 Share Posted October 30, 2022 The Unistor immersion is a standard immersion, as has been already stated. No need to change it. Link to comment Share on other sites More sharing options...
PeterW Posted October 30, 2022 Share Posted October 30, 2022 21 hours ago, Myatix said: I have an SMA Home Manager which is a smart meter for my solar inverter that also acts as a smart device the AC-Thor integrates directly with the home manager. That’s the main reason Does the SMA see whole house load then to be able to divert to the immersion ..? Your only other issue may be the Unistor immersion being pre-wired into the controller to do crap such as sterilisation cycles and so on. You then may need to RTFM to see if the controller has an external contact that allows you to power the immersion directly, or wether the sparks can remove it from the controller and the Vaillant not have a hissy fit that it can’t see the immersion load - some ASHP controllers don’t play nicely. Link to comment Share on other sites More sharing options...
Myatix Posted October 30, 2022 Author Share Posted October 30, 2022 6 hours ago, PeterW said: Does the SMA see whole house load then to be able to divert to the immersion ..? Your only other issue may be the Unistor immersion being pre-wired into the controller to do crap such as sterilisation cycles and so on. You then may need to RTFM to see if the controller has an external contact that allows you to power the immersion directly, or wether the sparks can remove it from the controller and the Vaillant not have a hissy fit that it can’t see the immersion load - some ASHP controllers don’t play nicely. Yes the SMA see’s the whole house load, the other reason for using a MYPV AC-Thor is that it supports 3 phases which Things like the NyEnergi Eddi don’t, unfortunately! It’s important to be able to change the immersion heater for a 3rd party immersion as most immersion heaters don’t like being turned on and off and running on load loads which is the whole point of a PV diverter. Link to comment Share on other sites More sharing options...
ProDave Posted October 30, 2022 Share Posted October 30, 2022 5 minutes ago, Myatix said: It’s important to be able to change the immersion heater for a 3rd party immersion as most immersion heaters don’t like being turned on and off and running on load loads which is the whole point of a PV diverter. That is the bit that is not making sense. The actual immersion heater is nothing special, it is a waterproof resistor. Changing it will do nothing. What you probably mean is if the immersion heater is connected to another controller e.g. for a backup or a periodic high temperature cycle then yes there could be a problem, so why not just disconnect it from that controller, it is probably not needed anyway, and just connect your diverter as the only thing connected to the existing immersion heater? Link to comment Share on other sites More sharing options...
HughF Posted October 30, 2022 Share Posted October 30, 2022 1 hour ago, Myatix said: Yes the SMA see’s the whole house load, the other reason for using a MYPV AC-Thor is that it supports 3 phases which Things like the NyEnergi Eddi don’t, unfortunately! It’s important to be able to change the immersion heater for a 3rd party immersion as most immersion heaters don’t like being turned on and off and running on load loads which is the whole point of a PV diverter. As ProDave says, an immersion is a resistor, you can turn it on and off as fast as you like. Changing the element will do nothing except hurt your wallet. Link to comment Share on other sites More sharing options...
Radian Posted October 30, 2022 Share Posted October 30, 2022 From their website: AC•THOR works perfectly with our immersion heater but it can also be easily used with existing heating rods. Link to comment Share on other sites More sharing options...
Myatix Posted October 31, 2022 Author Share Posted October 31, 2022 On 30/10/2022 at 17:46, ProDave said: That is the bit that is not making sense. The actual immersion heater is nothing special, it is a waterproof resistor. Changing it will do nothing. What you probably mean is if the immersion heater is connected to another controller e.g. for a backup or a periodic high temperature cycle then yes there could be a problem, so why not just disconnect it from that controller, it is probably not needed anyway, and just connect your diverter as the only thing connected to the existing immersion heater? The reason I wanted to know if the uniStor immersion could be changed is based on the statement also found on the MYPV website stating with regards to their own immersion heater. Due to their special design, there are only very low thermal surface loadsof the heating elements, which directly contributes to an increase of the product life-span. I didn’t really want to buy a cylinder that would last 25 years and find out the immersion broke as a result of using the AC-Thor??? Link to comment Share on other sites More sharing options...
ReedRichards Posted October 31, 2022 Share Posted October 31, 2022 Assuming you get the AC-Thor rather than the AC-Thor 9s then the immersion heater supplied to go with it consumes the standard 3 kW. I'm not sure what "very low thermal surface loads" actually means but if you make the immersion heater larger than usual then the surface will get less hot than a standard element. Regardless, an immersion heater should be easy to replace if one ever did fail. Link to comment Share on other sites More sharing options...
ProDave Posted October 31, 2022 Share Posted October 31, 2022 And for very much of the time an immersion heater heater fed from a PV dump controller is running at a low power input. 1 Link to comment Share on other sites More sharing options...
Benguela Posted November 2, 2022 Share Posted November 2, 2022 Hi Myatix! I'm also interested in getting the SMA Home Manager.... because I can integrate it with my Stiebel Eltron GSHP. 1. Is it any good? 2. What inverter do you have for your solar PV? Link to comment Share on other sites More sharing options...
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