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Mixergy HP Cylinder and Solar Diverter

Domestic Hot Water & Cylinders

Last Post by bontwoody 3 years ago

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Declan90

(@declan90)

Trusted Member Member

Joined: 3 years ago

Posts: 39

Topic starter 24/09/2023 1:25 am [#1110]

Please can I ask for any thoughts or experience with Mixergy HP Cylinder and Solar Diverter?

The part of me that refuses to turn our gas CH back on until at least the 1st of October is interested in making sure that any system I install has the option for using excess solar (outside of months requiring heating) to supply the DHW, with the potential for even turning the ASHP off over the summer (to avoid any parasitic loads). Or at least allow me to test which is/feels the most cost effective...

Ignoring the COP aspect, the main concern I have with immersion heating is that if only relying on convection to circulate heated water within the tank then the position of the heating element will make a notable difference in the quantity of water effectively heated (without running endlessly) and will likely result in lower overall hot water availability (although potentially at a higher temperature).

The Mixergy cylinders look attractive as they appear to overcome this?

Interested if anyone has any experience with one and if anyone knows whether any positive circulation is undertaken when heating solely from immersion on the HP variant of the tanks?

More generally those with solar diverters and batteries how do you ensure it's not just a case of fastest to act?

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bontwoody

(@bontwoody)

Noble Member Contributor

Joined: 4 years ago

Posts: 1056

24/09/2023 10:54 am

@Declan90

I have a 130lt mixergy cylinder powered only via my Eddi at the moment and two persons living here. So far I havent had any need to manually boost the cylinder at all. I have just switched to Octopus Cosy tariff so Im going to monitor it until I see a need to heat it during the cheap tariff period. The cylinder is as good as they promise with respect to heating less water and I can easily have a shower when its 10% full. One little rub though is that the mixergy app doesn't see energy diverted into the tank from the Eddi. I believe if you use mixergy's own diverter that isnt the case.

House-3 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
6.9 kWp of PV
10kWh DC coupled battery
Blog: https://thegreeningofrosecottage.weebly.com/
Heatpump Stats: http://heatpumpmonitor.org/system/view?id=60

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Declan90

(@declan90)

Trusted Member Member

Joined: 3 years ago

Posts: 39

Topic starter 25/09/2023 6:06 am

Interesting point about the Eddi not recording the energy diverted. Been mapping out potential monitoring desires/requirements and that would 100% be something I would want to monitor (given the aim to compare against just exporting and using the ASHP in the summer)

What setup have you got in place to ensure that your batteries and the Eddi don't fight over any excess solar capacity?

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bontwoody

(@bontwoody)

Noble Member Contributor

Joined: 4 years ago

Posts: 1056

25/09/2023 9:34 am

@declan90 Just to clarify Declan, its the Mixergy App that doesnt see it, the Eddi App does. I also have an OpenEnergyMonitor system which I can highly recommend too which I have monitoring all sorts of stuff including my heat pump efficiency.

Im using Home assistant to try and bring all the data together and be a bit smarter about when I use grid energy.

I have 2 solar arrays, an old 2.66 kW FIT system and a new 4.62 kW system which has a DC coupled battery. Because its DC coupled the new panels always charge the batteries before releasing energy to the grid (and Eddi). It actually works surprising well with the caveat that the old array cant charge the battery. The DNO wanted DC coupled so that I couldnt overload my grid connection with export and production at the same time.