UVC Set-up with Eddi

[Caddy]

I'm in the process of changing my DHW set-up. Currently my tank is ~100L vented system with 2 immersion elements, with the bottom element connected to my Eddi. When there is excess solar generation then I get hot water, if there is not, I just put up with cold water. The top immersion is connected to the mains I'm just too tight to put it on normally. I have no mains gas where I am and my heating is from A2A heat pump so I have no boiler and the HW has to be electric generated.

 

I'm being a bit stupid about all this so I'm updating my system. I was thinking about a heat pump cylinder but I live in  a small stone cottage and have nowhere to put one. My only space is where the current cylinder is and that is only 1200mm high and in my bathroom in the middle of the house. I was seriously thinking about a Sunamp and have been dithering over this for some months. I work with someone who has one and loves it but I have also seen the comments on this forum and elsewhere about reliability. A neighbour is a G3 qualified plumber, so I think I will take the advice of some of the members on here, keep it simple, and just go with a 200L UVC from Telford or Joule. They both make a direct model the correct size for my spacing.

 

My actual question is what is the correct configuration for the feed from the Eddi and the mains for heating the tank? Should the bottom immersion be connected to the mains via a timer on some cheaper rate tariff for heating during the night. Then the Eddi be connected to the upper immersion to top as and when there is excess solar generation or to use the boost function? Or should it be the other way around like I have it now and have the Eddi do the night time timer function? Also am I correct in that the Eddi has 2 outputs that can be connected to resistive loads. I have a fancy electric towel rail that is 300W resistive load and was thinking to wire this to the Eddi and use excess solar for towel drying and to take the edge off the cold in the bathroom . Maybe play around with the priority settings between the 2 outputs at different times of the day if that is possible.

 

Any advice much appreciated.

[JohnMo]

If you don't have a heat and unlikely to get on if you are happy A2A, why even think heat pump cylinder?

 

Get one that fits the space.

 

Sorry can't help you with the eddy. But we have a cool energy diverter, it powers 2 immersions, and has timers built in also.

[Bramco]

We have both immersions connected to the EDDI.  300l tank.

 

When we have solar, it is diverted to the tank and the EDDI controls whether it is heating the top element, or the bottom element, depending on how hot the top of the tank is. It's better to let the EDDI manage which element it uses because if you only connect it to the bottom element, you can end up with a tank full of luke warm water rather than a tank with hot water at the top.

 

We're on Octopus Go, so get 4 hours at night at 9p/kWh.  So we also have the EDDI scheduled to heat the tank on this cheap rate every night. So basically if there's not been enough solar PV during the day to heat the tank, then it gets topped up at night on the cheap rate.

 

Personally, I wouldn't use the EDDI to control your towel rail - why don't you put that on a cheap timer, so if you are on Octopus Go or similar, you can use cheap rates to get some warmth?

 

Simon

[Caddy]

1 hour ago, JohnMo said:

If you don't have a heat and unlikely to get on if you are happy A2A, why even think heat pump cylinder?

 

Get one that fits the space.

 

Sorry can't help you with the eddy. But we have a cool energy diverter, it powers 2 immersions, and has timers built in also.

@JohnMo I probably did not explain that well, I mean the integrated HW cylinders with the heat pump on top like an aroSTOR 200 or similar.

Edited October 18, 2023 by Caddy

[Caddy]

1 hour ago, Bramco said:

When we have solar, it is diverted to the tank and the EDDI controls whether it is heating the top element, or the bottom element, depending on how hot the top of the tank is. It's better to let the EDDI manage which element it uses because if you only connect it to the bottom element, you can end up with a tank full of luke warm water rather than a tank with hot water at the top.

@Bramco I have just been looking through the Eddi installation manual and seen this option. My Eddi was fitted by the PV installers and they did not discuss the different config options with me when installing. I'm going to look what is possible and your set-up is a definite contender, thanks for the info.

[JohnMo]

52 minutes ago, Caddy said:

@JohnMo I probably did not explain that well, I mean the integrated HW cylinders with the heat pump on top like an aroSTOR 200 or similar.

That makes sense. 

[Caddy]

On 18/10/2023 at 16:10, Bramco said:

When we have solar, it is diverted to the tank and the EDDI controls whether it is heating the top element, or the bottom element, depending on how hot the top of the tank is. It's better to let the EDDI manage which element it uses because if you only connect it to the bottom element, you can end up with a tank full of luke warm water rather than a tank with hot water at the top.

@Bramco I was reading your reply again and wondered if you could help with a quick question? In your set up is the Eddi using the thermometers on the immersions to know when to shut off or have you got the extra myenergi relay board and a couple of ST1000 sensors to monitor water temp?

[Bramco]

The EDDI knows when each of the elements has taken enough energy without the need for thermostats. Basically it monitors the energy that the element is taking and when it's taking no energy it stops. There is an internal CT that is measuring what is being consumed by the elements in the tank. No need for additional sensors.

 

So under normal circumstances, the EDDI just manages everything - no need for any additional sensors.

 

However, we have installed a relay board with a sensor which is at about half way up the tank.  The reason we did this is that, there are occasions when there's a lot of family around and the PV and overnight scheduled boost don't give us enough hot water. So the relay board is set to kick in when the temperature in the middle of the tank gets below 50 and stops when it is 60 (this is done with an external device). It's an expensive boost but saves the grief from the family if there's not enough hot water.

 

Simon