Solic Boosting Water or ASHP

[canalsiderenovation]

This may be a silly question - bear with.

 

Until a couple of days ago our solar has been doing our hot water, diverting an excess to the tank but we were finding it wasn't quite hot enough and not reaching the temperature we like. It is programmed in on the ASHP to 48 degrees but the heating and hot water on the ASHP has been off for 4 months completely. 

 

So hot water is back on the ASHP trips in at 8:30pn during our Octopus Go rate and heats it up to 48 degrees if the solar hasn't diverted enough.

 

On the Solic I notice a button where you can boost it for 90 mins. I guess means it will be like switching on an immersion. So is this powered by the ASHP too?

 

In essence what I'm asking is if it's better to let the ASHP heat the hot water or press the boost on the Solic which is the immersion - or is it the same? Am I overthinking this?

[joth]

1 hour ago, canalsiderenovation said:

On the Solic I notice a button where you can boost it for 90 mins. I guess means it will be like switching on an immersion. So is this powered by the ASHP too?

No, the Solic boost just boosts the immersion at full power for 90mins or whatever.

 

As to which is best, do you mean least cost or least CO2, or something else?

Generally the ASHP should be at least COP2 doing hot water, so in terms of absolute amount of electricity used you're always best using the ASHP rather than the immersion.

 

FWIW now I have a house battery, I've turned off my PV divert to immersion completely, and do 100% of DHW from ASHP early afternoon (when it  has best chance to be coming directly from PV, and moreover when it's likely to have the best COP due to highest outdoor temperature)

 

[Conor]

Same here, solar no longer enough to keep tank topped up on a cloudy couple of days if we have a couple showers and a bath for the wee one.

 

What we do now is have the ASHP set to 45c, and comes on 12pm to 6pm everyday.

 

The solar diverter is still there, but the thermostat on the immersion is set to 58c. 

 

My thinking is that if the ASHP needs to kick in, it's just a short top up from 35c to 45c and during the day when there is stil some PV generation and the air temp is 16-18c. And if it's really sunny, the PV diverter will push it on up to 56c.

 

I think in a month's time I'll change the timer on the ASHP to come on in the off peak period of 1am-8am. 

Edited September 22, 2022 by Conor

[canalsiderenovation]

Great thanks I'll stick with the ASHP. I never quite knew what that button did on the Solic as we have never used it!

 

In summer the tank was always pushed up to about 57 degrees with no ASHP from the solar alone. @Conor you have your ASHP water temp a few degrees lower than our 48 degrees but we only have it scheduled to turn on with the ASHP during the 5.5p Octopus Go rate.

 

May have to change that once our Octopus Go rate expires in March - no idea what that will rise to then, but at least we have cheaper rates than most to see us through our heating and hot water for the majority of winter.