What's your monthly SCOP

michaels

NedS said:

michaels said:

I find it annoying that our LG has no night time 'set back' which out previous Viessman gas boiler had on weather comp mode.  We don't really want to switch it off overnight and actually don't currently have the controls to do so.  Being such a newbie I would actually like it to get much colder so we can see how it performs against more of a challenge....

Can you not just set back the room temp with a room thermostat, to say 18C overnight?

Alternatively, with my Samsung, I have the option to change the WC/LWT by +/-5C, so can use that to easily reduce the flow temps in the radiators overnight, thus giving out less heat.

Don't yet have a thermostat connected due to not be certain that it uses a 240 switched live call for heat wire.

It doe shave +/-3 on the controller with WT but that can only be changed manually not programmed (I am pretty sure)

Spies

Every time I check flow/return/delta/pumpspeed on the MMI and do a manual calculation I'm tending to see a COP of 4 on my Daikin altherma edla 6kw

Thermostat is set to:
21c from 8am to 10pm
19c from 10pm to 3:30am
20c from 3:30am to 8am to catch the last two hours of my 7p window with Intelligent Octopus Go

Hot water runs from 3am to 4am

Overall electricity use is somewhere in the region of 8-10kWh

My weather curve is 50@-5c 30@16c with a modulation of 5 and a overshoot of 2 - this is working really well for me

Tonight I'm going to use Home Assistant to increase the LWT by 2c when IOG is 'dispatching' because - although there is efficiency loss, I'll still be paying 3.7x less than peak electric (and likely half the price of gas even if I get a COP of 3)

matt_drummer

My heat pump is working really well.

10c outside, 22c or so inside,  COP over 5,5 for the day, nearly 6 for the last few hours.

I am now on Intelligent Octopus Go so my electricity cost is 7p per kWh

I run entirely on batteries so allowing for charging losses my real cost is about 9p per kWh

The heat pump is using about 450w so about 4p per hour for heating when the heat pump is on.

The cost of heat is about 1.5p per kWh

This includes the controller and circulation pump so it is probably around a quarter of the cost of gas.

And I am not burning anything at my house.

It feels really good.

john-306

matt_drummer said:

My heat pump is working really well.

10c outside, 22c or so inside,  COP over 5,5 for the day, nearly 6 for the last few hours.

I am now on Intelligent Octopus Go so my electricity cost is 7p per kWh

I run entirely on batteries so allowing for charging losses my real cost is about 9p per kWh

The heat pump is using about 450w so about 4p per hour for heating when the heat pump is on.

The cost of heat is about 1.5p per kWh

This includes the controller and circulation pump so it is probably around a quarter of the cost of gas.

And I am not burning anything at my house.

It feels really good.

Matt, if you've got solar+batteries, a heat pump, and an EV, how do you get on with your main consumer unit fuse?
With just solar+batteries and a heat pump with induction hob, electric oven etc I'm at the limit of my 80A (max allowed) fuse. 
I'm thinking of an EV but at the moment can see how I can incorporate it.

Exiled_Tyke

john-306 said:

matt_drummer said:

My heat pump is working really well.

10c outside, 22c or so inside,  COP over 5,5 for the day, nearly 6 for the last few hours.

I am now on Intelligent Octopus Go so my electricity cost is 7p per kWh

I run entirely on batteries so allowing for charging losses my real cost is about 9p per kWh

The heat pump is using about 450w so about 4p per hour for heating when the heat pump is on.

The cost of heat is about 1.5p per kWh

This includes the controller and circulation pump so it is probably around a quarter of the cost of gas.

And I am not burning anything at my house.

It feels really good.

Matt, if you've got solar+batteries, a heat pump, and an EV, how do you get on with your main consumer unit fuse?
With just solar+batteries and a heat pump with induction hob, electric oven etc I'm at the limit of my 80A (max allowed) fuse. 
I'm thinking of an EV but at the moment can see how I can incorporate it.

My Zappi EV charger monitors the PV output and grid import so it knows when to take free electricity from the panels for free but more importantly also has a limiter (which can be set to any value) to prevent grid import going over the 80amp max. I can run my ASHP (at night for hot water), dishwasher, washing maching, charge my house battery and set the EV charger safely knowing that the EV will throttle back if needed to avoid breaching the 80amps

matt_drummer

john-306 said:

matt_drummer said:

My heat pump is working really well.

10c outside, 22c or so inside,  COP over 5,5 for the day, nearly 6 for the last few hours.

I am now on Intelligent Octopus Go so my electricity cost is 7p per kWh

I run entirely on batteries so allowing for charging losses my real cost is about 9p per kWh

The heat pump is using about 450w so about 4p per hour for heating when the heat pump is on.

The cost of heat is about 1.5p per kWh

This includes the controller and circulation pump so it is probably around a quarter of the cost of gas.

And I am not burning anything at my house.

It feels really good.

Matt, if you've got solar+batteries, a heat pump, and an EV, how do you get on with your main consumer unit fuse?
With just solar+batteries and a heat pump with induction hob, electric oven etc I'm at the limit of my 80A (max allowed) fuse. 
I'm thinking of an EV but at the moment can see how I can incorporate it.

My main fuse was upgraded from 60 amp to 100 amp

UK Power Networks told me that the fuse is not there to protect the house, it is there to protect the network and it takes a massive amount of power to blow. Even overloaded it would take days to blow.

In any case, I never draw that much power at any one time.

Lots of solar ensures that I am exporting for the majority of the year and if not living off the batteries.

The batteries supply at least 15 amps.

Charging a car and the batteries takes 42 amps.

The heat pump never uses more than 12 amps.

Two ovens and an induction hob could take 42 amps.

I could in theory get close or even exceed 100 amps but in reality I never get anywhere near, and even if I did the car charger would throttle back if required and if not it would never blow the main fuse unless there was a massive fault somewhere.

I also have a 100 amp circuit breaker that would trip first in any case.

I don't think there is an issue and neither do UKPN as they approved it all.

Exiled_Tyke

Northern  Powergrid upgrade my fuse from 60amps to 80. Apparently this is now the maximum they will now allow without a three phase supply.  

NedS

Exiled_Tyke said:

Northern  Powergrid upgrade my fuse from 60amps to 80. Apparently this is now the maximum they will now allow without a three phase supply.  

National Grid have also standardised on an 80A fuse.

See this document which explains the rationale, together with a nice graph of the operating characteristics of an 80A slow blow fuse:

https://www.nationalgrid.co.uk/downloads-view-reciteme/633928

The 80A fuse will allow 100A for up to 4 hours, and 300A for up to 10 seconds before it blows, so exceeding the rating for a short period is not generally a concern.

john-306

Thanks all.
Yes National Grid upgraded my fuse from 60A to 80A and that is the maximum they go to.

Reed_Richards

michaels said:

Our 12kw LG (possibly 5+ years old) seems to modulate down to a draw of about 1.3kw at the lowest - I guess the associated output will depend on the COP - should be over 4 with current temps but I guess could go as low as 2 with a high flow temp and sub zero ambient.

My 12 kW LG (1 year old) seems to have much the same minimum power draw.  But it starts at minimum and modulates up, usually.

michaels said:

I find it annoying that our LG has no night time 'set back' which out previous Viessman gas boiler had on weather comp mode.  We don't really want to switch it off overnight and actually don't currently have the controls to do so.  Being such a newbie I would actually like it to get much colder so we can see how it performs against more of a challenge....

I can confirm that later models are no better.  You can use the control panel to set back the target temperature but you would have to set an alarm, get out of bed and then manually set it back to normal, if you want it to be warm enough by the time you get up again at your regular hour.  There is no way to program this that I have ever found.