Intelligent Octopus Go works like a dream.

[johnb80]

It's not a condensing boiler though, if I remember a conversation from five years ago correctly.

I may be wrong here but I dont think you can get such high efficiencies without it being a condensing boiler? What make and model is it?

I hear what you're saying there, very interesting. I'll ask Ronnie what he thinks when he does the boiler service, because I may still need the central heating to heat the water if I need a boost during the day and don't want to raid the house battery for the power.

It will work fine just to a lower temperature as it stands.

The radiators can get quite hot, but I wouldn't cry if they were a bit hotter when the weather is very cold.

Turn up the flow temp at the expense of efficiency.

I did a trial last winter reducing our flow temperature to 33 deg C is where we ended up, the boiler left running 24/7. The house was warmer than we usually have it, the boiler efficiency went up dramatically etc. I did it mainly as a trial ready for heatpump operation but it's proving not to be cost effective at the moment with gas prices down at 4.3p kWh. It does ok on the 7p during off peak which is how it's configured at the moment via the logic in Home Assistant, if the cost per kWh approaches the same as gas, we run gas.

There is also a defect in the tank insulation that's been there since the thermostat was moved, so I should look at fixing that.

If it's foam type insulation, some duct tape over it and squirt expanding foam into it, that works well.

 

[KH11]

I locked this thread for a time and now I've unlocked it to get clarification from @andyvee and @johnb80 and whomever else who can lend an objective, unemotional opinion on what exactly is going on.

I am an IOG user. I have a Zappi and a Tesla S.
I'm a former coder and have been involved in the design of the user interface on several applications, so I have some experience on how people will understand and interpret user interfaces like the Octopus app.

This is the Devices screen in my Octopus app.

View attachment 28233

The Charging preferences section has two options.
The Charge limit is the figure that it will aim to charge your car to. I'm making an educated guess that IOG will know what state of charge your car is at whether IOG is connected either to your charger or your car and that's how it knows when to stop charging. However, the additional information under the CHARGING EXPLAINED link

View attachment 28234

states that IOG will not go beyond you car's set battery limit.
Which logically means that if your car's battery charge limit is 100% (because it's an LFP, say), and the setting in the Octopus app is 80%, then it will charge the car to 80%. But if your car is set to 80% and you set the app to 100%, it will charge to 80% as it will hit the car's limit. I don't think that this detail is particularly relevant to the argument being had in this thread, however.

The second charging preference is the Ready by time, which will be read and understood by most people as the time that they wish the car to be ready to drive. Very few people will genuinely want their car ready to drive at 05:30. I predict that most, according to my source below, will be setting off for work at some time between 07:00 and 08:30.

I could not find any UK sources to cite (the ONS website does not return any relevant information) but I found this data from America which is not limited to car drivers: Explore Census Data

The explanation page above also states

This is, I believe, Octopus covering their backs. IOG needs to know both your car's battery size and your charger's charge rate so that it can calculate how long it will take to charge our cars.

Example, my car has a 75kw battery and is 60% full and I have set a target of 80%.
60% of 75kw = 45kw
80% of 75kw = 60kw
Therefore IOG needs to add 60-45 = 15kw.
If it's a 7kw charger (I'm rounding for simplicity) then it will need to charge for just over 2 hours if the charge rate happens at full speed 7kw.

The guessed charge rate will be approximate because of charge curves and variances in battery state of health. I bet IOG aims to charge cars to the required % ahead of the ready time 'just in case' there is an error in the calculation of how long it will take.
And if the system is optimal, then it will continually adjust the charge rate to compensate for any differences in the actual charge rate vs the initial calculated charge rate.

So I don't see any scope to 'game' the system, here, because IOG will be charging your car within the time periods it chooses in order to get your car to the desired % charge before the ready time. (I also don't see any guarantee that this will happen, but maybe I missed that).
I'd like to know how many people have experienced their cars not reaching the desired % charge before the ready time.

One legitimate use case might be that someone works night shifts and returns home at 05:00 and plugs in and needs their car charged by 21:00. Unless they have a battery, I would expect them to unavoidably be paying the 'on peak' rate to charge the car. I wouldn't expect IOG to bend over backwards to charge their car at a cheaper rate.

So could someone please succinctly explain to me how it's possible to 'game' IOG to deliberately get cheaper electricity outside of the off peak time? I want to understand what the disagreement is in this thread and I admittedly don't have the time to read all 8+ pages.

Thanks.

In my experience it’s the car or the limit set in the car app that will determine how much Octopus will charge to. I have sometimes forgotten to alter the amount of charge required in the Octopus app and if I have set the car to finish at the setting of 80% it will finish at that if even if I have had the Octopus app set at 80% when actually I only needed 50% to get it to 80% as set in the car app.

 

[Rolfe]

I may be wrong here but I dont think you can get such high efficiencies without it being a condensing boiler? What make and model is it?

It will work fine just to a lower temperature as it stands.

Turn up the flow temp at the expense of efficiency.

I did a trial last winter reducing our flow temperature to 33 deg C is where we ended up, the boiler left running 24/7. The house was warmer than we usually have it, the boiler efficiency went up dramatically etc. I did it mainly as a trial ready for heatpump operation but it's proving not to be cost effective at the moment with gas prices down at 4.3p kWh. It does ok on the 7p during off peak which is how it's configured at the moment via the logic in Home Assistant, if the cost per kWh approaches the same as gas, we run gas.

If it's foam type insulation, some duct tape over it and squirt expanding foam into it, that works well.

You may be right, I could have my terminologies mixed up. It's a Grant Vortex Eco. Oh, it actually says on the cover of the manual that it's a condensing boiler so obviously I was wrong.

I was thinking of doing something like that with the tank insulation, although maybe using polystyrene chips.

 

[johnb80]

You may be right, I could have my terminologies mixed up. It's a Grant Vortex Eco. Oh, it actually says on the cover of the manual that it's a condensing boiler so obviously I was wrong.

I was thinking of doing something like that with the tank insulation, although maybe using polystyrene chips.

If you use polystyrene chips, a cotton cloth over the area and a steam iron will expand the polystyrene to fit the area snuggly.

 

[Rolfe]

Hadn't thought of that, thanks.

 

[johnb80]

Hadn't thought of that, thanks.

Often used technique in model flying to repair foam based aircraft.

 

[Tig170]

Just like this evening - if you plug it in with an abundance of power (e.g. agile was negative, discount on electroverse ) it will just charge as soon as you plug in (to the nearest 15 mins)