Weather forecast and using an oil filled radiator to save money?

[ericmark]

This month, very few days do we have excess solar, but it does happen, and it seems a shame to export for no payment when we could use the power our selves. What would seem the best option is iboost+ connected to an oil filled radiator, but that is a rather expensive method, a simple timer seems a better option, so we don't forget and leave it on.

By next year, I hope we will get payment for export, so only looking at now until April, suppose could fit a plug and socket to immersion heater supply and run an extension down the stairs, but for just 4 months that seems a bit OTT, plus the trip hazard.

But when we have clear skies, so loads of solar, using an oil filled radiator in the living room will likely save us money, but get the weather forecast wrong and it could also cost us. We keep an oil filled radiator handy in case central heating fails, don't fancy lighting a fire in the grate, but I am sure I am not the only one, who exports without payment.

So, has anyone worked out how to use excess solar to heat their house?

 

[flameport]

So, has anyone worked out how to use excess solar to heat their house?

Excess solar -> Battery -> Electric heating.

 

[ericmark]

Yes, I have 6.4 kW of battery. But I have marked where I have excess, but it varies day to day, and today no spare solar only charged to 85% and likely by the end of the day, will be using peak rate power. On the good day, down to 14% so as soon as state of change drops below 95% want to remove any load. But the good day shown, exported 6.1 kWh and the wall thermostat shows me so it seems boiler activated for a reasonably long time, which is common when we get clear skies, it does not mean the boiler was outputting full 20 kW at those time, or even if the boiler was running outside those times, the other thermostat shows so between 4 pm and 7 pm the other thermostat was activating the boiler, so boiler could run 4 pm to 9 pm, it may have cycled on/off, but 6.1 kWh of electric heating clearly would have reduced my oil use.

So looking for if SOC exceeds 95% then turn on heater until SOC is less than 90%, but I have no real option to run IFTTT with an oil filled radiator.

But I am sure I am not alone, so asking if anyone has worked out how to use energy rather than export it?

 

[robinbanks]

Do you run the immersion with it?

 

[JohnW2]

This month, very few days do we have excess solar, but it does happen, and it seems a shame to export for no payment when we could use the power our selves. What would seem the best option is iboost+ connected to an oil filled radiator, but that is a rather expensive method, a simple timer seems a better option, so we don't forget and leave it on. ... By next year, I hope we will get payment for export, so only looking at now until April,

I would have doubted that you will have much 'excess solar' between mid-November and April, will you - but, if you sometimes do, and given that it';s just a few months, could you not just manually switch on some sort of electric heating (not necessarily an oil-filled radiator) if/when the situation arises?

 

[ericmark]

Do you run the immersion with it?

Not in Winter, only use the iboost+ in summer.

 

[JohnW2]

Not in Winter, only use the iboost+ in summer.

Why is that? Do sunny days in Winter (it does happen ) differ from Summer days?

 

[hllns]

Is it enough missed energy to be worth bothering with? There are Home Assistant automations if you're someone enjoys programming and looking at graphs and spreadsheets a lot:

Predbat Documentation

None

springfall2008.github.io

 

[ericmark]

Why is that? Do sunny days in Winter (it does happen ) differ from Summer days?

The central heating uses the C Plan, so no way to turn off DHW when central heating is running, so in Winter the DHW is always hot, so the iboost+ does nothing.

Is it enough missed energy to be worth bothering with? There are Home Assistant automations if you're someone enjoys programming and looking at graphs and spreadsheets a lot:

Looks interesting, not sure how it controls things, but needs some looking into.

 

[JohnW2]

The central heating uses the C Plan, so no way to turn off DHW when central heating is running, so in Winter the DHW is always hot, so the iboost+ does nothing.

I thought the C-Plan had a motorised valve in the feed to the coil of the DHW cylinder? If so, couldn't you switch it off when you wanted to heat the water electrically (although yo0u would obviously have to 'have notice' of the wish to do that!)?

 

[ericmark]

There are 3 C Plans, the first, only control of DHW is time, the second has a tank stat for the summer, and the third has a motorised valve. The idea with oil fired central heating is that the boiler can cool by heating the DHW, so not a good idea to fit the motorised valve, as then no where for heat to go when it switches off.

Using Nest Gen 3 slightly different as the output is common. Due to programmer and thermostat being combined, and Hive has a software fix, so one relay works the boiler and the other relay the pump. As far as I am aware, Wiser can't be used with C Plan, unless you know different?

 

[JohnW2]

There are 3 C Plans,....

I didn't know that. As so often, "one learns something every day"

.... the first, only control of DHW is time ...

but how is that achieved,if not with a motorised valve?

, the second has a tank stat for the summer

Controlling what? Again, I would have expected a motorised valve ... and don't all DHW cylinders have stats - or doe they just let the tempof the DHW rise up to that of the water coming from the boiler?

... and the third has a motorised valve.

OK

The idea with oil fired central heating is that the boiler can cool by heating the DHW, so not a good idea to fit the motorised valve, as then no where for heat to go when it switches off.

... but one can surely not rely on that,since if the water oin the DHW is already up to its 'maximumtemp, it will not be able to do any 'cooling, will it?

 

[Murdochcat]

Not sure any excess lecky in the winter is worth faffing around with. You have an iboost for your immersion so let that do the job

As for heating an oil filled radiator - would it actually get warm?

 

[ericmark]

I didn't know that. As so often, "one learns something every day"

but how is that achieved,if not with a motorised valve?

Controlling what? Again, I would have expected a motorised valve ... and don't all DHW cylinders have stats - or doe they just let the tempof the DHW rise up to that of the water coming from the boiler?

OK

... but one can surely not rely on that,since if the water oin the DHW is already up to its 'maximumtemp, it will not be able to do any 'cooling, will it?

The original C Plan had not control over DHW in the winter, only in the summer was there any control, as said time only in the summer, before solar I would set it to 4 x ½ hour slots per week. The problem with this was it was a bit of guess work as to how long was required.

The first improvement would have been a thermostat, so it summer it only ran when required.

The second improvement was a motorised valve which gave control in winter as well.

The boiler in summer would run for 20 minutes before the return water temperature turned off the boiler, and boiler fixed output, so 20 kW x 4 = around 25 kWh per week, when I fitted solar, the iboost+ records kWh used today, yesterday, and last 7 days, and found it showed around 2.5 kWh per week. It only heats top of tank, where central heating heated whole tank, but it showed nearly 20 kWh was just heating the house, not what one wants in the summer, but in winter it hardly matters if heat gets into house from pipes or radiators, it is still warming the house.

We however had a problem with the living room, it seemed to cool faster than the hall where the thermostat was, but to move thermostat was a lot of work, and should not really be in living room, as there is also an open fire in the living room, and patio doors, so we fitted a second on in parallel to the first, this one wireless, and not connected to DHW, it worked, but it also pointed out the main problem was running time, the hall thermostat did not run the central heating for long enough for TRV's to close and push water through radiators in the cooler rooms.

The boiler active time is shown with the Nest Gen 3 thermostat, so as getting cooler, but not very cold we would get
the run time was simply not long enough to heat all radiators, hall would get hot, but not living room, I had simply not realised what the problem was. The thermostat in the living room now ensures the boiler runs for longer, but in turn that causes a hysteresis, but the hysteresis is better than being cold. I am sure there is a feature on wiser to stop the hysteresis, but not looked as yet.

It is mainly down to being oil fired rather than gas, as gas boilers modulate so they run for longer, so time to heat the radiator is less of a problem. Now I have Wiser which will link to TRV heads, I can swap the simple programmable heads for linked programmable heads, and also improve heating in other rooms.

As to using an oil filled radiator, what it would save, likely not worth the effort, as @Murdochcat has said, so abandoning that idea. Three days this month 10 kWh from solar, but most days not even 2 kWh so not even enough to fully recharge the batteries.