Hello all,

I am finding that the back up heating source (the gas boiler) is running more than the ASHP. I appreciate that temps have dropped but wondered if the ASHP should still be running at 2-5°C outside temp?

Do the weather curve settings have any impact on this? How does the controller decide at which point to run the ASHP or gas boiler? I have also noticed on occasion over the last few days that both can be on simultaneously.

Thanks,

Adam

Posted by: @adaml

Hello all,

I am finding that the back up heating source (the gas boiler) is running more than the ASHP. I appreciate that temps have dropped but wondered if the ASHP should still be running at 2-5°C outside temp?

Do the weather curve settings have any impact on this? How does the controller decide at which point to run the ASHP or gas boiler? I have also noticed on occasion over the last few days that both can be on simultaneously.

Thanks,

Adam

Hi Adam,

You need to look at page 208 in the Daikin manual which details bivalent control, where an auxiliary boiler is switched on and off dependent upon the setting of certain criteria.

Posted by: @derek-m

Posted by: @adaml

Hello all,

I am finding that the back up heating source (the gas boiler) is running more than the ASHP. I appreciate that temps have dropped but wondered if the ASHP should still be running at 2-5°C outside temp?

Do the weather curve settings have any impact on this? How does the controller decide at which point to run the ASHP or gas boiler? I have also noticed on occasion over the last few days that both can be on simultaneously.

Thanks,

Adam

Hi Adam,

You need to look at page 208 in the Daikin manual which details bivalent control, where an auxiliary boiler is switch on and off dependent upon the setting of certain criteria.

Thanks Derek! The settings as they were for equilibrium temp (A.5.2) allowed the gas boiler to take over at temperatures below 15°C whereas the default setting in the manual was -4°C.

I've put it back to the default for now. Any particular thoughts on improving this setting would be appreciated?

@adaml, good questions. As Derek says, please check your manual to get a better understanding of your bivalent controls.

Since you are running bivalent, if your objective is to save money, I would suggest, given the current price of electricity (unless your tariff is below 16p/kWh) to let gas heat your central heating below 3-4C when heat pump efficiency starts to drop off and defrost cycles are more common.

I also discovered this year that the boiler can run at the same time as the heat pump. That is purely a settings thing. In our case it was about setting parameters and conditions on when the heat pump should kick in and when the boiler should work. We have an ambient temperature control that instructs the heat pump to not work if, for example, the temperature has dropped below 5C. The reason yours is probably running both at the same time because you have setting ‘crossovers’.

Posted by: @editor

@adaml, good questions. As Derek says, please check your manual to get a better understanding of your bivalent controls.

Since you are running bivalent, if your objective is to save money, I would suggest, given the current price of electricity (unless your tariff is below 16p/kWh) to let gas heat your central heating below 3-4C when heat pump efficiency starts to drop off and defrost cycles are more common.

I also discovered this year that the boiler can run at the same time as the heat pump. That is purely a settings thing. In our case it was about setting parameters and conditions on when the heat pump should kick in and when the boiler should work. We have an ambient temperature control that instructs the heat pump to not work if, for example, the temperature has dropped below 5C. The reason yours is probably running both at the same time because you have setting ‘crossovers’.

That is very helpful, thank you. I'll spend some more time looking at this tonight and have set this to 5°C for now to stop the heat pump being used at lower levels of efficiency.

It would seem we also have some 'crossover' of settings as well with the boiler and ASHP running simultaneously. I need to get my head around the Daikin settings under Installer Settings > Overview Settings. The lists of number/letters are very confusing.

I have altered my weather dependent curve to 50°C flow at -7°C and 31°C flow at 14°C ambient. The DHW is now at 48°C, as 45°C felt a little low. The heating schedule is now running 06:00 till 00:00 at 21°C with the thermostat set to 12°C between 00:00 and 06:00.

I will keep an eye on usage over the next few days.

@adaml, looking good. The settings are very confusing and often not that clear in what they do. Just remember what you've changed. It took us weeks to figure things out.

The other thing to watch out for when the heat pump and boiler is running is that the boiler doesn't short cycle. That took us ages to figure out, but now (touch wood) everything is running quite smoothly.

@adaml 

Hi Adam,

In your first post you stated that DHW was from your gas boiler, in which case you could have both the gas boiler and the ASHP running at the same time.

Before I delve deeper into the manual, could you please confirm what it is that you are trying to achieve. Do you wish to keep your energy consumption to a minimum, or do you wish to keep your costs to a minimum?

@derek-m Thanks for your continued input, really appreciate it.

The DHW is on demand from the gas boiler as we have no storage tank. I have noticed occasionally the gas boiler and ASHP are firing for the heating when there is no demand for hot water.

Ohhh excellent question, at this moment costs to a minimum please. We are currently on a fixed tariff that ends on the 2nd Jan next year. We are 14.62 p/kWh for electricity and 2.57p/kWh for gas. This will of course increase substantially when we move to So Energy's variable tariff.

I'd really appreciate any further advice?

Posted by: @adaml

@derek-m Thanks for your continued input, really appreciate it.

 

The DHW is on demand from the gas boiler as we have no storage tank. I have noticed occasionally the gas boiler and ASHP are firing for the heating when there is no demand for hot water.

 

Ohhh excellent question, at this moment costs to a minimum please. We are currently on a fixed tariff that ends on the 2nd Jan next year. We are 14.62 p/kWh for electricity and 2.57p/kWh for gas. This will of course increase substantially when we move to So Energy's variable tariff.

I'd really appreciate any further advice?

Hi Adam,

If your system is correctly installed, then you should not have the ASHP and gas boiler running at the same time for space heating.

For best economy, you need to follow the instructions in the manual from page 208 to 210. An explanation of the bivalent system is given on pages 45 to 47. For details of how to set the energy prices see page 142.

@derek-m I wonder if perhaps someone upstairs was running hot water - I will keep an eye on it.

Thank you for these pointers. The installers manual I have only goes up to page 126. I wonder if you would be able to share the version you have please?

Posted by: @adaml

@derek-m I wonder if perhaps someone upstairs was running hot water - I will keep an eye on it.

 

Thank you for these pointers. The installers manual I have only goes up to page 126. I wonder if you would be able to share the version you have please?

Hi Adam,

This is the manual that I have been using. I afraid for some reason the forum will not allow me to attached the document, so you will need to download a copy. Here is the link.

EBLA09-163V3(3W1,V3,W1),EDLA09-16DV3(3W1,V3,W1)_4PEN620241-1_Installer%20reference%20guide_English.

@derek-m Thank you! This manual did not match my controller, however, this one does;

https://www.daikin.eu/content/dam/document-library/installation-manuals/heat/air-to-water-heat-pump-low-temperature/eblq-cv3/EDLQ_EBLQ-CAV3_EKC(2)B-CAV3_EKMBUHCA3V3-CA3V3_CA9W1_4PEN405544-1_IM_Installation%20Manuals_English.pdf

The link doesn't seem to work, sorry - if you Google this you should find it though.

Bivalent activation temp is currently set at the default of 0°C and bivalent hysteresis temp is currently set at the default of 3°C.

Please let me know if you have any suggestions?