@newhouse87

If your heat pump is starting and stopping 6 times or more each hour then it is deemed to be short cycling, which should be avoided. Starting and stopping 2 or 3 times per hour during mild weather conditions can probably be expected.

Your home would appear to be very well insulated or your heat pump could possibly be oversized, but don't panic if that is the case as long as it keeps your home warm without using lots of electrical energy.

Since you have an 11kW Daikin heat pump, what was the heat loss calculation for your home?

The upper and lower limits associated with the LWT setting are often adjustable, so it may be useful to check their settings.

If you can reduce the speed of the water pump that should increase the DT between LWT and RWT. If the heat pump controller can vary the speed of the water pump to control the LWT to RWT DT, then also check this setting.

@derek-m Do you mean compressor stopping and starting? Just keeping an eye on compressor seems to be on for 10 off for 10 approximates. House is 242sqm so think 11kw is correct. Il try find ber cert for heat loss. The heat pump is modulating down flow  itself probably trying to increase delta t. Not sure where i can check lwt settings for upper limit, seems to be 2 degree above desired alot today. 

My rwt is  not going below 23.4, my desired temp is 26 but its going up to 27.8. Only way it wont cycle is if my rwt goes down to 21, that wont happen. If i wanted higher lwt to heat house to 23 degree then i might get delta t at 5 which would mean it run longer. At this lwt its not possible to get delta t5 unless i was to leave house cool foe few dayS. IN the real cool weather i presume i wil have alot less cycling as lwt will be higher.

Looks like a user called hydros was having same issue few years back. Seems at temps above 8 degree you cant have low lwt without excessive cycling. 

Posted by: @newhouse87

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@derek-m Do you mean compressor stopping and starting? Just keeping an eye on compressor seems to be on for 10 off for 10 approximates. House is 242sqm so think 11kw is correct. Il try find ber cert for heat loss. The heat pump is modulating down flow  itself probably trying to increase delta t. Not sure where i can check lwt settings for upper limit, seems to be 2 degree above desired alot today. 

My rwt is  not going below 23.4, my desired temp is 26 but its going up to 27.8. Only way it wont cycle is if my rwt goes down to 21, that wont happen. If i wanted higher lwt to heat house to 23 degree then i might get delta t at 5 which would mean it run longer. At this lwt its not possible to get delta t5 unless i was to leave house cool foe few dayS. IN the real cool weather i presume i wil have alot less cycling as lwt will be higher.

Yes, when I say heat pump starting and stopping that would indeed include the compressor, and may or may not include the water pump.

A heat pump should be sized to the heat loss of the property, since a small poorly insulated home could require the same size heat pump as a large well insulated home.

The fact that your system appears to need to run with quite low LWT and RWT even though it is now getting cooler outside seems a little strange.

If you have the time to spare, I would suggest that you record the following during the 10 minute running period, if they are being displayed. LWT, RWT, IAT, OAT, Flow Rate, Compressor Speed, Water Pump Speed and any further parameters that are available that you think may be of use. Recording at 1 minute intervals over the period should be adequate.

Post the results when obtained.

Posted by: @newhouse87

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Looks like a user called hydros was having same issue few years back. Seems at temps above 8 degree you cant have low lwt without excessive cycling. 

I remember Hydros, but not the details. What was the outcome?

@derek-m I will do tomorrow when herself gone to work, she thinks im having an affair with the hp  at this stage. Not sure where i can find compressor and water pump speed, dont think its on daikin screen.

Posted by: @derek-m

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Posted by: @newhouse87

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Looks like a user called hydros was having same issue few years back. Seems at temps above 8 degree you cant have low lwt without excessive cycling. 

I remember Hydros, but not the details. What was the outcome?

 

Posted by: @newhouse87

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@derek-m I will do tomorrow when herself gone to work, she thinks im having an affair with the hp  at this stage. Not sure where i can find compressor and water pump speed, dont think its on daikin screen.

There are often additional screens available under the installer login, which you may be able to access. Maybe some Daikin owners can guide you?

Posted by: @newhouse87

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Posted by: @derek-m

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Posted by: @newhouse87

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Looks like a user called hydros was having same issue few years back. Seems at temps above 8 degree you cant have low lwt without excessive cycling. 

I remember Hydros, but not the details. What was the outcome?

 

He didnt quite say but he said he couldn't run low lwt when temps above 8, probably same as me by sounds of things. You suggested running on stats and not continuous in milder conditons. I might go back to that.

 

This is one of the problems, since as the LWT is reduced, the quantity of thermal energy that can be transferred to the heat emitters is also reduced, but if the LWT is increased to help reduce cycling the IAT starts to increase. If you can live with a higher IAT during the milder part of the day then this may be beneficial, since it should reduce the heating demand as the OAT falls during the cooler part of the day.

A gas or oil boiler does no run continuously, but switches on, warms the heat emitters and raises the IAT until the thermostat switches it off. The same technique can probably be used to reduce the frequency of cycling on a heat pump system. Set the required LWT to say +2C above the normal setting, set a room thermostat at say 1C above the desired temperature, allow the heat pump to be controlled by the thermostat.

I suppose it is a matter of experimenting with different methods of operation until you find one that best suits your lifestyle.

Posted by: @derek-m

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Posted by: @newhouse87

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@derek-m I will do tomorrow when herself gone to work, she thinks im having an affair with the hp  at this stage. Not sure where i can find compressor and water pump speed, dont think its on daikin screen.

There are often additional screens available under the installer login, which you may be able to access. Maybe some Daikin owners can guide you?

 

Just seen, unit is set to request and ext rt control. Have option for continuous and lwt control, wonder would they make a difference?

coming to conclusion after talking to hydros too, you cannot run hps at lwt less than 27 in my house anyway. Currently running at 28deg desired, no cycling full flow, lwt 28.4/ rwt 22.8. Any lower and i will just have endless cycling. Obviously this is mild weather and running continuously is not possible.

With last week of heating, if my daikin is correct im getting cop of 6, which is Great, however im using 2kwh per hour usage or close to it, this is lwt27/28deg and mild weather 10degrees. I know lots of factors but it still seems excessive. That is when its flowing through all loops at34l/min. Now the house is nice and warm but at that usage, no way would i run continuously, im better off heating for 6 hours maybe in cold weather and if my produced energy at cop 6 is correct, that should keep house warm. Just wondering are some heat pumps set up to use lot of energy but also produce alot in shorter period of time?