Daikin Short Cycle Query - Air Source Heat Pumps (ASHPs)

RE: Daikin Short Cycle Query

RadWhisperer — Wed, 12 Nov 2025 07:53:13 +0000

Just a suggestion but upload your images to an AI agent such as Grok with a full description of your installation and you will get a good description of the symptoms and some suggestions of things to check. I've used this method to dial in my 4KW Daikin when switching to "pure" weather comp.

RE: Daikin Short Cycle Query

TreeWizard — Tue, 11 Nov 2025 09:40:50 +0000

@ashp-bobba That would explain it thank you, I'll take a look at the manual. If not, I'll ask Daikin at the next service.

RE: Daikin Short Cycle Query

ASHP-BOBBA — Sun, 09 Nov 2025 21:24:38 +0000

@treewizard is this not the electrical pulse that keeps the compressor warm? most of these top end builds use around 1kW per day in the winter to either power a heater tape wrapped around the compressor or send a current to the windings that does not move the motor but keeps it warm and I would imagine Daikin does one of these? (I not an expert on Daikin ASHP)

RE: Daikin Short Cycle Query

TreeWizard — Sun, 09 Nov 2025 18:49:04 +0000

I've also got an 8kw Daikin, in the last week I've noticed it oscillating between 350-600W at quite a high frequency for longer periods.

Is there some explanation for why it might be ramping up and down every minute?

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RE: Daikin Short Cycle Query

Toodles — Sun, 09 Nov 2025 16:15:31 +0000

Herewith a plot of flow rates during the last 36 hour or so. Regards, Toodles.

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RE: Daikin Short Cycle Query

Toodles — Sun, 09 Nov 2025 16:09:14 +0000

I might add that we do have an LLH with a secondary pump (Wilo Pico). Having put temperature probes on all four LLH ports, I have been able to set pump speed to match the primary pump in the Daikin which, once the system settles down, runs at a flow rate of 15 litres/min. As this is the flow rate the majority of the time, I have been able to set the pairs of LLH ports to be within 0.2 degrees C most of the time. When the pump starts up, it runs at a flow rate of 28 litres/min. but very quickly settles back to 15 litres. There are also brief excursion down to 7.5 litres occasionally so at some points the LLH must be experiencing some distortion - but minimal I think. Regards, Toodles.

RE: Daikin Short Cycle Query

Toodles — Sun, 09 Nov 2025 15:07:23 +0000

@ubert767 Just for comparison, here is a plot of my Daikin EDL08 Monobloc system from the last 36 hours or so; the pump is controlled via a Homely smart controller and we heat the whole house to 22.5 deg. C 24/7. You will see that when the OAT drops to ~7 deg. C, the system just ticks over at ~400 - 500 Watts without any cycling. Regards, Toodles.

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RE: Daikin Short Cycle Query

Ubert767 — Sat, 08 Nov 2025 15:26:10 +0000

@jamespa

Thanks again for your reassurance.

Rob

RE: Daikin Short Cycle Query

JamesPa — Sat, 08 Nov 2025 15:18:53 +0000

@jamespa

Initially, I didn't know wether the dreaded "short cycling " was regarded as the frequency of the modulation of the compressor by the inverter or as the frequency of "cold "compressor starts.

I'm very grateful for you responses.

Rob

Its the heat pump, more specifically the compressor, cycling on/off quickly. The most important parameter is the on time, anything less than about 10mins would be considered short. Short cycling reduces efficiency (because heat is wasted, and for other reasons) and increases wear. Given what the expanded plot shows I now dont think this is cycling at all so nothing to worry about.

RE: Daikin Short Cycle Query

Ubert767 — Sat, 08 Nov 2025 14:41:02 +0000

@jamespa

Initially, I didn't know wether the dreaded "short cycling " was regarded as the frequency of the modulation of the compressor by the inverter or as the frequency of "cold "compressor starts.

I'm very grateful for you responses.

Rob