Daikin heat pump defrosts 16kw

We’ve had our Daikin 16kw for over a year now. We recently had the Octopus annual service, which was highly disappointing - as I wanted to discuss the amount of times it defrosts and what I should be expected. However, the guy clearly had no idea what a defrost cycle on a HP was.

I know that it’s all very dependant on temperature and humidity. However, I can’t help feel like ours defrosts a lot.

We run using Madoka, fully open system, UFH downstairs - we had an overlay system installed so I think the pipes are 16mm or less. Radiators upstairs. The primary pipework from the HP to the cylinder is 28mm. There are 3 radiators which are still piped with microbore.

Our heat loss from Octopus was 11kw, BG gave a heat loss of 9kw. I think we sit between the two but closer to 9kw than 11kw.

The weather curve is relatively flat with a max flow temp of 43 @ -3 and min flow temp of 32 @ 15 from memory.

There are a number of things that I’ve thought:

  1. Is the primary pipework too small from HP to cylinder - someone mentioned it should be > 28mm
  2. Alternatively, change the HP from 16kw to 11kw?
  3. We have plastic running to the UFH manifold - would upgrading to copper change anything
  4. Flow rates through the UFH - additional pump?
  5. Change the microbore
  6. Larger volumiser

https://emoncms.org/app/view?name=MyHeatpumpv2&readkey=7034e0830547fb8e3d56978a24793bc0

Hi David,

It looks perfectly consistent with my experience of what is in effect the same heat pump.

They need to defrost about twice an hour at the peak.

All you can do is reduce flow temperature.

At 40c mine was like yours, at 34c it was much better and didn’t ice up so quickly.

There’s nothing wrong with it other than what it is!

Just looked at it again, I forgot how horrific it was!

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