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JamesPa
@jamespa
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Illustrious Member
Joined: Apr 3, 2023
Last seen: Sep 14, 2025
Profile Activity
Topics: 17 / Replies: 2844
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RE: Hot water tank losing temperature quickly: Daikin Altherma 4kW

Agree. I changed mine because I reheat only once per day, which is fine so long as hysterisis set too high cause it to skip a cycle. However you see...

9 months ago
Forum
Air Source Heat Pumps (ASHPs)
Reply
RE: Heat loss calculators and spread sheets

Thats interesting and exactly what one installer said to me. We seriously need to do a survey of door blower testers - @editor have you any contacts...

9 months ago
Forum
Safety, Regulations, Tools, Plumbing & DIY Installations
Reply
RE: Heat loss calculators and spread sheets

Based on my own experience there are installers out there who will use more realistic values for ACH and/or take note of measured data. They are in t...

9 months ago
Forum
Safety, Regulations, Tools, Plumbing & DIY Installations
Reply
RE: Hot water tank losing temperature quickly: Daikin Altherma 4kW

My 200l Vaillant DHW tank falls from 70 to 65 (immediately following a legionella cycle) in about 11 hrs, just shy of 0.5C/hr. Yours is quite a lot f...

9 months ago
Forum
Air Source Heat Pumps (ASHPs)
Reply
RE: New 5kW Samsung Gen6 heat pump owner with loads of questions

Completely agree that 'efficiency' is strictly incorrect terminology. The efficiency (of a heat pump) would be (something like) heat out/theoretical ...

9 months ago
Forum
Air Source Heat Pumps (ASHPs)
Reply
RE: Heat loss calculators and spread sheets

I completely agree based on my personal experience, and I have now heard a sprinkling of installers say this, but is there any wider evidence that you...

9 months ago
Forum
Safety, Regulations, Tools, Plumbing & DIY Installations
Reply
RE: Trying to work out COP

... If as a result you can turn the flow temp down then that could make quite a difference!

9 months ago
Forum
Air Source Heat Pumps (ASHPs)
Reply
RE: Trying to work out COP

So your heating COP is (30-4)/(10.5-2.5) = 3.25 Your DHW COP is 4/2.5 = 1.6 As you imply sacrificing COP for low cost electricity saves money. Its...

9 months ago
Forum
Air Source Heat Pumps (ASHPs)
Reply
RE: New 5kW Samsung Gen6 heat pump owner with loads of questions

No process is 100% efficient, so yes some is lost from pumps, electronics, pipework etc. I think Vaillant monitor deltaT and flow rate to calculate e...

9 months ago
Forum
Air Source Heat Pumps (ASHPs)
Reply
RE: Trying to work out COP

Overall about 43/15 = 2.85 However this is made up of space heating COP and DHW COP, which normally are quoted separately, because they are typicall...

9 months ago
Forum
Air Source Heat Pumps (ASHPs)
Reply
RE: Trying to work out COP

It doesn't directly contribute. The energy in basically powers the compressor (plus a bit for other things) and the energy out is the heat in the ga...

9 months ago
Forum
Air Source Heat Pumps (ASHPs)
Reply
RE: Heat loss calculators and spread sheets

Here is the measured data (2 years worth of half hourly meter data) my selection was based on. You don't need 2 years worth and the 24, 12, 6,3 hour ...

9 months ago
Forum
Safety, Regulations, Tools, Plumbing & DIY Installations
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