My aroTHERM plus is misconfigured

[mediaNen]

On 21/02/2022 at 18:08, J1mbo said:

The COP is (Yield+Consumption)/Consumption roughly - more like 3.7

J1mbo I thought that the COP was calculated from Yield/Consumption. Usage directly translated to effect. Could you put a few more words into explaining the calculation if possible?

 

Thanks :)

[J1mbo]

One way to check would be to let the DHW go completely cold, then heat it to some temperature. Since you then know the quantity of water heated and by how much, as well as the consumption and yield to do so, it can be checked with some degree of certainty.

 

By observation, we know that the working number is greater than yield/consumption and from the manual, "The working figure is the ratio of thermal energy generated to the operating current used."

 

My understanding is that yield is the energy collected across the coil. So thermal energy generated would then be consumption + yield - losses. Though I've not seen it written anywhere directly.

Edited February 28, 2022 by J1mbo

[mediaNen]

7 hours ago, J1mbo said:

One way to check would be to let the DHW go completely cold, then heat it to some temperature. Since you then know the quantity of water heated and by how much, as well as the consumption and yield to do so, it can be checked with some degree of certainty.

 

By observation, we know that the working number is greater than yield/consumption and from the manual, "The working figure is the ratio of thermal energy generated to the operating current used."

 

My understanding is that yield is the energy collected across the coil. So thermal energy generated would then be consumption + yield - losses. Though I've not seen it written anywhere directly.

 

Wow, thank you for the explanation. That makes more sense to me now, as my search on this topic has found quite different answers but nothing explained like above. Calculating the COP on my unit (aroTHERM plus 125/6) for February, im landing at around 4.17 which I believe is quite good.

[J1mbo]

@mediaNen - I let the DHW cylinder go cold yesterday and ran a legionaries cycle over night.

 

• 250 litres heated (according to the pocket sensor) from 18°C to 67°C - 14.2kWh.
• DHW consumption 6kWh and environmental yield 8.5kWh, total 14.5kWh.

 

4.17 is very good; I presume you have under-floor heating and probably no heat exchanger? For February, with average temperature of 6.8°C my system achieved 3.4.

 

Edited March 2, 2022 by J1mbo

[mediaNen]

@J1mbo - nice, that proves your COP thesis I believe, at least roughly as you describe it


Yes, under-floor heating in concrete and 5 heat exchangers (radiators right?) on first floor. Thankfully they are quite new, so I can run them at lower temperatures. My heatcurve is at 0.65 at the moment, and my inlet temperature is around 37 to 42C depending on weather which is just about enough to keep the house at 22.5 degrees. My installation is quite new, so I am playing with the curve a bit. Also I have a 100L buffertank installed.

[J1mbo]

By heat exchanger, I meant a plate heat exchanger that provides hydraulic separation between the property heating circuits and the ASHP circuit, so that glycol is only needed in the short ASHP circuit between it, the DHW cylinder, and the heat exchanger. There is always a temperature drop across them and hence this increases flow temperatures and reduces COP.

[mediaNen]

Got it, im kinda new to this so learning every day ?