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What is the 'Eco' mode on hot water do?

Air Source Heat Pumps (ASHPs)

Last Post by mjr 3 years ago

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Tufty

(@tufty)

Estimable Member Member

Joined: 3 years ago

Posts: 54

Topic starter 02/01/2023 11:45 am

I have an Ecodan. My DHW is set to come on once every 48 hours to heat the cylinder up to 45c.

The DHW is set to 'Eco'. What does this setting actually do, and is it really 'eco'?

Thanks

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Kev M

(@kev-m)

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Joined: 4 years ago

Posts: 1276

02/01/2023 11:54 am

Posted by: @tufty

↑

Hi

I have an Ecodan. My DHW is set to come on once every 48 hours to heat the cylinder up to 45c.

The DHW is set to 'Eco'. What does this setting actually do, and is it really 'eco'?

Thanks

@Tufty

It heats the water up slower. I'm not sure of the details but it's something like this. Say you have your HW set to 50 deg. Normal will make the ASHP heat the flow in the HW coil to 55 or more until the tank reaches 50. Eco will use a lower flow temp (=better COP) for longer. It's the same concept as the Eco programmes on dishwashers and washing machines; lower temp tor a longer time.

I haven't measured and compared the two modes.

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Tufty

(@tufty)

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Posts: 54

Topic starter 02/01/2023 12:27 pm

Ah great - thanks Kev!

(this is very useful to know as for years Ive been using the washing machine in 'Eco mode'. Its always taken much longer than the other modes. Now I know why! 😀 )

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SUNandAIR

(@sunandair)

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02/01/2023 7:13 pm

It would be interesting to know if the ECO mode also prevents the immersion heater from being activated?

It would appear that when the DHW target temp is set above or near 55degC the immersion heater is activated to help the HP reach the target temp. This could possibly be a costly situation.

I’ve also wondered if the heating period needs to be a little longer than 60 minutes, in ECO mode? Since it will switch itself off once it gets up to the target temp anyway!

any thoughts?

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mjr

(@mjr)

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02/01/2023 9:06 pm

Posted by: @kev-m

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I haven't measured and compared the two modes.

On my 170 litre tank, the difference heating to 48° does not seem measurable in the wild. I suspect other factors dominate. It may be different for a larger tank.

👍

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Bob77

(@bob77)

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Posts: 36

03/01/2023 1:13 pm

Is this different from the “Eco” vs “Comfort” setpoints?

My Altherma has two temperature settings, which you can schedule for various times. Eg I have “comfort” set at 52C and “eco” set at 47. It’s scheduled to heat up to the comfort temperature overnight while the electricity is cheaper, and then it is set to “eco” in the early evening to top the tank back up to the lower temperature if required. As far as I know it doesn’t change the way it actually beats the tank though.

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mjr

(@mjr)

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Posts: 301

03/01/2023 2:24 pm

@bob77 yes, the ecodan on/off eco hot water setting seems to cap the power input to the unit for DHW, resulting in it taking longer but using fewer kW. The total kWh isn't noticeably significantly different to me. I suspect that's because 48 is well within spec for our unit. Heating to near the performance limits may show larger differences.

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