Help with getting Ecodan ASHP settings right with Octopus Cosy

[Happy Valley]

We have recently moved over to Octupus Cosy and the plan is to run the heating fairly hard for the 3 cheap sessions which total 8 hours initially then add more if necessary but not within the 3 hour peak of 1600 to 1900 hours.

 

I tested the system yesterday having changed the heater timings to 0400 to 0700, 1300 to 1600 and 2200 to 2400 hrs. 

 

I was surprised that the fan on the ASHP was still going at 1700 hours drawing electricity at the peak rate. The timer had worked correctly and the status on the FTC controller was a square which I believe equates to "stand by". The pump had been heating for a four hours prior to 1600hrs.

 

Question: Is there anyway to turn it off stand by to off at 1600 and not draw on the expensive rate without taking the system off timed?

[JohnMo]

Even though the times are set, is there a thermostat overriding, so during the none heat periods if a thermostat still believes its not warm enough is it still making the system run?

 

The other issue you will have on cosy, with a heat pump sized to match your house heat demand, is the heat pump cannot deliver 24 hrs of heat in 8 hrs. So if you have a heat demand of 5kW (so 5 x 24 hrs is 120kWh required in 24hrs), you need a 15kW ASHP (so 15 x 8hrs is 120kWh) for Cosy to work at design temp.  Or have a battery to allow the heat pump to run during expensive times.

 

 

[Happy Valley]

19 hours ago, JohnMo said:

Even though the times are set, is there a thermostat overriding, so during the none heat periods if a thermostat still believes its not warm enough is it still making the system run?

 

The other issue you will have on cosy, with a heat pump sized to match your house heat demand, is the heat pump cannot deliver 24 hrs of heat in 8 hrs. So if you have a heat demand of 5kW (so 5 x 24 hrs is 120kWh required in 24hrs), you need a 15kW ASHP (so 15 x 8hrs is 120kWh) for Cosy to work at design temp.  Or have a battery to allow the heat pump to run during expensive times.

 

 

 

Thanks for the response. Yes there is an overriding thermostat which I ensured was lower than the actual temp (set at 20 when the room was 21.5). 

 

Am aware that the pump will need to be used more than 8 hours deeper into the winter. Just didn't want it running during the peak cost period.

[JohnMo]

7 minutes ago, Happy Valley said:

Just didn't want it running during the peak cost period

Isn't that just 4pm to 7pm, so only 3hrs, not 16hrs you have programmed to be off?

[Happy Valley]

5 minutes ago, JohnMo said:

Isn't that just 4pm to 7pm, so only 3hrs, not 16hrs you have programmed to be off?

 

Yes that's the one I want to avoid, don't mind it falling into the standard rate for a while. I think I will run it for a 24 hour timed period and see what happens whilst it is still relatively mild and see if it keeps on doing the same.

[JohnMo]

2 minutes ago, Happy Valley said:

think I will run it for a 24 hour timed period

I would and try and log electric data and actually work out costs, then switch off in the expensive period and again work out costs and compare. You may see very little difference most of the year, you may see a big difference depending on your house.

[Andehh]

Had an "issue" with our Samsung ASHP where I had set an 'on time' for hot water at 6am to hit a temperature with an hour duration assuming it would then turn off, but instead I then had to also set a manual 'off' time.

 

Maybe there is something equiv with yours?