@justinsb Actually, when I was looking at your settings yesterday I noticed the 10C switching differential, and was going to suggest that you change it to 5C. As Mark pointed out, the daily heat loss on a hot water tank is probably in the order of 1kWh to 2kWh. The main heat demand for DHW is heating the cold water that replaces the hot water used. So you can be smelly and rich, or fragrant and poor, the choice is yours!!!!
The house is all warm except for one room. All things considered, the kitchen seems to have an undersized radiator (100 x 70 K2 Stelrad), so I'm going to have a word with the installers about it (or, TBH, their boss, who designed the system & told them which radiators to put where).
The Honeywell controller I left set to 21°C to match the settings on the FTC. I haven't touched the curve at all. It all seems to have settled nicely, & for the past couple of days my whole house electricity consumption has been almost exactly 38Kwh - prior to the install my house used 13Kwh per day in Winter, so it looks like my 14Kw Ecodan is using around 25Kwh per day to run my 14 Stelrad radiators & hot water system.
ps. I really appreciate all the help that you have given on this. I'd still be cold & expensive without all of this guidance
Hi Justin,
From what you have stated, I am not certain your system is fully on weather compensation, thermostat control, or a combination of both.
Try increasing the setting of your Honeywell thermostat to 22C or 23C and see if the indoor temperature starts to increase. It may take some time to respond. If the indoor temperature starts to rise, then it would indicate that the thermostat is having an effect on the control system, which should not happen when under weather compensation control. If possible record how often the ASHP and central heating pump are running.
What heating system did you have before installing the heat pump? Do you know how much energy it used?
I can't remember if you have mentioned the size of your home and the heat loss calculations.
This post was modified 3 years ago 2 times by Derek M
@derek-m If the Honeywell is overruling the Ecodan system, how do I stop it please?
Hi Justin,
By increasing the setpoint on the Honeywell a degree or two above the actual indoor temperature, the control of the indoor temperature will then be delegated to the ASHP remote controller, which is in turn being regulated by the weather compensation curve. I am not 100% certain of how the inner workings of the remote controller and ASHP actually function, but I suspect it is somewhat along the following lines.
The remote controller measures the ambient air temperature and calculates the required water flow temperature based upon the parameters set by the weather compensation curve.
If the water flow temperature is below the required value, then the ASHP starts and begins to raise the temperature of the water flow temperature.
The ASHP also measures the water return temperature, which is normally in the region of 5C lower than the water flow temperature.
If the water flow temperature increases above the desired value, the heat pump will reduce its output power until the correct temperature is achieved. If the ASHP pulls back to its minimum output power level and the water flow temperature continuous to increases above the desired level then the ASHP will shutdown for a period of time.
If the ASHP is operating normally at the desired water flow temperature, but the differential between the flow and return temperatures starts to reduce below the nominal 5C, the controller may decide that the heat demand is lower the the heat energy being supplied by the ASHP, so may again shutdown the ASHP for a period of time.
If the weather compensation has calculated a required water flow temperature of say 35C, but the present heat demand only requires a water flow temperature of 32C, then the indoor temperature will increase until the heat loss is balanced by the heat energy supplied. As the indoor temperature increases in relation to the outdoor temperature, the heat loss increases. It is similar to driving your car with the accelerator pedal at a fixed position, the car will accelerate until the power output from the engine is balanced by the wind resistance and other losses being exerted on the car.
If your thermostat switches off your ASHP before the energy balance has been achieved, then it will not be fully apparent that the weather compensation requires further adjustment.
@derek-m If the Honeywell is overruling the Ecodan system, how do I stop it please?
Hi Justin,
By increasing the setpoint on the Honeywell a degree or two above the actual indoor temperature, the control of the indoor temperature will then be delegated to the ASHP remote controller, which is in turn being regulated by the weather compensation curve. I am not 100% certain of how the inner workings of the remote controller and ASHP actually function, but I suspect it is somewhat along the following lines.
<snip>
OK, I'm going to wait until the ASHP is doing nothing, then I will bump up the set point on the Honeywell to 25°C - I had to turn it all off to take some photos of the interface (see next post) & it always seems to like to run for a short while when you power it all back on again.
@justinsb That is quite normal, the compressor needs to build up the gas pressure, and I do believe that the ASHP runs the internal water pump to check the water flow and return temperatures before going into normal operation.
I suspect that there is an error in the software for the display. The graph actually displays the true settings for Justin's system, water flow temperature of 45C @ ambient air temperature of 0C for the left hand end of the graph and water flow temperature of 20C @ ambient air temperature of 20C at the right hand end of the graph.
The 45C value displayed above the graph would appear to be correct, but the -30C to the right of the graph is obviously wrong.
Maybe you should point this out to Mr. Mitsubishi!!!!!!
Press & Hold the Menu button, as normal. Once it goes into edit mode, scroll along until you get to the Settings icon & click OK
The Quiet Setting... OK, this took a while to find again as I couldn't remember where I had seen it. It's another one of those "Feel the fear - Do you want to power off the system, Yes/No" times. I selected the first menu option & when I opened it, it asked me to power down the system. I did, then came back to look for the Quiet Mode settings.
Scroll down until you reach the second screen, Select Heat Pump Settings and press OK
This gives you a new menu with the Quiet Mode listed
Once you go in, it gives you a timer setting menu
Please note, I haven't actually played with it yet...!
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