Recent installation of an 8kw Ecodan air sourced heat pump, working my way through understanding the system.
One thing I’m not understanding is the graph for the power usage, I seem to be using the same amount of power due my heating as my hot water. But the heating is switched off .
Heating is an underfloor heating system with a seperate thermostat in each zone. Each thermostat is switched off so there’s no demand for heat.
Attached is a,screen grab of the app of energy use since installation mid June. It’s currently reporting since installation I have used about 101kw of power and produced 190kw of heat (read from controller on the wall I can’t see same info on app). Which I don’t think is a very good Cop.
Hot water is set to 53c, underfloor heating has no sensor fitted so it continually reads -39c. There is also no room thermostat (as I have several rooms) so that just reads 25c, unless that’s the temperature in the utility room?
I know I have other things to configure but wanted to start with understand why it thinks breathing is using 50% of the power when it’s not on.
UFH with lots of zones isn’t the best install in most circumstances. Reason, the heat pump will have a quite high minimum flow need, but a small zone could have a really small flow requirement, so the heat pump has nowhere to flow too except the buffer, you get loads of flow temp distortion and may also get lots of short cycles. Leading to very poor CoP.
To support the multi zones, did the installer also install a buffer?
Where are you located, as it strange you currently have the heating on in the summer? If you have actually got it on your should be a CoP of about 7 not below 2. So something very wrong.
Hot water, heating to 53 degs could be causing the immersion to be fired up each heating cycle depending on the hysterisis. Your poor CoP would sort of indicate this. So it would be helpful to post system settings.
We do NOT have our heating on. This is the question. Although we are on the Isle of Skye and too much heat in summer has never been an issue
Its a 26 year old house well insulated timber frame with NuHeat Underfloor heating. We have a buffer installed.
While each room still has a thermostat, there is one demand signal that goes to the Ecodan system to request heat to the UFH. But as I said we have all thermostats off so there is no demand for UFH.
I will go through the Controller screen and app and get a list of current settings and post. The Ecodan system replaced an oil fired boiler system.
One thing I wish to fix is there is no Thermistor on the flow to the UFH, it currently reads -39C all the time assume as none fitted. Is it easy enough to fit one?
And the hot water appears to have to drop about 10C before it kicks back in again.
This is poor for COP (1.8), though not too surprising during the summer while only heating water. The Ecodan will be drawing around 20 W of power in standby, which adds up to 14-15 kWh per month. COP will be higher in the winter when the heat pump is running for longer and at lower temperatures.
However it is peculiar that so much power consumption is attributed to heating when the thermostats are off. Not sure how that could happen.
This is optimal for heat pump use, and the actual temperature out the top of the tank is likely to remain hot even if the temperature sensor near the bottom reads lower. This offset can be adjusted to match household consumption. A larger offset (i.e. waiting for a cooler tank before reheating) will be more efficient.
Thanks. I’ve dropped the hot water to 49c. Is it worth setting a time for system just to heat water for ca few hrs overnight for the morning showers and some vkitchen use during the day whilst just using it for HW in summer?
I still don’t understand why it is attributing so much power to heating. I’m going to put a WiFi power monitor onto the 25a supply to monitor actual power use
Yes, a strategy that works well for many owners is to heat the water just once a day (or every other day), in either the cheapest or warmest part of the day. You can do this by setting times to “prohibit” DHW heating. (This won’t affect heating, so works in winter too).
Personally I find 45°C is warm enough for showers and washing up, but do experiment to find what’s best for you.
The legionnella settings might be worth a look. Assuming you have a 200 (?) litre cylinder, increasing the temperature by 15° requires 3.5 kWh of energy, so at least 14 kWh per month. A little more to maintain 65° for 30 minutes, and more still if the tank is cooler.
Unless you have very young or very old family members, this is probably unnecessary. The number of domestic cases of legionnella is extremely low. See article below for more detail:
