Icy cold weather, weather compensation and consumption
Thought I’d share this as a point of comparison. Two winters ago, our heat pump had been set to run the heating at a 45C set point. When we hit 0C for 24 hours, we did 120kW in electricity consumption. Admittedly, it was a happier time when we were paying 11p per kWh.
This winter it’s all weather compensation for us. Here’s our consumption over 24 hours with temperatures dropping to -2C and rising to 3C. Cold. While the 82 kWh is still high, that’s our full electricity consumption for the day including cooking (and I home brewed which uses power for a few hours). Our ASHP is an 18kW unit.
The house is warm, 21C in most areas.
Feel free to share your consumption data.
Buy Bodge Buster – Homeowner Air Source Heat Pump Installation Guide: https://amzn.to/3NVndlU
From Zero to Heat Pump Hero: https://amzn.to/4bWkPFb
Follow our sustainability journey at My Home Farm: https://myhomefarm.co.uk
This will be my first winter with my HP, and it currently seems to be struggling ... it's been trying for 3 hours to hit the target LWT for 0°C (46.5) but the interference of the defrost cycles keeps pushing it down. 3 days ago we didn't get above zero all day, and couldn't get about 20°C without additional heaters. My estimated COP is hovering just below 2.
Consumption peaked around 45kWh. These temperatures are more like January than November though!
(red line is LWT; orange line is OAT, averaging 0)
Grant Aerona 3 10kW
mine for the 29th, max 3C day then -2 at night. 41kwh of electricity for 110kwh of heating. short-term COP is nearly 3 when it stable running in heating mode but the frequent defrosts bring it down 10% ish.
@mikefl if your system is struggling to reach target LWT with the frequent defrosts, that could make it worthwhile looking at your overall system to see if you can run with a lower WT?
My octopus signup link https://share.octopus.energy/ebony-deer-230
210m2 house, Samsung 16kw Gen6 ASHP Self installed: Single circulation loop , PWM modulating pump.
My public ASHP stats: https://heatpumpmonitor.org/system/view?id=45
11.9kWp of PV
41kWh of Battery storage (3x Powerwall 2)
2x BEVs
@iancalderbank Yes, that's something I'll be looking at. But I'm trying to hold off changing any WC parameters until I've sorted out the flow rates / balancing / commissioning, etc. (i.e. the stuff the installers should have done before leaving). Right now, I want to be confident the monitoring I've added is stable and accurate, so I can actually see the impact of any changes I make. And my strategy is "change one thing a week and see what happens", which is slow, but hopefully fruitful.
Grant Aerona 3 10kW
I recently installed a 5kw Mitsubishi ecodan to heat a small barn conversion- ground floor 35m2 with ufh. 1st floor ufh under engineered floor.
@kenneth Ecodans don’t modulate down well I have ufh and it won’t run below 32C without cycling on and off which is what you are seeing. The delta T is low as the flow temp is close to the actual temp of the room so the ufh can’t transfer the heat hence only a 2C difference between flow and return. Delta T isn’t an issue, a lot of cycling is bad for the compressor. You could turn up the flow temp and let it get the room to temperature quicker then let the thermostat turn it off and on as required. You would get less cycling and shorter run times the energy consumption msg not be much different
@gary Thanks for the advice. I will increase the flow temp and see what happens. If it gets noisy at higher temps I might revert back - neighbours haven’t complained about the noise but when it’s working hard it seems quite loud. From my point of view I’m relieved it’s working well heating this house. Lots of insulation in the floor ,walls. And roof have paid off. Minus 4.5 now outside but still 21c in here.😊
kenneth
30th November was a bit cold we operated a setback to 16C and still got a TOPUP in the middle of the night
Room temp is black line. Green is Outside temp.
Flow temps for us typically around 40c with an all radiator system.
17th C house, 180sqM area, 21kw Rads (DT50), 8.5Kwh Ecodan, operating in Auto Adapt
typical defrost and recovery back to 40C
-10°C here overnight and still currently. House is just about at 18°C, so comfortable, but we've pulled 41kWh so far today. 😱
The one noteworthy thing, apart from eye-watering consumption, is that defrost frequency has been only around every 80-90 mins which has allowed the LWT to reach set point. Presumably this is a function of humidity - at around 0°-2°C with damp air or snow falling the defrost frequency can be every 30-40 mins so the LWT never really builds to its target.
2 x 12kW Samsung Gen6 ASHP, 5.6kW solar PV ground mounted c/w 10kWh Puredrive battery & Solis inverter.
- 25 Forums
- 1,513 Topics
- 31.8 K Posts
- 24 Online
- 1,283 Members
Join Us!
Latest Posts
-
RE: Additional Battery v Wind Turbine v Ripple
I should add, being an investment, the value of your in...
By Old_Scientist , 4 hours ago
-
RE: Ecodan - flow rates, sensors, settings
Achieving an accurate flow measurement is probably the ...
By Derek M , 7 hours ago
-
RE: Ecodan ASHP - How to optimise my set up?
Again, thank you for another thorough post, @derek-m - ...
By rhh2348 , 9 hours ago
-
RE: Delivering a smart and secure electricity system: government consultation
@Transparent.Now that I am represented by a new MP I th...
By IanMK13 , 11 hours ago
-
RE: Vaillant aroTHERM plus not level or flat - what base is best under an external unit?
Similar thread here
By Johnmo , 12 hours ago
-
RE: VDI 2035 heating water specification
Been looking and it seems a good little project. Ever...
By Johnmo , 1 day ago
-
RE: Do I accept an ASHP and Solar Panel retrofit under the HUG 2 scheme?
Will do. I'm currently waiting for another survey / vis...
By dssr , 2 days ago
-
The company that did the borehole were expecting us to ...
By Johnmo , 2 days ago
-
-
RE: The Misquote That Ruined the Heating Industry
@abernyte manufacturer training is pretty average. They...
By Mars , 2 days ago
-
-
RE: ECO4 Scheme and EPC ratings
@mellow Thanks. Given there is a scheme requirement to ...
By Old_Scientist , 3 days ago
-
RE: Do I just go with the lowest quote for my heat pump?
@jancold To me its a no-brainer then, a max 40C flow te...
By bontwoody , 3 days ago
-
-
RE: Heat Pump Books Beginners – Bodge Buster & From Zero To Heat Pump Hero
@editor Presumably he had some good weather Compensatio...
By Toodles , 4 days ago
-
RE: New Vaillant 7kW aroTherm ASHP or oil boiler dilemma/decision??
Storage capacity really is dependent on storage tempera...
By Johnmo , 4 days ago
-
RE: HP Cycling, Expected or Undesirable
Just a little update. I ordered a longer shielded twin ...
By bontwoody , 4 days ago
-
RE: Domestic hot water timer doing crazy things on my Grant Aerona3 10kW air source heat pump
Thanks @allyfish for the pics and info. Spoke to the in...
By Mellow , 4 days ago
-
RE: Aira Heat Pump: Stylish Scandinavian Heating
It's been a busy day for calls and emails from Aira. I ...
By MikeH , 4 days ago
-
RE: Heat Pump Servicing & Maintenance – Good Value or Rip-Off?
Hmm. A bit of a nuanced answer, methinks. As I've alr...
By Majordennisbloodnok , 4 days ago
Latest Topics
-
Ecodan - flow rates, sensors, settings
By rhh2348 10 hours ago
-
Replacing mains water with well water
By Johnmo 2 days ago
-
Additional Battery v Wind Turbine v Ripple
By bontwoody 2 days ago
-
By jamespipe 3 days ago
-
VDI 2035 heating water specification
By Johnmo 3 days ago
-
Do I just go with the lowest quote for my heat pump?
By Jancold 5 days ago
-
The Misquote That Ruined the Heating Industry
By Alec Morrow 5 days ago
-
Battery Storage Wiring Gauge Question
By Puff 6 days ago
Members Online
No online members at the moment