Thread by @glynhudson

Following on from my air source heat pump installation thread, this thread will document the performance of the system #ASHP🧵🤓

HP is a 5kW Samsung Gen 6 with 150L DHW tank and 7x upgraded radiators in a 200yr old 2 bed end-terrace house with sold stone construction, max heat loss at -3 degC ambient is estimated to be between 3.3kW-4.2kW, 28mm pipework to 3-port, mostly 22mm primary with 15mm drop to rads

The monitoring system is a @Openenergymon Level 3 setup with class 2 MID approved heat and electricity meters (Sontex 749 M-BUSand Estron SDM120 Modbus), data logging and graphing is done using Emoncms guide.openenergymonitor.org/applications/h…

The ASHP has now been installed for almost 2 weeks, it's been a heatwave, so no heating required! My DHW has been heated from solar PV divert, however the last couple of days have been dull so DHW needed a topup...

This evening the ASHP heated my DHW tank from 20 degC to 55 degC with a COP of 4.2, it still feels like witchcraft how a meagre 1.25kWh of electricity results in 5.3kWh worth of piping hot water!

I had planned to limit DHW temp to 45 degC to maximise COP, however I was pleasantly surprised how it managed to go from 45 degC tank (50 degC flow) to 55 degC tank (60 degC flow) with a respectable COP of 3.6, so not need to limit max temp, at least not at this time of year

Heat loss calculations are covered in more detail here

I also had an airtightness test done which indicated the house was not as leaky as I though which should mean max heatloss is closer to 3.3kW rather than 4.2kW, the 5kW ASHP I fitted is the lowest output ASHP widely available

In terms of noise, I've found the outdoor unit to be quieter than expected, I can't tell if it's running without going outside, the rubber dampers and flexi connections on the wall-mount must be doing their job, no noticeable vibrations, however...

I've found the pump Grundfos UPM3 PWM located in cupboard next to bedroom to be louder than expected during DHW cycle, setting 70% inverter limit (FSV 4051) reduces pump speed from 23l/min to 17l/min during DHW which makes pump almost inaudible, no noticeable performance diff

I've noticed the Samsung display reports about 10% less heat energy delivered than the class 2 MID heat meter, maybe the Samsung calculation is assuming I'm using glycol? @JeremyClimas

I was expecting the opposite, i.e Samsung to be reading slightly higher since there will be some heat loss between the outdoor unit (where Samsung reading is calculated) and indoors where the heat meter is located, the flow rates and temperature readings from each system match

Coldest night of the year so far last night, ambient dropped to 5.4°C, indoor averaged 21.5°C, ASHP averaged 4.8 COP for heating in the evening and 4.37 COP including DHW cycle top-up overnight and some heating this morning 👍

It still feels like witchcraft how 1.5kWh of electricity results in over 7kWh of heat 😁 #magic

Ran a test this evening to see how hot the ASHP is able to heat DHW without using an immersion, I stopped the test when middle of tank hit 56C with a flow temp of 64C which is close to max for my R32 ASHP, ambient was 9C and overall COP of 3.3...

Therefore, maybe using an immersion for legionella is not always required since apparently 90% of any potential legionella is killed within 2hrs at 50C so 56C should be pretty safe, COP of 3.3 is not great but much better than COP of 1 from an immersion!

Now the outside temperature has dropped a bit the ASHP is running for a bit longer, in last 24hrs: average outdoor 12C, average indoor 20C, 18kWh of heat delivered using 3.6kWh of electricity, overall COP of 4.9 for central heating and DHW, or COP of 5.5 for just central heating