Slides from presentation given by Trystan Lea in N.Wales Tech meetup Dec 15

1. Heatpumps & heatpump monitoring
OpenEnergyMonitor Trystan Lea
Thanks to John Cantor heatpumps.co.uk

2. Heatpumps
For every 1 unit of electrical power the heatpump provides on average 3 units of heat
output by moving heat from the air, water or ground into the building.
Carnot COP = (T_condencing+273) / ((T_condencing+273) – (T_evaporation+273))
Practical COP = 0.5 x Carnot COP

3. Average home today
Lighting, Appliances and cooking
10.6 kWh/d
Space heating gas input:
34 kWh/d
Water heating gas input:
5.8 kWh/d
Provided by a mix of gas and present grid
electric = ~ 5 tonnes of CO2//year
Average ZeroCarbonBritain home
Lighting, Appliances and cooking
4.5 kWh/d
Space heating electric input:
4.2 kWh
Water heating electric input:
2.3 kWh
Provided by renewable electric
at zero carbon
83% energy saving from insulation
+ draught proofing + heatpumps
Open source zero carbon energy system model
http://openenergymonitor.org/energymodel/

5. 1) Model the heat loss rate of your house
MyHomeEnergyPlanner, open source home energy assessment software, collaboration
with Carbon Coop in Manchester who carry our home retrofits saving households 70%
on their energy use.
http://github.com/emoncms/MyHomeEnergyPlanner
How to design and install a heatpump system
Heat loss rate: 109W/K
When its -1C outside and I
want it to be 21C inside it will
need a heat input of:
22K x 109W/K = 2398W
Average requirement is:
11K x 109W/K = 1200W

6. 2) Calculate heat emitters required: number of radiator or under floor heating to provide
max heat output demand at an efficient heatpump COP
- Radiator datasheets
- Heatpump flow temperature needs
to be ideally ~ 35C to 40C to run
efficiently
- 1703 W @ 35C
- 2231 W @ 40C
- 2878 W @ 45C
1x Dimplex smart rad SRX180
0.9 kw @ 10C (30C MWT)
1.2 kw @ 15C (35C)
1.5 kW @ 20C (40C)
1.9 kW @ 25C (45C)
2.3 kW @ 30C (50C)
2.7 kW @ 35C (55C)
3.0 Kw @ 40C (60C)
1x Standard double panel convector
http://www.screwfix.com/p/kudox-
premium-type-22-compact-double-panel-
convector-radiator-700-x-
1200mm/30717
2407W @ 50K
503W @ 15K (35C)
731W @ 20K
978W @ 25K
heat output = rated heat output x (deltaT / rated_deltaT) ^ 1.3

7. 3) Select a heatpump
Many available
5 kW mitsubishi ecodan, more
than I need for stage 1 but
enough for expansion into
other rooms.
One of the smallest heatpumps
on the market, has a good
record.
3) Misc components:
- Efficient circulation pump
- water filter
- expansion vessel
Energy monitoring
Total installation cost ~£3000

8. How well does it work? … open source heatpump monitoring
- EmonPi electricity monitoring
- Kamstrup multical 402 billing grade heat meter,
connected to emontx via mbus and open source
mbus reader implemented on emontx
- EmonTH internal and external temperature monitoring
From October 17th
to November 10th
:
24 days
Electric input: 88.9 kWh
Heat output: 260 kWh
Average COP 2.92

9. Detailed heatpump run visualisations, running off the emonpi

10. Average COP of 23 test runs: 3.45
1 unit of electric in
3.45 units of heat out
Heat cost at electric rate of 16p/kWh = 16 / 3.45 = 4.6p/kWh
Seasoned wood: 5.41p/kWh, Propane gas: 12p/kWh

11. Next step
Dedicated open source heatpump
monitoring board and accompanying
software to make this monitoring
easier to replicate.
Arrived back from ragworm PCB
manufacturing today.