Heatpumps & heatpump monitoring

OpenEnergyMonitor Trystan LeaThanks to John Cantor heatpumps.co.uk

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

Average home today

Lighting, Appliances and cooking 10.6 kWh/dSpace heating gas input: 34 kWh/dWater 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 cooking4.5 kWh/dSpace heating electric input: 4.2 kWh Water heating electric input: 2.3 kWh

Provided by renewable electricat zero carbon

83% energy saving from insulation+ draught proofing + heatpumps

Open source zero carbon energy system modelhttp://openenergymonitor.org/energymodel/

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 willneed a heat input of:

22K x 109W/K = 2398W

Average requirement is:11K x 109W/K = 1200W

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 needsto 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 @ 50K503W @ 15K (35C)731W @ 20K978W @ 25K

heat output = rated heat output x (deltaT / rated_deltaT) ^ 1.3

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

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 daysElectric input: 88.9 kWhHeat output: 260 kWhAverage COP 2.92

Detailed heatpump run visualisations, running off the emonpi

Average COP of 23 test runs: 3.451 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

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.