What type of heat pump to choose? – PART 3

After you found out that your building does not have too much specific heat losses and would be suitable for installing heat pump, you must consider what type of heat pump to install and how powerful should it be.

For choosing a type of heat pump you must first decide what will be the source of energy. I would recommend deciding according to the following sequence. If you have a plenty of land space around your house, at least double or triple of house quadrature, I would recommend installing horizontal collector based heat pump. If you have underground water sources I would recommend to install ground water based heat pump – in that case you must drill two wells 20 – 50 meters deep to reach underground water. If you don’t have neither a lot of space around your house, neither underground water, I would recommend installing vertical geo-collector based heat pump as I did. This option is expensive but very reliable; you must drill one or two wells from 60 to 150 meters. In case none of above options suits your situation, then I would recommend installing air sourced heat pump that is using outdoor air as source of energy. This is the cheapest solution, but also less effective in comparison to others. I would not recommend installing outdoor air sourced heat pump if winter temperatures frequently drops under -5 degrees Celsius.

To be on a safe side I would recommend making few calculations before deciding. Find an engineer and decide together. Maybe you would be able to decide what type of heat pump to choose, but you will definitely need help when deciding how powerful the heat pump should be and how much of energy resources it will require – there are a lot of factors to be considered (type of heating, winter temperatures, specific heat loss, peak winter temperatures…).

What type of heat pump to choose? – PART 2

First step is to calculate how much specific heat loss your building has per square meter of usable floors (heat loss in W/m2). If your house has more than 60W/m2 maximum specific heat loss then I would not recommend installing heat pump. You should first think of additional insulation of the house. Typical house where heat pump is much recommended:

• Net floor area = 150m2


• Needed heat per year = 45kWh/m2 per year


• Max Specific Heat loss 35 W/m2

To calculate heat loss you need a bit of engineering and mathematics, but I would recommend finding an engineer who has experience in calculating building heat loss. It also depends in what climate area you are living, what are your additional heat sources during the winter (solar roof, windows to the south…).

What type of heat pump to choose? – PART 1

Winter is knocking on the door and I started my heat pump again. Since last post one idea occurred to me and that is answering quite frequent question: What type of heat pump to chose. I prepared relatively simple decision making model for choosing a heat pump for heating the house during the winter. Everybody knows that we have several types of heat pumps multiplied by number of producers and you can get 1000 of different heat pumps … O.K. it is not so bad :-) … actually we have few types of heat pump to choose between – in general: air to air heat pump, air to water heat pump, ground sourced heat pump (water to water). To be able to choose the right one you must consider: type of heating to be used, current/new building conditions, available heat sources, legislation, building restrictions, climate, heat losses, preparing also hot water, heating regime (low or high temperatures), and financial part.

In general one could say – every heat pump is better than no heat pump. But let us check in details in PART 2 … coming soon.

Finalizing Heat Pump Implementation schema and installation schema

After all parameters for my home heat pump project were calculated, all kilowatts, meters, centimeters, constants were known, I have prepared final implementation schema (partly shown it the picture) and detailed installation schema for pipes, valves, other pumps, collectors, electrical installation and other stuff. Installation schema was later used by service providers for implementing my project. If you would like to have a copy of detailed installation schema, please send me an e-mail to: toskog@gmail.com.

Calculation of energy losses and energy needs for the building

Building insulation is the most important factor when calculating energy loses or on the other hand energy needs for heating. Heating system must be aligned according to building energy loses. Here are my final numbers and calculations:

Building parameters:

• Building square meters (room surface): 180 square meters to heat
• Type of heating: ground heating
• Building walls: 30 cm brick and 10 cm isolation (glass wool)
• Building roof: wood structure with, 21 cm of isolation (glass wool), standard knauf
• Building ground floor (to the ground): 5 cm concrete, 8 cm isolation, 5 cm concrete, 40 cm sand layer
• Windows: thermo glass

Coefficients:

• Windows thermal transmittance: U=1,1W/m2K
• Glass wool thermal conductivity: 0,035 W/mK

Final calculation for heat pump system installation. We need:

• Heat pump with output power: 14kW + 6kW Optional Extra Heater for Extreme Low temperatures
• Geothermal vertical collector according to ground structure: 2x100m
• Water Heater: 300 liters

There were also other numbers and quite complicated parameters and calculations. I think shown numbers are enough to get an impression. I will put some calculations in PDF to this blog for download in near future.