Ground source heat pump – Top 5 mistakes

There are quite many failures or mistake when purchasing or installing ground source heat pumps. Here are top 5 I'm hearing from users:

1. The output power of the heat pump is too high or too low. The problem is that nobody made his homework. Nobody made calculations how much power is needed according to the heat loss of the house. Usually the customer buys too powerful heat pump.
2. The dimension of vertical or horizontal ground sourced collector is too small, too weak. Again nobody made his homework. There is absolute need that one engineer prepares the blueprint and proper energy/heat calculations for the heat pump and for the collector.
3. The low temperature heat pump is attached or installed to existing high temperature heating systems. This is usually a big mistake. In such cases heat pump can be used as secondary heat source for low temperatures, but for very cold days your should use more powerful and high temperature source (e.g. gas or oil).
4. Instead of existing furnace (oil, gas, wood) the heat pump of same power is installed. Usually this will not work. One one hand existing furnace was probably too much powerful and there is no need for the heat pump of the same power. On the other hand heat pump will probably ensure only temperatures up to 50 Celsius which is too low, unless high temperature heat pump is used. 
5. Installations in the ground are not of good quality. Since the investment in ground source collector is pretty high, the installation must be of 100% quality. No errors, damages or leaks are permitted. If there is a problem it is very hard first to find the spot of error and second the repairs are very expensive. The vertical collector must run without problems for 30 years. Request proper warranty.

When installing a heat pump in old house and old heating system, I would definitely propose to first insulate the house and change windows and after that install heat pump system.

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…).