- 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.
- 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.
- 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).
- 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.
- 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.
