Buffer capacity for the thermal pump

Owing to specifics of operating modes, heating systems with use of the thermal pump should answer defined requirements for the minimum expense and heat-carrier volume. Besides, for thermal pumps of type air/water heat enough for a mode of a defrosting of the evaporator should be reserved.

For performance of these conditions two options of realization of system holodo-heat of supply with the thermal pump are possible:

  • The system has sufficient volume of the heat-carrier without use of adjusting fittings (a thermohead, or expense valves)
  • Existence of buffer capacity for the thermal pump

The option of heatpump system without installation of buffer capacity, so-called «direct system» will be the least expensive. Such option will approach, if as heating devices systems of heat-insulated floors (warm walls) with big capacity of heating water are applied only.

Buffer capacity for the thermal pump

System without application of buffer capacity

However there is one condition – at such system there should not be a thermohead, channel regulators etc., and existence of the perepuskny valve obligatory.

Such heating system demands detailed and difficult design on hydraulics as all contours of a heat-insulated floor should be equal among themselves on resistance. Giving and obratka pipes in heating contours should be precisely calculated for providing the minimum demanded channel of the heat-carrier according to parameters of the thermal pump.

Besides, in systems with air thermal pumps there can be shortages of heat at inclusion of a mode of a defrosting of the evaporator. It, in turn, can lead to decrease in comfort.

Installation of buffer capacity with the thermal pump

In more difficult systems of heating with various heating devices and existence of mixing valves, regulators of a channel and thermoheads it is necessary to establish buffer capacity. Installation of a tank can be one of requirements of the producer for reduction number of start-up of the compressor.

The majority of systems are realized with in parallel connected buffer tank. The volume of the buffer pays off concerning capacity of the thermal pump. Many producers specifies in technical documentation that the minimum volume of capacity should be not less than 25 liters on 1 kW of capacity of the thermal pump.

Buffer capacity for the thermal pump

Parallel connection of the buffer

Connection of buffer capacity solves the main problems connected with integration of the thermal pump in system of heating. However such scheme has one essential shortcoming connected with need of maintenance of constant temperature in the buffer. Thus there are undesirable thermal losses that can lead to decrease in efficiency of the thermal pump for 5 %.

The most optimum option is application of the scheme of direct system combining advantage and systems with buffer capacity. Such decision allows to prevent excessive thermal losses in the buffer, at the same time reduces number of start-up of the compressor. In that case the buffer serves for accumulation of superfluous heat from the thermal pump and provides with heat enough for defrosting function for the air thermal pump.

Buffer capacity for the thermal pump

The combined connection of buffer capacity

Important that diameter of a pipe between a buffer tank and the thermal pump was more than in system of heating and the total stream of the heat-carrier in heating contours did not exceed a stream between buffer capacity and the thermal pump. This scheme most approaches where the thermal pump is the main source of heat.

The scheme with installation of a buffer tank in a contour of heating is consistently usually used in a combination to the air thermal pump.

Buffer capacity for the thermal pump

Consecutive turning on of the buffer

Such scheme does not demand installation of the additional sensor of temperature in the buffer. In that case the buffer performs function of the accumulator of heat for ensuring work of function of a defrosting without comfort loss in a heated room.

Updated: August 24, 2015 — 12:42 pm