The ground heat exchanger enables preheating of the air supplied to the house by mechanical ventilation devices. Most often it takes the form of a more or less sophisticated pipe system, in which only air or a fluid that accumulates temperature from the ground circulates (e.g.. glycol) The earth has a constant temperature below a certain depth, that is why it is tempting to use the free heat source (winter) or cold (in the summer).
However, is the game worth the candle in a situation where we have a recuperator??
Not at all, it is not obvious. Today's recuperators are so efficient, that these devices working in one system start to duplicate each other. As a result, the temperature of the air supplied to the house may be only a few percent higher in the gwc-recuperator duo compared to the recuperator itself.. However, the cost of making gwc is not negligible. ( It depends a lot on the adopted variant - the cheapest option is to dig an ordinary pipe into the ground yourself, the most expensive - complete, systemic, technologically advanced devices )
That is why there are many declared opponents of the construction of gwc cooperating with a recuperator among professionals. They point to the lack of economic sense and negligible heat gains, and therefore little savings on heating costs.
In practice, the gwc made with a low cost has advantages. I would classify as the main ones:
– a slightly higher temperature of air supply in winter - admittedly, it may be e.g.. 2 degrees, but 2 degrees also make a not little difference when it comes to feeling comfort. Let's remember, that the supply air itself has a cooling effect (it's about subjective feelings) and even small differences are significant.
– in summer, the lower achievable air supply temperature allows you to ventilate the house even in hot weather. In systems with only a recuperator, it is common practice to turn off the ventilation in hot weather and turn it on again in the evening hours..
– having an efficient GHE, you can even try to cool the house with e.g.. more powerful external fan, which directs the air through the external circuit outside the recuperator.
I will try to answer the question whether it is worth building GHE: in purely financial terms, the topic is indeed debatable. However, when it comes to comfort, the GHE has some advantages. If these aspects are important to us - it is worth building GWC and enjoying better comfort of living at home.
Let's also remember, that it is best to decide on the GHE during construction, because later the wife is unlikely to let her carefully tended garden be ruined.