I would like to talk about the operation of a ventilation system with recuperation to which a ground heat exchanger is connected. Namely, the ground heat exchanger.
In one of the houses Project 500.
soil heat exchanger was dug.
Two branches of a pipe with a diameter of 200 mm and a total length of 80 m were buried, buried with a slight slope towards the house where the condensate collector is installed, to collect condensate in the summer, when the air is cooled. The pipe is double-walled, corrugated on the outside, can withstand heavy loads and dig into the depth of up to 10 m (PVD material), inside is smooth HDPE. The pipe is chained to a depth of 1.5-1.8 m
The ground heat exchanger was created to heat the incoming air in front of the heat exchanger so that it would not be subjected to freezing and critical temperatures.
Naturally, before entering the ground heat exchanger, it is necessary to put a filter
It looks like this beforehand. (not yet ennobled, then it will be a curbstone finished with clinker)
In the House
The house has a supply and exhaust system with recuperation electrolux star epvs-1300 (power was chosen due to long routes and pressure drops)
A booster fan is also installed on the ground heat exchanger
The automation system allows you to control the installed dampers, namely:
1. at an outdoor air temperature of +5 to +25, air is supplied from the street without a ground heat exchanger, at any other temperature, air goes through a ground heat exchanger
2. the house is divided into three zones, 1 - bedrooms on the 2nd floor, 2 - rooms on the 1st floor, 3 - living room, any zone can be turned off, for example, at night the living room is usually not needed, respectively, ventilation works only in the bedrooms, or during the day when no one is in the bedrooms, the ventilation works in the living room
The average amount of air passing through the ground heat exchanger is 600 m3 per hour
Air supply goes to the living rooms, air intake from bathrooms and kitchens. The kitchen hood above the stove is not connected to the heat exchanger.
At the same time, at a temperature on the streets up to -15, after the ground heat exchanger to the heat exchanger, a stable temperature of +9 - +11 degrees
The ventilation system does not work all the time, the house is on short visits, when no one is there, it is naturally turned off. But the operating mode during the New Year holidays showed stable temperatures for more than two weeks. Of course, by the end of winter, the soil will freeze in a constant mode, but in this embodiment, the length of the pipe is designed for this mode of operation, with constant operation it is needed a little longer, although frosts with a strong minus are not constant, and do not last more than a week.
We will not consider the temperature after the heat exchanger, because and so it is clear that with an air flow of 600 cubic meters with a recuperator designed for 1300, the efficiency will be maximum, and in reality the difference is a maximum of 2 degrees.
For information, so that there are no questions on this topic: after the heat exchanger, the heating from the heating boiler is installed in the system
This was done in order to quickly warm the air in the house to +22, which, in the absence of people, can be lowered to 18 degrees, for this we heat the air supply to +26.
Results: The ground heat exchanger showed good work in the winter period, completely replaced the reheating of the incoming air to positive temperatures.
Calculation of the length of the recuperator can be found here
