DE9408602U1 - MC heating and boiler control - Google Patents

Description

Dip!.-Phys. Max Winkler, Steghäus.er'S^^S^i^irpiigQiis'.tQn 22.5.94

Description

Integrated micro-controller system for controlling heating and boiler systems

State of the art

The state of the art is that the heat output from the boiler is adjusted to the heating energy requirement by reducing the boiler temperature depending on the outside temperature. This is intended to control the heating and the boiler water supply according to the weather-related heating energy requirement. The introduction of low-temperature boiler technology was therefore justified by the fact that lower radiation and standby losses could be expected and thus considerable energy savings could be achieved through low-temperature boiler technology.

In addition, the heating pumps are switched on or off by setting time windows for the operating times of the heating circuits (day operation/night reduction).

problem

However, a number of unsatisfactorily resolved issues remain in the current state of technology, and new problems have arisen due to the introduction of fin technology for low-temperature boilers, which in practice even lead to a deterioration in the overall efficiency of the heating system. In addition, low-temperature operation leads to increased condensate formation on the boiler heating surfaces and in the chimney and leads to increased corrosion problems.

Recent studies on energy savings in low-temperature boilers have revealed the following problem: With flow temperatures of 40-45 ⁰ C, it is not possible to heat domestic water, e.g. to charge a storage water heater. To do this, the boiler must be heated to 60°C at least twice a day. However, when the storage tank has finished charging, the boiler is at this high temperature and after the priority circuit is cancelled, the hot boiler water is pumped into the heating network, where this high temperature is not needed, ie energy is wasted and the rooms are overheated.

In addition to energy-saving operation, hygiene aspects, operational safety, and timely and sufficient provision of heating and hot water are important requirements.

Dipl.-Phys. Max Winkler, Steghäus.er;d9.a, i|43£5^§imb*aßh»(jnn 22.5.94

According to the current state of the art, the following problems remain unsolved:

Circulation pumps run for an unnecessarily long time and waste electrical and thermal energy

The desired energy savings through low-temperature operation with night-time shutdown are not achieved in practice due to the poor control behavior of the low-temperature finned boilers.

If the boiler temperature is lowered for a longer period, problems with Legionella contamination can arise in the domestic water circuit. Particularly in the case of slow heating systems (underfloor heating), a lack of heat demand forecasts leads to incorrect control (delayed provision of heating or overheating of the rooms).

The MC heating and boiler control system allows these problems to be solved with new technical approaches.

invention

The invention is a microcontroller-based measuring and control system that continuously measures the outside temperature, the boiler temperature and the set heating parameters, monitors compliance with the limit values and automatically initiates corresponding control actions. Based on the set parameters and the measured outside temperature as well as their change over time, a heat requirement can be predicted and the necessary heat provision and an adapted heat transport capacity can be ensured in good time. This is done by an outside temperature-dependent power extraction of the MC-controlled average circulation pump speeds in the heating and hot water circuits.

The micro-controller permanently monitors all temperatures and timer requirements of the various heating and domestic water circuits. A battery-buffered real-time clock with battery-buffered RAM memory guarantees mains-independent security of the set operating parameters, timer intervals and the clock and date functions.

Dipl.-Phys. Max Winkler, Steghäuser» 3ö.a, ^43^<§iipßaf^j(jpn 22.5.94

Process description :

The MC heating and boiler control measures the boiler water temperature (A1.1) and compares it with the entered setpoint value (A2.3). If the boiler water temperature falls below the specified setpoint, the burner is switched on and heated up with a specified temperature hysteresis (for example of 5 K). If there are two flow tapping points at different temperature levels (claim 4), the boiler temperature (A1.2) must also be taken into account in the burner control.

When the test button (B2) is pressed, the burner and all pumps (P1, P2, P3) are switched to full power regardless of the respective operating status parameters.

The domestic water pump (P3) is switched on depending on the set domestic water charging time (T3) and the domestic water temperature (A1.4) if this has not yet reached the specified domestic water setpoint (A3.3). In addition, the long-term periodic specifications of the special program for legionnaires' destruction (T4) control the domestic water pump and the burner status for a correspondingly higher setpoint specification of the domestic water temperature (= 7O ⁰ C).

The domestic hot water pump (P3) is blocked if the boiler temperature (A1.2) <the
Domestic hot water temperature A1.4.

The MC heating and boiler control measures the outside temperature (A2.1) and compares it with the specified target value (A2.6) for the full load temperature. If the outside temperature A2.1 < A2.6, the heating circuit pump (P1) and the underfloor circuit pump (P2) are switched to full load (100%).

If A2.1 > A2.6, the partial load ratios for the radiator circuit (φ1) or for the underfloor circuit (φ2) are calculated by the microcontroller. The assigned pumps are then controlled in the corresponding switching ratio (claims 1 and 2). The set operating ranges in (T1) and (T2) must be in the active state and the burner temperature (A1.1) must not have fallen below the flow temperature setpoint (A2.3).

The boiler can also be kept at the minimum flow temperature when the circulation pumps are not in operation, e.g. at night, so that complicated start-up programs are no longer necessary. The switching difference of the flow control should be around + 5K, that of the boiler controller + 7K.

Dipl.-Phys. Max Winkler, Steghäb$ei;eQa _t ^3^3iriiSa$$ij(Jpn 22.5.94

Specification for oil/gas boiler control

(specially designed for "NT boilers" according to Gerhard Metzner)

A. Microcontroller - Part

A1 Temperature sensor

A 1.1 Flow temp. (<=> Boiler temperature at a flow extraction temp.)

A 1.2 boiler temp. (is » 15 K above A 1.1, with two flow temp.)

A 1.3 Outside temp.

A 1.4 Domestic water temperature (also serves for domestic water hygienisation)

A 1.5 Exhaust gas temp. (sensor optional, serves as cleaning indicator)

A 2 Displays

Ä2.1 Outside temp. (oA1.3)

A 2.2 Actual flow temperature («►ALI)

A 2.3 Flow temperature setpoint - adjustable by the operator from 40 to 70 ⁰ C A 2.4 Partial load ratio radiator circuit &phgr;1 (in %) A 2.5 Partial load ratio floor circuit &phgr;2 (in %) A 2.6 Full load outside temp. = 100% pump output design temp. of the system

A 3 time slots

A3 T1 Operating times for radiator circuit (2 operating time ranges can be set) A3 T2 Operating times for floor circuit (1 operating time can be set) A3 T3 Domestic hot water charging time - A 3.3 Domestic hot water temperature setpoint can be set A3 T4 Special program "Legionella elimination"

B. Conventional part

B 1 On/off switch

B 2 test button (chimney sweep)

B 3 Maximum controller type-tested, fixed setpoint = 85°C

B 4 Safety temperature limiter type tested 100 ⁰ C

B Ü Bridging switch in case of MC fault

Sensor arrangement:

The sensor A 1.1 goes into the flow outlet for the "mixed flow temperature. The sensors for A 1.2, B 3 + B 4 go into a common immersion sleeve in the warmest boiler zone.

Features:

The functional connections correspond to the enclosed block diagram

Claims (6)

Dipl.-Phys. Max Winkler, Steghäus£r:39a,843S9*Sjrab*äci)£fon 22.5.94 MC heating and boiler control Integrated micro-controller system for controlling heating and boiler systems (hereinafter referred to as "MC heating and boiler control") Protection claims 1. MC heating and boiler control, characterized in that the control of the heat output from the boiler is carried out depending on the respective requirement by changing the heating water volume flow fed into the heating network at a constant flow temperature. 2. MC heating and boiler control according to claim 1, characterized in that the heating water volume flow is adjusted by a clock circuit and/or a speed change of the circulation pumps, whereby the outside, boiler, domestic water and room temperatures are continuously recorded and the firing devices and the circulation pumps are controlled according to the set time programs and target values. 3. MC heating and boiler control according to claim 1 and 2, characterized in that the lowest outside temperature at which the full pump delivery capacity is to be available can be freely selected by the user and that different partial load ratios can be set for different heating circuits (eg radiator or underfloor circuit). 4. MC heating and boiler control according to claim 3, characterized in that it can be used for heating boilers with two flow tapping points at different temperature levels and accordingly processes the temperature sensor input signals in such a way that the useful heat requested in accordance with the current time program is provided at the lowest possible temperature level. 5. MC heating and boiler control according to one of the preceding claims, characterized in that an automatic summer/winter operating detection is possible by a separately evaluated day/night temperature sum limit value query. 6. MC heating/boiler control according to claim 2, characterized in that the entire domestic water circuit can be hygienized by weekly periodic domestic water heating above 65°C and thus the risk of legionella can be prevented in particular, whereby this is possible without any significant energy loss by means of a time-limited hygienization heating and monitoring of the domestic water circulation.