GT/GTM/GTG 300/II GT/GTM/GTG/GTI 300 K/II GT/GTM 300 ...

ENGLISH 

GT/GTM/GTG 300/II 

GT/GTM/GTG/GTI 300 K/II 

GT/GTM 300 DIEMATIC-m Delta/II 

GTG/GTI 300 DIEMATIC-m Delta/II 

Oil/gas-fired boilers 

Technical instructions 

for installation 

and maintenance 

08/04/03 - 94863871 - 8553-4148

● DECLARATION OF CONFORMITY / 

MARKING 

This product complies with the requirements of the 

ollowing European directives and standards : 

- 90.396 EEC, Gas Device Directive 

Relevant standards : EN 303.1 / EN 303.2 / EN 304. 

- 73/23 EEC, Low Voltage Directive 

Relevant standard : EN 60.335.1. 

- 89.336 EEC, Electromagnetic Compatibility Directive 

Relevant standards : EN 50.081.1 / EN 50.082.1 / 

EN 55.014 

- 92/42, Efficiency Directive 

It will be marketed in the following EEC member states : 

FR - DE - BE - LU - GB - IR - ES - PT - DK 

SE - AT - CH - GR - NL - IT 

with a gas burner of the associated category. 

CONTENTS 

1. GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

1.1 Models available . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

1.2 Control panels available . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 

1.3 Technical specifications - boilers for EXPORT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

1.4 Technical specifications - boilers for EUROPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

1.5 Main dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

2. INSTALLING THE BOILER IN THE HEATING ROOM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 

3. ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 

4. HYDRAULIC CONNECTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 

4.1 Important recommendations for connecting the heating circuit to the boiler and to the drinking water system . . . . 9 

4.2 Filling the system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

4.3 Sludge removale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

5. CHIMNEY CONNECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

5.1 General recommandation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

5.2 Flue size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

5.3 Connection between boiler and flue pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

6. FUEL-OIL OR GAS CONNECTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 

7. ELECTRICAL CONNECTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 

8. MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 

8.1 Installation - water level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 

8.2 Boiler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 

8.3 Precautions required if the case of a boiler stop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 

9. IDENTIFICATION PLATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 

10. WARRANTY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 

11. EXPLODED VIEWS AND LIST OF SPARE PARTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 

2 

● DIRECTIVE 97/23/EC 

Gas and oil boilers with a maximum operating temperature 

of 110°C and hot water tanks with a maximum operating 

pressure of 10 bar pertain to article 3.3 of the directive, 

and therefore, cannot be CE-marked to certify 

compliance with the directive 97/23 EC. 

The De Dietrich boilers and hot water tanks are designed 

and manufactured in accordance with the sound engineering 

practice, as requested in article 3.3 of the directive 

97/23/EC. This is certified by compliance with the directives 

90/396/EC, 92/42/EC, 73/23 EC and 89/336/EC.

1. GENERAL 

Warning : 

The boiler shall be assembled and 

installed by a qualified professional only. 

Strict compliance with these assembly, 

installation and maintenance instructions 

is a pre-requisite for the correct operation 

of the boiler. 

1.1 Models available 

GT 300/II : automatic pressurised hot water boiler 

range designed for connection to a flue pipe. This 

boiler range can be equipped with a separate oil or gas 

fired burner. 

GTM 300/II : automatic pressurised hot water boiler 


boiler range is equipped with a one or two-stage oil burner, 

with an output power ranging from 55 to 280 kW. 

GTG 300/II : automatic pressurised hot water boiler 

range designed for connecting to a flue pipe. This 

boiler range is equipped with a one or two-stage gas 

burner. 

GTI 300/II : automatic pressurised hot water boiler 


boiler range is equipped with a modulating gas pressure 

jet burner. 

3

1.2 Control panels available 

1.2.1 Standard control panel 

Control panel which integrates setting, control and safety 

devices, allowing the autonomous operation of the 

boiler without weather compensator. The standard control 

panel allows the connection of the boiler to the electrical 

cabinet of the heating room. The electrical cabinet 

can be equipped with control units. 

The standard control panel can be mounted on GT 300/II, 

GTM 300/II and GTG 300/II boilers. 

1.2.2 K control panel 

Control panel which integrates setting, control and safety 

devices, allowing the autonomous operation of the 

boiler without weather compensator. The K control panel 

may be fitted with an optional SV-matic weather 

compensator for heating only or heating and domestic 

hot water production or an MB2 domestic hot water 

priority and regulation module. 

The boiler with K control panel may also be used as a 

“slave” boiler in cascaded installations with 2 to 10 boilers, 

one of which is fitted with a DIEMATIC-m Delta 

control panel. 

The K control panel can be mounted on GT 300/II, 

GTM 300/II, GTG 300/II and GTI 300/II boilers which 

then become GT 300 K/II, GTM 300 K/II, GTG 300 K/II 

and GTI 300 K/II boilers. 

1.2.3 Diematic-m Delta control panel 

Electronic high level control panel with digital display, 

which integrates setting, control and safety devices allowing 

the autonomous operation of the boiler. 

The DIEMATIC-m Delta control panel integrates from 

factory a weather compensator, which allows regulation 

according to the external temperature. 

GT 300 DIEMATIC-m Delta boilers are also used as 

“master” boilers in cascaded installations with 2 to 10 

boilers. The other boilers (1-9) must necessarily be fitted 

with a K control panel equipped with a cascade pcb. 

The DIEMATIC-m Delta control panel can be mounted 

on GT 300/II, GTM 300/II, GTG 300/II and GTI 300/II 

boilers which then become GT 300 DIEMATIC-m 

Delta/II, GTM 300 DIEMATIC-m Delta/II, GTG 300 

DIEMATIC-m Delta/II and GTI 300 DIEMATIC-m 

Delta/II boilers. 

4 

D I E M T I C 

30 

I 

0 

30 

I 

0 

8219N036 

8555N040 

8555N041

1.3 Technical specifications - boilers for EXPORT 

Working conditions : 

- Maximum operating temperature : 100°C 

- Maximum operating pressure : 6 bar 

- Thermostat adjustment range : 30 - 90°C 

- Safety thermostat setting : 110°C 

Boiler type 

GT 304/II GT 305/II GT 306/II GT 307/II GT 308/II GT 309/II 

GTM 304/II GTM 305/II GTM 306/II GTM 307/II GTM 308/II GTM 309/II 

GTG 304/II GTG 305/II GTG 306/II GTG 307/II GTG 308/II GTG 309/II 

GTI 304/II GTI 305/II GTI 306/II GTI 307/II GTI 308/II GTI 309/II 

Range of output power kW 70-105 105-140 140-180 180-230 230-280 280-330 

Number of sections 4 5 6 7 8 9 

Burner (optional) Oil (GTM) M 31/32-5S M 32-6S M 32-7S M 32-8S M 32-9S M 42-1S 

Natural gas (GTG) G 31/32-5S G 32-6S G 32-7S G 32-8S G 32-9S G 43-1S 

Gas modulating (GTI) G 33-5N G 33-6N G 33-7N G 33-8N G 33-9N G 43-1S 

Number of baffle plates 6 10 10 6 6 6 

Water capacity l 96 116 136 156 176 196 

Stand-by losses at 50 °C (D) % 0.17 0.14 0.13 0.11 0.10 0.09 

Water resistance (E) ∆t=15 K mbar (B) 6.2 10.9 20.4 30 44.5 63.8 

Combustion chamber 

- diameter mm 377 377 377 377 377 377 

- lenght mm 621 781 941 1101 1261 1396 

- volume m3 0.096 0.122 0.148 0.174 0.200 0.226 

Volume of the flue gas circuit m 3 0.163 0.206 0.249 0.292 0.335 0;378 

(combustion chamber + flue ways) 

Flue gas temperature (E) °C 210 210 210 210 210 210 

Mass flue gas flow rate Fuel oil kg/h 172 231 297 379 464 541 

Natural gas kg/h 160 206 270 331 411 500 

Pressure in the combustion chamber(C)(E) mbar(B) +0.3 +0.6 +1.1 +1.6 +2.2 +2.5 

Net weight GT kg 510 608 694 791 886 977 

GTM/GTG/GTI kg 529 627 714 811 921 1012 

- (A) Stand-by losses as per applicable standard. 

- (B) 1 mbar = 10 mmWC = 10 daPa 

- (C) Pressure in the combustion chamber for 0 

nozzle pressure. 

- (D) Nominal operation (top power of the power range) 

5 

Test conditions : CO2 with oil = 13 % 

CO2 with natural gas = 9.5 % 

Ta (room temperature) = 20°C

1.4 Technical specifications - boilers for EUROPE 

Working conditions : 

- Maximum operating temperature : 100°C 

- Maximum operating pressure : 6 bar 

- Thermostat adjustment range : 30 - 90°C 

- Safety thermostat setting : 110°C 

Boiler type 

GT 304/II GT 305/II GT 306/II GT 307/II GT 308/II GT 309/II 

GTM 304/II GTM 305/II GTM 306/II GTM 307/II GTM 308/II GTM 309/II 

GTG 304/II GTG 305/II GTG 306/II GTG 307/II GTG 308/II GTG 309/II 

GTI 304/II GTI 305/II GTI 306/II GTI 307/II GTI 308/II GTI 309/II 

Range of output power kW 55-90 90-115 115-150 150-185 185-230 230-280 

Range of used input power kW 61-100 100-128 128-167 167-206 206-256 256-311 

Burner Oil (GTM) M 31-4S M 31-5S M 32-6S M 32-7S M 32-8S M 32-9S 

Natural gas (GTG) G 31-4S G 32-5S G 32-6S G 32-7S G 32-8S G 32-9S 

gas modulating (GTI) G 33-4N G 33-5N G 33-6N G 33-7N G 33-8N G 33-9N 

Number of sections 4 5 6 7 8 9 

Number of baffle plates 6 10 10 10 12 12 

Water capacity l 96 116 136 156 176 196 

Stand-by losses at 50 °C (A) % 0.150 0.135 0.125 0.115 0.100 0.085 

Water resistance ∆t=10 K mbar (B) (C) 11 18 31 46 68 105 

Combustion chamber 

∆t=15 K mbar (B) (C) 4.6 7.4 14.2 19.5 30;1 46 

∆t=20 K mbar (B) (C) 2.6 4.2 8 11 17 26 

- diameter mm 377 377 377 377 377 377 

- length mm 621 781 941 1101 1261 1396 

- volume m3 0.096 0.122 0.148 0.174 0.200 0.226 

Volume of flue gas circuit m 3 0.163 0.206 0.249 0.292 0.335 0.378 

(Combustion chamber + flue ways) 

Flue gas temperature (B) °C 200 190 190 190 190 190 

Mass flue gas flow rate (B) Fuel oil kg/h 149 191 248 306 381 463 

Natural gas kg/h 160 206 270 331 411 500 

Pressure in the Combustion chamber(B)(D) mbar (C) 0.2 0.4 0.7 1.2 1.8 2.2 

Net weight GT kg 510 608 694 791 886 977 

GTM/GTG/GTI kg 529 627 714 811 921 1012 

- (A) Stand-by losses (as per NFD 30 002) in % of the 

input power. 

- (B) Nominal operation (top power of the power range) 

- (C) 1 mbar = 10 mmWC = 10 daPa 

- (D) Pressure in the Combustion chamber for 0 nozzle 

pressure. 

The pressure at the nozzle must never exceed 

0,2 mbar. 

6 

Test conditions : CO2 with oil = 13 % 

CO2 with natural gas = 9.5 % 

Ta (room temperature) = 20°C

1.5 Main dimensions 

● GT 300/II 

H 

1192 

398 

796 

L 

D 

(a) 

153 

A 

53 

398 

101 594 101 

Rp 2 1/2 diameter sludge 

removal hole 

137 

387 

Ø R 

98 

P 195 105 

Boiler type GT... 304/II 305/II 306/II 307/II 308/II 309/II 

Standard A 130 130 130 130 130 130 

control B 105 105 105 105 105 105 

panel C 165 165 165 165 165 165 

D 738 738 738 738 738 738 

H 1297 1297 1297 1297 1297 1297 

K + DIEMATIC-m A 355 355 355 355 355 355 

Delta B 195 195 195 195 195 195 

control C 145 145 145 145 145 145 

panel D 755 755 755 755 755 755 

H 1387 1387 1387 1387 1387 1387 

E GTM version 347 387 387 387 387 417 

GTG/GTI version 459 459 459 549 549 549 

L 991 1151 1311 1471 1631 1791 

M GTM version 1338 1538 1698 1858 2018 2208 

GTG/GTI version 1450 1610 1770 1930 2180 2340 

P 490 650 810 970 1130 1290 

ø R 180 180 180 200 200 200 

7 

153 

● GTM 300/II - GTG 300/II - GTI 300/II 

H 

1192 

796 

L 

D 

153 

A 

(a) 53 

398 398 

101 594 101 

Rp 2 1/2 diameter sludge 

removal hole 

137 

387 

Ø R 

98 

153 

M 

C 

B 

ø 2” 1/2 heating return 

(flange + counter flange) 

C 

B 

P 195 E 

105 

ø 2” 1/2 heating return 


ø 2” 1/2 heating flow 


= = 

115 

137 

827 

1017 

8553N001 

Rp 1 1/2 draining outlet 

(supplied with plug) 

ø 2” 1/2 heating flow 


= = 

115 

137 

827 

1017 

8553N002 

Rp 1 1/2 draining outlet 

(supplied with plug) 

(a) Rp 1 1/2 socket 

for safety unit 

Rp = tapped

2. INSTALLING THE BOILER IN THE HEATING ROOM 

Comply with the minimum dimensions indicated in the 

drawing below in order to ensure that the boiler is accessible 

from all sides. 

Ventilation : in order to enable the intake of combustion 

air, appropriate ventilation having the section and 

location required by applicable standards shall be provided 

in the boiler room. 

Air outlet 

8553N003B 

Boiler type 

Mind the volume of the burner when the door is open. 

These dimensions must be adapted for systems with 

several cascaded boilers. 

3. ASSEMBLY 

1m 

B 

1,19m 

0,15m 

A 

1,5m 

GT GT GT GT GT GT 

304/II 305/II 306/II 307/II 308/II 309/II 

Dimension A mm 840 1000 1160 1320 1480 1640 

B 

Standard control panel mm 105 105 105 105 105 105 

K, Diematic -m Delta cont. pan. mm 195 195 195 195 195 195 

See the yellow booklet for the assembly instructions. 

8 

Please note that boilers installed in or 

close to rooms in which the atmosphere 

is polluted with chlorine or fluorine compounds 

may be subject to high corrosion. 

For example : hairdressing salons, industrial 

premises (solvents), cooling equipment 

etc. 

Boilers installed in such locations shall 

not be covered by the warranty. 

0,5m 0,8m 0,5m 

Air inlet

4. HYDRAULIC CONNECTIONS 

4.1 Important recommendations for connecting the heating circuit to the boiler and 

to the drinking water system 

The installation shall be made in accordance with 

applicable regulations and codes of practice. 

The expansion tank shall be connected to the boiler 

without any valve or stop valve between the boiler and 

the expansion tank. 

Similarly, the safety valve shall be connected 

to the boiler without any valve or stop valve 

between the boiler and the safety valve. 

Example of installation : 

The example below does not cover all the possible cases of 

use. It is only aimed at drawing attention to the basic rules 

which must be complied with. In all events, comply with applicable 

codes of practice and national or local regulations. 

Example of a GT 300/II boiler with domestic hot water 

production via one or more independent calorifiers. 

11 

27 

3 

10 

4 5 

7 26 25 7 

8 

7 

7 

7 

13 

1. Heating outlet 

2. Heating return 

3. 3 bar safety valve and pressure gauge 

4. Flow switch (if necessary) 

5. Air separator 

6. Automatic venting valve 

7. Valve 

8. Recycling pump (recommended for GT 304/II, 

compulsory for GT 305/II to 309/II) 

9. Expansion tank 

10. Draining valve 

11. Sludge removal valve 

12. Mixing valve 

13. Non return valve 

14. Heating pump 

15. Low-water safety pressure-sensitive switch 

9 

7 

6 

7 

22 

10 

7 

6 7 

9 

21 

The heating system shall be designed and installed in 

a way as to prevent the water from the heating circuit 

and any substances added to it from flowing back into 

the drinking water circuit located before it. The installation 

shall not be directly connected to the drinking 

water system. 

12 7 

1 

17 

7 

24 

13 

23 

13 

7 

19 

7 

14 

20 

15 

10 

16 

7 

2 

Heating 

circuit 

8219N008A 

18 

16. Sludge decanting pot (particularly recommended for 

older heating systems) 

17. Independent calorifier 

18. Sealed safety unit calibrated to 7 bar with indicator 

type discharger 

19. Pressure reducer (if mains pressure > 5.5 bar) 

20. Domestic cold water inlet 

21. Domestic hot water outlet 

22. Load pump 

23. Domestic hot water circulation pump (optional) 

24. DHW circulation loop return 

25. Water meter (if any) 

26. Water treatment if TH > 25° 

27. Heating circuit filling (with disconnector if required 

under applicable regulations).

4.2 Filling the system 

Filling shall be performed with a low flow rate from a low 

point in the boiler room in order to ensure that all the air 

in the boiler is vented from the high point of the system. 

VERY IMPORTANT : Instructions for starting 

up the boiler for the first time after 

the system is fully or partly drained : 

If all the air is not vented naturally to an 

expansion tank which opens out onto the 

air, the system must include manual venting 

valves, in addition to automatic venting 

valves with the capability to vent the system 

by themselves when it is 

operating. The manual venting valves are 

used to vent all the high points of the system 

and to make sure that the filled system 

is free of air before the burner is turned on. 

4.3 Sludge removal 

A tapped 2” 1/2 hole with a plug has been provided on 

the bottom of the front of the boiler to remove the sludge. 

Fit a quarter-turn valve on the opening to remove 

the sludge (the fitter can also use the optional desludging 

kit - package FD 37). Sludge removal leads to the 

draining of large quantities of water. After this operation, 

fill the installation according to § 4.2. 

5. CHIMNEY CONNECTION 

5.1 General recommandation 

The high-performance features of modern boilers and 

their use in specific conditions as a result of the advance 

in burner technology (e.g. modulated low-temperature 

operation) lead to very low flue gas temperatures. 

This requires : 

- the use of flue pipes designed to enable the flow of 

condensates which may result from such operating 

modes, in order to prevent damage to the chimney; 

5.2 Flue size 

Refer to applicable regulations while determining the 

size of the flue. Please note that GT 300/II boilers have 

pressurised furnaces and that the pressure at the nozzle 

must not exceed 0 mbar, unless special precautions 

have been taken to seal the connection between the 

nozzle and the chimney outlet. 

5.3 Connection between boiler and flue pipe 

The boiler shall be connected to the flue pipe in accordance 

with codes of practice with a sealed pipe made 

of material capable of withstanding hot combustion gas 

and any acid condensation. The connection shall be 

removable and offer minimum load losses, i.e. it must 

be as short as possible with no sudden change in section. 

Its diameter shall always be at least equal to that of 

10 

Always stop the recycling pumps before filling. 

Do not add cold water suddenly into the 

boiler when it is hot. 

Note : never replace a boiler in an existing system 

without carefully rinsing the system first. Install a sludge 

decanting pot on the return pipe, very close to the 

boiler. 

- the installation of a draining tee at the foot of the 

chimney. 

The use of a draught moderator is recommended as 

well. 

If required, the baffle plates of the four upper flue ways 

may be removed partly to increase the flue gas temperature. 

the boiler outlet, i.e. ø 180 mm for boilers with 4, 5 and 

6 sections and ø 200 mm for those with 7, 8 and 9 

sections. 

To allow the setting of the burner and control of the 

combustion, the installer must preview a measurement 

hole (10 mm ø) on the flue pipe.

6. FUEL-OIL OR GAS CONNECTIONS 

Refer to the instructions supplied with the burner. 

Burner 

door 

insulation 

Deflector 

8553N004 

Important : 

The burner head deflector must be in line 

with the insulation of the burner door. 

125 

7. ELECTRICAL CONNECTIONS 

Please refer to the instructions supplied with the control panel. 

11 

45° 

45° 

Burner door drilling diameters 

ø 155 (1) 

ø 175 (1) 

ø 135 

Door thickness with 125 mm insulation 

(1) precuttings 

4 ø M8 on 

ø 170 

4 markings 

on ø 200 

4 markings 

on ø 220 

8219N112

8. MAINTENANCE 

8.1 Installation - water level 

Regularly check the level of the water in the system and 

top up if required, taking care not to add suddenly cold 

water into the boiler, when it is hot. This operation should 

be required only a few times in each heating season, 

with very small quantities of water. 

8.2 Boiler 

The boiler will only operate efficiently if is kept clean. 

The boiler should be cleaned as soon as required and 

as the chimney, at least once a year, or more, depending 

upon applicable regulations. 

● Cleaning the flue gas circuit 

- Turn off the power to the boiler. 

- Remove the front panel. 

- Open the sweeping door (upper door) by unfastening 

the four closing nuts (17 mm spanner). 

- Remove the baffle plates. 

- Carefully sweep the six flue ways with the brush 

supplied. 

- Also brush the baffle plates and the front panel. 

- Use a vacuum cleaner if possible. 

- Put the baffle plates back in place complying with the 

instructions given on next page. 

Important : the first two baffle plates of the two lower 

flue ways are fitted with stops to position them properly 

in the flue ways. 

- Close the door. 

Cleaning the combustion chamber 

- open the burner door (lower door) by 

unfastening the four closing nuts (17 

mm spanner), 

- brush the inside of the combustion 

chamber, 

- vacuum any soot deposited in the combustion 

chamber, 

- close the door and put back the front 

panel. 

12 

Otherwise, look for the leak and repair it immediately. 

We advise you against draining the heating system 

unless it is absolutely necessary. 

8553N005 

The operations described below shall only 

be performed with the boiler and main 

supply off. 

8553N049

● Positionning of the baffle plates 

A 

B 

C 

Stops 

8553N006 

- All boilers excepted Export-boilers 

Baffle plates Flue ways GT 304/II GT 305/II GT 306/II GT 307/II GT 308/II GT 309/II 

- upper - lg 410 mm A + B 8 8 4 

- lg 570 mm A+B 4 4 8 8 

- lower - lg 412 mm C 2 2 2 2 4 2 

- lg 572 mm C 2 

- ”Export” boilers 

Baffle plates Flue ways GT 304/II GT 305/II GT 306/II GT 307/II GT 308/II GT 309/II 

- upper - lg 410 mm A + B 8 8 0 0 0 

- lg 570 mm A+B 4 4 4 4 

- lower - lg 412 mm C 2 2 2 2 2 2 

13 

Important : 

The first two baffle plates of the two lower 

flue ways are fitted with stops to position 

them properly in the flue ways.

● Cleaning the flue gas box 

Proceed as follows : 

- open the left and right-hand sweeping covers of the 

flue gas box (2 H12 nuts and flat washers) with a 

19 mm spanner and vacuum any soot deposited 

there. 

- put back the sweeping covers. 

● Cleaning the burner 

Refer to the instructions supplied with the burner. 

8.3 Precautions required in the case of a boiler stop 

- The boiler and the chimney must be swept carefully. 

- Close all the doors of the boiler to prevent air from circulating 

inside the boiler. 

- If the boiler is to be stopped for several months, we 

advise removing the pipe which connects the boiler to 

the chimney and closing off the nozzle with a cover. 

9. IDENTIFICATION PLATE 

(1) 02=2002, 

03=2003, 

... 

Type of boiler 

14 

8553N007 

- We recommend the use of a correctly dosed antifreeze 

agent to keep the heating circuit from freezing. 

If this cannot be done, drain the system completely. 

F 67110 NIEDERBRONN 

Unit serial no. 

XX - XX 

Date of manufacture 

8553N047 

year (1) 

week 

F 67110 NIEDERBRONN

10. WARRANTY 

You have just purchased a DE DIETRICH appliance and 

we thank you for the trust you have placed in our products. 

Please note that your appliance will provide good 

service for a longer period of time if it is regularly checked 

and maintained. 

Your fitter and the DE DIETRICH customer support network 

are at your disposal at all times. 

Warranty terms 

Starting from the purchase date shown on the original 

fitter’s invoice, your appliance has a contractual 

guarantee against any manufacturing defect. 

The length of the guarantee is mentioned in the price 

catalogue. 

The manufacturer is not liable for any improper use of 

the appliance or failure to maintain or install the unit 

correctly (the user shall take care to ensure that the 

system is installed by a qualified fitter). 

In particular, the manufacturer shall not be held responsible 

for any damage, loss or injury caused by installations 

which do not comply with the following: 

- applicable local laws and regulations; 

- specific requirements relating to the installation, 

such as national and/or local regulations; 

- the manufacturer’s instructions, in particular 

those relating to the regular maintenance of the 

unit; 

- the rules of the profession. 

11. EXPLODED VIEWS AND LIST OF SPARE PARTS 

Refer to the following pages. 

15 

The warranty is limited to the exchange or repair of 

such parts as have been recognised to be faulty by 

our technical department and does not cover labour, 

travel and carriage costs. 

The warranty shall not apply to the replacement or 

repair of parts damaged by normal wear and tear, 

negligence, repairs by unqualified parties, faulty or 

insufficient monitoring and maintenance, faulty power 

supply or the use of unsuitable fuel. 

Sub-assemblies such as motors, pumps, electric 

valves etc. are guaranteed only if they have never been 

dismantled. 

The above provisions do not restrict the benefit of the 

legal laws regarding hidden defects applicable in the 

buyer’s country. 

TR112

20 

16 

10.2 

10.1 

10 

8553N059 

Spare parts 

Note : while ordering spare parts, do not forget to provide the code number given in the list opposite the part reference. 

BOILER BODY AND ACCESSORIES 

19 16 18 

51 

11 

50 

11 

9 

31 32 

Bag of fasteners 

for boiler body 

1 

Bag of fasteners 

for buner door 

28 

16 

2 

4 

16 

3 

5 

33 

6 

8 

7 

12 

29 

12 

30 

13 

21 

25 

26 

34 

16 

16 

15 

14 

24 

23 

8553-4156 



GT/GTM/GTG/GTI 300 DIEMATIC-m Delta/II 

DE DIETRICH THERMIQUE S.A.S. au capital de 21 686 370 • Centre Pièces de Rechange/Spare Part Centre 

4, rue d'Oberbronn • F-67110 REICHSHOFFEN • Tél. : +33 3 88 80 26 50 • Fax : +33 3 88 80 26 98 

cpr@ddt.dedietrich.com 

22 27 

17 

17 

AD042A

INSULATION 

BASE FRAME 

8553N060 

90 

70 

12x 




2/6 

8553N061

CASING 

100 

104 

102 

Bag of casing 

fasteners 

109 

106 




107 

3/6 

102 

101 

103 

108 

105 

8553N062

STANDARD CONTROL PANEL (Package FA3) 

K CONTROL PANEL (Package FA2) 

30 

I 

0 

DIEMATIC-m Delta CONTROL PANEL (Package FA1) 

D I E M T I C 

30 

I 

0 




4/6 

See separate list of the standard control panel 

See separate list of the K control panel 

8219N036 

8555N040 

See separate list of the Diematic-m Delta control panel 

8555N041

GT/GTM/GTG 300/II - GT/GTM/GTG/GTI 300 K/II 


Ref. Code no. DESCRIPTION Ref. Code no. DESCRIPTION 

BOILER BODY 

1 8219-8912 Complete rear section 

2 8219-8966 Complete intermediate section 

3 8219-8976 Complete front section 

4 8116-0571 Nipple 

5 8219-8968 Complete assembly rod, 4 sections 






6 8202-0028 Rp 2 1/2 plug with Rp 1/2 hole 

7 9536-5611 Rp 1/2 pocket 

8 9495-0249 R 1 1/2 plug 

9 8553-5513 Flow flange, 3 to 9 sections 

10 8553-5514 Return flange, 3 to 7 sections 

10.1 8553-5515 Return flange with water distributing tube, 8 sections 

10.2 8553-5516 Return flange with water distributing tube, 9 sections 

11 9501-3022 Flange gasket 

12 8104-8984 Hinge 

13 8219-8916 Complete sweeping door 

14 9425-0306 Inner protection of sweeping door 

15 9425-0305 External insulation of sweeping door 

16 9508-6032 ø 10 Thermocord gasket 

17 9756-0203 Pin for hinge ø12 x 350 

18 8219-8913 Complete 180 ø nozzle for 4 - 6 sections 

18 8219-8914 Complete 200 ø nozzle for 7 - 9 sections 

19 8219-0206 Right-hand nozzle cover 

20 8219-0207 Left-hand nozzle cover 

21 8219-8953 Complete 135 ø burner door 

22 9425-0303 Internal burner door protection (soft) 

23 9425-0302 Intermediate burner door protection (soft) 

24 9425-0301 External burner door protection (rigid) 

25 8015-7700 Sight glass + gaskets 

26 9757-0027 Sight glass flange 

27 9495-0050 1/4" plug 

28 8219-0539 Guide rail for burner door 

29 8219-0017 410 mm long upper baffle plate 

29 8219-0018 570 mm long upper baffle plate 

30 8219-0019 412 mm long lower baffle plate 

30 8219-0020 572 mm long lower baffle plate 

31 8219-7724 Bag of fasteners for boiler body 

32 8219-8957 Bag of fasteners for burner door 

33 9430-5027 Lubricant for nipple 

5/6 

34 9432-0214 Silicone filler (Novasil S 17) 

50 9750-5025 Brush 

MISCELLANEOUS 

51 9750-5076 1000 mm long brush rod 

51 9750-5060 1300 mm long brush rod 

BASE FRAME 

70 8553-7060 Complete base frame, 4 sections - package FD 30 






INSULATION 

90 8553-5507 Complete boiler body insulation, 4 sections 






CASING 

100 8553-5500 Complete casing, 4 sections 






101 8219-1000 Insulated front panel 

102 8553-8000 Upper fastening bracket 

103 8553-5506 Insulated lower cover 

104 8553-8519 Complete rear panel 

105 8553-8500 Right-hand side panel, 4 sections 






106 8553-8506 Left-hand side panel, 4 sections 



106 8553-8509 Left-hand side panel, 7 sections

GT/GTM/GTG 300/II - GT/GTM/GTG/GTI 300 K/II 


Ref. Code no. DESCRIPTION Ref. Code no. DESCRIPTION 



107 8553-8512 Rear cover, 4 sections 






108 8553-8518 Complete front cover 

109 8553-8520 Bag of casing fasteners 

STANDARD CONTROL PANEL 

PACKAGE FA 3 

See separate spare part list 

of the control panel 

K CONTROL PANEL - PACKAGE FA 2 

See separate spare part list of the control panel 

DIEMATIC-m Delta CONTROL PANEL 

PACKAGE FA 1 

See separate spare part list 

of the control panel 

BURNER 

See separate spare part list of the burner 

6/6 

18/02/03

DE DIETRICH HEIZTECHNIK • Rheiner Strasse 151 • D-48282 EMSDETTEN 

www.dedietrich.com • info@dedietrich.de 

Verkaufsbüro Emsdetten : Tel. 0 25 72 / 23-179 

Fax 0 25 72 / 23-451 

Regionalverkaufsbüro Berlin : Tel. 030 / 5 65 01-391 

Fax 030 / 5 65 01-465 

Verkaufsbüro Neunkirchen : Tel. 0 68 21 / 98 05-0 

Fax 0 68 21 / 98 05-31 

Regionalverkaufsbüro Erding : Tel. 0 81 22 / 9 93 38-0 

Fax 0 81 22 / 9 93 38-19 

DE DIETRICH • SPINOFF - CENTER Romeinsestraat 10 • B-3001 LEUVEN / LOUVAIN • Tél. : 016 39 56 40 

Fax : 016 39 56 49 • www.dedietrich.com 

DE DIETRICH HEIZTECHNIK • Am Concorde Park 1 - B 4 / 28 • A-2320 SCHWECHAT / WIEN • Tél. : 01 / 706 40 60-0 

Fax : 01 / 706 40 60-99 • www.dedietrich.com • office@dedietrich.at 

Pour le LUXEMBOURG : les produits sont commercialisés par la société NEUBERG 

In LUXEMBURG werden die Produkte durch die Fa. NEUBERG vertrieben 

NEUBERG SA • 39 rue Jacques Stas • L - 2010 LUXEMBOURG • Tél. : 02 401 401 

Fax : 02 402 120 • www.dedietrich.com 

DE DIETRICH THERMIQUE S.A.S. au capital de 21 686 370 • BP 30 • 57, rue de la Gare • F-67580 MERTZWILLER 

Tél. : (+33) 03 88 80 27 00 • Fax : (+33) 03 88 80 27 99 

www.dedietrich.com • N° IRC : 347 555 559 RCS STRASBOURG 

In the interest of customers, DE DIETRICH THERMIQUE are continuously endeavouring to make improvements in product quality. 

All the specifications stated in this document are therefore subject to change without notice. 

AD014J

GT/GTM/GTG 300/II GT/GTM/GTG/GTI 300 K/II GT/GTM 300 ...

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