Index

1	Warning	2

2	Appliance details	3
2.1	GWH 425 PN specifications (Technical data)	3
2.2	Unpacking the GWH 425 PN heater	4
2.3	General rules to follow for safe operation	4
2.4	Dimensions and installation clearances	5

3	Installation instructions	6
3.1	Introduction	6
3.2	Proper location for installing your heater	6
3.3	Heater placement and clearances	6
3.4	Mounting Heater	7
3.5	Combustion air requirements	8
3.6	Venting	9
3.7	Gas piping & connections	11
3.8	Measuring gas pressure	13
3.9	Water connections	13
3.10	Recirculation application	14

4	Operation instructions	14

4.1For your safety read before operating your water heater 14

4.2	Lighting instructions	15
4.3	To turn off appliance	15
4.4	Setting the water temperature	16
4.5	Draining water from heater	16

5	Maintenance and service	17
5.1	Maintenance intervals	17
5.2	Water valve	17
5.3	Pilot	17
5.4	Main burners	18
5.5	Vent assembly	18
5.6	Mineral scale build-up	18

6	Troubleshooting	19
6.1	Introduction	19
6.2	Pilot does not light	19
6.3	Pilot lights, but goes out when button is released	19
6.4	Pilot goes out during or after hot water use	19
6.5	Burners do not light with water flow	20
6.6	Hot water temperature fluctuates at tap	20
6.7	Water is too hot	21
6.8	Water is not hot enough	21
6.9	Burners ignite without hot water flow	21
6.10	Low hot water pressure	21
6.11	Noise when heater is running	21

6.12Burners do not operate cleanly; yellow flames

	when operating	22

7	Protecting the environment	23

8	Interior components and diagram parts list	24
8.1	Interior components	24
8.2	Components diagram	25
8.3	Parts list	26

9	Fifteen Year Limited Warranty	27

1Warning

Warning: The heater must be isolated from the gas supply piping system during any pressure testing of that system at test pressures equal to or more than 0.5 psig.

Caution: Any changes or modifications not expressly approved by the party responsible for compliance could void the user’s authority to operate the equipment.

Fig. 1

2	6 720 608 034