Gas igniter circuit for water heater

Thread Starter

saesaria

Joined Mar 22, 2021
10
Dear expert,
I would like to build my own gas igniter circuit for water heater like below.
Pulse ignition of gas water heater.jpg



The circuit inside the module is looks like below.
20210323_055928.jpg



Anyone of you know the circuit diagram of this gas igniter circuit for water heater? please share.
And if you know the circuit explanation of how it works, please also share the knowledge with me if you don't mind.

Thanks.
 

Thread Starter

saesaria

Joined Mar 22, 2021
10
I have not experience in this area, but how can you make sure that the gas is not left on without a flame being present?
The plan is, there will be a sensor to detect the presence of the flame, if the flame is not present for a particular time then the switch valve will shut the gas line.
 

Alec_t

Joined Sep 17, 2013
11,981
I don't know which country you're in, but some have strict safety laws regarding the manufacture, installation and use of gas appliances. Have you checked if what you are proposing is legal and approved by your house insurer?
 
There is an explosion hazard with these devices so they have safety certifications and testing.
I'm sorry but we can't give you a schematic and explanation of the circuit, that is something you learn on your own, you'll actually have to do some work.
Because these ignitors and flame detectors have a safety function it is best you know what you are doing instead of copying. Or just buy one, as you have already shopped for them, they don't cost much.
 

wayneh

Joined Sep 9, 2010
17,029
Anyone of you know the circuit diagram of this gas igniter circuit for water heater? please share.
And if you know the circuit explanation of how it works, please also share the knowledge with me if you don't mind.
That thing with the copper coil is part of the spark igniter. It looks just like what you find in a barbecue grill, or anywhere you need a big spark to jump a gap. I'm sure you could search "spark igniter circuit" and find all kinds of option. But you could also find all kinds of off-the-shelf commercial products. These are likely far cheaper than you could make yourself.
 
OP is showing an entire control board, it has a MCU and does a lot more than igniter.
I've designed these before. There is CDI ignition, flame detection, MCU timers for purge and restart, output for gas solenoid valve etc.
You have to know the applicable functional-safety and gas safety codes, they exist for a reason - to prevent explosions. Nobody likes a MCU crashing and leaving the gas solenoid stuck on...
 

Thread Starter

saesaria

Joined Mar 22, 2021
10
There is an explosion hazard with these devices so they have safety certifications and testing.
I'm sorry but we can't give you a schematic and explanation of the circuit, that is something you learn on your own, you'll actually have to do some work.
Because these ignitors and flame detectors have a safety function it is best you know what you are doing instead of copying. Or just buy one, as you have already shopped for them, they don't cost much.
Yes you are right it has explosion hazard. That's why there is a safety switch circuit integrated in the module to shut the gas line by the valve when the flame didn't start for a particular time.
 

Thread Starter

saesaria

Joined Mar 22, 2021
10
That thing with the copper coil is part of the spark igniter. It looks just like what you find in a barbecue grill, or anywhere you need a big spark to jump a gap. I'm sure you could search "spark igniter circuit" and find all kinds of option. But you could also find all kinds of off-the-shelf commercial products. These are likely far cheaper than you could make yourself.
Yes, I found some circuit similar to this module. And yes the module is cheap but it has reliability issue, it always damage after a couple of months use, always found burnt component inside the module. That's why I eager to build it my self because in fact the module I bought from local store seems a home scale industry production which I believe it is also a DIY.
 

Thread Starter

saesaria

Joined Mar 22, 2021
10
OP is showing an entire control board, it has a MCU and does a lot more than igniter.
I've designed these before. There is CDI ignition, flame detection, MCU timers for purge and restart, output for gas solenoid valve etc.
You have to know the applicable functional-safety and gas safety codes, they exist for a reason - to prevent explosions. Nobody likes a MCU crashing and leaving the gas solenoid stuck on...
I found an IC inside the module named "CW508" or in some other modules has different name that is "GM812C", is it the MCU you are referring to?

Yes I know that this module is not only for a gas igniter but also contains gas control, safety valve control, flame detector etc
 
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