Rinnai error code 10, what sensor determines air flow?

[case310350]

Have several tankless water heaters all have error code 10 issues. But currently working on a rinnai tankless with a short vent. 1 year old, and get error code 10 only in warm weather. What sensor determines error code 10. I know code 10 is blocked intake or exhaust, but how does the unit determine that? Flame sensors? Don't believe it has an airflow sensor.

 

[Bannerman]

I don't know the Rinnai units specifically but it likely uses a diaphragm pressure switch which senses the pressure differential between the sample location and ambient.

Pressure switches are often used to verify the burner inducer fan is operating before ignition and while there is flame.

If the intake plenum pressure is significantly lower than ambient, that would signify too much restriction within the incoming plenum, resulting in burner shutdown and an error code. For exhaust, excessive pressure would indicate a flow restriction also resulting in burner shutdown and an error code.

Diaphragm switches often utilize a small diameter tube that is inserted through a small hole into the air plenum to be sampled.

There are many versions of diaphragm switches but here is a link showing a style that is common within HVAC devices.

https://images.app.goo.gl/1whHxVHf5HTaMMXh6

 

[Sponsor]

 

[case310350]

I don't know the Rinnai units specifically but it likely uses a diaphragm pressure switch which senses the pressure differential between the sample location and ambient.

Pressure switches are often used to verify the burner inducer fan is operating before ignition and while there is flame.

If the intake plenum pressure is significantly lower than ambient, that would signify too much restriction within the incoming plenum, resulting in burner shutdown and an error code. For exhaust, excessive pressure would indicate a flow restriction also resulting in burner shutdown and an error code.

Diaphragm switches often utilize a small diameter tube that is inserted through a small hole into the air plenum to be sampled.

There are many versions of diaphragm switches but here is a link showing a style that is common within HVAC devices.

https://images.app.goo.gl/1whHxVHf5HTaMMXh6

thanks for the reply. Yes I have seen those used in furnaces, but I do not see them in this unit.

 

[Bannerman]

You didn't mention which specific model(s) you are experiencing issues with. Perhaps this YT video will be helpful.

Warm air is less dense than cooler air so that may be why there are more frequent issues during warm weather.