minimum gas pressure "for the purpose of input adjustment"

[comegetmehere]

Most ventless gas log burners specify "minimum gas pressure for the purpose of input adjustment".

What does "for the purpose of input adjustment" mean? This phrase is usually not used for the maximum pressure ratings, only the minimums.

Does it mean it's not a safety issue to turn the input pressure lower? Does it mean it just affects the adjustability of flames via the control on the burner? Can the flame height safely be lowered (adjusted) with the fireplace shutoff valve? Will the combustion be negatively affected if input is too low?

[ascj]

Most ventless gas log burners specify "minimum gas pressure for the purpose of input adjustment".

What does "for the purpose of input adjustment" mean? This phrase is usually not used for the maximum pressure ratings, only the minimums.

Does it mean it's not a safety issue to turn the input pressure lower? Does it mean it just affects the adjustability of flames via the control on the burner? Can the flame height safely be lowered (adjusted) with the fireplace shutoff valve? Will the combustion be negatively affected if input is too low?

It's the minimum input pressure to provide the rated manifold pressure. If you input pressure drops below the rate spec, then more than likely you will no be able to properly set your manifold pressure.

[comegetmehere]

What is the likely impact of input and manifold pressure too low on a ventfree applicance, for whatever reason? It appears all burners have safety features for oxygen depletion, carbon monoxide, thermocouple etc., but none against falling pressure. Upon throttling the fireplace shutoff valve, the burners seem to burn just fine at lower flame height and BTU. None of the instructions and (otherwise abundant) safety alerts specifically advise against this. In fact, in an older thread on the board, it was mentioned that the fireplace shutoff valve is not meant to adjust or throttle the gas flow, but many home owners use it to do just that to save energy, have the fireplace on without overheating the space, etc. I am curious if it could negatively affect the combustion. It is clear that too much gas can lead to incomplete combustion. Too little gas has not been as extensively discussed. I can regulate my stove down to a tiny flame; but then again, a stove may be not comparable to a ventfree gas log in this respect. I acknowledge that one should abide by specifications in any case, but I would still like to know the likely impact and how much of a hazard it may likely be or not.

[logdoc_rob]

All gas appliances are tested, rated and approved to operate within a very specific pressure range. Throttling the shutoff valve back may not lower the gas pressure, but it WILL decrease the gas volume which can affect the air/fuel ratio that is needed for proper combustion. Once you alter the volume of fuel, that can cause the oxygen depletion sensor and other safety sensors to not operate as designed.