Some demand heaters have a modulating gas valve......some. Not all.
And certainly not the low end units.

I'll say it again. I'm not saying that demand heaters aren't
efficient....they are. But there are a few issues with them regarding
efficiency across the board and low flow.

Geez guys, settle down a bit and read the whole post before you flame.
All I told the guy was to evaluate his usage and be aware that there
are some circumstances where the demand heaters, well, I'm repeating
myself.

End of discussion--at least for me.