Does HLF setting speed up the FR when the stove calls for heat & slows the FR decline when stove reaches temp. Thanks.
Not exactly. HLF only affects behavior upon setpoint changes (either programmed or manual overrides). At the time of the setpoint change HLF will play into how much of an initial "bump" in FR is dialed in. After this initial bump it has no effect. It does not change the rate at which the FR will climb or fall after that initial change and it does not affect FR as setpoint temperature is reached. It was a safe way to try to address the "overly damped" situation where it can take an inordinate amount of time to reach a new setpoint. This typically happened in situations where there was poor air circulation or the stove was undersized or the heating job being asked of it. As a last resort solution for the customer we wanted to offer a way to make the control make more aggressive on setpoint changes. It was intended as a last resort solution though. Only after trying to improve air flow and heat transfer in the dwelling (if possible) was this to be tried since it would have the effect of making the room the stove is in get even hotter during the setpoint change while the rest of the house plays catchup.
We've been working on other methods of making the control more responsive on setpoint changes, some of which do affect rate of change on the FR. We plan to have one of these methods replace the HLF method in the next version of the thermostat software.