adding fire bricks

I have a harmon sf160 boiler. thinking of adding an extra row of fire bricks. would it help with heat distribution or waste of time? would like to make fire box deeper. I already am running it roughly 4inchs higher than fire factory fire brick now. any ideas if it would help?

Not sure if I'd add another full set of vertical firebrick. It might bring your heat too close to the air tubes in top of the boiler.

Not to mention you might have trouble filling it without it running out the door.

I have though of adding a horizontal row on top of the existing firebrick to raise my level be 4", but I'm getting more than 12 hrs between fills. I'd caution trying to get it too deep in the firebox.

Jaeger

i am only hitting 12 to 14hr burns using mammoth nut. that seems to be the best that i have burned in the last three yrs. was just wondering, the only tubes are dhw and those are being used to heat concrete pad in shop. there is an inch between those and main water tank. thank you for the reply.

That's a good burn time!

With these warm temps we've been having (40's) I'm going 14hrs +/-. Still might get too hot near the top for the stove.

What do you have you thermostat set on? I run mine at 160 deg and it seems to be the sweet spot.

Good luck!

Jaeger