Monitor sizing

[catamount]

I am currently heating the 2nd floor of a 1,050 sq foot raised ranch with an old Monitor 21 (I think?).

I'd like to upgrade to a programmable model and notice that there are used 2200s and 2400s for sale in my area.

My fear is over-sizing. The back rooms of my house were cold on some -15 degree nights last week but they are down a long hallway and I'm not sure that having the larger monitor is going to solve that problem -- that is more of an air flow problem specific to space heaters.

The heater sits in the main living room / kitchen and does a pretty great job of keeping the space warm providing the temps don't reach below zero (95% of the time).

I've over-sized a Rinnai in another house before and the thing would cycle on-and-off every 10 minutes because it couldn't run at a low enough BTU level to keep the temperature steady so I don't want to make that mistake again.

The question is... do I go for the 2200 or the 2400?

[HayZee518]

the 2400 is the max size for output, next for a lower Btu output is the 2200. other than being nerve racking ten minute cycling isn't a problem. if you use the econo function the temperature overshoot is eight degrees over the setpoint as opposed to 2-4 degree overshoot so the cycle time is lengthened. what do you think - should I put together a booklet with drawings on the monitor? since the troubleshooting flowchart of that pdf file is hard to read, maybe I'll re-do it so its readable.