CoalBurner5 wrote:I do have a boiler bypass on the system.
Do you have it adjusted to temper the water going to the radiators?
When you have a large boiler and multiple small zones, starting the stoker with every heat call will inevitably drive the boiler temperature up to the high limit. In this case, the strategy described by Ken will certainly save some coal and reduce the standby losses of the boiler.
When you have a system with a lot of mass like yours, unless you make use of the bypass piping or turn the circulators on and off, the boiler will quickly get flooded with cool water and be running at a low temperature anyway...regardless of the high limit setting on the aquastat.
If this were my home, I would repipe the boiler in a primary/secondary fashion, and run the zone circulators independently of the stoker and primary circulator...that way you can turn the primary circulator on and off to protect the boiler, and in the mean time the zone circulators keep on running. This would ensure that all the radiators get ample & continuous flow during a heat call. I understand that repiping the system might not be an option at the moment, so lets explore other options.
Back to the bypass, get that adjusted so the EFM doesn't get slammed with cold water every time something calls for heat.
If you want to experiment with controls, Honeywell offers an outdoor reset module for your aquastat: http://www.pexsupply.com/Honeywell-W873 ... oor-Sensor
The outdoor reset module will allow you to set a "curve" for the boiler temperature based on the temperature outside...Honeywell claims up to 15% savings. It is just an electronic means to get the circulators to run more and the stoker to run less
. Sting has been after us for years to get things balanced out...he is right.