chlop wrote:Question 1: Is there any way to maintain a fire during extended days of heat/humidity?
Yes. Use EFM's recommended settings that they have kindly provided in the manual. 200/160 on the aquastat, 2 minutes every half hour on the timer, 4 teeth & 4 air (maybe a little over 4 on the air...4.25-4.5 depending on the coal).
Your high and low limit settings are too close together, and your feed/air settings are probably not helping. What do you have the timer set at? Has the boiler and flue pipe been cleaned?
I have installed four different EFM 520's and none of them have ever experienced an outfire with EFM's recommended settings:
What is the pressure in the boiler? Should be roughly 12-18 psi. If your expansion tank was water logged, that probably caused the pressure relief valve to bleed off some water...it may have a piece of dirt that is preventing the valve from seating properly. Shut the boiler off and let it cool, put a bucket under the down-tube, and open the relief valve manually a few times to "flush" it. Monitor it for a while to see if it is still dripping...if it is, and the boiler pressure is correct, it is time to replace the relief valve.