My 35 year old Homart Gas fired Steam Boiler from time to time won't kick in. When it works, it's fine for a few days to weeks, but sometimes when the weather gets real cold, it will come up in the morning, but then stop running and not make it to the temperature set on the Thermostat. I've even just recently replaced the Thermostat to a new Honeywell digital one, thinking that it was the problem. To give you a little history as an aside, I've been working with a manual water feed system for the past 20 years or so, being that the old Auto Feeder would get stuck in the "open" position and allow too much water to come into the boiler thereby creating a high cutoff condition. Manually feeding water has been fine with me every few days to about a week during the winter time. So that's not the issue. But recently I've found that the system would not heat up to its target temperature, and it would just stop! We happen to schedule the boiler to go down to 55 degrees over night so we can sleep, and then I have it come up to 66 starting at 5:15am. This morning it tried to make it to 66, but stopped at 60 degrees. I went down to the basement and turned the boiler switch off and on a few times, but no dice. I then went up to raise the thermostat temperature up to about 73, and then I went back down to the boiler and turned the switch off and on several times and also hit what I think is the white Actuator device (or maybe modulator device, not sure), and the boiler then came on. I then went back upstairs to the thermostat and brought it back down to 66 degrees. I checked to make sure that the boiler was still running, and it was. I then went to work and called my wife to see if it ever made it up to the target 66 degrees, but she said that it was still at 60, and it seemed as though the boiler turned off again. Could it be that it might be one of these electrical devices that's at fault (either the Switch or the Actuator Modulator device)? Any help here would be greatly appreciated! Thank you very much!

Unusual question: regarding a gravity flow check valve, can it be installed on either side of the pump? If installed on the suction side, will the pump suction lift the cone and allow circulation? Is it an approved practice to install one in that manner?