Replacing a Gravity Circulation Boiler
Replacing a Gravity Circulation Boiler
(OP)
I am in a competitive bidding situation and have been asked to replace a gravity fed (i.e. no pump) boiler. It is an old Utica hot water boiler.
Does anyone make a gravity boiler anymore? Is it recommended? I can add pump if necessary, but again, I'm in a tough competitive market. The boiler serves cast-iron radiators in a 3-story building. I think the boiler use to be coal-fired and has since been converted to natural gas. The burner input was a max of 400,000 BTHU, but I have calculated a building load around 250,000 BTUH.
I was told by a vendor that a Weil-McLain EGH boiler could be used without a pump, but the W-M tech support could not give me a conclusive answer. That particular boiler had only 2" supply and return connections, which seems to be a bottle-neck for natural circulation. The old Utica had two 3" supply and two 3" return connections.
Any thoughts?
Does anyone make a gravity boiler anymore? Is it recommended? I can add pump if necessary, but again, I'm in a tough competitive market. The boiler serves cast-iron radiators in a 3-story building. I think the boiler use to be coal-fired and has since been converted to natural gas. The burner input was a max of 400,000 BTHU, but I have calculated a building load around 250,000 BTUH.
I was told by a vendor that a Weil-McLain EGH boiler could be used without a pump, but the W-M tech support could not give me a conclusive answer. That particular boiler had only 2" supply and return connections, which seems to be a bottle-neck for natural circulation. The old Utica had two 3" supply and two 3" return connections.
Any thoughts?





RE: Replacing a Gravity Circulation Boiler
But seriously, I'm sure someone makes a natural circ boiler. Probably going to be a chore to find it. You may be money ahead adding a pump just to get more bidders. Does the rest of the system appear to have been designed to a uniform pressure rating? What is the Code situation? Is this stamped as a LP HW boiler?
Is there any chance you could bid a retrofit that would have a better energy cost, and justify a higher bid?
RE: Replacing a Gravity Circulation Boiler
RE: Replacing a Gravity Circulation Boiler
Thermosyphoning systems will operate when the electricity fails and parasitic losses are very low.....very green.
RE: Replacing a Gravity Circulation Boiler
RE: Replacing a Gravity Circulation Boiler
DrRTU, this is a Chicago job. I'm going to quote it the right way with a pump. There is a vented tank up top that I was going to eliminate and use a bladder tank in the basement. I have not been asked to do anything with the piping other than to replace the individual radiator valves with Danfoss valves so that they can have some means of control.