The next two schemes may be used for many boilers and pumps. Multiple Boiler & Feed Pump Controls with Automatic Standby The pump panel will have boiler switches marked “Hand-Off-Pump 1- Pump 2.” This will assure the contact closure will start the right pump after the owner has opened and closed valves. The challenge, again, is to make sure the controls match the intended sequence. This control would indicate to me that one of the boilers is standby most of the time. The pipe between the two boilers, along with the boiler shutoff valves, will allow the owner to manually have pump 2 serve boiler 1 and vice versa. The level control on each boiler operates its respective pump. The difference now is to make sure the water gets in the right boiler. Each boiler must be able to activate the appropriate pump or pumps. They may have standby boilers or use all of the boilers in very cold weather. Most larger buildings will have two or more boilers. Two Boiler, Feed Pump Control with Manual Standby Let the boiler manufacturer figure out how and what McDonnell Miller pump controls to use. I don’t recommend using a safety switch as part of an operating pump strategy. It is not wise to use the low water cutoff switch as a pump control. The boiler must have two level switches to activate the pumps on low level and turn the pumps off on high level. The electric alternator will assure equal wear on the pumps. It will either be supplied by the boiler manufacturer or the contractor will have to install it.Įach pump will have a “hand-off-auto” switch with an electrical alternator so we can turn the pump on manually, disengage the pump, or control automatically. There must be another level control on the boiler. Something must tell the second pump or standby that the first pump is not keeping up. The important thing here is the second level control on the boiler. The boiler must have a single level control to activate the pump on low level and turn the pump off on high level. The pump panel will have a “hand-off-auto” switch so we can turn the pump on manually, disengage the pump, or control automatically. Starting with the control of a single boiler may seem simple but it will get the idea of control logic required in the feedwater system as well as the level controls on the boilers. This is where the engineer’s specification and drawings become critical. This seems elementary but it will require coordination between the boiler, boiler feed pumps, and the installing contractors. The goal is to make sure the boilers have the correct level controls, and the pump system will recognize the call for water and start the correct pump. The boiler feed unit will have some number of pumps including standby. Some Thoughts about Boiler Feed Pump Control If you understand the content in this article, you can apply it to any system you wish to design. It is long but easy to read and will clearly get the concepts of pump and boiler control across. Deppmann Company offers many choices which we have used in Michigan and Northern Ohio. Level controls at the boilers must match the pump controls on the feedwater system. When selecting and specifying a steam boiler feed unit or deaerator, the engineer must pay attention to the controls.
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