Boiler feed pump control
Hi I'm replacing a boiler that currently has a boiler feed pump and I'm trying to understand how to wire this thing.
The old boiler had 2 lwco that seem to be mounted at the same exact height and one of them was controlling the pump it was a regular 67 triangle type float.
As far as I understand these pumps will turn off the second call ends what is the correct way to control the fill so it doesn't fill a bit every time the boiler falls below the water line the boiler doesn't have to turn off every time.
And is there any way to have it work like a regular boiler feeder maybe some sort of a control that I could set it for one or two minutes of pumping every time it triggers. Why can't I just wired into a boiler feeder and not have the feeder even connected to anything besides for using it as a controller.
Thx
Levi
Comments
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If it is a boiler feed tank and not a condensate pump and it was controlled by a control sensing the boiler water level it must remain that way.
Depending on what boiler you are installing you may need to be creative on where to mount the controls and what controls you use.
Is this commercial or residential?
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This is residential eg-65 boiler
It was controlled by the boiler using a standard low water cut off but from my understanding that would not maintain proper water level that would only maintain minimum water level.
Also does the control have a high and low switch so the pump turns on at the low switch and fills up till the high switch?
Lastly is there any option for an electronic control not a flow type so it doesn't get gummed up with rust.
Thx
Levi
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The boiler feed pump control — whether it's a float type or electronic — should be set at or close to the normal boiler steaming water line, and there should be some difference in the "on" level and the "off" level. I believe the MM67 will do that — if it's set at the correct level. The low water cutoff should, of course, be set at the bottom or near the bottom of the sight glass as usual. Therefore the boiler feed control and the low water cut off can't be the same device!
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
Seems like MM has a 47 feeder control that does low water cut off and does feeding control the part I don't like is the fact that it is a float and floats tend to get clogged up if not maintain properly.
What is the model number for a electronic feed control?
Thx
Levi
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I was wrong the 47 is a water feeder and low water cut off but does not control a external pump as far as I could see
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So… since I assume you have a condensate receiver tank… with a pump in it… what does control that pump? If it's a float in the condensate receiver thank, it's not a boiler feed pump, it's a condensate return pump. And the odds of flooding the boiler just rose to 100%. It's not will it happen, it's when.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
Given that this is residential, I'm going to ask this question.
Are you sure you even need the tank and pump?
Sometimes they were added by unknowing contractors that assume steam needs a tank and pump.
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The pump control low water cutoff combination control is a #150 McDonnell Miller big $$$$$$. Hydrolevel 250/250wc is an electronic low water cutoff and pump control. You could look at that one I have no experience with it.
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No I definitely have a boiler feed pump and it was controlled with a 67 low water cut off.
I was just saying that the mm 47 control I found online will not work for my application.
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It is a extremely large house (so maybe it did have a slow return) and being that it's already there for a while I'm a bit scared to get rid of it .
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If it ain't broke… don't fix it.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
What I want to understand is why this won't work. Why can't I wire my low water cut off to a standard boiler feeder (not connected to any water source just used as a controller) then take the wires that used to go to the solenoid and power a contactor to turn my boiler feed pumps on. This will let me decide how many minutes the feed pump should run in order to get my desired amount of water. And if I feel like it's feeding too much I could throttle it with a valve.
Am I totally crazy?
Levi
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And why has no one created a controller that does just that?
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The mm 47 is not recommended for a feed pump because the switch contacts are not robust enough to handle the repeated duty of a pump. It is rated for an occasional low water cut off interruption, not operating under substantial load repeatedly throughout every day. As a result, you may be replacing switches frequently.
Perhaps you can control a relay or contactor with the 47 switch that will be rated to better handle a pump motor, though that would be considered jury-rigging. That said, Levy, I think your plan would work fine. Just size the contactor according to the load, and budget for a switch replacement from time to time in case it doesn't like that type of service.
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I guess I'm not that crazy after all.
I still have the existing contact that was working all these years I'm just going to wire it through a feeder without any solenoid connected. Going to be interesting.
The only part I'm worried about it is if the lowest setting on the feeder might be too much water for this boiler because of the amount these pumps pump. Although I might be able to fix that with a throttling valve.
Thx
Levi
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Now I'm thinking just to put an HVAC fan delay (to the contactor so I don't max out the amps) that I can set for a certain amount of seconds and it will feed exactly how much I want
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