Aquastat help on steam system


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Old 10-20-14, 05:44 PM
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Aquastat help on steam system

Recently purchased a home that has a Burnham IN7 steam boiler. The basement is heated with hotwater from the steam boiler which is circulated with a Bell and Gossett pump controlled by a Honeywell R845A and a separate thermostat in basement. There's a Honeywell L4006A aquastat attached on the hotwater copper pipe but the aquastat isn't connected electrically to anything.
I think the aquastat is supposed to be connected somewhere to limit the temperature of the pumped hotwater to 180 degrees and also to be able to start the boiler if the upstairs thermostat isn't calling for heat?
Does anyone know how this aquastat must be connected?
The boiler has an intermittent electronic pilot connected to a probe type LWCO and a vent damper.
Thanks
 
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Old 10-21-14, 05:13 AM
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Post pics please.
How is the B&G controlled now ?
I would think that the aquastat might be installed to prevent steam from hitting the circ if the water level in the boiler dropped.
I do not think you want to fire that boiler on just a basement call for heat, you will over heat the primary boiler load unless it's zoned. If's it is zoned you might be bouncing off the limit (water or steam pressure) a bunch and that short cycling is hard on the boiler and fuel. Steam is already very hard on fuel.
 
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Old 10-21-14, 04:16 PM
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I would think that the aquastat might be installed to prevent steam from hitting the circ if the water level in the boiler dropped.
Typically the aquastat is used to fire the boiler only up to about 180 or so in the event that the baseboard zone calls for heat but there is no call for steam from the rest of the system.

B&G used to have an excellent paper on setting up a hot water zone off a steam boiler but since Xylem took over the papers are almost impossible to find. I'll look...
 
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Old 10-21-14, 04:22 PM
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Start here with Dan Holohan:

Hybrid Hydronics, by Dan Holohan - Old-House Journal

Here's the TEXT ONLY of the B&G article... and of course in their infinite wisdom the new proprietors apparently chose not to include the drawings.

http://websupport.completewatersyste...a-Steam-Boiler

Here's the drawing that I believe originally was with that article:



Here's the link to that page with more Q & A from Dan the Man.

https://heatinghelp.com/systems-help...-steam-boiler/

More DtM:

The Limit To A Hot Water Zone Off A Steam Boiler by Dan Holohan - MasterPlumbers.com PlumbViews

Should give y'all enough to chew on for a while.
 
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Old 10-26-14, 05:47 AM
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NJ Trooper:
Read the articles by Dan the Man. Thanks
Think I've figured out how to proceed. Let me know what you think.
The boiler and pump comes on at the same time when the basement thermostat calls for heat and the aquastat limits the water to 180 degrees so steam isn't made. Upstairs gets no heat at this point.
If upstairs thermostat is calling for heat the water temp will be about 212 degrees at least, and if downstairs thermostat calls for heat at this point then the aquastat has no effect on boiler but the bypass piping reduces basement watertemp to around 180 degrees.
I've included a schematic.
 
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Old 10-26-14, 08:40 AM
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Yes, I believe that's all correct.

Is the system piped as shown with the bypass and all? Bronze pump?

If so, then you should be good to go.

If all of your baseboard in the basement is below the water line of the boiler, the flow check valves may not be necessary.

Many hot water loops off steam boiler don't include the bypass... probably installed by the uninformed... they really should have that.
 
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Old 10-26-14, 09:44 AM
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Unfortunately there's no bypass so I'm going to add that before I proceed with the re-wiring. Pump isn't bronze, it's the red pump. I'll leave that until it dies. Incidentally the pump flow is in the wrong direction. It's pumping into the boiler via the equalizer instead of pumping into the baseboard radiation. I checked the Bell and Gossett site and found how to flip the direction of pump flow. It seems that the only correct thing done on this install was having the pipes and baseboards below the boiler water line. Later in the week I'll attempt to remedy the situation.
Thanks for your help NJ Trooper
 
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Old 10-26-14, 10:32 AM
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Pump isn't bronze, it's the red pump
It could be painted red. What's the model number of the pump?

It seems that the only correct thing done on this install was having the pipes and baseboards below the boiler water line
It's possible to have a hot water zone above the water line though... but like I said, MOST hot water off steam is not done properly.

Let us know how it goes!
 
 

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