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StanFromVan
12-23-2008, 10:31 PM
An older hydronic gas-fired hot water boiler has 2 Honeywell L4006A aquastats. One is on top and one is on the front side. I setthe one on the front to 200F with a 20F. diff. It seems to be working well in the cold winter weather.

My question is what do I set the other one to (temperature and diff) and what's its function? The boiler is only for heating and not for domestic hot water, so could I just disable it??
jwiehagen76
12-23-2008, 10:38 PM
more than likely one is over temp and one is circulator control
superheatrman
12-23-2008, 11:10 PM
one is the operating control {pumpstat} the other high limit..?
beenthere
12-24-2008, 01:23 AM
one is the operating control {pumpstat} the other high limit..?

Yep.

Why is the one in front set to 200.

Do you like to pay more for heat then you need to.

Do you have copper fin baseboard, cast iron baseboard, or cast iron rads.

Set the top to 210 max.
Its your safety/high limit.
StanFromVan
12-24-2008, 01:28 AM
Yep.

Why is the one in front set to 200.

Do you like to pay more for heat then you need to.

Do you have copper fin baseboard, cast iron baseboard, or cast iron rads.

Set the top to 210 max.
Its your safety/high limit.


It's copper fin baseboard. Won't it turn to steam at 210?

What should the front one be set at?
StanFromVan
12-24-2008, 01:31 AM
Yep.

Why is the one in front set to 200.

Do you like to pay more for heat then you need to.

Do you have copper fin baseboard, cast iron baseboard, or cast iron rads.

Set the top to 210 max.
Its your safety/high limit.

Is there any maintenance I can do to the aquistat, like spray some WD-40 inside?
beenthere
12-24-2008, 01:46 AM
Nope. No maintainence.
Won't turn to steam at 200 while the system is under presure.

You shouldn't have your front aquastat set as high as you have it.
It just waste fuel.
StanFromVan
12-24-2008, 01:48 AM
Nope. No maintainence.
Won't turn to steam at 200 while the system is under presure.

You shouldn't have your front aquastat set as high as you have it.
It just waste fuel.

OK, so I should set the top one at 210 and the front one at 180? What about the diff?

Thanks so much!!
beenthere
12-24-2008, 01:51 AM
20° diff is fine.
Base board is rated at an average temp.
So that will give you a 170° average.
StanFromVan
12-24-2008, 01:54 AM
20° diff is fine.
Base board is rated at an average temp.
So that will give you a 170° average.
Thank you BeenThere!