Boiler Temp Question/Problem

My original temp gauge on my system was broken. I replaced it yesterday. I'm running a Honeywell L8124A Hi is 180, Lo 140 Diff 10. My boiler temp is never going over 145 - 150. I noticed since I started the system that the water temp in the oil unit never gets above 140 either even though I've got a recirc pump on the system. I attributed that to the distance from the coal unit (35 feet), obviously a wrong assumption.
When a call for heat is satisfied the system shuts off at around 150. I thought it should run up to the high limit of 180. Am I misunderstanding the aquastat's function or is there a problem?

Hey Bill

I don't know it all about an aquastat but here is how mine works.

when a zone calls for heat the boiler will stoke until the zone stops calling for heat OR the high limit is reached

When the boiler reaches the LOW set point it will stoke until the differential is met. so 10 deg in your case (mine too)

the timer will run your boiler according to your settings so long as you are not at your high limit. in which case the timer will not run until it falls below that.

I think thats about it... So theoretically if you have a tigh house it is maybe possible that you don't need to stoke that high as the zone is satisfied before your stoker gets the water temp really high?

Ok so I will repeat... I don't know it all so these are my observations. which could be wrong! Clear as mud now i'm sure.

The low temp is what the aquastat keeps the boiler at.. the differential is how much below the target temp the burner or stoker is triggered..

I keep my low setting at 160* right now, the differential at 20*, so my boiler fires up at roughly 140* and shuts of at roughly 160*.

Greg L.

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Bill If your T stat gets satisfied the stoker will shut off before it hits the set high point so right now with the warm
weather 145 to 150 is all you need now to satisfy the house T stat. Wait until it gets cold out you will see the 180 or 190 mark. It is just is not cold enough yet to work the stoker . Mine does the same thing 140 L 180 H 10 diff The water is 150 155 all the time. When it does make heat 160 maybe 170 then it shuts off . I seen 180 once Don;t worry think about it Your saving coal.

I was playing around with the settings tonight. I jacked the low up to 160. The water temp went up in both units. I had to think about it for a while. I'm used to watching my oil unit. Once the low was reached it would fire until it hit the high limit, irregardless of a call for heat. Can't do that with coal because if the water temp is at the high setpoint the timer wouldn't come on. Sometimes I need a brick bounced off my forehead for the light bulb to come on.

The reason I was concerned is because I have a DHW coil in the oil unit that feeds an electric water heater and wanted to keep the oil unit around 160 to save electricity. I'll bump the low up when it gets colder out. For now I'll leave it at 140. Next summer I plan on changing that around to an indirect heater or maybe a coil in the EFM. I may even disconnect the oil unit completely and replace it with an old Pittston hand fired kitchen stove in case of a power failure. I'm getting real comfortable with this coal system.

Thanks guys.

Oh, JC, if I remember right you have a coil in yours. Do you get enough hot water with the boiler temp at 140?

Hey Bill. Do you want to check out something real cool? Put your hand into the barometric damper for your oil boiler and feel the heat pushing out your chimney. Scott

My first reaction was to say that you don't have wires on the thermostat terminals in the Aquastat. If not, it need's em to go above low setting. If you have a thermostat hooked up, then it's just not needing to make that much heat.

stokerscot wrote:Hey Bill. Do you want to check out something real cool? Put your hand into the barometric damper for your oil boiler and feel the heat pushing out your chimney. Scott

Right now my the thimble for the oil unit is stuffed with insulation, the exhaust pipe is disconnected and power is off. The heat coming out of the stack right now is going into my basement.

Freddy,
it must be because it's warm. The last cold spell we had the timer didn't come on once. (I need to get out the basement more often) I was blind as far as water temp was concerned because of the stuck gauge. It probably was at the high set point. I'll know for sure this weekend, it's supposed to get cold again.

billw wrote:I was playing around with the settings tonight. I jacked the low up to 160. The water temp went up in both units. I had to think about it for a while. I'm used to watching my oil unit. Once the low was reached it would fire until it hit the high limit, irregardless of a call for heat. Can't do that with coal because if the water temp is at the high setpoint the timer wouldn't come on. Sometimes I need a brick bounced off my forehead for the light bulb to come on.

The reason I was concerned is because I have a DHW coil in the oil unit that feeds an electric water heater and wanted to keep the oil unit around 160 to save electricity. I'll bump the low up when it gets colder out. For now I'll leave it at 140. Next summer I plan on changing that around to an indirect heater or maybe a coil in the EFM. I may even disconnect the oil unit completely and replace it with an old Pittston hand fired kitchen stove in case of a power failure. I'm getting real comfortable with this coal system.

Thanks guys.

Oh, JC, if I remember right you have a coil in yours. Do you get enough hot water with the boiler temp at 140?

5 gal water coil there are 4 people in the house two kids that love to swim in the bath tub the wife & myself does 3 to 4 loads of wash a day. I shower twice a day the wife twice a day sometimes three and I never run out of hot water I have a ball valve between the hot & cold line on the coil to mix the water because 140f to 150f is way to hot for the kids when they wash there hands well it is to hot for me to. At the tap it comes out between 125f to 130f actually code around here says no more then 120F out of the tap . So Yes I have enough of hot water Bill if 5 gal is not enough for yor household
you can get a 7 gal same length as the five Just two more loops in coil you need 29" of clearance from the back of the
boiler to the wall to insall it . The 520 Highboys are in the front . Hopefully efm will go back to that way with the new units makes it much easier install & take out . And you can move the unit back closer to a wall .