Oil Boiler water temperature questions

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Old 01-03-13, 08:47 PM
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Oil Boiler water temperature questions

Hi, I have an old Utica oil boiler that has a L7224U aquastat controller. I do NOT have hot water connected to the boiler.

My high limit is set at 180 my low limit is set to off. Hi diff is 15 degrees.

My question is this: my water temperature is only in the 130-140 degree range at the end of a heat cycle (heat demand satisfied). Is this normal? Efficient?

the house seems to heat ok, but I woudn't know if it could be more efficient. I only know what it has been doing all along.

any help appreciated.
 
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Old 01-03-13, 09:49 PM
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my water temperature is only in the 130-140 degree range at the end of a heat cycle (heat demand satisfied). Is this normal? Efficient?
This is not a bad thing really. It costs less to heat water less.

BUT, with a boiler running that cool, you have to watch for flue gas condensation issues.

Since you say this is an OLD boiler (how old?) it shouldn't be nearly the issue it would be with a modern 'tight' boiler.

How does it look inside when it is opened for cleaning each spring?
 
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Old 01-03-13, 10:04 PM
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thanks for your input. the boiler is about 30 years old. it gets a lot of soot in it but I dont see a lot of rust.

I guess I wonder if the circulator pump was set to come on at a higher temperature, it would give the boiler time to heat up the water more, and circulate hotter water to start with. it does seem to take a long time to heat up the house in the morning (recovering from overnight lower temp setting).

Is their a particular setting on this controller to tell the circ. pump when to kick on, or is it an internal pre-set?
 
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Old 01-04-13, 06:23 AM
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Is their a particular setting on this controller to tell the circ. pump when to kick on, or is it an internal pre-set?
It sounds like you are looking to delay the circulation pump from starting while the boiler heats?
This would cost you more fuel then your current setup and would cause the house to warm up slower.
It may be worth considering a less aggressive temp adjustment on your t-stat or setting it to warm up a bit earlier then current.
What temperature are you setting at night, and what temperature are you going to in the morning?
 
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Old 01-04-13, 09:18 AM
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Northern Mike, Hello! I was trying to increase circulating water temp initially to heat up faster, but also trying to avoid boiler condensation I was warned about with circ. water temp in the 130' range.

I set the house temp to about 69 in the day and set back to 63 at night. lots of nights I dont hear the boiler at all for those 7 hours. the house is pretty well insulated.

Really, I am just confused.
 
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Old 01-04-13, 09:41 AM
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Ed, now I'm confused...

Are you only seeing temps in the 140 range while the boiler is recovering from that night time setback? That would not make sense. If the home has cooled several degrees overnight and you kick the t'stat up, I would think it would go to 180 high limit at least once during that recovery time.

I could see it only going to 140-ish while it was 'maintaining' the temp though... mine does the same thing.
 
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Old 01-04-13, 09:58 AM
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NJ Trooper, good morning. good question. when I first started worrying about the boiler temp. it was past mid-day, and the boiler had already brought the house up to temp hours before. Just an hour ago, I kicked the themostat up a couple of degrees and the boiler ran the temp to 166' before I turned the thermostat back down to 69.

tomorrow morning I will watch the boiler temp after the night cool and see what it maxes out to. as you say, this may all be normal.

(the boiler temp increased up to 192 after burner and circ off over a few minutes, and then boiler temp starts to drop back......normal I suspose.)

my low limit is set to off. I read that without a hot water tank, the low limit should be off. Can you confirm this?

thanks!
 
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Old 01-04-13, 03:56 PM
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(the boiler temp increased up to 192 after burner and circ off over a few minutes, and then boiler temp starts to drop back......normal I suspose.)
Yes, normal. I call it 'heat soak'. There's heat trapped in the cast iron that conducts into the water after the boiler shuts down. Because there is no circulation at that point, the heat stays in the boiler.

without a hot water tank, the low limit should be off. Can you confirm this?
Yes, I can, and will! With a slight modification...

If you have an INDIRECT hot water tank, you STILL want to keep the LL set to OFF. The only time you would want to run a LL is if you had a 'thankless coil' installed inside the boiler to provide HW for the home.
 
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