Should it really be running up to 220 DegF. + ?

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Old 12-05-07, 05:53 PM
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Should it really be running up to 220 DegF. + ?

First of all, hey everyone, I'm Joe! Just stumbled upon this forum, and I gotta say, I like it! Hopefully at some point I can contribute to the place.

Here's my question:
I have a Weil McLain 68 or 68V oil fired boiler, and the thing is running real hot (I think). The Honeywell triple duty aquastat (model L8124) is set to 180 for Hi, 140 for low and 10 deg Diff.

The boiler is running between 190 (on) and 210-225(off). As far as I can tell, the Taco Cartridge pump is working fine. I have only 2 zones in the house and they seem to be working fine, although one of the t-stats is acting up a bit, its running cold. I'm not sure that the issue lies there or with the aquastat?

I'm worried about damage to the system with such high temps. Any advice?

Thanks!
Joe B.


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Old 12-05-07, 08:26 PM
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High Temps

I suspect a bad aquastat but it would be best to verify the temp before replaceing the control. The easiest way is with an ifrared thermometer aimed at the supply pipe coming off the top of the boiler & going out to the heating loop(s) in the house. Check the temp of the pipe as close to the boiler as you can.
 
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Old 12-05-07, 08:50 PM
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Just to add a note about the IR thermometer... last weekend I borrowed one from work to play with around the house. On my supply pipe (copper) I have a well type thermometer that I believe is reasonably accurate. Taking the temp of the copper pipe 1" away from the thermometer showed almost 30* LESS than the analog in the well.

I was told I needed to paint a black spot on the copper... I used a black magic marker, no difference... maybe flat black paint would work, didn't try that.

My cast iron air scoop about 18" downstream read within 2* of what the analog thermometer was reading.

Ditto with the return side... the steel nipple was very close to the actual temp, while the copper again was much lower.

If you do use an IR don't count on the temps at the surface of copper pipe being accurate. Steel or cast iron seems fine though.
 
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Old 12-05-07, 08:54 PM
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By the way, just in case you don't have an infared thermometer hanging out in the garage somewhere , you may want to try draining some boiler water from the boiler drain valve into a pot (make sure your wife doesn't see you if you are using here Farberware!) and measuring the temperature with a thermometer that can go up to 220 degrees, or at least close to 200. You aren't looking for an exact number, you just want to make sure the tricator is reading ballpark numbers.

A word of caution: NEVER go by the settings printed on the aquastat, usually they are off at least 20-40 degrees on older boilers!

Good Luck-----Charlie
 
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Old 12-06-07, 06:23 AM
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Originally Posted by NJ Trooper View Post
Just to add a note about the IR thermometer... last weekend I borrowed one from work to play with around the house. On my supply pipe (copper) I have a well type thermometer that I believe is reasonably accurate. Taking the temp of the copper pipe 1" away from the thermometer showed almost 30* LESS than the analog in the well.

I was told I needed to paint a black spot on the copper... I used a black magic marker, no difference... maybe flat black paint would work, didn't try that.

I process explosives for a living so I have a few of those IR thermometers also. I'm told by someone in another processing area at the plant that black paint will work for an accurate reading, the magic marker won't. I tried the marker on a 10 gallon melt kettle and the readings were all over the place.
 
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Old 12-06-07, 02:49 PM
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Thanks Joe! I'll try the black paint...

I'd like to add a word of caution to draining water from a boiler when the temperature on the gauge is above the boiling point... let's remember our physics !

When water is under pressure, the boiling point is RAISED. That is why it's possible for boilers to read above 212*F and the same is true with your automobile cooling system.

If the water is above the boiling point, and you open a valve, you could have an almost explosive eruption of super-heated water and steam geysering out of that valve, and heaven help anyone who happens to get hit by that. If you are able to get the valve closed at all, it will be too late.
 
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Old 12-06-07, 07:02 PM
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Thanks for the response everyone.

So I have a bead temp sensor that goes to my multimeter, and I have verified that the well thermometer is accurate. I have the aquastat set to 150 hi and 130 lo, but the boiler is still getting up to 195 before shutting off.

If I turn it down any lower, I get the opposite extreme with water temps of about 135-140.

Am I doomed to having to buy a new aquastat right at Christmastime?
 
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Old 12-07-07, 03:42 AM
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Aquastat

It would seem you do need a new aquastat. Another possibility, although remote, is the well is crapped up & insulating itself from the actual water temp but if the aquastat is holding it's range (20 or whatever it is set for) the well is pretty much out of the question.
 
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