HI LO aquastat setting

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Old 11-26-12, 09:34 PM
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HI LO aquastat setting

I just checked out the temp on my boiler and I noticed that it was around 200, 201. I checked the temp during operation and the boiler shuts off at 190. The high is set at 190 but after the boiler shuts down the temp continues to rise to around 200. I dug through my paperwork and the original aquastat was set at a high of 180.

It is a well mclain boiler go3. Its a honeywell l7224 aquastat, two zone heat (one for each floor baseboard) and an indirect water heater off the boiler on another zone. The High was set at 190 with a 10 diff. The low is at 110 with a 10 diff.

I also noticed that there was a few drips of water coming out the boilers saftey relief valve tube. I noticed these drips when the boiler gets up to like 200. The drips are not hot to the touch.

So far I lowered the hi to 180 as it was originally set when I moved here. Any thoughts where it should be.... and is it normal for the temp to climb 10 degrees after the boiler shuts down.

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Old 11-27-12, 03:31 PM
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Any thoughts where it should be.... and is it normal for the temp to climb 10 degrees after the boiler shuts down.
Yes... 180F is more or less the 'standard' temperature used in designing hydronic systems. Leave it there.

The temp climbs because when the system shuts down (along with the circulator) no more water is circulating and the heat that is in the cast iron continues to heat the water in the boiler. I call it 'heat soak', and it's perfectly normal.

The low is at 110 with a 10 diff.
Why not turn it OFF ? Is there a reason you are running the boiler as a warm start system?

The High was set at 190 with a 10 diff
Increase the HI DIFF to at least 15, even 20.

I also noticed that there was a few drips of water coming out the boilers saftey relief valve tube. I noticed these drips when the boiler gets up to like 200.
Read this:

http://www.doityourself.com/forum/bo...sion-tank.html
 
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Old 11-27-12, 06:41 PM
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I rather leave the low at 110 for the indirect wh.
If I leave it at 110 can I still set the high at 180 with 15 or 20 high diff.

The water out of the hp valve tube is cool, and a drip or two and not hot...do you still think the exp tank needs a few psi. I could see if it was apuddle, or squirting.
thanks again appreciate it
 
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Old 11-27-12, 07:19 PM
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If I leave it at 110 can I still set the high at 180 with 15 or 20 high diff.
Sure...

do you still think the exp tank needs a few psi. I could see if it was apuddle, or squirting.
Dunno if it's down a few until it's checked. If it hasn't been charged in two years or more I guarantee it's down a bit. Thing is, a relief valve shouldn't even drip a single drop.

What's your pressure gauge reading when the boiler is full hot?
 
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Old 11-28-12, 11:40 AM
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The pressure reads about 20 to 25, but it always seemed that high . Ialso notice that backflow tube has a drip too. These aree both copper tubes thatrun from the valvesto near the floor, could it be condensation in the cold copper tube when the boiler heats up and then the pipe gets warm.
 
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Old 11-28-12, 05:34 PM
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The pressure reads about 20 to 25, but it always seemed that high
Have you EVER seen the gauge move?

Read this:

http://www.doityourself.com/forum/bo...ure-gauge.html


could it be condensation in the cold copper tube when the boiler heats up and then the pipe gets warm.
No, not likely.

If you only get an occasional drip or two from the backflow preventer, it's pretty safe to ignore that for the most part. If it starts dripping more than an ounce or two a day, think about replacing it.

But the relief valve should never drip...
 
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Old 11-28-12, 08:36 PM
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Yes, it was below 20 when cooler today and wnt up to around 20 to25 psi at 190 degrees with baseboard zones closed.

Nice idea with the homemade test guage!

The only thing that bothers me about the pressure valve tube is the water that dips out or I feel in the tube is not hot, thats why I thought it might be condensation. I can literally touch it and is cool, shouldnt it burn me if its pressure related? Cold cheap window in tbe winter on hot interior of house scenario is why I thought condensation as the thbe is about 20 in long. Thought it might produce enough condensation I also have a fresh air inlet that brings in makeup air that could be higher in humidity?

Just want to check before.i.call the tech. Again thanks for all the input, really appreciate it.
 
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Old 11-28-12, 09:01 PM
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The only thing that bothers me about the pressure valve tube is the water that dips out or I feel in the tube is not hot,
It doesn't take long for a few drops of water to cool off.

I know what you are thinking, and it sounds logical, but I have never seen condensation on any pipe connected to a boiler in the dry of the almost winter.

Summertime, yes... I've seen boiler pipes sweat...
 
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