I turned on my boiler today..boiler too hot if all thermostats are set low.


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Old 11-04-12, 05:32 PM
W
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I turned on my boiler today..boiler too hot if all thermostats are set low.

I read a great post in this forum today:

http://www.doityourself.com/forum/bo...ml#post1835448

i have this aquastat too...really great post and great helpers!.. here is my story...
1. i have same aquastat as the person in that post...White Rogers 8f42a-5. is there a manual available? What is the hole under the words limit control in the picture in that post? Is there a second adjustment on it?

2. I have a hydronic system and 3 story house with a zone for each floor. My boiler is a Weil Mclain pcg-5.

Outside it is 50 degrees today, and I turned on my boiler for the first time this season. If my 3 thermostats are set low, my boiler continues to increase temperature at the temperature gauge, even after the boiler flame shuts off.
It gets up to 220 or so.I saw a tiny drop of water at the pressure release valve.

If I have the zones turned on by raising the thermostat setting, the system only reaches 190 with same aquastat setting.

i played with my 8f42a-5 all day and believe it is working... the referenced post was so informative and helpful!!!

i can adjust the temperature setting screw and it changes the points that the boiler turns off and on... consistently for a given situation. I think my problem is elsewhere.

With all the zones off by setting my thermostats low, the temperature reached 220. Any ideas why my boiler temperature rises quickly after the boiler has already shut off at times when no zones are circulating water? Pressure increase at that time has me concerned too. I set the aquastat lower than the original setting...

Note I changed my expansion tank last year and my heat system ran ok with no issues all last winter.

3. What temperature should i set my aquastat? At what temperature should my boiler turn on and off for efficient and safe operation?
 
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Old 11-04-12, 05:48 PM
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First off please verify the boiler... I dont see a PFG 5 in the data list...

Discontinued Boilers | Weil-McLain

Then we can answer some questions.

Tankless coil?
 
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Old 11-05-12, 07:46 AM
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It is PCG-5 not PFG 5. I have was able to download a manual for this series boiler,
but I also do not know how to tell if it is tankless coil or not.

Since I lowered the aquastat yesterday, I think the boiler temperature is a little low...
I can check for more things tonight if I get more input what to do...
 
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Old 11-05-12, 04:26 PM
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This is because your pumps shut off when the t-stat stops the call for heat. Any residual heat from the cast sections will continue to heat the water located inside the boiler and with no water movement, this water can continue to heat and cause the relief valve to drip. A pump delay will work in this case, i actually have a Tekmar control for my house so my water temp never even hits 180 unless its 0 degrees outside.
 
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Old 11-06-12, 01:26 AM
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Tekmar...

Thanks!!!!Tekmar sounds really interesting. I tend to keep house at 58 during the day and raise it to 63 at night. Also outside temperatures vary and I saw some Tekmar units have system shutdown for warm days.

I am concerned my boiler pressure went up with no zones running,
but now I think that was an expansion tank issue. I will check expansion tank on first warm day......

Questions: What Tekmar model do I need? I couldn't figure out their web site:

1. I have 3 hydronic zones (but only really use 2) Basement zone is set to 55 but heat leakage from other zone pipes from boiler keeps it warm anyway..
So I may save some money with a 2 zone controller instead of 3...

2. Next thing, for sure I want a warm weather outdoor sensor...There are plenty of days I am not really using heat at all. I wonder if temperature
cycling my boiler back to room temperature many times a year will shorten its life????
 
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Old 11-07-12, 09:34 AM
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The best bang for your buck would be the tekmar 256. One stage boiler with warm weather shutdown and minimum temp settings. Im assuming you have a cast iron boiler, so i set my control with a 140 degree minimum. I dont want to run the risk of the cast sections condensing and causing excessive corrosion.
 
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Old 11-09-12, 06:27 PM
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I am concerned my boiler pressure went up with no zones running,
but now I think that was an expansion tank issue.
I don't think so.

RD mentioned in his earlier post about the cast iron continuing to heat the water after the burners and pumps shut off...

I'm guessing that you may be an auto tech... so you know how sometimes the electric fans come on at the radiator after the car has been shut off? Same reason.

I call it 'heat soak'. The cooling water temp rises after the flame is gone.

Not an expansion tank issue at all.
 
 

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