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point the camera at the copper pipe not the aluminum fins

Or at the copper return pipe at the boiler.

Hi all, I just wanted to give you some updates:

I had some repiping done - supply header is now 1 1/4" and return is 1". Left the circs on the return. Added a Caleffi 573 feed valve. Set low limit to off, so boiler is now a cold start. High limit is set to 180, economy off and differential to 30. Thermal pre-purge is enabled on the hydrostat 3250.

I changed the headbar to 1.00/85 and put in a .85 nozzle at 145 psi pump pressure.

Here are some numbers:

Boiler sat overnight with no calls and dropped to 105 degrees and 10psi water pressure.
I turned on two of the three heating zones to call the boiler on.
This is with the thermostat reading 72 degree house temperature, so it's not really testing at ideal conditions.

3 minutes runtime - stack temp=340, boiler temp=122
4 minutes runtime - stack temp=350, boiler temp=137
5 minutes runtime - stack temp=358, boiler temp=149
6 minutes runtime - stack temp=359, boiler temp=147
7 minutes runtime - stack temp=356, boiler temp=135 - return pipe just getting warm, water feed at 15 psi
8 minutes runtime - stack temp=357, boiler temp=134
9 minutes runtime - stack temp=362, boiler temp=144 - return pipe warm
10 minutes runtime - stack temp=368, boiler temp=155 - baseboard temp=126
11 minutes runtime - stack temp=374, boiler temp=161 17psi water feed, return pipe hot
12 minutes runtime - stack temp=375, boiler temp=165
13 minutes runtime - stack temp=378, boiler temp=171 - baseboard temp=145
14 minutes runtime - stack temp=379, boiler temp=175
15 minutes runtime - stack temp=383, boiler temp=180 - baseboard temp=157

I've never had the boiler run this long, but it might have to do with starting at such a low temperature.

The indirect called about 30 minutes later when the boiler was still at 180 high limit - here are the numbers for that:

145 degrees - boiler fires
2 minutes runtime - boiler temp=149
3 minutes runtime - boiler temp=157
4 minutes runtime - stack temp=350, boiler temp=166
5 minutes runtime - stack temp=360, boiler temp=171
6 minutes runtime - stack temp=372, boiler temp=177
6 minutes 30 seconds - boiler hits 180 high limit again with indirect still calling

I have to do a combustion analysis to see where my numbers are with the .85 nozzle.

Do my stack temperatures look good enough to prevent condensation, or should I increase to a .90 or 1.00 nozzle?

I couldn't measure the return pipe temperature exactly to see if I got 140 degrees after 5 minute. My infrared camera was not picking up the return pipe temperature that well.

Thanks!