Boiler Newbie needs help!

bob_46

I would try this before I made any other changes. Try turning the pump on temperature down as low as it will go so the pump runs all the time. Let us know how that affects system behavior. Look inside the fire box, is it a big rusty yucky mess with a lot of rust falling down on the burners? I doubt it. Your boiler is 50+ years old. What does that tell you about quality? bob

Brent O'Connor

Boiler Newbie needs help!

We have a 1950's American Standard Arcoleader boiler with the original American Standard Arcoflame burner in our 1935 built 2 story home in Nova Scotia Canada. Heat is delivered thru cast rads in each room.
The system settings have been monkeyed with, and the system always overshoots the thermostat temp 2 degrees C or more. The boiler seems to be set up in a cold start fashion. Aquastat High limit set at 160F and Circ set at 120, with no other settings on the 'stat. Water Guage temp is 60F when thermostat calls for heat, burner starts and runs for the duration of the call for heat, circ kicks in at 120F on guage, and high limit never cuts burner off, as the circ cycles on and off as return water cools the boiler. I've never seen the boiler reach 140F before the house thermostat stops asking for heat (45 mins later)

That is how it runs now. I am worried that the water temps are to cold, and I may be risking thermal shock/corrosion due to burner condensation. I am also worried that turning the temps up will cause wider swings in house temperature, and worse overshooting.

Before the obvious "replace the system" answer, that is the plan, but I will need to live thru this winter first. What settings should I look at, and how can I avoid the feared overshoot (too hot!) that will come with higher boiler temps. Thanks in advance.

Brent

Kentville Nova Scotia

psd_3

T-Stat overshoot ...

A couple of points ...

It sounds like you need a T-Stat with heat anticipation, or one that self learns the heating response of the system. Perhaps your T-Stat has a heat anticpator that just needs to be adjusted?

In your case you have a lot of thermal mass stored in those cast iron radiators that will continue to drive the room temp up after the T-Stat is statisfied. Do all rooms on the heating loop (zone) overshoot, or just some? Where is the T-Stat, near the being of the loop, or closest to the return side? Are there individual adjustment on/at the rads that can be used for balancing?

For a modern day boiler swinging between 120-140F on a heating cycle would not be problem, especially since your circulators shut down below 120F. For an older boiler, this range seems too low as you suggest.