I have a Utica Boiler and it will only heat the water to 170 degress while the boiler thermostat is set to 190.
When I bring the thermostat down to 170 it will shut the boiler off while the circulating pump still runs due the the house thermostat is not satisfied.
So it appears everything is working.
The boiler has been installed for 4-5 years and has not had this problem in the past.
The output BTU's is 63,000 which is the same size I have for the downstairs apartment which is the same square footage and number of radiators and heats just fine.
Any advise would be appreciated.

Randy

 

That's really not an uncommon occurrence, and in general nothing that should concern you.

At least not that you have noticed anyway... or perhaps you are diligent and check the gauges/temps on a regular basis?

Let's talk terminology, that way we're all on the same page and understand each other:

The 'boiler thermostat' is properly called the 'aquastat' (a'stat).

Are there ANY other controls on either boiler that we should know about? For example, an OUTDOOR RESET module? Maybe a "Heat Manager" module? These things would normally affect the boiler temperature.

Since the thermometer and the aquastat are likely sensing temperatures is somewhat different areas of the boiler water, there is going to be some difference between them because of that. The water in the boiler is turbulent and mixing differently with the cooler return water... this can cause differences between readings.

As components age, their accuracy make suffer a bit. The temperature GAUGE can drift, as can the accuracy of the aquastat sensing bulb. They may both drift in the same direction, or may drift apart.

What ultimately matters is that the water is hot enough to heat the apartments properly, and that the aquastat setting is REPEATABLE. It MUST shut down at the same temperature all the time. If one time it shuts down at 170, the next at 190, the next at 180, it's time to think about replacing it. If it shuts down within a few degrees each time, don't worry about it.

You probably don't need the settings at 190. I would turn both apartments down to 180. You might not save much, but you will save some fuel.

Continue to do due diligence and keep an eye on the pressures and temperatures. If you see things starting to drift around in the settings, then consider tracking down the problem. I don't think there is one now.