How do I adjust temp on Thermoflow OWT-3?

CoolUsername

My apartment has an (old?) Thermoflo OWT-3 Series 1 oil-fired water boiler. I live on the second floor and have been having trouble getting/keeping hot water. When I first turn on the water, it gets kind of hot within a minute, but then cools; it then takes several minutes to get hot again.

This issue is new, and according to a neighbor, the landlord had the boilers serviced around the time the problem started. I am guessing it could be simply an adjustment to remedy. The problem is I am not sure about what to change and don't want to break something (or burn myself). I have attached photos of the furnace for reference.

HVACNUT

Can you post a pic showing the whole boiler?

Its a triple acting aquastat, so it's assumed DHW is produced from a tankless coil. There should be a thermostatic mixing valve. Maybe it needs adjustment? In winter, the settings are typically 180° High, 160° Lo. 160° High, 140° Lo if it heats the space fine on the coldest days. Always minimum 20° between the two. Put the differential to 15.

CoolUsername

Sorry for the delay in getting more photos…

bburd

That is a tankless coil system, assuming there isn't a tank we can't see in the pictures. Your low limit, inside the aquastat (gray box with the "C" on it), is set for 130°F. Try raising it to 160°F, and the high limit to 180°F.

There is a thermostatic mixing valve to prevent the danger of scalding, on the copper piping on the right side of the boiler. It may or may not be working correctly, so be aware that the water from the hot taps may exceed safe temperatures until you get things adjusted or repaired as needed.

CoolUsername

Thank you for responding so quickly!

hot_rod

The pressure is a bit high, the pressure relief valve is commonly a 30 psi.

Although those gauges are not always 100% accurate.

If you crank the temperature up, keep an eye on the pressure.

A gauge like this could screw onto one of the purge valve to confirm pressure. Do that with the power off and the boiler at it's highest temperature. Find them at a plumbing supply, online or at the box stores.

The usually come with a 100- 300 psi gauge. You can replace that with a 30 psi gauge for better accuracy.