Getting heat with thermostat turned all the way down

StephenO

I have a brand new Slant Fin TR-20 oil burner.The boiler sends heat with out any call from the thermostat when ever it kicks on. I changed the thermostat and it still happens. Only have one zone with circulatory pump.The boiler seems to be running fine shuts off when reaches high limit. In the Aquastat, when I get to the TT display for Local Thermostat Status it is displaying OFF is this the correct position and if not how do you change it. I am a new licensed oil technician and could use some help thanks.

STEVEusaPA

let's check the settings first,

then the wiring.

When you say the boiler sends heat, do you mean the burner fires without a call from the thermostat?  Is it because the boiler is also used for domestic hot water?  It seems the circulator isnt running if the boiler shuts off on high limit.

What are the settings on the aquastat (hi low diff)?

How is it wired? where are the thermostat wires?, what wires are on what terminals?

After you answer these questions, they we'll talk about how to check out the aquastat.

Unknown

Getting back to you

The high limit is 190. The low limit is 150. The diff is 10. The thermostat is wired to TT, the circ. is wired to C1 Black and C2 White. We are getting domestic hot water from the boiler.This was a package unit so most of the wiring was done.

billtwocase

sounds like

you are getting gravity feed heat. What do you have for a flow check? Is it closed and seating? Is it an IFC pump? Disconnect "TT" from the aquastat, and let it set for a while. You will know if it is a thermostat problem, or ghost flow. Pics of your system will help us to help you

Unknown

Will check that

I can't get that information till tomorrow and I will take some pictures. Thanks for the help.

billtwocase

You're welcome

hope we can get you some answers

StephenO

Gravity heat

It was gravity heat, put in a check valve in heats working good now.

Thanks again for the help

Steve