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Rick
Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 19554
Experience:  40+ yrs. experience as a licensed oil & gas technician.
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I have a service required signal on my lochnivar knight

Customer Question

Hi I'm Gad. I have a service required signal on my lochnivar knight boiler
JA: Thanks. Can you give me any more details about your issue?
Customer: it says set point met but actually no hot water going out
JA: OK got it. Last thing — HVAC Technicians generally expect a deposit of about $18 to help with your type of question (you only pay if satisfied). Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 9 months ago.
Category: HVAC
Expert:  Rick replied 9 months ago.

What's the model number of your boiler? What do you mean "no water is going out"? do you mean it's not circulating?

Customer: replied 9 months ago.
KB 081-286
Customer: replied 9 months ago.
The water is circulating but cold.
Expert:  Rick replied 9 months ago.

Is boiler cold?

Customer: replied 9 months ago.
Customer: replied 9 months ago.
Set point met right after ignition
Customer: replied 9 months ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Rick replied 9 months ago.

Ok sounds like a bad board or a bad sensor. Give me a few to pull the specs for your boiler. A phone call is an additional charge.

Customer: replied 9 months ago.
Ok
Customer: replied 9 months ago.
How do I check the sensor? I see the board easily
Expert:  Rick replied 9 months ago.

Do you have an ohm meter?

Customer: replied 9 months ago.
At home. I'm at office
Expert:  Rick replied 9 months ago.

Sensors are thermistors. System sensor is connected to terminals 21 & 22. Inlet sensor is S2, operating sensor is S1a, limit sensor is S1b. The readings are all different and there too much info to relay here. Here are the service manual
http://www.lochinvar.com/_linefiles/KBII-SER%20Rev%20J.pdf

thermistor ratings on page 35

and the install manual

http://www.lochinvar.com/_linefiles/KBII-I-O%20Rev%20R_100161470_2000013387.pdf

sensor connection points shown on page 80