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ER4 lack of 24v

Sanjo
Sanjo Member Posts: 3
in Radiant Heating
Has anyone had any experience on ER4 - lack of 24v on the NTI ti400?
This is occurring on 2 of 3 boilers intermittently. For the sake of this conversation let’s say B1 & B2 gives me ER4 and B3 is operating properly.
Sometimes they (B1 & B2) both lockout together and sometimes it’s just 1 of them. Also noticed that it seems to lock out in the mornings only or overnight. 
This is what I’ve done so far. I’ve adjusted the PRV and set the pressure to 17psi. I know the ti150-200 have a low water pressure switch and the boiler will not operate if system pressure is under 9psi (I think). The ti400 does not have this switch. At least not that I see on the wiring diagram or parts list. For both B1 & B2 I Made sure both boiler pumps are working. Made sure main circ pump is working. I checked the secondary side of the transformer and I have 27v. On the 24v circuit I have a flow switch, LWCO, thermal fuse, Limit switch. Prior to resetting error I checked to see which of these switches were open and according to my multimeter they were all closed. Then I pulled the wires off each one and checked resistance. I got 0.1ohms for each one. I checked these numbers and compared it to B3 (the boiler that doesn’t give me an ER4) and I also got 0.1ohms on those switches. I then by pass each switch on the 24v and fired the boiler and no error. And shortly after rewriting all safety back to the circuit it doesn’t error out anymore. The next day it error out again so I swapped the fenwal on B1 with B3 and on B1 I get ER4. So this tells me it’s not the fenwal. Then I take the sentry and swapped it from B1 to B3 and I get the same error on B1. So then I by-pass all 4 safety switches and ran it for 30 minutes and nothing... no error.
I also looked at the venting to make sure there’s no obstruction at the outlet. Any suggestions is appreciated. The boilers are also controlled by a tekmar controller. But if the tekmar is faulty or if there’s a setback then why is it only doing it to B1 & B2 and not B3?

Comments

  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    @Steve_Wheels is the NTI guy. Hopefully he’ll chime in

    There was an error rendering this rich post.

  • Sanjo
    Sanjo Member Posts: 3
    Update: customer called in the morning and true enough ER4 on B1 again. Just B1 this time. I pulled out the combustion air and checked the Venturi for anything obvious and everything seems to be ok. I isolated the boiler and drained it and checked the probe on LWCO. They well black so I cleaned it. Removed the pump and checked the inlet and outlet for any obstruction. Nothing. Checked the impeller for damage, nothing. The thought was maybe there’s something in the pump restricting flow cause the flow switch to not make or possible over heating the boiler causing the limit switch to trip... I wasn’t lucky. Desperate move I by passed the limit switch overnight. 
  • Sanjo
    Sanjo Member Posts: 3
    Update: Got help from one of our Journeymen and what it was was the external LWCO switch would open then it would reset itself But the boiler will not. Came across by fluke as he heard the LWCO click. Replaced the LWCO and put a manual reset on it. Likely air in the system. I hope I never come across something like that again. I ate a lot of time on that job

  • Steve_Wheels
    Steve_Wheels Member Posts: 28
    Sanjo, Was your external LWCO tied into the low voltage wired on the boiler or breaking 120V to the boiler? Keep in mind, even on a old Ti400 (or the original T series) you can always call our 14 hour a day, 6 day a week, tech line 1-800-688-2575 ext1. We're here to help you!!! (average call waiting time is 93 seconds).

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