Tjernlund Power Vent Issue

rozeltf

Hi,

I was hoping someone could give me some help on troubleshooting my venter, I have the UC1 controller. It is about 5 years old and on occasion the post-purge cycle never ends. It happened 3 or 4 times last winter and 5 times this past weekend. The purge setting is 2 minutes. The boiler will not run while it is in purge. The only way to stop the purging is to press reset button on burner. Last year I had the prover switch replaced to try and fix this. There are no error codes and the led's match the manual for normal operation. I had a previous tjernlund installed at same location for 18 years and it never did this. Any help would be greatly appreciated.

World Plumber

is it

Is it stuck in post purge or is it not proving? You may need to take it apart and clean it. Be sure to clean the little tubes. If there is dust or soot blocking the passages the pressure switch doesn't sense the air movement and turn the burner on. Depending on how the system is wired it can cause the burner to go off on reset. or just not start.

   The post purge is an electronic timer that would necessitate changing the board.

rozeltf

-

I've never had a problem with it proving and I cleaned it well. I'm fairly certain it's the post purge cycle. I think last year I was actually nearby as the burner was firing/shutdown and the vent went into post purge but never stopped. I usually discover it after waking up freezing. Also, The LED's status indicate Post-Purge. I tried setting the dip switch to 1 minute a couple days ago but it did it again. I just noticed there is a setting for 0 seconds, not sure if that might promote oil smell?

billtwocase

your older vent

has a better control system. It has a timer relay as opposed to the troublesome board that is in the one you are having this problem with. Sounds like you need a new board

rozeltf

Thanks for the help...

It looks like I was misinterpreting my problem. Whenever I discover the PV running but the burner not, the PV indicator lights match the manual for call for heat, proving switch closed, circuit complete. While in this state I tested the PV T1 and T4 and both had 115V. According to the manual when T4 is energized the circuit is complete and power to burner. I also tested aquastat and it had 115v. This was happening 1 or 2 times daily. last sat. I was in the basement when it happened, I heard the pv start but no sounds from the burner. I had the primary control replaced on Tue. night. The problem did not happen again until this morning. Woke up and boiler was cold , pv running. the new control has a red light on it and that was on (Carlin 48245). For now I'm assuming that it always happens in this manner i.e. PV proves circuit and burner does not fire instead of it locking out during firing. This morning I've been sitting in the basement for 3 hours now waiting... also logging starts and stops. I've been trying to learn about oil burners. Some things I'm wondering:

1. Could the Cad cell be getting too hot?

2. Is there loose wiring?

3. Cad cell resistance, I checked when not running by placing test leads on each F terminal and it read 3,000 - which doesn't seam correct. Did I do this right? Can I test while running?

4. The one time I was there, I didn't hear anything. Should I be able to hear the motor or fan?

5.The transformer cover is really hot - is that normal? Once there's a flame is there still ignition?

6. note, service man replaced nozzle on tue. also. he's coming back for full cleaning wed.

7. I have my PV set to 0 pre-purge because length of run is so small, didn't know if adding time would help?



getting up at 3:30 am to make sure having hot water is gonna get old



Thanks

rozeltf

add'l info

Having monitored the boiler this morning for 3 hours, the burner is firing for about 1/2 of that time. This situation seems to occur late at night/early morning when boiler is probably firing less.

rozeltf

Update

Got up at 2:30 am... -10 outside and burner locked out power vent running... hit reset and locked out after about 5 seconds of brilliant flame. Did it again, same result. turned off power , turned on immediate lock out. turned off power, flipped open the transformer had a look around for a couple minutes. turned back on and it's been running for 1/2 hour now.

rozeltf

Tested Fire Eye

I removed leads to Cad cell off F2 and F1, started burner, jumpered F2 and F1. Cad read 480 ohms. Let run for a little while. No change.

rozeltf

...

replaced igniter after testing

rozeltf

again

Locked out again sometime between 1100pm and 300am. Seems to always happen at this time of day.

rozeltf

looking at fuel now

blew out crud in line from tank to burner.