Power vented boiler keeps acting up

TLM

System has a field with a ck63 control. Dunkirk boiler w Beckett afg. Has a 7505 genesis. On call for heat, power vent starts, then burner fires immediately..even though control had 15 sec pre purge. If I shut off power to burner and turn back on, power vent re starts the burner starts and does its 15 sec pp then lights. I have a genesis "scan tool" and according to it, all is good - 400 ohms , 123v avg. etc... Unit goes off on safety for no apparent reason. I asked customer to call when happens so I can see what's going on. Yesterday it happened again. I removed the genesis. Installed a 8184g. It's out again. Haven't gone to house yet. Any ideas?

Steamhead

How is the burner wired to the power venter?

I've seen all different variations and the only one that works reliably is to have the thermostat (or aquastat-relay unit) start the power venter (thru a relay if needed) then have the power venter's fan proving switch start the burner.

TLM

That's the way it's wired. I wrung out all of the wiring as per the field controls website. I think by going from a 7505 to the "old school" 8184, I can rule out the burner itself and see if something acts up now. If it does act up, it will be in the field control unit/ circuit board.

Steamhead

But you lose the error reporting. Might look at the Honeywell 7284 or the new Carlin, I think they have better error reporting than the GeniSys. The 8184 has none at all, which is one reason we no longer use it.

billtwocase

Sounds like an intermittent clean cut pump stem problem, or failing DOV base. The power vent has nothing to do with your pre-purge

billtwocase

Also make sure someone didn't wire the DOV thru the prover. Only your motor should be wired thru it

TLM

It is. Wired properly that is. Now that I think of it the pump is a bit whiney. I did do a pump pressure and cut out test at the beginning of last month when all of this weirdness started. I swapped the genesis control out. I was told by the factory that the controls that have a "K" on the label in front had problems and "kind of snuck out of the factory". Even with the 8184g control its still an intermittent lockout problem. I was thinking the CK-63 control wasn't sending power back to the motor/igniter etc

icesailor

Did you check the Cad Cell ohms? Did you time how long the control takes to drop out after you pull a F-F wire? Sometimes, controls dropout too quickly i9f the timing is too long.

I hated "Clean-Cut" pumps because you can't by-pass them to see if there is a delay on the opening. Suntec took a Trouble shooting tool away from us. Plus, you can't put a quik-check pump tester on the nozzle line because the coil is in the way.

TLM

Cad cell ohms were 400 all of the time. I ended up changing the pump and - knock wood- haven't heard from them.

Robert O'Brien

Probably a bad pump stem,if the Genisys sees pre-time flame it will go into safety after 8 seconds and will say pre time flame in history as cycle end. I hope you put 7505 back on , without it you loose pre-purge and interrupted ignition