Beckett Genisys 7505 no power on R terminal. not running

steveh2112

hi all, when i power up my Beckett Genisys 7505 oil furnace, i see the lights blink on for 1 sec then shut off. according to becket i should check R and W are bridged to call heat (which i did) and check i have 110v on L1 and L2. not sure where L1 and L2 is but i checked there is 110v on 2 terminals on a thing that goes into the furnace body.

https://www.beckettcorp.com/support/troubleshooting-guides/#oil-burners

it also says '120v is present at (L1 to L2) and (Limit to L2) of the GeniSys Primary Control.'
i don't know what that means, Limit to L2. any ideas?

also, notice i have 24v ac on the 2 thermostat terminal in front of the reset switch that feeds into the terminal block that goes to the thermostat. however, when i measure voltage between C and R on the terminal block i have nothing. its my understanding C is common and R is 24V and by connecting R to W it should call for heat.

and finally, the reset button (thing with the LED display) doesn't feel like a button at all to me


it doesn't move at all when i push on it.

any ideas please, i;'m freezing my nuts off.

thanks

UPDATE, i just realized the TW and TR terminals in the instructions are the 2 thermostat terminals on the front of the unit, so tomorrow i'll bridge those and see it it helps

HVACNUT

Do you have this AC Ready Kit also near the primary? The red and white wires are connected to Tr and Tw? And no 24 volts between R and C on the AC Ready Kit?
It could be a bad transformer. Hence no 24 volts. 
There might be a temporary solution if you can post a pic of the furnace wiring diagram. 
If the transformer is bad, install a 3 amp inline fuse to protect the transformer. It's unknown if the existing transformer just quit, or there is a short somewhere in the low volt circuit.

109A_5

Hello @steveh2112,
Maybe a bad Aquastat. The Honeywell L8148 is known for failed solder joints at the internal relay to circuit board connections.
Wiring is underneath the 7505.

Some wiring diagrams here.
https://www.beckettcorp.com/wp-content/uploads/2022/05/61649-GeniSys-7505-Control-Manual.pdf

EdTheHeaterMan

On the underside of the control are the 120 VAC terminals.
This is what must have 120 VAC to get the control to operate.



You must have 120 VAC Hot on both the L1 and the LIM at the same time for the control to power up. If the LIM is not powered with 120 VAC then the control is not turned on. if the L1 does not have 120 VAC then the control is not powered. Both terminals need 120 VAC to operate the burner.

LIM must be powered thru a high limit control that will shut the burner off if the water temperature in the boiler gets too hot. That limit MUST be on the 120 VAC circuit by code. If you are not familiar with how to safely operate an oil burner, then you should have a Professional that is familiar with oil burner controls make the repair.

steveh2112

thanks for all the comments. i bridged the TW and TR terminal on the 7505 and turn on the power and it fires up. great!!! it gets warm, the heat and fan green leds both light and it works for about a minute. then it just dies. no waring lights, nothing on the display.

what now?

i'll look into the AC Ready Kit but am i connect in thinking i should be able to run it manually just by bridging the TW and TR if i can find out why its cutting out and stop it?

thanks

109A_5

Hello @steveh2112,
Help us help you, pictures of the whole system may help. When it drops out is the whole 7505 dark, like no power to it ? If so, verify it has power to it when it is in this state.

Looks like you have the "AC Ready Kit" or at least part of it. Is that a transformer hiding underneath the terminal strip.

steveh2112

yes, when it cuts out it still has power. if i turn it off and wait 5 mins, i can power it up and it starts again.


FYI, i ordered a new 7505 from HD, should arrive friday. not sure if its the problem but cheaper than a service callout

109A_5

Hello @steveh2112,
Maybe this will help if there is still "no power on R terminal" when it acts up.



https://s3.amazonaws.com/s3.supplyhouse.com/product_files/Beckett-51970U-Install-Instructions.pdf

steveh2112

thanks, but i think the 7505 must be cutting out for some reason
that troubleshooting guides lists this https://www.beckettcorp.com/support/troubleshooting-guides/#oil-burners
--------------------
Burner runs, ignites, then stops
Cause 1 – Flame is present but sensor has weak or intermittent signal
Action: Check and correct flame sensing circuit (cad cell and wiring).

Notes: See the Cad Cell Tech Bulletin for more information.

Cause 2 – Burner setup out of recommended adjustments
Action: Verify burner specs.

Notes: Refer to our Residential Oil Specification Guide to see start up settings.

Cause 3 – Flame failure

Action: Check and correct:

Fuel supply.
Proper flue draft and chamber draft.
Nozzle and air settings.
See if a low firing rate baffle is required for this burner combination.
Verify electrode condition and settings
Notes: Refer to our Residential Oil Specification Guide to see start up settings.

Cause 4 – Lack of retention

Action:

Check chamber.
Draft oil supply, 3 nozzle spec.
Notes: For more information about the Low Firing Rate Baffle (click here).
--------------
i don't really understand 4
i doubt its 3 flame failure because i know its starting, the flue gets hot
don't know why it would be 2, it was working fine until recently
maybe 1, i guess i need to check the sensor?

none of the links on that webpage work.

109A_5

Hello @steveh2112,
Well if it is actually not an electrical issue, it just may need a tune up. Oil = frequent maintenance.

EdTheHeaterMan

What is the possibility of taking a video? If you can post a video on YouTube or Facebook then post the link for the video (make sure the link is available for public viewing) then we can see the sequence of operation and hear the flame and motor operation.

Sometimes I can walk in on a problem, hear how the system acts and reacts, then rule out a dozen or more possibilities. That will point me to the ones that are most likely to cause your problem and we can eliminate those one by one.

Parts Cannon is the last resort.

I can tell you from experience that I have had problems with that tiny relay on that AC Ready Kit. I have actually wired in a RIB to take the place of that el-cheapo relay Beckett uses, after replacing that AC ready kit 2 times within 3 years, on a furnace.

As far as eliminating the AC Ready Kit on some furnaces... I know that there are some furnaces that require that second transformer to operate some components, even if you do not have air conditioning. I can't remember what particular furnaces are that way, I just remember having that problem.

If you post the wiring diagram for your furnace, Then I can tell you how to eliminate the AC ready kit if it is possible.

Final Question: After your replace the 7505 and you have the same problem, What will you check next?

HVACNUT

If you read 24 volts at Tr,Tw, then the relay in the AC ready kit never closed. They have been problematic in the past. 

steveh2112

thanks, i've been busy and using my portable gas heater so haven't worked on it today.

i'll order an AC ready kit, they're quite cheap. but do not actually included the relay by the looks of it, just the transformer and terminal block.

i don't have a wiring diagram for the furnace, its a lenox. will google it tomorrow. thanks

pell

If the burner runs for one minute the stops, with no lights on the control the blower is not pulling in on the furnace and the high limit circuit shuts the burner down. I would say it is a bad relay on A/C ready board, as that is what pulls in the relay on furnace which starts in the blower. Not an uncommon issue.