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  1. #1

    R7184A versus R7184B

    My house has two identical Low boy furnaces with becket AFG burners and R7184B primary controls. Two years ago right after I moved in one furnace locked-out so I called service. He worked on it for quite a while and couldn't find anything wrong, but swapped out the R7184B with a R7184A and that worked and it has been working fine every since. Nevertheless, I have always wondered why.

    Can you think of anything that would cause a system to run fine with a R7184A and not with a R7184B.

  2. #2
    Join Date
    Sep 2003
    Location
    Portland.OR
    Posts
    313
    part was defective... bad before/repalce part now works... There wasnt a model B on his truck..

  3. #3
    Join Date
    Mar 2010
    Location
    Baltimore, MD.
    Posts
    92
    The B model has a delayed oil feature and the A model does not. If you have a Beckett clean cut pump the B model would be the one that sould be on the unit.
    Do it right, or dont do it at all!

  4. #4
    I have a beckett pump, but how would I know if I have a clean cut? Does the clean cut have a delay built in? Is it important enough to have them order the exact correct part and replace it?

  5. #5
    Join Date
    Mar 2010
    Location
    Baltimore, MD.
    Posts
    92
    here is a solenoid on the top of the pump then it is a clean cut pump. The only way you should use a 7184A with a clean cut pump is with a PD timer attached to the pump solenoid. It will be a little black plug on the solenoid and it will say PD timer on it. If there is a simple plug that goes into the solenoid (usually with the letter N on it which indicates no delay) there is no timer. If you do have a clean cut pump and no PD timer than yes you should have the proper control installed(7184B)
    Do it right, or dont do it at all!

  6. #6
    Thanks Ritt98 for your past replies.

    So I checked and I have a clean cut pump with no delay built into the plug (there is an N on the plug). I read about the clean cut pump and Beckett warns not to use it without a value of delay primary, yet my oil company service guy installed the R7184A almost 2 years ago.

    I will call them and ask them to upgrade the primary, but what, if any, damage might have been done? Does it hurt the pump? Foul the heat exchanger? The unit is only about 6 years old so I want to take good care of it and keep it working.

  7. #7
    Join Date
    Mar 2010
    Location
    Baltimore, MD.
    Posts
    92
    Should not have caused any long term damage. May not have been starting very clean. The pump was designed for better start up and shut down. Get the proper relay put back and have the tech do a combustion analysis and all should be fine.
    Do it right, or dont do it at all!

  8. #8
    Thanks again Ritt98. I will soon get a new primary with prepurge and postpurge. I did some research and found that the PD Timer has a built in 4 second delay. It seems that most primaries have a 15 sec valve on delay, but some or selectable. I am sure the guy will configure it, but what timings do you suggest for valve on delay and blower on delay?

  9. #9
    Join Date
    Mar 2010
    Location
    Baltimore, MD.
    Posts
    92
    The primary does not control the blower. The B control has a 15 sec fixed valve on delay with no post purge. The blower on delay is usually a fixsd setting by most manufacturers and is not ajustable. 4 seconds is plenty of time for the pump to get up to speed. This is why they make the pd timer like that. When you buy a new clean cut pump it comes with a pd timer in the box.
    Do it right, or dont do it at all!

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