Oil valve delay

slade8200

Hi, I'm putting in a honeywell 7284 in place of my carlin 40200-02.  My current setup has the valve tied to the motor.  I'm going to separate it out on the honeywell and use the actual valve terminal.  I've heard a lot of different valve on-delay times I should use, anywhere between 4 and 15s.  Seems to me 4s is enough time to get the motor up to full speed, correct?

HVACNUT

Pre purge is typically 15 seconds for a residential burner.
It's not to get the motor up to speed, it's to expel any unburned flue gases in the chamber to help ensure clean ignition. 
Remove the cad cell eye and cycle  the burner to make sure the safety works on your new primary. Then of course, put it back.

EBEBRATT-Ed

probably won't make any difference.

EdTheHeaterMan

I have used that control and set the valve on delay to the minimum with no issue. It is unlikely that your chamber will have any combustible gasses leftover in the chamber. There are new standards happening every year. Some believe that it is against the law for the old R8184G type control to be replaced with a similar control.

That is all hogwash. A safe stack relay job installed in 1950 is able to have a service technician replace it with a new replacement stack relay. Just because the technology is 70 years old, does not mean it is against the law to use it.

That said, anyone who replaces a stack relay on a heating system today should have their head examined, but I don't recall there being any laws against being an idiot. If that were the case, our political system wouldn't be in the toilet.

(think about that one)

Yours truly
Mr.Ed

Big Ed_4

What type of valve , the Honeywell valve will have a disk timer for delay ,you would have to twist jump if you are using the primary to control ..

slade8200

Not sure what type of valve.  But I know there's no delay right now.

STEVEusaPA

Not all valves are delay valves, nor can they be used that way. But if it can, then stick with @HVACNUT 's advice.
Don’t forget about post purge too, if able.

EdTheHeaterMan

I agree that the 15-second Pre-Purge is a good idea. It is just not a requirement! If it is available then use it. If it is not available then don't lose sleep over it.

I get my chops busted by an old-timer fuel delivery guy (very good friend) that would get excited about the pre-purge feature. The first time I installed a Riello burner in his home, the fan and motor ran for 15 seconds with no flame, then it lit off smoothly.

As a fuel oil driver, he has experience with priming oil burners after a customer ran out of oil, and delayed ignition with a PUFF after 15 seconds. He always felt uneasy every time the burner would run for 15 seconds without a flame. That was 30+ years ago. He still tells my son to "WATCH - OUT" during a 15-second pre-purge. just to mess with him.

Big Ed_4

You would post purge on a direct vent

EdTheHeaterMan

Big Ed_4 said:

You would post purge on a direct vent

Certainly... The max available on the control.

If you let the combustion chamber stay that hot and the wind hits the vent just right... you will melt the innards of the burner (the plastic burner coupling) and the electrodes will get all black and messy.