oil burners

kevin

didn't Riello have a bunch of problems w/ the K7R control?

kevin

oil burners

What are your opinions on post purge controls, especially with normal chimney applications. Are they nice, over kill, a good idea, or does it really matter? kevin C.

Robert O'Connor

post purge

In my opinion, post purge on a convential, natural draft, oil boiler connected to a proper chimney is not necessary.


Pre purge I believe, offers a clean start and is worth while.

There seems to be a trend toward post purge right now. What is driving it?.... Boiler chic?

Regards,

Robert O'Connor

Alan R. Mercurio

One of my favorite subjects

Hi Kevin, These controls also offer a valve on delay feature and work in conjunction with an oil valve to initiate cleaner light off and cleaner shut downs. Remember without the solenoid valve the fuel pump will allow flow to the nozzle before the burner has had a chance to come up to full speed. You see when a 3450 rpm motor reaches about 2800 rpm the fuel pump begins its delivery through the nozzle port to the nozzle. The trouble with this is that since the motor has not come up to full speed the proper amount of air is not being delivered nor has the static pressure reached its full potential. On top of all that we also have not reached the desired pump pressure yet therefore we don’t have proper atomization of our fuel.

The worst part of all of this is the burner has already ignited. This is why we get traces of smoke on start up. And we’re not done yet. Now when the call for heat ends the burner does all of this during shut down. As the burner motor decelerates the air delivery decreases the static pressure drops and so does the pump pressure. The pump will not cut off until the motor reaches about 2600 rpm the result, we end up with traces of smoke on burner shut down.

Have you ever wondered why some of those systems you have done your P&M on when you finished you had it adjusted for optimum efficiency and it was burning nice and clean. but when you returned next year there was a layer of soot in the flue passages? And this is one of those customers that keeps the area around the burner clean all year, no animals, saw dust or lint. There’s plenty of combustion air. Well, now you know how this mysterious soot appears each year. Remember an 1/8th of soot decreases efficiency by 9%.

With the availability of this new control technology you can make your annual P&M go a lot smoother and offer your customer the reliable efficiency they deserve. This is because with the new controls oil delay and it’s pre purge feature the burner will now come up to speed before introducing any oil and it will have established the desired static pressure and air delivery for a clean light off.

Also with this type of control when the call for heat ends the oil valve will close immediately however the air and static pressure will remain at there peak for a pre selected time period, because of the post purge feature. This also helps to remove any residual flue gases. Do you see the value in this new control technology? Sure you do.

As Paul Harvey would say, Now you know the rest of the story!

Your friend in the industry,
Alan R. Mercurio

John@Reliable

Purge controls

In a word Great!!!! But even better pre & post why? pre purge will get draft going before flame, gives nice clean light off. Post will get rid of that little bit of smoke at end of cycle, these two things will keep heat-x so much cleaner,you will see after doing service on these you will wish they were on all. In fact most new systems are coming from factory with oil delay valves and pre&post purge controls.Took usa awhile to catch why riello was so good.
Hope this helps

Bill NTSG

Post Purge

After a burn cycle the combustion chamber is still very hot. This heat reflects on the nozzle and causes the oil to expand and could cause after drip and nozzle coking. Any method to reduce this heat, post purge, will help from sooting as Alan M mentioned. As Wilfred Brimley used to say, " It's just the right thing to do ". Two minutes or so of post purge is not going to send that much heat up the chimney. You will lose more efficiency with a dirty heat exchanger over a course of a year. Some may argue that the post purge valves kill pumps. I have not seen a great deal of evidence of that yet. With a power vented sytem I say it can't hurt here either. You want to get rid of the heat in the chamber. A chimney draws heat out 24/7 - 365. A post purge timer works 2-4 minutes ? I like them. When I look at a boiler - burner combo , my choice goes to the product with the tricked out burner. Carlin and beckett both offer pre - post purge controls. Try to find the post purge for a Riello, not so easy too find.

kevin

Thanks guys..

for the really great info. That is why I come here for the great minds !!!!

Jed_2

Riello P/P Burner

Bill, yes they are available now. The BF is now available for retrofit, with the K7R, there's your Pre- and Post Purge. Great idea. And the new integrated control is supposed to be available shortly, if not already.

Jed

Joel_3

Allen

You the MAN an excellent response couldn't have said it better myself. I agree 110% I switched my Ultimate/beckett boiler to pre and post purge with interupted duty 14k transformer from Carlin controlls (still on an AFG)The difference inside after 1 year was simply amazing.

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Big Ed

Post Purge Control Wiring

Something that bugs the beasels out of me it the extra "non limit" hot leg that is needed to run a post purge control . All you need is silly problem .......like say "A dog desides to spray the control " and you now have a bomb...........Don't like it I tell ya.....

P.S. I like the post purge but I would like to see a safty limit also......

Big Ed

Post Purge Control Wiring

Something that bugs the beasels out of me it the extra "non limit" hot leg that is needed to run a post purge control . All you need is silly problem .......like say "A dog desides to spray the control " and you now have a bomb...........Don't like it I tell ya.....

P.S. I like the post purge but I would like to see a safety limit also......

Big Ed

Post Purge Control Wiring

Something that bugs the beasels out of me it the extra "non limit" hot leg that is needed to run a post purge control . All you need is a silly problem .......like say "A dog desides to spray the control " and you now have a bomb...........Don't like it I tell ya.....

P.S. I like the post purge but I would like to see a safety limit for that extra hot leg.....

John@Reliable

Xtra leg?

I don't get what you mean? That red/white wire should be wired so when service switch is off that is off also.Alot of systems w/ say 8184 relay are power all the time w/ no trouble/ true.

Unknown

I thought we had that problem today

A very rare occasion - we used a Carlin burner in a Peerless boiler . Had to run the extra hot wire for the nozzle warmer and post purge . We had the setting on the high limit at 180 , and the boiler kept going - I saw it and shut it down at 230 degrees . It turned out to be a bad 4081 aquastat , but I thought about that extra hot wire , and what could happen if it accidentally comes in contact with another wire . I would rather stick with Riello and a prepurge only .

By the way , is there a dual aquastat with a built in secondary cut out , something like the one you see on water heaters , but with a low limit ? One with a manual reset would work great on the jobs we install .

Unknown

What you got with the extra leg

is power all the time going to the burner - no limit interrupts that power . Granted , its hooked up to a post purge control , or nozzle warmer , but something could go wrong internally or 2 wires could accidentally touch , and then......

Bill NTSG

limit wiring

I have had a run away boiler due to an oil valve that stuck open. I like the idea of a secondary high limit that kills power to the burner circiut. Operating limit stops burner flame, secondary limit stops all power to burner circiut. Vega and Biasi boilers both have this on their direct vent burners w/carlin. I got the idea from Jim quincy of QHT. All commercial boilers require manual reset high limit it probably wouldn't be a bad idea for residential.

John (jcg)

But

Riello's aren't Post-Purge, they are Pre-Purge only. For the life of me I can see no real advantage of post -purge controls with the majority of instlations. Exceptions would bea boiler or furnace with a lot of raiant chamber material and units without natural draft. In fact we have been using direct vent units for years without post-purge contols with very good results. Now add this to the fact that the control copmpanies have had more problems with these things than they care to admit. Any pre-purge control will give you a nice clean start & stop while running trouble free.

jcg

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Jed_2

Me, Too, Bill

and that's where you can get the Riello BF. They corrected the K7R, according to Jim, and Riello. Definitely have the Safety High Limit wired in. On shut down, with the Safety High Limit energized,set 20 deg above operating limit, protection is in place. I'm not good at wiring, as I am not in the field, have to look at the schematics, but the Safety is constantly powered with the gray wire through the safety circuit.

Jed

Antoni

small flame

I have Carlin burner, ignition is OK, when solenoid valve

opens I have very small flame and Cad cell doesn’t see it and shuts off the

burner. The pump pressure is 100 PSI, at cut off is 10 PSI drop. Looks like I have

enough oil flow to the pump. Any suggestions?