I have a Peerless WBV-03 boiler with a Riello 40 F5 oil burner. It was installed two years ago with .85 W nozzle (set to run 1.05 gal/hr). When I got my first cleaning from my service company, naturally - they replaced the nozzle... with another .85W. However, last week (for the boiler's second cleaning), the service tech installed a .85 "A" nozzle.

The specs on the side of the boiler recommend that for Riello 40 F5, at 1.05 GPH, that a .85 "W" be installed.

Is it a big deal that the service tech installed a nozzle with a different spray pattern last week? Will I see a decrease in efficiency due to the fact that a W nozzle was not installed? Should I request that they return and install the manufacturers suggested nozzle?

Thank you.

 

It is always better to use nozzle recommended by manufacture as they have done a lot of experiments to find the best all around performance.In some installations another nozzle may solve a particular problem such as late ignition,but it is safer to make the burner operate correctly with intended nozzle.Did the tech. do a co2 test and leave you a print out of his results,which should look like this co2-11to 12.5, smoke 0-#1.over fire pressure 0 to-.03 should match that recommended by manufacture,stack temp.350f to 450f, efficiency 80% to 85.5%.

 

The tech did not perform a CO2 test. He did perform a draft test though. "Draft over fire -2. Draft at breech -4."

I do have the results of a previous combustion test - performed 6 months after install:

O2% 6.4
CO2% 10.7
COppm 18
COaf ppm 25

Flue *F 504
Ambient *F 65
NETT *F 439

EFF (G) 81.6
Losses 18.4
XAIR % 44.1

I am thinking that I should call them and ask why they changed the nozzle from a .85 60*W to a .85 60*A.

I think that I should also ask for another combustion test. Are these numbers for combustion okay, or do you think something should be tweaked? (Does this show too much excess air? Should a damper be adjusted?)

Thanks!

 

They're gonna give ya a BS line about why they changed the nozzle... they'll say something to the effect: "Naahhhh, it don't make no difference, you're fine!"

And, they might be right... there is only a slight difference in the spray pattern. You've probably already researched and found that the A is a 'hollow' pattern, and the W is a 'semi-solid'. B pattern is what they call 'solid'.

I'm pretty sure that the other guys here are gonna say that they should have replaced the nozzle with the one spec'd by the manufacturer, and I would agree.

Have you found this PDF in your travels?

http://www.delavaninc.com/pdf/total_look.pdf

 

By the way, the excess air number isn't far off given that the CO2 is at 10.7%. There's a direct relationship between the two.

If the combustion results you posted were at the beginning of the season, they may be the best compromise the tech was able to achieve. Since over the course of a heating season, conditions change, techs will give a little 'windage' to the adjustments to allow for various factors that change during the season.

 

The CO2 is low and the draft is high for a Riello. As the OD temp gets colder the draft will increase and cause more air to enter the burner. This will drop the CO2 and drop the efficiency. If the burner is in a location where combustion air will get colder that also will cause lower efficiency due to higher content of oxygen in colder air.
I do not a real problem with a "W" nozzle as opposed to an "A" or "B" nozzle. I would not change the spray angle or gph flow but many manufacturers, though not published will use a "W" nozzle for a cold oil/air situation.

 

My first question is why on a 2 year old unit it is not running at least 85% efficency.The next question is, does the burner run 18 to 24 hours on the coldest day of the year for high A.F.U.E. if it does not the unit is too big for the building.

 

The reason the efficiency is so low is because the burner is set too lean. The CO[SUB]2 [/SUB]should be above 11.5%. Decrease the draft & the stack temp will come down as well thus increasing combustion efficiency. Get the CO[SUB]2 [/SUB]up to 12% & the net stack temp down to 350[SUP]0 [/SUP]and the combustion efficiency will be 85% or a bit over.

 

Looks like you need to get them back with all the test equipment and set the burner up properly.

 

Thank you all for the great insight. I will most certainly call the service company on Monday. This is the second of two years of a 'free service contract,' as they installed my boiler/burner exactly two years ago. I will most likely be shopping for another company (although their prices for oil are nice!).

I will try to get them to come back with a W nozzle and perform a combustion test. I am assuming that they will make a change in the burner assembly [to decrease available combustion air] to make it run 'less lean' thereby decreasing the stack temperature in an effort to increase efficiency.

Trooper: I have come across Delavan's site. Great information over there about actual burn rates and nozzle descriptions.

Saves: I do not believe that my burner has ever run 18-24 hours - meaning that it probably IS oversized. The boiler heats 1664 sq ft dormered cape cod on Long Island, NY. 2 zone baseboard heat, and 5 gal DHW coil. The house is not sealed up too well, but - I'm doing my best (in the 2 yrs that I've been here) to tighten it up. During a call for heat, the burner runs for about 3:30 - 4:00min then about 13:00min dormant time between cycles. So far, this heating season (quite mild so far!), avg of 13.7HDD per day, Avg of 1.57gal per day. KFactor of 8.72. Though, my KFactor has been as high as 9.89 over a 2 month period between fillups.

I was considering asking them to lower my burn rate. Instead of .85 nozzle >> 1.05GPH, .. change to .60 nozzle >> .85GPH, but - I haven't asked them to do that yet so as to not sacrifice recover time for my DHW 5Gal coil.

Rbeck: My burner is in a relatively 'tight' basement - with an indoor 275g fuel tank. It never gets too cold in the basement. It does get quite cold and windy outside though! I've seen the barometric flue damper that is positioned 10" above the boiler 'go crazy' at times (which is probably a bit of a problem as well - pulling or blowing cold air into the firebox)

In any case, I will try to bring them back to do a combustion test and change out to the W nozzle, as specified by the mfr.

Once again, Thank you for all of your help!

 

This is not to blow my horn,but i live in Amherst Nova Scotia Canada and i own two 100 year old houses converted to apartments both are fired with 0.40. nozzles and the D.H.W. is produced by the boiler coil and a 40 gal. hot water tank. The burner runs 12 to 15 hrs./ day on a -10C day .It is not easy to modify a boiler that is rated to fire 1.75 gal. / hr. and of course it is no longer C.S.A. approved.The manufacture are slow to provide units that can fit the heat lose of most homes.I find it amusing when there is talk about doing a complicated heat loss calculation for a 1400 ft. home when a 0.40 nozzle is to big. This all started when i read a manual by Becket burner company that a perfectly sized unit is one that the burner runs 24 hrs. on the coldest day of the year and puts in just enough heat to keep you comfortable.I have a 7 day week timer that tell me how long the burner runs each day.Have the smallest nozzle put in that the appliance allows for the highest efficiency.

 

Please tell us more about the modifications.

I'm down to .60 gph and it is still too big, i think.
The coldest day here last January was -10f for a night. It ran about 4 hours out of 5 during the coldest period and for the 24 hours about 10-11 hours. The longest run was 55 minutes.
We are going to try a .4 at 170lbs for a net .55gph next tune up.

Peter

 

To accommodate such a small nozzle i installed a 6 inch dia. cera felt chamber, removed the heat re claimers from the tubes,and as the boiler was a horizontal i inserted deflectors to make it a triple pass. The result was the first pass retained it heat much longer and thus no soot build up after ten years of operation and 4000 gal of oil.The flue is a balance type. The over fire pressure +.02, co2 11. stack temperature 250f , pump pressure 140lb.The burner is a Riello Bf3, i tried to get Benjamin boiler here in Springhill Nova Scotia interested, also Kerr control in Parrsboro N.S.

 

With such a low stack temperature, into what kind of chimney are you venting? How are the CO levels?

 

I built my own stainless steel balance flue, out the side wall.I have a wet co2 tester so can only do co2.