Experiences using bio-fuel with oil fired boilers

The biggest, if any, problem with bio fuels result from people unaware of a few important points.
1. Make sure the equipment (filters, gaskets, burner) are rated for the blend of bio you will be using.
2. Up in NE, don't use an outside tank.
3. Don't expect to just start dumping B20 into an old tank and think it will work fine. If you have an old tank. Start treating it or drain it and have it cleaned. If it's very old, you should replace it.
4. Don't buy off spec bio from your supplier. Also don't buy bio from a company who stores/blends their own, unless your location makes that impossible. Proper spec, blended at the refinery is the best.

Bio, combined with ULSD, will initially clean your tank and foul your filters, strainer, and eventually nozzle. I recommend double filtration at the oil tank. I'd also probably recommend changing or at least checking your fuel filters mid season during the first year of use. More so if you're going with B20. Probably won't notice too much change with just B5.
Good practice also recommends you don't let your tank sit empty over the summer. If heat only, fill up in the spring, or fill up in the fall with a bottle of fuel treatment that disperses water.

Otherwise, bio burns much cleaner, less overall pollution than natural gas.
Most of my customers with newer equipment only need to be cleaned every 2 years (or more). With the exception of the EK, which recommends opening up and checking annually.

As some of you may be aware, I work part time for National Oilheat Research Alliance ( NORA). I discussed this topic today with the lab director Dr. Tom Butcher,PhD and this is his input on the question.

Thanks to @STEVEusaPA for a lot of good suggestions on this. I’d like to just add a bit more. There are a lot of cases out there where folks have switched to high biodiesel blends. In many cases these are “early adopters” who want to push the limits. I’m thinking here of blends over B20 since that is now pretty routine.
I strongly agree that the biodiesel needs to be a quality, on-spec product. Over the past 15 years, based of on field experience the specs for biodiesel have improved and this includes keeping contaminants out and ensuring stability. There are occasional cases of non-spec biodiesel out there and this can really lead to problems.
The cold flow properties of biodiesels vary but generally B100 will gel at temperatures well above petroleum No. 2. The cold flow properties of blends are roughly in proportion to blend level. I agree outside tanks should be avoided with high blends. If the fuel specs are available, it’s best to know what is the pour point of the fuel you might use and plan around that.
Many of the high blend pioneers used conventional equipment not approved by the manufacturer or rated for high blends. Generally this has been OK. However, increasingly products are becoming available that are approved for higher blends. We are in a transition period now and I suggest using manufacturer approved products whenever they are available.
There has been a lot of discussion about the need to change filters after changing to biodiesel blends. From what I hear the field experience has been mixed. This is not always the case. I certainly agree with dual filtration. Cleaner fuels entering the pumps is always a good thing. After tank fills, with conventional filtration, you will still see high fuel particulate contamination getting to the pump. This happens with all fuels and can be minimized with a 10 micron or finer fuel filter.
There has also been lots of discussion about the need to retune the burner after changing to high biodiesel blends. Biodiesel does have oxygen and so can lean-out a flame. Test results have shown this to be a pretty small effect. If the burner is set for a CO2 near the low limit on No. 2 oil, changing to a high biodiesel blend without retuning could lead to cold ignition or cad cell/lockout problems. Checking burner tune after changing blend level is always a good idea.

I have no experience with bio-fuels or the equipment that burn it however I do have a little experience with waste oil burners. This may be a little off target but it could provide a source of information as you proceed with your exploration. A company called "Clean Burn" makes waste oil equipment that will burn waste oil and most flammable waste products. I worked on a couple of these burners before retiring. A call to them may offer answers to questions you have.
This reminds me of the S T Johnson rotary cup burner and other of similar design that were designed to burn almost any flammable oil product regardless of the oils properties. (if you could pump the product through a pipe, this burner would most likely burn it).

My first experience with bio-fuel was not good. Just tried B20 this month for the first time in my 17 year old system with a Riello burner. Before I ordered it, everything I read about Bio-fuel was good. But the morning after I filled my indoor tank, it failed to fire. I pressed the reset button, then it worked. The next morning, same thing. But it shut down after 10 minutes. Reset again, shut down again after 15 mins. Pressed once more, than ok for the rest of the day. Then again the next day. Reset once, then fine. Happened a few more times over the next few weeks where it did not fire in the morning. Usually fine the rest of the day. Maybe once it's warmed up, it's better?
Anyway, reading up on problems with Bio-fuels found some articles about how the solvents inherent in Bio-fuels ends up loosening any built in sludge in the tank walls which end up getting your filters dirty and possibly other problems. This article recommends introducing Bio-fuels in increasing concentrations to acclimate your system. https://homeguides.sfgate.com/use-biodiesel-oil-furnace-82829.html
I may have to give my system another tune up soon, though I just had it done a few months ago. But this also begs the question of whether I should continue with this cleaner burning fuel after changing the filters. Or will the sludge in the walls take years to dissolve, meaning a longer transition time before my filters will only need to be replaced in normal intervals?

srvsan said:

Our 25-year-old Burnham oil boiler with a Beckett burner is limping on its last legs..

Not really sure what that means. If the boiler isn't leaking water or air and the chamber is solid, that system could (should) run smoothly, quietly, reliably, and probably 80% efficient with little effort. Even a 25 year old Beckett will run perfectly with a small bit of professional attention.

In Connecticut, we have 7% bio now and the law says CT will go B50 in 12 years. That of course may change and the percentage could go higher.