Hi,
I'm looking to upgrade an old but solid steel boiler that has 3 heating zones and single circulator pump. The current equipment is a non-flame retention burner and R8182A aquastat with cold start. The nozzle has been derated from 1.5 gph to 1.0. I want to install a Beckett AF (or AFG?) and an L7224U aquastat. I presume almost all burners come with the R7184 for interrupt ignition.

Regarding the aquastat, I looked at the docs and I see where LL can be shut off, but I think I still want LL for the circulator. What happens with the circulator during call for heat, with LL turned off?

Should I be looking at other burner/control combinations?

Thanks.

 

If you are looking at Beckett, the AFG is the burner you would want.

You don't need the LL for circulator control, if the current setup is cold-start, then just turn the LL off on the 7224. The circulator will run when there is a call for heat. The LL is only used with boilers that provide domestic hot water via a tankless coil.

Swapping out the burner is going to involve some experimentation ... there are different heads for the burner, and of course different nozzles.

You've been running it with the smaller nozzle size, and that's well and good as long as someone has done the combustion testing to insure that it's burning cleanly at that lower firing rate. Swapping out the burner there's no guarantee that it's gonna run well...

Other burners to consider would be the Riello 40 series.

What's the goal of the swap ?

Grady will probably weigh in on this one too... I hope.

 

I want to reduce my oil bill, since I burned 700+ gallons last winter for our 2150 sq.ft. home. However we won't be here for more than 3-4 years so I don't want to spend a fortune on an entire new system. The next owner my well want to switch to gas, since we have gas service to the house.

We already redid the attic insulation and windows, and installed setback thermostats. The Slant/Fin heat loss calculator put us at around 60,000. The boiler is a vertical tube 147,000 btu unit.

Currently the aquastat is set at 120/160 and with call for heat the circulator doesn't make until it hits LL. The logic here (maybe flawed?) is, why circulate cold water while the boiler is coming up to temp? Would it work the same with the new aquastat?

 

I'm not real sure that what you might save by switching out the burner will even pay for the cost of doing so in 3-4 years... and switching out a burner is the kind of thing where experience really comes into play in order to get it running right. It's not as cut and dry as it might seem. Yes, a flame retention burner _may_ save some oil, but nothing drastic. I bet it won't be 5%. You still need to produce the same amount of BTUs to heat the home, and to do that, you need to burn the same amount of oil.

You said the current system is cold start ... meaning if there is no call for heat, the boiler won't fire ... right ? In other words, with no call for heat, the boiler will go 'stone cold', yes ?

How do you heat your domestic hot water ?

With a cold start system, the circulator will start as soon as there is a call for heat. There's no harm in that. There's nothing really to be saved by, and no advantage to, holding the circ off. The only reason the triple aquastats do so is because when they are running on the low limit setting, the aim is to keep the boiler warm to heat domestic water and not the home.

 

Thanks NJ Trooper.

I thought the savings from a retention flame burner were a bit higher, on the order of 20% or so. DHW is electric and the tankless coil was disconnected. The aquastat had a jumper removed recently for cold start, and to just keep the circulator on LL.

I did some research into nozzle and burner head sizing with a new burner. As far as I know, for the basic Beckett AF/AFG installation I need to match the air tube size, and I will be switching from intermittent to interrupted ignition controlled by the R7184.

The stack temp is running 500-550 so, considering also increased fuel pressure, there is probably room to lower the nozzle rate. The current one is 1.00 60B. I also got a new ceramic fiber blanket to replace some missing boiler insulation. Once it's all installed, I'll have my oil service guy test, analyze, and adjust combustion.

Regarding aquastats, it looks like I can go with L7224U, L8124A (w/blue wire capped), or L8148A. A Beckett Heat Manager is also in the works.

At least thats the plan. I have all summer so every step will be well planned and deliberate. But if the savings really aren't that great, then I could just stick with what's there, since it operates very reliably as is.

 

The new Beckett change will save money as the newer burner will be more efficienct and a hotter flame. You do not want to hold the circulator off with the aquastat. You want the circulator to come on as soon as the boiler fires. This will allow the system water temp to go as high as needed to satisfy the thermostat. Allowing the circulator to come on with burner will also increase comfot levels in the home by gradually increaaseing system temperature and eliminate expansion noises.
I would caution you on reducing the nozzle size anymore as there is a ratio of btu input and fireside heating surface to avoid condensation. Mya also consider a boiler bypass with this installation.

 

OK, you've answered my question about the cold start... one thing to keep in mind is that _any_ modification to the aquastat (including capping the blue wire) negates the UL approval. If something unfortunate were to happen, your insurance company _could_ get their panties in a wad if they discovered the mod... not that they would, but they could.

If the existing aquastat is working, why replace it ? There certainly won't be any savings by doing so, since all it is is a switch that turns the boiler on an off...

I've seen and read claims of 20% savings by going to flame retention, but I'm skeptical. I don't have any hard facts to cite though, so I could be wrong here. Kinda hoping that one of the 'burner heads' might weigh in on this question.

[I see rbeck just replied ... and said you will save ... but how much ? that's my question ... 5% ? 10% ? ]

He also cautioned about reducing the nozzle size any further... I agree ... but what you really don't want to decrease is the 'firing rate'. You understand that the fuel pump pressure determines the flow in a given nozzle. A 1GPH nozzle will only flow 1GPH at 100 PSI. If you run 140 PSI (without looking at the chart... if my memory serves...) to achieve 1GPH firing rate, you would be down around a .85 nozzle or so .

Here's my thinking about fuel saving with the FR burner... I said previously that you still need the same BTUs to heat the water, regardless of the burner. Flame retention burners probably tend to operate a few percent more efficiently in the burning of that oil due to better control of the air and the flame. But, you still need to burn the oil to make the heat.

The REAL savings comes from the design of the boiler, specifically the heat exchanger.

Your flue temps are running 500-550... that's fairly normal for an older boiler, but a bit on the high side by today's standards. I'd say that 400 is closer to the norm nowadays, perhaps even lower. This means that you have less heat wasted going up the chimney, and that's how the newer systems get the extra bit of efficiency. Even so, I'd be surprised if you were to get 20% fuel savings with a brandy new 3-pass design.

What say you other burner heads ?

 

I would only replace the aquastat if I get a new burner, since the cad cell relay has been relocated to the burner. Are there any reliable sources where I can find real life efficiency gains? Beckett claims 35%. Discounting the marketing hype and other fudge factors, I'm figuring 20%. Now you say 5%, so I'm confused!

 

The only real way to know how much can be saved is if you know the current efficiency. On an oil burner this is derived from the flue temperature and the CO2 level of the flue gas. The flue temp you have, the CO2 you should try to get.

As an example an old "New Arco Flame" ('50s vintage) runs at 8% CO2 with some smoke. Flue temperature of about 400 F net. This runs at 79% efficiency. Over three months of cold weather (Winter) running the smoke increased the flue temperature and dropped the efficiency to 77%.

An AFG is supposed to run in the area of 12% CO2. With the same flue temperature of 400 F net, that is an efficiency of 83.6%. This is with 0 smoke, so it holds that efficiency throughout the heating season.

Taking the difference in efficiency, 83.6% - 78% (average) is an increase of 5.6%.

For 700 gallons at $4 a gallon at 5.6% less is:

700 * .056 * 4 = $157 in fuel savings

For 700 gallons at $5 a gallon at 5.6% less is:

700 * .056 * 5 = $196 in fuel savings

With a self-install that is a 1-1/2 to 2 year payback. And, less time spent cleaning the boiler. That can make it a 1 year payback.

Beckett's advice is that if the current burner is 75% or less in efficiency, then it pays to go to an AFG. However, that is with the oil prices from 2 - 3 years ago.

Al.

{edit: I figured that I should add a little more. To get the 79% efficiency I ran as high a CO2 level as possible. The tradeoff was smoke. Which over time reduced the efficiency. There is also a tradeoff for "bad air days" where the smoke could increase dramatically. A 2% loss in efficiency over 3 months shows just that. Realistically, the burner should probably have been set up at 6% CO2, where there was no smoke along with a margin for "bad air." This would lower the efficiency to the 75%. Which provides an efficiency increase of 8.6% by going to an AFG.}

 

That's very interesting information. Here are the stats from last year's tune-up:

CO2: 6%
Stack Temp: 500
Smoke: 0-T
Draft at Breaching: .04
Over Fire Draft: .02

Does this imply 68% efficiency? So the AFG would yield about 80% at 500F flue temp, or 12% gain, right? Does it mean that Beckett's 35% claim starts with a <50% efficiency boiler or 60%? 60 + 35% = ~81. Where do they get 35%?

Would it make sense to lower the firing rate more to decrease the flue temp to 400-450?

 

Yes, 68-70 % COMBUSTION efficiency, but I don't believe that percentage point improvement in combustion eff will relate directly to the same savings in fuel. There are losses other than stack loss that come in to play. So your fuel savings will be somewhat less than the efficiency improvement at the combustion level.

I wouldn't lower the firing rate any more than you have. As rbeck stated, you will start running into other problems. At some point, you won't be able to get proper combustion, and will start condensing flue gases.

The 35% figure Beckett states is probably worst case, to best case, and unlikely obtainable.

 

oil_boiler, I was wondering if you could post a link or such to where Beckett makes the 35% claim. I, just as you are, sorta' question that level of increase in efficiency. I wonder if there is something else involved then just a burner upgrade.

As for not obtaining the fuel saving percent as shown by the increase in combustion efficiency, I don't see why not. A higher efficiency has the fuel converted to a greater amount of useable heat. The burner will run for a shorter period of time to provide the same level of BTU's that is transfered to the boiler water.

There is also another factor that will reduce the fuel consumption with an increase in efficiency via higher CO2.

This is that less inside air is being used for combustion. Which means that less cold air is pulled in from outside to replace the already heated inside air that is consumed and sent up the stack.

If you search for my first thread here from late last year(?), it was pretty much unanimous that I should upgrade to a flame retention burner. At that time all I wanted to do was to reduce the stack temperature. Had to do with baffling within the boiler.

Al.

 

From Beckett's web site:

Model AF Oil Burner
The Model AF oil burner can be found on millions of installations where it has set the industry standards for operating efficiency and fuel savings. A choice of six different flame retention burner heads offers a firing range from 0.40 to 3.00 gph. The highly stable flame is locked in place on the combustion head. Savings up to 35% are not unusual.

I guess 'up to' could mean anywhere from 1 to 35!

 

Yes, a 35% increase in just combustion efficiency is quite a feat. However, an older burner with low CO2 typically runs with a higher flue temperature. This is from the excess air. So it is a double whammy on the combustion efficiency: low CO2, and high stack temperatures.

As I touched on in my previous post, by using less excess air (higher CO2), there is less _heated_ air being drawn from the room and sent up the flue. As less heated air is replaced by cold outside air, which will then be heated, this results in less run time, and less fuel used.

Now granted, the boiler may be located in an unheated space, which negates any savings in this area.

It is also important that the burner never, ever smokes. When it does the soot insulates the inside of the heat exchanger. The stack temperature goes up and efficiency drops. This is where a decent flame retention, high static pressure burner has the advantage over an older unit.

Another area that helps in savings is electrical usage. Not sure if Beckett is counting this in the "up to 35%" savings. But with the cost of electricity in this area I count it.

There are two areas of electrical savings: from lessor run time, and lessor usage during run time. Although the percentage of electricity savings against todays fuel cost is much lower then a few years ago.


You mentioned controls: OutDoor Reset (ODR) can save quite a bit. This past winter I did the poor mans ODR by manually turning the aquastat down during the shoulder seasons. There are units such as the TechMar 256 and the Beckett HeatManager that are worth looking at.

ODR just lowers the peak boiler temperature relative to the outside temperature.

Al.

 

Well it looks like my boiler revival has been cancelled. I pulled out the burner and there is 5 or 6 inches of crumbled red material in the bottom of the firebox. There is also a crack straight down from the edge of the air tube hole. The material looks like red brick and cement, and I was able to punch a piece out of it easily with a light tap. It's much worse than I imagined. I guess I just had to prove it to myself.

So now I have to choose between a new oil or gas unit.

 

Hello all,

I am sorry I did not get involved in this one sooner. I was having computer problems.

Here are a few of my thoughts:

I am not well versed on some of the newer controls, but I understand the concept you have been talking about.

What kind of burner do you have right now?
Unless it is a real old burner(softflame, 1725, etc), I would not think there would be a great difference in efficiency.

Have the baffles ever been replaced in the boiler.
If it is old as you say, they are probably pretty burnt up and will cause your stack temp to be increased. High stack temp is money up the chimney. Most steal boilers will not get a terrific efficiency because of the verticle tubes and burnt baffles.

The red brick inside the boiler can be replaced with a new wet pack combustion chamber.

If you are in the market for a new boiler, personally I would go with a boiler that can be easily converted to the fuel of the day.

I installed a Biasi B-10 oil boiler recently, which claims an 86% efficiency, reasonably priced, simple install, and is a replica of the pensoti boiler.
http://www.qhtinc.com/biasib10.html

I have installed many Peerless oil boilers and Peerless claims to have a condensing oil boiler with an efficiency of 93% efficiency.
http://www.peerlessboilers.com/

And for gas, I highly recommend the Munchkin Mod-Con boiler with efficiency ratings of 92+ efficiency, as I have installed a few and the customers loved them.
http://www.htproducts.com/products/m...ial/index.html


Well, I hope this helps in your decision making.

 

Thanks plumbingods:
I'm not sure if there were baffles or not. When I look inside the chamber there are 10 vertical tubes about 2 inches in diameter. Their bottoms start pretty much right over the dry base.

As far as replacing the chamber goes, it looks like it would require draining, disconnecting pipes, unstacking the sections, etc, and dealing with any more surprises. That is well past a DIY for me. I can afford a new system. I just thought this would be fun to do, but it no longer is.

The Biasi B-10 looks good. Is it the same as the Solaia? Regarding dual fuel, whats involved in converting the Biasi from one to the other? Is it just a matter of switching burners? We have gas service available.

 

The only way to view the baffles is to take the top of the boiler off as if you were going to give it an annual cleaning. Once the top was opened you would see the baffles I am talking about.

As far as the combustion chamber is concerned, the old chamber and the new is done through the hole for the burner using a wet pack chamber. I did not say it was easy.

I have never heard of Solaia, but after some research, I have found a third boiler that is a replica to the Pensotti boiler.

If you purchase a gas boiler, you usually get an atmosphere type burner on it that can not be converted. But if you buy an boiler with a pressure burner (usually oil), it can be converted from gas to oil as needed. With the purchase and piping of a gas power burner. I would check with the manufacturer to be safe, but I have converted boilers and the gas companies do it all the time.

 

I can't speak about the crack without seeing it, but the red flakes and stuff that looks like cement could be nothing more than the byproducts of combustion...

how long has it been since someone actually cleaned the boiler ?

 

It sounds like the crack was caused by excessive heat to the front cover plate where the burner is mounted. That could be replaced. I personally hate dry base steel boilers, but I want OldBoiler to know his options.

 

Please, let me know my options. Ones that will last well past the warranty period and give a return on the investment.

Even at the current cost of #2, I'm not buying it.

18 years ago no-one would work on our boiler. Too old, I'll break something, it'll leak . . .

Their answer was a NEW ALUMINUM PIN-BOILER. Blech. Wrong answer. All CI rad's, r-i-g-h-t, didn't happen. Still running a 3-pass CI boiler and am very happy with it.

Can't understand how we could go from 1300 gal's a year to 900 gal's a year with just a self{!!} tune up. Maybe has to do with a conflict of interest. To put it bluntly: the fuel oil delivery firm is also the ones that sent the techs out to claim 84% efficiency.

Al.

 

Are we getting OldBoiler confused with oil_boiler ?

 

Ooopps, sorrryy!

See what happens when I don't wear those cheater glasses.

Those options were for oil_boiler.

 

Sorry about the name selection. It IS confusing.

The metal part of the boiler where the burner mounts to is fine. The air tube on the burner is 7 inches long and passes through an air gap and into the chamber. The chamber material is where the crack is, and also where a piece broke off. I don't think the burner was removed in many years, so likewise I doubt the boiler was cleaned in that area recently, if at all. The flange gasket was brittle and came off in several pieces. It really is a pitty because I like to see things work past their expected lifetimes. But I guess I should also be thinking about resale value.

 

oil_boiler, sorry for the rant in your thread. It is just that if a decent boiler was offered back 18 years ago, such as the Biasi B-10 that plumbingods recommended, it would have been installed.

I never wanted to be a burner guy, it is that I was forced into it. There is only so much that one can do around the home and still have time for the other items in life.

I don't believe that you posted which boiler you actually have. It may be worth staying with it. What I'm working with is a late '50s American Standard. All cast iron, wet leg, 3-pass. The burner should really be upgraded.

http://www.dynamicefi.com/~al/OilBoiler.html

However, how can one argue with a system that has been running for 20+ years for us with NO BREAKDOWNS. Nada, nothing. This burner is STILL running the original motor and ignition transformer. Probably the original SunStrand pump and coupler.

I know for a fact that the only thing that has been replaced since we moved here is the filter and nozzle.

That is 50 years of service on the original equipment. It isn't until the price of todays fuel that even a burner upgrade has an ROI worth considering.

How much does anyone here want to bet that if the ALUMINUM PIN BOILER was installed 18 years ago, it would need to have been replaced by now?

If your system is in decent shape it can be very worthwhile to fix the minor issues. Putting out 10K - 12K for a new system won't pay for itself for a long time.

Al.

 

Its a Thatcher, installed in the mid-60s. The company went out of business in 1969. There is soot all over the fiber insulation surrounding the tank, so there must be some flue gas seepage somewhere.

 

So I've decided to go with a new gas boiler. I want Energy Star ratings, but the mod/cons I've looked at are out of my price range, plus venting is a problem.

I've narrowed it down to 3: Solaia SL4100, Burnham Revolution V4, and Smith G8.

Pros:
The Smith and Solia can be converted back to oil if prices change drastically.

Cons:
The Burnham uses a proprietary vent system that drives up the cost.
The Solaia Gas does not have sealed combustion (not sure about the others).

Any comments or opinions regarding these, or others I may have missed?

 

I can't comment on which boiler is the better choice. However, being able to switch between gas and oil is a plus. I know of a few folks on LI that do just that. They have a power gas burner and an oil burner. Then swap in the one that uses the lower cost fuel.

Al.

 

Due to the recent runup in natural gas prices, I'm going to hold off on a new purchase. This also gives me some time to look again at our old unit, and I think I can get a few more years out of it. The crack in the ceramic fiber chamber is only about 4 inches long and I think it can be patched.

Since the area all around the boiler is clean and soot-free, The dirty insulation around the tank is probably from sloppy handling during cleaning.

Most of it is now apart. There is a gap between the burner mounting plate and the chamber that I suspect was once filled with some kind of insulation (asbestos?). The gap is open at the top which I think is a bad thing. Maybe the insulation sealed it up at one time. Should I seal it with furnace cement?

This boiler is very similar to the Columbia Emerald.

 

Yes, you can use furnace cement, but cement dries and shrinks, then can fall off. If you have a heating supply house in your area, I would look into getting some high temp gasket material, like cerafelt. It works great and lasts a long time.

 

The gap is about .5" in the middle, and since the tank is round and the mounting plate is flat, the gap grows to about 2" on each side.

 

could you possibly get a picture to us here?

 

If I am thinking about this correctly, after rereading your post, there is no need for a gasket just some heat protection. Is that correct?

 

It looks like combustion gasses can seep between the chamber and burner air tube, then go up.

I have 2 photos. Does this site accept pictures?

 

Open a free account with a site like Photobucket.com
Then upload the pictures and post a link to the pictures here.
Then I will be able to view them and give proper advice.

 

http://i286.photobucket.com/albums/l...r/IMG_1055.jpg

http://i286.photobucket.com/albums/l...r/IMG_1054.jpg

 

That is your flame viewing port.
I would still use the white gasket material and just fill it in, being careful not to get it into the port. If you try that with furnace cement you will plug the hole unless you put a tube the same size as the inside of the hole to prevent cement from entering the tube while the cement dries.

The white gasket material comes in different sizes and is inexpensive. You can get it 1" thick x 2" wide etc.. Much easier to work with. not messy either.

If you have a heating supply house available, bring the pics with you and ask there opinion. They should set you right up.

 

Thanks for all the good info so far. I removed all the dirty old fiber glass insulation that was surrounding the tank. There was none on the smoke hood on top.

I should be able to use regular fiber glass all around, but I'm not sure about the top, or even if the top ever had insulation. It gets very hot, as the stack is connected to it.

I also think foil backed insulation would work well, but am having trouble finding some without paper in it.

 

I got the new AFG burner a few days ago. Wow, this thing is half the size and weight of the old one! I ordered a .85-80B nozzle. The boiler had a 1.0 nozzle before, but since the fire is supposed to be more intense, I'll try this and see if the stack temp is still high enough.

My question is regarding the low firing rate baffle that came with the burner. .85 is the cutoff point with the F3 head, but the instructions say to refer to the equipment manufacturers specifications. Of course, there aren't any. What difference does the baffle make, or should I let the oil tech decide when he comes to tune it?

 

Sorry about getting in here so late. You should see about a 20% savings in efficiency if you can get 86% which is do able with this conversion.
To see what you savings will be on a new burner it is simple math.
New efficiency - old efficienct / new efficiency (as a decimal)
If you get 86% and the old burner was 68% the math looks like this;
86-68/.86=20% savings.
A few things which can affect this is air leaks, burned off baffles and excess draft.
Have the tech take an overfire co2 along with a breech co2. When taking an overfire co2 he will have to block off the viewport opening around his probe. They should be very close to the same reading. Air leaks low in the boiler will lower co2 which lowers efficiency.
If baffles are missing or burned off they can still be replaced. The OF draft should not exceed -.02