Weil-McLain downfiring disagreement with my oil company

jesmed1

Well, that was fun. I just spent half an hour having a "spirited" discussion with the supervisor of boiler techs from my oil company. I had asked his tech to downfire our two Weil-McLain WGO-5 boilers to a 0.75 gph nozzle at 145 psi, resulting in 0.9 gph input. The boilers are rated for an input of 1.45 gph, so firing at 0.9 gph would have been at 62% of the rated input.

The reason for this request is to try to reduce our oil consumption. The boilers serve one 4-unit condo building and are way oversized. Our heat loss is about 100,000 BTU/hr on a zer-degree day, and both boilers have a combined net output of 350,000 BTU at 1.45 gph input. My request to downfire to 0.9 gph was based on a lot of research and discussion with techs here and elsewhere. I'm aware of the issues involved (condensing, corrosion, etc) and was willing to try it for one year, check the pins next year, and see if there was enough corrosion to warrant increasing the firing rate.

Even so, my oil company's supervisor basically refused to go lower than what Weil-McLain "approved" over the phone, which was a 1.0 gph nozzle running at 140 psi, resulting in 1.18 gph. This is 81% of the boiler's rated capacity. But I've had people on this forum saying we could downfire Weil-McLains to around 65% without losing efficiency, which was my plan.

So this is more of a rant than a question. I just find it annoying that (1) I own the boilers, (2) I pay the oil company, but (3) they refuse to downfire the boiler more than a token amount, which won't do much to reduce oil consumption. It's like you own a 25-year-old car (these boilers are 25 years old) that's already way out of warranty, and you're willing to take the risk of changing the engine tuning chip, but your mechanic won't do it because he's afraid of "liability."

GRRR.

jesmed1

PS, I'm looking into the cost of converting to natural gas using Carlin EZ Gas burners in place of the Beckett AFG's we now have, and today made me want to do that conversion more than ever.

mattmia2

The tech and the company are liable for any safety issues they create when servicing the boiler. If the documentation specifies not to downfire it below 1 gph than I wouldn't downfire it below 1 gph either. You aren't going to save an appreciable amount of oil by downfiring it. Shorter cycles somewhat increase the loss in the boiler heating and cooling but you aren't going to see anything dramatic.

STEVEusaPA

Yeah I side with the oil company. You just can't down fire oil burner because you want to. You'll also have to change the end cone, depending on burner type. And if you don't get the correct flame pattern out of that down fire you'll destroy the boiler.
And condensation in the flue would be a major problem, destroying your boiler and your chimney.
You're not going to save money. You're boiler will be less efficient.
If you want to boil water, do you put the burner on low, to save money?
Maybe you just need a buffer tank, and/or some other control strategy.

If your heat loss is 100k, 2-60k boilers, or one two stage burner is what you need-and maybe a buffer tank. Everything else is a problem.
Any properly sized equipment will save you money. And modern oil still may be overall cheaper than gas.

"... It's like you own a 25-year-old car (these boilers are 25 years old) that's already way out of warranty, and you're willing to take the risk of changing the engine tuning chip, but your mechanic won't do it because he's afraid of "liability..."
Yeah, then be your own mechanic, pay for everything required to run a business-rent, insurance, tools, labor, benfits utilities, etc. Then get some cry baby come it and tantrum they want you to do something that is wrong. Risk a huge problem just for them...good luck to you.

jesmed1

I respect the work of professionals and the difficulty of running a business that does involve liability. And I do understand the issues involved with condensation. We have a lined flue, and what I said to the tech was, "I understand there could be an issue with condensation if the flue gas gets too cool. So let's try running it at 0.9 gph and see what the gas temperature is. If it's below 325-350 net, we can turn the pump pressure up to increase the BTU input."

I've read on other threads here where techs have said they've downfired Weil McLains to 65% with no issues. I guess I just wish one of them worked for my oil company.

Jamie Hall

I would imagine that if you could find a lawyer who would write an ironclad release for the oil company and Weil-McClain, stating conclusively that you assumed all risks and costs associated with the work, and accepted that you and you alone would be liable for them as well as for any other damages whatsoever, you might be able to persuade them to do it.

If I were your oil company, I wouldn't touch it with a barge pole, and I'd probably walk away from you whole account, but that's me. I don't care to be in a position where I know I'll get sued when something I advised against doesn't work.

You bring up the mechanic who works on older vehicles. The ones who are any good -- and they are few on the ground -- offer no warranty whatsoever, particularly if the client specifies what is to be done. The shysters -- and there a lot of them -- happily do what they are told, but good luck getting anything out of them when it doesn't work right.

And furthermore -- the guys above are right: downfiring like that won't save you much money, if any.

realliveplumber

Would you go to your Doctor and tell him to remove your appendix because you read up on it on the interweb and thats what you think you need?

How about your Dentist? Demand a root canal because you might have a cavity?

pecmsg

Jamie Hall said:

I would imagine that if you could find a lawyer who would write an ironclad release for the oil company and Weil-McClain, stating conclusively that you assumed all risks and costs associated with the work, and accepted that you and you alone would be liable for them as well as for any other damages whatsoever, you might be able to persuade them to do it. If I were your oil company, I wouldn't touch it with a barge pole, and I'd probably walk away from you whole account, but that's me. I don't care to be in a position where I know I'll get sued when something I advised against doesn't work. You bring up the mechanic who works on older vehicles. The ones who are any good -- and they are few on the ground -- offer no warranty whatsoever, particularly if the client specifies what is to be done. The shysters -- and there a lot of them -- happily do what they are told, but good luck getting anything out of them when it doesn't work right. And furthermore -- the guys above are right: downfiring like that won't save you much money, if any.

Cheaper to replace the boiler(s) with the right size. 

MaxMercy

I know you're absorbing some flak over this, but I have to agree with the others.

I made the mistake of replacing my 30 year old boiler with a boiler of the same size having not checked my heatloss (and before I joined this learned forum).

My boiler was shipped with two nozzles - a 1.10 and 1.25. Well, this boiler short cycles like crazy so I contacted Slant and asked them what was the lowest I could fire the TR-30 that I had. They said 0.85 gph was the lowest so that's what I did.

It still short cycles and the only time it will run 25 straight minutes is on a very cold night with both zones calling at the same time.

Lesson learned.

I would call Weil directly and ask what they recommend. If the minimum is 1.18gph, I'd stick with that and *still* check stack temp and check for condensing. WM should know the boiler better than your oil company or other techs who have said they downfired further.

EDIT: any chance you could re-pipe and run one boiler?

Mad Dog_2

I know its aggravating, but in this litigious society, no company or tech with a half a brain is going to take that chance.  Judges always rule against "The Professional" in such cases because they contend they have the training and experience and "know better." 

Buy  a Combustion analyzer, pay for advanced  training, go to BOCES at night for 3 years oil burner 1, 2, 3 and then you can do it yourself and are fully responsible.  You see my point?  The same guys that cheer you on will vanish if something bad happens.  Mad Dog 🐕 

HVACNUT

jesmed1 said:

PS, I'm looking into the cost of converting to natural gas using Carlin EZ Gas burners in place of the Beckett AFG's we now have, and today made me want to do that conversion more than ever.

So instead of a drizzle, you're looking for a downpour. 

I feel your pain but nobody wants to put their name on what you propose. 

The boilers are oversized. Converting to downfired gas burners won't change that. And bring an umbrella because then you'll really see some condensation.

Was the building 3 times the size at one point? Why are those boilers so big?

jesmed1

MaxMercy said:

I know you're absorbing some flak over this, but I have to agree with the others.

I made the mistake of replacing my 30 year old boiler with a boiler of the same size having not checked my heatloss (and before I joined this learned forum).

My boiler was shipped with two nozzles - a 1.10 and 1.25. Well, this boiler short cycles like crazy so I contacted Slant and asked them what was the lowest I could fire the TR-30 that I had. They said 0.85 gph was the lowest so that's what I did.

It still short cycles and the only time it will run 25 straight minutes is on a very cold night with both zones calling at the same time.

Lesson learned.

We've all learned the hard way at one time or another.

Yes, I've done the heat loss calcs four different ways, and they all agree that our heat loss is 90-100MBTU/hr for a design temp of zero degrees (in Boston). This includes instrumenting the boilers with a data logger and measuring actual run-time during a zero-degree day, during which the boilers ran less than half the total time of one 24-hour day/night period. And that was with the boilers running at less than rated input.

So there's no doubt the boilers are massively oversized. I'm guessing someone used a "rule of thumb" decades ago and sized them at 40-50 BTU/sq ft, when our actual heat loss is around 18 BTU/sq ft. In fairness, it's a 100-year old house, so people assume it leaks, but we've had all the windows upgraded, and attic insulation blown in. So it's actually quite efficient, even for a modern house.

Anyway, we're stuck with what we have. I'll just run the boilers until they crap out, then get smaller ones that are properly sized.

jesmed1

MaxMercy said:

EDIT: any chance you could re-pipe and run one boiler?

That is a good thought, but no. There's no way to connect the separate loops without creating more problems by messing with a piping layout that works remarkably well for a building that has 4 unconnected dwelling units, on 2 different floor levels, with only 2 thermostats, and no thermostat/zone control for the 2 upper floor units. The old timers who plumbed these loops knew what they were doing. The basement looks like a spaghetti nightmare of iron pipes of varying size up to 2", branching and reducing every which way, and yet the damned thing works like magic. The 2 upstairs units stay comfortable regardless of outdoor temperature even though they have no thermostats (the Tstats are in the downstairs units) and no active control. So I don't want to mess with sucess.

We'll just leave it be until a boiler goes, then replace it with a smaller one.

jesmed1

HVACNUT said:

The boilers are oversized. Converting to downfired gas burners won't change that. And bring an umbrella because then you'll really see some condensation.

Was the building 3 times the size at one point? Why are those boilers so big?

Thanks for your input. If we switch to gas burners, we won't downfire any further than Weil-McLain allows, which is apparently 80% of rated capacity. And I do understand that natural gas combustion produces more water vapor than oil on a per-BTU basis. But as long as we keep the flue gas temp high enough, it shouldn't condense, right? Also, the chimney is lined with terra cotta. And if we do see condensation in the chimney, we can always up the BTU input on the burner. But the cost differential between oil and gas is so large right now that we would save almost $2,000 in one heating season by switching to gas. And based on past year data, we would have saved in the range of $1,000-$2,000 over the last 9 heating seasons that I have data for.

Re the boiler oversizing, it's a 100-year old house that has had gradual efficiency improvements over the years and is now probably almost as good as new construction at 18 BTU/hr/sq ft heat loss in the Boston suburbs. Plus there is a ton of piping in the basement, and I think the last installers got scared and figured 40-50 BTU/hr/sq ft as a rule of thumb, instead of the 20 BTU/hr/sq ft which would have been accurate.

ChrisJ

Who specifically on this forum said they ran the same boiler you have at 65%?  Can you show us the thread?

jesmed1

ChrisJ said:

Who specifically on this forum said they ran the same boiler you have at 65%?  Can you show us the thread?

Al Letellier said this about my exact boiler. (The poster said his was a Weil McLain 170,000 BTU output, mine is 175,000 BTU DOE rating, so probably the same.)

Quoting Al verbatim: "You can drop it to about 65% of rated efficiency, but be careful."

https://forum.heatinghelp.com/discussion/comment/848318#Comment_848318

So if you guys want to rip me for believing a pro with over 700 posts, OK...he may not be around any more, but he seemed to know his stuff.

EBEBRATT-Ed

All you need is a good technician to come over with a box of nozzles and start testing. It would take some time You can't just put a smaller nozzle in it and be done with it

You don't have to check for condensation your test equipment will tell you if the stack temperature is too low. And you have to check that when you are getting the coldest return water that the boiler will see.

Firing it at 80% of rating is pretty safe. Going lower than that may not be.

Going below 80% may increase efficiency because the stack temp will drop...less heat up the chimney

But combustion may suffer

jesmed1

I appreciate everyone's input, pro or con (mostly con on this thread!) and I learn from each one. But I think you can understand my frustration. I'm a mechanical engineer and former rocket propulsion engineer (not kidding) with advanced course work in combustion, heat transfer, etc, and I can ask the same question of 20 heating techs and get 10 different answers.

So imagine what the average Joe Schmo homeowner feels like. He gets 10 different conflicting opinions ranging from "Yes, you can downfire to 65% as long as you're careful" to "No way you can do that," to insults for asking his boiler tech to do what other boiler techs said it was OK to do.

SMDH...

ChrisJ

A single post from 19 years ago?

That counts as other threads and pros?

jesmed1

ChrisJ said:

A single post from 19 years ago?

That counts as other threads and pros?

I've discussed this here and on other heating forums. Other boiler techs have told me they've downfired boilers below 65%, and you just have to be careful to check the flue gas temp to avoid condensation.

Ron Schroeder has said on another thread on this forum that he downfired a 1.5 gph boiler to 0.3 gph using a Beckett AFG with the correct head and low fire baffle, both of which I have.

https://forum.heatinghelp.com/discussion/comment/917531#Comment_917531

But the issue is dead now, because I'm tired of wasting my time. Enough pros had said they had downfired well below Weil-McLain's recommended minimum that I was willing to try it, and keep an eye on flue gas temps and condensation/corrosion, for one year. At the end of the year, if the corrosion/condensation was an issue, I would have gone back up to a larger nozzle.

I couldn't convince the boiler tech's boss to try it, and I'm tired of pursuing it, so I'm going to accept his verdict that a 1.0 nozzle at 140 psi is as low as they'll go, and leave it at that.

ChrisJ

jesmed1 said:

A single post from 19 years ago?

That counts as other threads and pros?

I've discussed this on other heating forums. Other boiler techs have told me they've downfired boilers below 65%, and you just have to be careful to check the flue gas temp to avoid condensation. The issue is dead now, because I'm tired of wasting my time. I discussed it extensively for the last month with pros on this and other forums. Enough pros had downfired well below Weil-McLain's recommended minimum that I was willing to try it, and keep an eye on flue gas temps and condensation/corrosion, for one year. At the end of the year, if the corrosion/condensation was an issue, I would have gone back up to a larger nozzle. I couldn't convince the boiler tech's boss to try it, and I'm tired of pursuing it, so I'm going to accept his verdict that a 1.0 nozzle at 140 psi is as low as they'll go, and leave it at that.

What others have you discussed this extensively with on this forum?  Because all I see is everyone on this forum is telling you no and to listen to the manufacturer.


I asked where someone talked about this and you gave a 19 year old thread.  

HVACNUT

If you're going to do the conversion, installing properly sized boilers would be the wise thing to do obviously, but maybe upfront money is a concern? Are the boilers twinned? Can you get away with running only one?

jesmed1

ChrisJ said:

I asked where someone talked about this and you gave a 19 year old thread.  

Al Letellier and Ron Schroeder have both said they have successfully downfired to 65% and below. I just posted the Ron Schroeder quote while you were posting, so our paths crossed.

Yes, those are old quotes. Does that mean they were lying, or wrong?

Another tech I talked to was on JustAnswer.com, which is a paid service. I talked to a boiler tech there named Billy who said he had downfired many boilers to the level I was asking about, and said I just needed to watch for a decent temperature rise in the flue gas.

So I apologize for believing a handful of guys who said they were pros and had downfired successfully to the level I was asking about. I've been pummeled enough today that I give up and promise not to pursue it further.

jesmed1

HVACNUT said:

If you're going to do the conversion, installing properly sized boilers would be the wise thing to do obviously, but maybe upfront money is a concern? Are the boilers twinned? Can you get away with running only one?

Yes, up-front money is a concern. This is a 4-unit condo building, and I can only convince the other owners to do something if (1) it's going to save money with a short payback period, or (2) something breaks and needs replacing.

Can't run only one boiler because the re-plumbing risks messing up two independent well-balanced hydronic loops that would then need further costly balancing/rezoning.

Maybe if both boilers broke down simultaneously we could consider replumbing to a single new boiler, but in reality one boiler is going to break first, and we'll replace that one, then wait for the other to break.

EBEBRATT-Ed

@jesmed1

You may be able to down fire to below 80%. The question is, is it practical to do that? How much time do you want a technician to spend doing this?

When you start changing the firing rate drastically (and below 80% is drastic) a lot of things change.

Changing the head on the burner and maybe the static plate if it has one

fooling with pump pressures

combustion chamber design

Also, with a water boiler lowering the firing rate will affect the water td or temp rise through the boiler unless the flow rate is monkeyed with.

changing nozzles.

The nozzle spray pattern is not always consistant with different nozzles of the same spray pattern. You may have to try different brand nozzles, hollow spray, solid spray or semi solid spray to determine the best combustion and that is after you determine the size you need to heat the building and determine that that firing rate will not condense in the flue passages.

I am not saying it can't be done. A good tech with a good combustion test kit can figure it out if he is willing to spend the time.

But it is a better job done in the MFGs lab

Steamhead

jesmed1 said:

Can't run only one boiler because the re-plumbing risks messing up two independent well-balanced hydronic loops that would then need further costly balancing/rezoning.

This will NOT be a problem if done right.

jesmed1

Steamhead said:

jesmed1 said:

Can't run only one boiler because the re-plumbing risks messing up two independent well-balanced hydronic loops that would then need further costly balancing/rezoning.

This will NOT be a problem if done right.

I'll take your word for it. But the words "if done right" are what worry me. If it's done wrong, we won't know until too late, and then we have to redo it.

My concern is that each boiler serves two independent condo units: one on the first floor, and one directly above on the second floor. But the thermostat is on the first floor, and the second floor unit has no thermostat or zone control. It just gets whatever heat happens to flow to it as a result of the first floor thermostat. Because the guys who installed the system piped it correctly, the system works perfectly. The second floor stays comfortable in any weather despite having no control whatsoever over the heating system.

So I worry about upsetting that perfect balance between first and second floors. It would be impossible to install thermostats and zone controls for the second floor, because the second floor supplies to the second floor radiators all branch off at different points from the main supply "trunk" that supplies both floors.

Maybe that's irrelevant, because the two boiler supply and returns would be tied together right where they exit and enter one new boiler, and there would be one zone control valve there for each half of the building. Then everything else downstream stays the same. So if you say that new zone valves where the two supplies branch off one boiler wouldn't affect how the hot water gets distributed out of the supply trunk to the various radiators downstream, I guess I can understand that.

MaxMercy

jesmed1 said:

So I worry about upsetting that perfect balance between first and second floors. It would be impossible to install thermostats and zone controls for the second floor, because the second floor supplies to the second floor radiators all branch off at different points from the main supply "trunk" that supplies both floors.

The way I see it (virtually of course!) is that if both boilers are in a common basement, they should be able to be plumbed into a single unit without too much effort and at least duplicate what you have now for balance. Of course, we aren't there so can't be sure.

As far as balance, hydronic is a lot more forgiving than steam, and if this was a steam setup, I would be very clear to keep what's working.

But I think your plan to go with WM's recommendation for downfiring your particular boiler model is the right plan for now, and honestly, even if you could downfire another 20% safely, you wouldn't be seeing a 20% decrease in oil usage.

captainco

There has never been a "field study" or report on downfiring a piece of equipment The only reason to do something like this is because of a poorly installed system. but it will increase your fuel usage. Moduoating equipment downfiring a lot more than that. Based on field feedback, this uses quite a bit more energy. Every study I have readd for the past 40 years was done in a lab under fixed conditions and simulated computer calculations.

Steamhead

captainco said:

There has never been a "field study" or report on downfiring a piece of equipment The only reason to do something like this is because of a poorly installed system. but it will increase your fuel usage. Moduoating equipment downfiring a lot more than that. Based on field feedback, this uses quite a bit more energy. Every study I have readd for the past 40 years was done in a lab under fixed conditions and simulated computer calculations.

So, what do you say about boilers which are advertised as having one model that can be fired at different rates? For example, the Dunkirk Empire series:

https://dunkirk.com/wp-content/uploads/2022/04/EWC-Dunkirk-Sell-Sheet-04-19-22-WEB.pdf

The four-section version is advertised as having a slightly higher efficiency at the lower rate. The five-section is advertised with the same efficiency at both rates. Where is this supposed inefficiency?

Edit- same thing with the Weil-McLain WGO series:

https://www.weil-mclain.com/products/wgo-series-4-oil-fired-water-boiler#technical-data

pecmsg

Steamhead said:

There has never been a "field study" or report on downfiring a piece of equipment The only reason to do something like this is because of a poorly installed system. but it will increase your fuel usage. Moduoating equipment downfiring a lot more than that. Based on field feedback, this uses quite a bit more energy. Every study I have readd for the past 40 years was done in a lab under fixed conditions and simulated computer calculations.

So, what do you say about boilers which are advertised as having one model that can be fired at different rates? For example, the Dunkirk Empire series: https://dunkirk.com/wp-content/uploads/2022/04/EWC-Dunkirk-Sell-Sheet-04-19-22-WEB.pdf The four-section version is advertised as having a slightly higher efficiency at the lower rate. The five-section is advertised with the same efficiency at both rates. Where is this supposed inefficiency? Edit- same thing with the Weil-McLain WGO series: https://www.weil-mclain.com/products/wgo-series-4-oil-fired-water-boiler#technical-data

The e been tested and verified with those settings. 

captainco

You can downfire most equipment but you will lower iits efficiency,'' If you read all the actual reports on how they calculate efficiency it is a joke. Nothing is more efficient when fired lower. We recommend firng at 100% when ever possible.

Steamhead

captainco said:

You can downfire most equipment but you will lower iits efficiency,'' If you read all the actual reports on how they calculate efficiency it is a joke.......

Care to elaborate?

EBEBRATT-Ed

Easiest way to increase efficiency is to lower the stack temp. Down firing does this. If the combustion stay's ok Co2/O2 smoke, co then you're ok. But there is a limit to everything.

Boiler mfg. like to get the most fire with the least amount of iron to be competitively priced but heading in that direction lowers efficiency. Less input (down firing) raises efficiency, but boiler prices go up.

CTETeach

I missed in the thread if these are heat only boilers? I agree with the professionals who posted. You are not really going to realize any savings. If they are heat only you may want to look at outdoor reset controls. With these you can lower you water temperature in the boiler if necessary depending on outside temperature

captainco

adjusting air or draft to lower flue temperature increases efficiency. Adjusting fuel to lower flue temperature (downfire) decreases efficiency

Steamhead

I'm just trying to understand this. Boiler manufacturers say basically that using a lower firing rate on a given block increases efficiency slightly, at least to a point. But you say that's not true.

Steamhead

Another case in point: The Burnham MegaSteam 288 and 396 use the same block, but the 288 has about 25% lower firing rate. Both are rated 86% AFUE:

https://s3-us-west-2.amazonaws.com/catsy.782/MegaSteam+Product+Data+Sheet.pdf

jesmed1

Steamhead said:

Another case in point: The Burnham MegaSteam 288 and 396 use the same block, but the 288 has about 25% lower firing rate. Both are rated 86% AFUE:

https://s3-us-west-2.amazonaws.com/catsy.782/MegaSteam+Product+Data+Sheet.pdf

My understanding of this is that the AFUE only tells you the steady-state heat transfer efficiency from the fuel to the metal and water inside the boiler. That will be more or less the same regardless of the firing rate. But because the boiler doesn't operate at steady-state for an entire winter, but rather cycles on and off, that's where the difference comes in. At a lower firing rate, the boiler runs longer cycles, and therefore fewer cycles over the same time period. And every time the boiler shuts off, some of the residual heat stored in the cast iron goes up the chimney. If the boiler cycles off fewer times, there are fewer "cycle ends" where the residual heat in the cast iron goes up the chimney. Ideally, you'd want the burner to be running all winter and outputting exactly the amount of heat needed at any given time. Then there would be no start/stop inefficiences, and you would get the full benefit of the 86% AFUE at steady state. But in reality, because of the start/stop inefficiencies you don't ever really get the full 86% steady-state efficiency as an average over the entire heating season. So because down-firing reduces the number of starts/stops for a given time span, the start/stop inefficiencies are reduced.

Mebbe wrong, but that's how it looks to me.

bburd

There is also the more favorable ratio of heat exchanger surface area to heat input.

HVACNUT

captainco said:

adjusting air or draft to lower flue temperature increases efficiency. Adjusting fuel to lower flue temperature (downfire) decreases efficiency

So you're talking combustion efficiency, not overall system efficiency. I'll sacrifice a few decimal points of combustion efficiency on a properly sized and piped mod con if it can handle the load at 24K BTU vs 130K BTU. 
How did you solve short cycling on the tests, buffer tank and a huge differential?