Weil-McLain downfiring disagreement with my oil company

DJD775

When I moved into my current house the boiler was a Crown TWZ150 that had an input of 1.5gph. Knowing that the boiler was over double the size needed for the home and that the TWZ150 was essentially the same boiler as the TWZ90, I had my tech change it to the TWZ90 settings. Low and behold when I calculated my oil usage, corrected for HDD, the difference in oil usage between the two firing rates was insignificant. In my opinion oil usage is determined more by the actual heat exchanger design + size and not so much the firing rate. Without changed the boiler, which I ended up doing, I doubt you with see a noticeable improvement.

jesmed1

DJD775 said:

When I moved into my current house the boiler was a Crown TWZ150 that had an input of 1.5gph. Knowing that the boiler was over double the size needed for the home and that the TWZ150 was essentially the same boiler as the TWZ90, I had my tech change it to the TWZ90 settings. Low and behold when I calculated my oil usage, corrected for HDD, the difference in oil usage between the two firing rates was insignificant. In my opinion oil usage is determined more by the actual heat exchanger design + size and not so much the firing rate. Without changed the boiler, which I ended up doing, I doubt you with see a noticeable improvement.

Thank you for the data point. So you went from 1.5 gph to 0.9 gph and saw only an insignificant improvement, if any, and I believe your report. OTOH, I talked to a boiler tech on JustAnswer who said he had downfired "many" boilers and his customers had seen reductions of 15-20% in their oil usage. So it seems like there's no consistency in the results. Some people say they get no improvement, some people say downfiring even decreases efficiency, and some people report 15-20% improvement in efficiency. So as you say, it seems there are some other factors involved.

DJD775

15-20% sounds very ambitious and probably a number that was never validated.

jesmed1

DJD775 said:

15-20% sounds very ambitious and probably a number that was never validated.

Here's an article from the October 1980 edition of Popular Science titled "Burner Adjustments to Cut Fuel Costs." The author downfired his boiler from 1.0 gph to 0.65 gph, and reported a fuel savings of 15%-20% per HDD. He discusses the technical aspects of downfiring and seems to know what he's talking about, so I believe his claim of 15-20% savings. Though I agree that not everyone is as scrupulous about actually calculating their fuel usage per HDD and reporting it honestly.

https://books.google.com/books?id=_VEEAAAAMBAJ&q=downfire#v=snippet&q=downfire&f=false

ChrisJ

jesmed1 said:

DJD775 said:

15-20% sounds very ambitious and probably a number that was never validated.

Here's an article from the October 1980 edition of Popular Science titled "Burner Adjustments to Cut Fuel Costs." The author downfired his boiler from 1.0 gph to 0.65 gph, and reported a fuel savings of 15%-20% per HDD. He discusses the technical aspects of downfiring and seems to know what he's talking about, so I believe his claim of 15-20% savings. Though I agree that not everyone is as scrupulous about actually calculating their fuel usage per HDD and reporting it honestly.

https://books.google.com/books?id=_VEEAAAAMBAJ&q=downfire#v=snippet&q=downfire&f=false

Everyone seems to use 20% as the savings number.
20% is huge. I don't even know how you'd pull that off unless the system is broke in the first place.

Where is that 20% going?

Sure, there's furnaces and boilers that claim 96 even 98% efficiency now, and older ones were only 80% but most of that is explained via condensation and better air control. It's not just magically happening on the same equipment.


P.S. that meme applies to this forum as well, even this response.

In this case, text counts as hearing.

STEVEusaPA

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

I know you know this, but many times (like the MPO) it involves a little more than the nozzle. In the MPO case it's a different nozzle, different pump pressure, different OF draft, (even different burner) and changing the number of, or removing the flue baffles. I consider that more like 2 different set ups, not the same set up, but lowering the firing rate via the nozzle.

ChrisJ

STEVEusaPA 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

I know you know this, but many times (like the MPO) it involves a little more than the nozzle. In the MPO case it's a different nozzle, different pump pressure, different OF draft, (even different burner) and changing the number of, or removing the flue baffles. I consider that more like 2 different set ups, not the same set up, but lowering the firing rate via the nozzle.

WM EG series. Yes it's gas but still a similar situation.  Every *0 and *5 boiler is the same I.E. EG30 and EG35.   The only difference is 1 less burner tube and a modified draft hood to slow the air thru the block.   The results are two different firing rates with the same efficiency.

Steamhead

STEVEusaPA said:

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

I know you know this, but many times (like the MPO) it involves a little more than the nozzle. In the MPO case it's a different nozzle, different pump pressure, different OF draft, (even different burner) and changing the number of, or removing the flue baffles. I consider that more like 2 different set ups, not the same set up, but lowering the firing rate via the nozzle.

Actually, if you use the 150-PSI specs for the 396, it is a direct comparison. The same burner is used, with different nozzles and a low-fire baffle on the 288. The 396 does use baffles in the second pass, but the 288 does not:

MST288 AFG 0.60 X 60°A 150 S-6 / B-1 5880 L1 3⅜” AFG70MMAQN 2” 58020204 9, 16

MST396 AFG 0.85 X 60°B 150 S-7 / B-1 L1 3⅜” AFG70MMAQN 2” 58020204 9, 16,
51, 52

The point here is that it's not a cut-and-dried issue.

DJD775

jesmed1 said:

DJD775 said:

15-20% sounds very ambitious and probably a number that was never validated.

Here's an article from the October 1980 edition of Popular Science titled "Burner Adjustments to Cut Fuel Costs." The author downfired his boiler from 1.0 gph to 0.65 gph, and reported a fuel savings of 15%-20% per HDD. He discusses the technical aspects of downfiring and seems to know what he's talking about, so I believe his claim of 15-20% savings. Though I agree that not everyone is as scrupulous about actually calculating their fuel usage per HDD and reporting it honestly.

https://books.google.com/books?id=_VEEAAAAMBAJ&q=downfire#v=snippet&q=downfire&f=false

I'm skeptical of this article too. If he did the calculation, where is the data and what was the result? Sounds like he is trying to peddle the standard 15-20% promise.

captainco

AFUE = Assumed Fictitious Useless Efficiency. 10% - 15% of AFUE is add on points for flue dampers, inducers, spark ignition, 2-stage etc. Has nothing to do with heat transfer. Is also based on the bogus combustion efficiency calculation we has been using for years. All the efficiencies are the same equipment at different gas pressures. Somehow I keep erasing my posts so I am going to separate them.

captainco

I worked with energy auditors in the 80's and not once did we find anyone that saved money by downfiring. In all cases their usage increased.
There is no such thing as advanced combustion diagnostic training. Scientific training, lots of formulas but no training on equipment performance or adjustment.
If an air conditioner is oversized does letting a little refrigerant out help resize it??

captainco

I agree oversizing is not a good thing, but 90% of the year most equipment is oversized based on design temperature. Short cycling can be minimized by wider differentials, as stated before, indoor out door reset.

Any time I see people talking about efficiency and I don't see any combustion readings or necessary operating parameters then they are making things up.

If you have a hot water boiler making 180 degree water or a steam boiler making 15# steam what combustion readings should be the same?

ChrisJ

If you have a steam boiler making 15 PSI I hope it's not for heating.

jesmed1

captainco said:

Short cycling can be minimized by wider differentials, as stated before, indoor out door reset.

When I moved into this 4-unit condo building and started doing most of the building maintenance myself, we had a problem getting heat to the upstairs units (in a 2-story building). After much investigation and troubleshooting, which finally involved putting data loggers on the boilers so I could see exactly how long each boiler was running, I found five different problems:

1. The thermostats had been installed without changing the "swing" (temp differential) setting from its default value, for forced hot air systems. So the swing was set too low, and the boilers would shut off before the cast iron radiators got hot enough.

2. The thermostats were mounted on the dining room walls, right in front of the chase where the hot water pipes ran up into the second floor units. As soon as the hot water began rising, it heated the wall right behind the thermostat, causing the thermostat to heat up and shut off prematurely.

3. The radiators were full of air. No one here knew that radiators had to be bled regularly. One radiator at the far end of one loop was so full of air that it took multiple attempts with a 5-gallon bucket to get all the air out.

4. Some of the branch shutoff valves had been closed in the basement, probably in an attempt to divert more hot water elsewhere.

5. Some unit owners didn't know they needed to close their storm windows in winter (with 100-year-old wood double-hung windows that leaked like a sieve).

The hardest thing to figure out was #2 above. I had to use a thermal gun on the walls to figure out that the walls where the Tstats were located were being heated from the riser pipes and making the Tstats shut off prematurely.

Anyway, I fixed all the above and the second floor units finally got decent heat. The main thing was fixing the short cycling by relocating the Tstats and increasing the swing settings to 0.5 degrees. Now the boilers run long enough cycles to be more efficient.

Outdoor reset wouldn't help us because the boilers start cold, and our water temp never gets above 140 degrees or so before the Tstats are satisfied.

ChrisJ

I do not have hot water.... But it's my understanding a proper system doesn't need regular bleeding and that's an indication of an issue.

jesmed1

ChrisJ said:

I do not have hot water.... But it's my understanding a proper system doesn't need regular bleeding and that's an indication of an issue.

Whenever make-up water gets introduced into the boiler, the make-up water has dissolved air that eventually gets driven out by heating. We have an old-school plain steel 75-gallon expansion tank with no diaphragm that gets drained every year by the boiler tech who does the boiler cleaning. Then when the boiler tech partially refills the expansion tank, that's fresh aerated water coming into the system. And over the course of the heating season, some of that air inevitably gets driven out and turns into air pockets in radiators. Those air pockets then grown over the years if no one bleeds the radiators, and eventually one or more radiators go cold.

So the air is getting into our system as a by-product of normal drain-and-fill annual maintenance. It's not a lot, but it gets significant over the years if ignored.

Robert O'Brien

https://www.weil-mclain.com/sites/default/files/field-file/Weil-McLain_WGO-Series3_WM1905-web.pdf

The Energy star spec is 1.20GPH, can you live with that?

Robert O'Brien

Steamhead said:

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.

Frank, you are correct. Firing to the load will yield greater combustion efficiency and system efficiency, longer cycles. A lot of other factors at play of course, stack temp, venting, combustion numbers. Most oil-fired pin boilers can be derated 25%, sometimes more.

jesmed1

Robert O'Brien said:

https://www.weil-mclain.com/sites/default/files/field-file/Weil-McLain_WGO-Series3_WM1905-web.pdf

The Energy star spec is 1.20GPH, can you live with that?

The Energy Star 1.20 gph rating is, as I understand it, for the WGO-5RD with a vent damper kit installed. I did consider installing the Field Controls vent damper kit to reduce stand-by heat losses up the flue, but then I read several complaints from users who said the dampers were poorly designed and sometimes crapped out in a year or two and needed to be replaced, or resulted in expensive service calls. Since the point is to save money, I'm hesitant to install a component whose net result might be to cost us more money on service calls or replacement units than we save in oil.

My other concern with the vent damper is that if it fails while I'm out of town, the burner will lock out for safety, and half our building will be without heat until someone can get a boiler tech over to futz with it. And based on the reviews of the Field Controls vent damper, sooner or later that's going to happen.

WMno57

jesmed1 said:

We have an old-school plain steel 75-gallon expansion tank with no diaphragm that gets drained every year by the boiler tech who does the boiler cleaning. Then when the boiler tech partially refills the expansion tank, that's fresh aerated water coming into the system. And over the course of the heating season, some of that air inevitably gets driven out and turns into air pockets in radiators. Those air pockets then grown over the years if no one bleeds the radiators, and eventually one or more radiators go cold.

So the air is getting into our system as a by-product of normal drain-and-fill annual maintenance. It's not a lot, but it gets significant over the years if ignored.

I have an air over water tank. I'm one of the few on HeatingHelp that likes them. For annual service, I drain and DO NOT refill any water into the tank. As pressure goes from zero to 12 psi, some water does migrate back into the tank, but I start with an empty tank and the drain closed.
I don't think they are a good fit for a condo, because as you have found, the radiators do need occasional bleeding, usually on the top floor.

Robert O'Brien

jesmed1 said:

Robert O'Brien said:

https://www.weil-mclain.com/sites/default/files/field-file/Weil-McLain_WGO-Series3_WM1905-web.pdf

The Energy star spec is 1.20GPH, can you live with that?

The Energy Star 1.20 gph rating is, as I understand it, for the WGO-5RD with a vent damper kit installed. I did consider installing the Field Controls vent damper kit to reduce stand-by heat losses up the flue, but then I read several complaints from users who said the dampers were poorly designed and sometimes crapped out in a year or two and needed to be replaced, or resulted in expensive service calls. Since the point is to save money, I'm hesitant to install a component whose net result might be to cost us more money on service calls or replacement units than we save in oil.

My other concern with the vent damper is that if it fails while I'm out of town, the burner will lock out for safety, and half our building will be without heat until someone can get a boiler tech over to futz with it. And based on the reviews of the Field Controls vent damper, sooner or later that's going to happen.

Never suggested damper, just 1.20GPH input.

jesmed1

WMno57 said:

I have an air over water tank. I'm one of the few on HeatingHelp that likes them. For annual service, I drain and DO NOT refill any water into the tank. As pressure goes from zero to 12 psi, some water does migrate back into the tank, but I start with an empty tank and the drain closed.
I don't think they are a good fit for a condo, because as you have found, the radiators do need occasional bleeding, usually on the top floor.

I didn't mean that the boiler tech takes a hose and refills the tank manually. I meant that he closes the drain valve and opens the automatic feeder valve that reppressurizes the tank. I think you're saying you do the same thing.

The alternative to the air-over-water tank is a diaphragm tank which is only going to last 5-10 years. I'd rather stick with something that's going to last decades and accept the small inconvenience of bleeding radiators.

jesmed1

Robert O'Brien said:

jesmed1 said:

Robert O'Brien said:

https://www.weil-mclain.com/sites/default/files/field-file/Weil-McLain_WGO-Series3_WM1905-web.pdf

The Energy star spec is 1.20GPH, can you live with that?

The Energy Star 1.20 gph rating is, as I understand it, for the WGO-5RD with a vent damper kit installed. I did consider installing the Field Controls vent damper kit to reduce stand-by heat losses up the flue, but then I read several complaints from users who said the dampers were poorly designed and sometimes crapped out in a year or two and needed to be replaced, or resulted in expensive service calls. Since the point is to save money, I'm hesitant to install a component whose net result might be to cost us more money on service calls or replacement units than we save in oil.

My other concern with the vent damper is that if it fails while I'm out of town, the burner will lock out for safety, and half our building will be without heat until someone can get a boiler tech over to futz with it. And based on the reviews of the Field Controls vent damper, sooner or later that's going to happen.

Never suggested damper, just 1.20GPH input.

OK, thanks. Our heating company called Weil McLain and got permission to downfire to a 1.0 gph nozzle at 140 psi, which puts us right about 1.20 gph. So we'll be running that this winter.

STEVEusaPA

Permission...lmao...Did they do the sign of the cross and mumble in Latin too?

Steamhead

STEVEusaPA said:

Permission...lmao...Did they do the sign of the cross and mumble in Latin too?

They're probably used to that, as some inspectors demand it.

Mad Dog_2

Dominus Vobiscum...et tu spirito tuo! I miss The Tridentine Mass.  Mad Dog 🐕 

jesmed1

STEVEusaPA said:

Permission...lmao...Did they do the sign of the cross and mumble in Latin too?

LOL. Yeah, I told him it was a 25 year old boiler, and I didn't need Weil-McLain's permission to downfire it however I wanted, but he wanted the papal blessing first.