Trying to identify best sizing and models for a new boiler

MrMike · November 2020

Hi all, this is the first time I’m posting, but I have been a long-time reader and have learned an enormous amount of stuff from the information you all have contributed on this site which has helped me a lot over the years. After quite a while working on my system, insulating and making tons of adjustments I can use a little help:

The homes original boiler is still working fine, a 1960 Crane SunnyDay 5, but since resolving most of the basic insulation and draft causes of my homes heat-loss, and looking at .66 efficiency of this old unit, I know I've delayed enough and am ready to move forward on replacing the boiler. As it is, over ten years and even increasing the size of the home by 25%, with all the changes and renovations my total oil use dropped to 1,200 gallons (give or take) per year (includes domestic hot water), from well over 2,000 gallons per year before I started all the work. This may sound like a basic issue to experts, but learning what I can, and because of the age of the boiler and all the modifications I made, sizing a new unit is confusing me a bit, especially given all the information I collected and looking at different manufacturers ratings, such as IBR, DOE Net and Gross, AHRI and AHRI Net. Some include pickup losses, others say these are not really losses in the conditioned space, etc. Some sites say to size a new boilers AHRI Net to installed radiation, or not to exceed (more obvious), others say BTU heat loss calcs must be performed (and there are at least three levels of complexity for these calculations, lol), some say size just above the lowest one-or-two day outdoor temp of the year, most say never undersize, some say never oversize. Use outdoor reset or not? A lot of stats and measurements with many opinions floating around.

I've also spoken to some plumbers and plumbing supplys and they all use a quick estimate method or say I should stick with supporting the existing radiation (some rooms warmer than needed, some cooler - so original radiation not perfect to begin with - I'm also working on that). Others mentioned that if I’m getting good heat go with another unit with the same rating. Looked at a lot of boilers and some of them are right on various thresholds and have various pluses and minuses, but its tricky to figure the real Net of a 1960 boiler that has been modified many times.

Hope you understand my confusion with moving forward with complete confidence, so here are some actual home details I'm working with:

132,500 BTU of installed radiation (first and second floor only – baseboards and two kick heaters).

Possible addition of 15-17,000 BTU radiant 3/8 pex if I finish part of basement and put in tile floor. (basement floor below grade except for one small spot).

We have had no heating issues with outside temps in the low single digits, also going down to zero when it does around here - once or twice every few years.

A basic BTU calculation derived from the industry Heating Climate Chart, Zone 3 (LI, NY) instructs to use 40-45 BTU per sq.ft. (+10% poor insulation / -10% super insulated - I used -10%) First and Second Floor: 130,720 BTU. If I include basement square footage (which is unrealistic) it jumps to 218,800 - it can't be accurate because the boiler output and installed radiation is lower and the basement has no radiation installed. Home heats easily with the 132K installed baseboards and approximate 116,000 BTU output coming from boiler (downfired to 1.25gph, and more mods). Basement temp seems mostly managed by "ground" temp - since its underground (great in summer as well - no cooling required even through August).

The Weil-McLain Boiler selection / BTU-calculation system gives results of about 80,000 BTU loss for first and second floor and 28,500 for basement, for a total of 109,000 BTU Heat loss. (Weil McClain does not compensate for all the sliding glass-doors, windows, vaulted ceilings, superthick insulation, etc., which the house has).

So then I found the downloadable Slant-Fin BTU Calculation app where you enter an enormous amount of detail for every room. After spending a few days learning and getting used to the program I spent an entire weekend entering my data, measuring absolutely everything and calculating for every surface, window, door, ceiling height, exposed & cold walls, etc. (I was personally involved in the construction so I know what is in every wall/ceiling/floor). For a zero-degree outdoor temp baseline (70 degrees indoors) the first and second floor comes to 99,000 BTUs heat loss, and the basement an additional 24,900 BTU Loss (or 17,000 loss if I only look at areas I would plan to finish. So for one or two days a year at zero degrees the homes total heatloss is about 116,000 BTU.

When I recalculated for a five degree lowest outdoor temperature (more common, as our lowest period is usually a few days or a week between 4 and 7 degrees) the first and second floor comes up as 92,000 BTU loss with 23,000 BTU (15,500 finished) totalling 113,000 BTU.

Should I be looking for a boiler with a 113-115K BTU AHRI Net output, or something closer to my radiation capability, like 132K BTU - which seems high? Could the programs/these estimates also be high for a safety margin? Since I added 5 1/2" of rockwool all around the boiler (and whatever I could jam under) I may have increased the efficiency from .66 - so its "output" would be higher than my basic estimate of 116,000 BTU output - I really don't know.

I could easily just pick a 1.20 GPH system with 87% efficiency, but if I wind up with minimal additional oil savings I feel like I just upgraded the boiler for no real reason (and possibly adding extra complexity), I did spend a bit on the insulation and other efficiency improvements which exceeded expectation.

I don't want a condensing boiler requiring drains for acidic condensate, etc. My Chimney is over 30'tall. I measured the piping and all the different piping sizes (original builder put in a large zone that "splits" sending hot water in two directions: 1.25 pipe, split down to 3/4 and rejoining after radiation to 1.25, etc - total water volume in pipes alone is about 25 gallons including all zones (there is alot of pipe).

So here were some boilers I found - but I am open to other mfgs, ideas and thinking!

Weil-McClain (right-side opening fire chamber - preferred):
------------------------------------------------------
WGO-4 1.20 GPH, 145 BTU AHRI Capacity, 126 BTU Net AHRI, AFUE 85%
WGO-4RD 1.0 GPH, 123 BTU AHRI Capacity, 107 BTU Net AHRI, AFUE 87% (Energy star mods)

WGO-3 .90 GPH, 115 BTU AHRI Capacity, 100 BTU Net AHRI, AFUE 85.3%

(Does the basement really need radiation? Especially if I insulate all walls as well? First and second floor come to 99K BTU at 0 degrees using SlantFin calcs - 92K at five degrees. On the other hand a warm tile floor sounds nice.)

US Boiler/Burnham (left-opening chamber - slightly tighter placement issue):
--------------------------------------------------------------------------
V8H3WE 1.0 GPH, 120 BTU DOE Capacity, 104 BTU Net AHRI, AFUE 86%
V8H3WES .90 GPH, 109 BTU DOE Capacity, 95 BTU Net AHRI, AFUE 87% (Energy star mods)

V8H4WE 1.20 GPH, 148 BTU DOE Capacity, 129 BTU Net AHRI, AFUE 86.1% (Seems way over)
V8H4WES *** shows all same stats as above non EStar - may be a typo as it shows 87% AFUE, the only difference)

So that's it - any questions/comments/thoughts, boiler recommendations or direction would be greatly appreciated! I can provide a ton more info on the existing system and home construction.

nicholas bonham-carter · November 2020

What temperature water is set now on the aqua stat? Are you making hot water with the boiler?
You really want the boiler to handle the total heat loss on a design day, but to be able, if desired to use lower temperature water when the temperature is warmer, assuming you add in the feature of outdoor setback. This is where the EDR calculations come in for the radiation in each room. Larger radiators will permit a lower temperature in the loop, but you can’t go lower than 130 degrees with a cast iron boiler.
How are the radiators piped-series, parallel return, mono flow etc?—NBC

STEVEusaPA · November 2020

If you only used 1500 gallons on LI, your heat loss is about 60-70k.
Put in an Energy Kinetics.
Don’t take hydronics advice from plumbers, and supply house counter people.
I didn’t read your entire post...way too long.
Have a hydronics person, plenty of Wallies from LI, come over to evaluate your system, do a heat loss, make on site recommendations.

Jamie Hall · November 2020

Of the three heat loss calculation methods you mentioned, the only one which is even remotely reliable is the Slant/Fin calculation. The others are quick and dirty, true, but not useful. My own feeling is that the Slant/Fin slightly overestimates heat loss, but not by much -- and I don't have enough examples to be certain of that statement. That's not too different from the Weil-McClain estimate, either.

Therefore... somewhere right around 116,000 BTUh as a design day heat loss seems pretty reasonable.

You mention that you have a usable existing chimney and are none too keen (don't blame you) on dealing with the highly acidic condensate from a condensing boiler. Can't fault you on that, either. That limits your maximum efficiency to around 86%, but that is, realistically, what you would get from all singing and dancing mod/con, too, on the colder days.

Both boiler makers you have mentioned make excellent equipment. So does Energy Kinetics, which is promoted heavily by some. Pick the one with the net output which matches your load reasonably closely and -- far more important is liked and supported by the folks who are going to install it. Their all good -- but the installation and setup will make or break the job, and future support is critical.

MrMike · November 2020

Thanks for all the reply's, advice and interesting info - I definitely learned a few new things, will try to respond to the questions and apologize for the long post.

Yes, I have a separate hot water heater. In 2017 I had to replace the old DHW heater and installed a Bock 50Gal with a Carlin EZ-1 burner.

The aquastat setting on the Crane is not that straight forward: at risk of seeming silly I admit manually adjusting it from time-to-time over the winter. When I first start it up for the season and it is in the 50's outside I set it to 140, as the winter progresses I increase it in 10 degree intervals to 170-175. I only raise it to 180-185 if the weather is predicted to be in the low single digits. Because the beast has such a huge, empty chamber (and I discovered any kind of interior liner missing and the far-end of the firing box damaged) I got a pile of refractory brick and basically added about 140 lbs. of internal mass and increased the "height" of the box, as a part of the flame went over the top (whoever put it in put in too short a chamber though the length and width are pretty close to the Beckett guide (dumb luck I think). Around March I start lowering the aquastat temp and at some point in May I shut the boiler down.

Three zones are series and one large zone is parallel and it splits twice with one section returning directly and the other split rejoining before the final return. Long story, but this very large zone was originally two; either the previous or original owner combined them, and based on the room layout and use-experience I plan to split off a section to restore the old zone.

I looked at a lot of boiler mfgs, including Slantfin and Peerless (I don't know anyone with either). I have two neighbors with Buderus - they like their heating bills but complain that its difficult to find service that is familiar with these units. I will definitely look into the Energy Kinetics to learn more about it - I've never heard of this mfg.

Getting even close to 85% or 86% efficiency sounds great to me. So, if 116,000 BTU/h was the loss number would I use a manufacturers AHRI Net number or the AHRI capacity number? The boiler and all piping is in the basement and in spite of insulating every inch of piping and boiler itself, it contributes to heating the building interior - in spite of this my guess would be "Net", but I'm not certain.

Thanks again to all!

MrMike · November 2020

I know that Degree Days are used by oil companies to estimate scheduled deliveries, but STEVEusaPA's comment about annual consumption vs. BTU loss made me wonder if there is a formula that combines DegreeDays and Annual Oil use into a BTU solution. Does something like this exist?

SuperTech · November 2020

I'm definitely a big fan of Energy Kinetics boilers. They are high quality and as efficient as you can get with oil as well as being reliable and easy to service.
From the sound of the way you manually adjust your aquastat temperature based on the outdoor temperature you might want to look into whats called outdoor reset for your aquastat. An outdoor sensor automatically adjusts the high limit on the aquastat based on outdoor temperature. It's great for fuel savings.

Jamie Hall · November 2020

Manual outdoor reset -- and why not? Good solution!

And for capacity -- use the AHRI net figure.

You can use the oil use -- into BTU quite easily. To start to get deeper, you need to have a clue as to the energy efficiency of the boiler, since the oil use is a gross figure, of course. Then you can get the BTU per degree day, if you know the degree days -- which are available from several sources. You can then use that number to get an estimate of the oil use for a given day.. Sort of...

MrMike · November 2020

I'll respond to the comments in detail tonight, but here is a side-question to sizing, related to boiler model selection: is a boiler rated for 50psi (truly) better built than the same unit rated for 30psi? Some mfgs. offer the same model boiler at a 50psi spec - it makes me think the seals between sections and fitting are tougher: so might this mean the boiler in a typical residential 30psi setting (really 12-18psi) last a very, very long time without issues? Kinda like this 1960 Crane?

MrMike · November 2020

Based on the comments here and pulling together a bunch of information (some of which I thought was lost over the past summer) It took me a bit of time but I managed to put together some past season operating numbers. This also produced a crazy result I really don't understand.

Last year I attached a run-time meter (vibration) to the Beckett Burner on the boiler. There were mishaps and faulty meters replaced, throwing in the towel a few times, etc. But I did collect some good data and compiled it, combining degreeday.net data that I found online, as suggested:

2019/2020 Dec17-Jan11 25 Days in period
-------------------------------------------------
Avg Temp 36.39
HDD 715.2
Avg.HDD 28.61
Nozzle 1.25 (Very Old)
Avg Run time 4.09 (102.3 hours)
Avg daily Gal 5.115
Avg daily BTUs 716100
FIRE BTU's/Hr 29,838
HDD/gal 5.59
BTUHeatLoss@AT 47,675
FireBTU per HDD 1,043

2019/2020 Jan18-May21 124 Days in period
--------------------------------------------------
Avg Temp 44.00
HDD 2624.2
Avg.HDD 21
Nozzle 1.10 (New)
Avg Run time 3.28 (406.5 hours)
Avg daily Gal. 3.606
Avg daily BTUs 504847
FIRE BTU's/Hr 21,035
HDD/gal 5.82
BTUHeatLoss@AT 36,880
FireBTU per HDD 1,002

What I don't get is that based on the run-time of the burner, the FIRE input BTU is so much lower than the home's BTU heat loss for the corresponding temperature (I have some individual days tracked from midnight to midnight as well - they follow the same pattern as these period averages).

This seems crazy, because even assuming my old boiler's burner is tuned for 80% combustion efficiency this would mean that out of the Jan18-May21 example of 21,035 BTUs of fire, only 16,828 BTU's could possibly be transferred to the water. Unless I'm not understanding something I'm sure the BTU's transferred are quite a bit lower as a bunch goes up the 8" stack right over the fire. For the Jan-May period the heat loss program indicates I would have needed 36880 BTUs per hour to maintain 70 deg - so my fire numbers aren't even close. I did some test-runs with various indoor temps and even accounting for thermostat setbacks would not makeup the difference.

Having said this a few details: I have two numbers for the boiler oil consumption for last season (Which caught me by surprise because they are even lower than I expected, in spite of the mild winter): 796 or 776.6 gallons, depending looking at the run-time figures and extrapolating (776) or looking at the bills, fill dates and some recorded oil tank gauge readings (400gallon Ross Tank in basement), as well taking out the DHW which amounts to .5gal per day for that 50gal system: 796 gallons. All the numbers seem to correspond within 5% or less - which includes burner oil-pressure at around 100lbs (I don't know the actual pressure, but a higher pressure would have used the oil in the tank at a faster rate). Over time I did wind-up 'super' insulating most of the house and I also made modifications to the boiler before the last heating season started - I can go into that if necessary.

Any ideas on what is going on or what I'm not accounting for? Can the BTU numbers for Hydronic Explorer be that far over?

Last heating season (for my system) was 194 days. The total HDD in this period was 4430 and my oil use was 796 gallons. This amounts to about 111.4 million BTUs or around 24,000 Fire Input BTUs per hour on average. The average temp in the 194 days was 42.16 (or 22.84 HDD/day) which indicates an average heat loss 39,700 BTUs - 15,000 BTU's higher than the fire BTU: any kind of net-calculation and the delta would be way higher!

Robert_25 · November 2020

MrMike said:
I know that Degree Days are used by oil companies to estimate scheduled deliveries, but STEVEusaPA's comment about annual consumption vs. BTU loss made me wonder if there is a formula that combines DegreeDays and Annual Oil use into a BTU solution. Does something like this exist?

https://hydronicshub.com/heat-loss-calculation-on-every-residential-boiler-replacement

MrMike · November 2020

Thank you for that Robert_25 - so well explained even I can understand enough to get dangerous and screw things up (haha). Great stuff!

I know it's key to have absolutely accurate data to plug in, so I'm pulling together some hard-info. SlantFins Hydronic Explorer Heatloss Program shows 99,000BTU @ Zero degrees for my fully finished ground and second floor with a combined sf of 3,823. I designed, and was hands-on, with the renovation and adding on a partial second floor - so I know what is in every wall/ceiling and floor: the house is super-insulated in every location possible, (well past R60 in some attic spaces with cross-layed insulation, sill-plate and perimeter between first and second floor are heavily insulated (min R-30 rockwool) and the house is caulked/air-sealed and wrapped, as well as having new gas filled windows and certain north-wall windows "triple" glazed (foam-lined plexi inserts wedged into casement window-bay. Having said that the house has a lot of glass relative to a typical home (7 multi-panel sliders, vaulted ceilings, windows everywhere and quite a few original ground-floor wall bays with R-12/13).

Using Ron Beck's LI typical home rule-of thumb of 20BTU per sq foot the house might be 76,460. Going back again, HExplorer shows 99,000 (includes the thick walls, lots of glass, vaulted ceilings...averaging the height - but nothing in the program accounts for "super insulated" sections, wrap, caulk, expanding foam srayed between every window frame and rough opening). Using Ron's run-time method and formula (which requires knowing my boilers efficiency *Fat chance!* I picked 80% I get 66,000 for this past Tuesday:

Date                11/24/2020
Nozzle                1.25/80/B @100
Aquastat            160
Runtime    Hours            4.02
Gallons                5.025
BTUs                703500
IBR/AHSRI    0.80        562800
BTU per DD    24.87        22630
BTU per DD per Hour        942.90
Indoor Temp    70 (no setback)    66,003    = TOTAL BTU's Used to heat home

Based on the amount of oil being used, if I pretend the unit is "energystar" and give it an efficiency of 87% I can 'goose' the resulting BTU loss to almost 72,000:

Date            11/24/2020
Nozzle            1.25
Aquastat        160
Gallons            5.025
BTUs            703500
IBR/AHSRI    0.87    612045
BTU per DD    24.87    24610
BTU per DD per Hour    1025.41
Indoor Temp    70    71778    = TOTAL BTU's Used to heat home

Not 77K or close to 99K - BUT - I have numbers that show a large wind-effect which suprised me because the whole house is wrapped (with new siding over it), new windows and a little more than half the house was "air sealed" with spray-foam along every stud-sheathing-interface (isolating the bays). Check out the wind effect:

Date    Av.Tmp    HDD    Wind    RunT    Gal    HDD/gal    BTU loss
11/19    37.96    27.04    11.9    4.85    6.063    4.46    1,308
11/20    52.42    12.58    13.1    2.93    3.663    3.43    1,698
11/21    53.75    11.25    6.4    1.75    2.188    5.14    1,134
11/22    50.00    15.00    10.5    2.92    3.650    4.11    1,419
11/23    53.64    11.36    13.5    2.46    3.075    3.69    1,579
11/24    40.13    24.87    5    4.02    5.025    4.95    1,179
11/25    49.72    15.28    6.5    2.27    2.838    5.39    1,083
11/26    55.94    9.06    7    1.03    1.288    7.04    829

The 20th and 23rd had similar temps and winds - (9% variation accounted for by the slight temp diff); compare to the 21st, similar temp, half the windspeed and suddenly a 28% BTU loss difference for almost the very same temp on the 23rd. (19-23 thermos on hold at 70, after that, evening setbacks).

Really interesting stuff, I couldn't account for the variations until I looked at the wind, did some research and found an old study from the 70's which analysed heatloss effects of wind. Single-pane glass vs. double glaze, vs. masonary, etc. What jumped out at me was that for double glazing most heatloss increses occur in the 0-10mph range, much less in the 11-15 and almost negligible increases above 15. Makes me wonder, if the possibility for wind-effects are included in the heatloss programs: this would be significant for many homes/areas. In fact my home is located on a crest: Westward the ground is almost level for a long distance, Eastward (back yard area) is fully wooded but the elevation rises from 0-104 ft above sea level in about 750-800' (9 degree rise, maybe?), in the winter there are no leaves to help block the wind though - check this out:

Last Heating Seasons 1.10 Noz / 160 aquastat
Date    Av.Tmp    HDD    Wind    RunT    Gal    HDD/gal    BTU loss
1/23    32.33    32.67    0-1    5.36    5.896    5.54    1,053
1/24    38.58    26.42    4    4.53    4.983    5.30    1,100
1/25    45.35    19.65    15    4.70    5.170    3.80    1,535

1/24 is about 7 degrees warmer than 1/23 and the wind is about 3-4mph so even though it's warmer the BTU losses climb 4%. 1/25 is another 7 degrees warmer than 1/24 but the wind increases to 15mph (about 12mph more than the day before) and suddenly there is a 28% increase in BTU loss though it is significantly warmer. This is amazing - am I missing something or not maybe looking at this in the right way?

Effect of Wind on Energy Consumption in Buildings. Air velocity surface heat transmission, Fig4, Page4:

https://www.aivc.org/sites/default/files/members_area/medias/pdf/Airbase/airbase_00017.pdf

Dave T_2 · November 2020

Install the Energy Kenetics boiler. EK1 or Frontier model.
Consider using this new boiler to heat your hot water as well even though you have a fairly new water heater. Energy Kenetics boilers are great, efficient hot water heaters and having one burner vs 2 is an ongoing savings.
I am not a fan of trying to get the Energy Kenetics boiler to use outdoor reset.

EdTheHeaterMan · November 2020

@MrMike, I hope this is not too long for you

I have has some very analytical engineering OCD type customers that overthink every mechanical decision in their home. Sometimes they exhaust my patience and I give up on them. I sometimes like to let my competition deal with them on purpose. even to the point of recommending particular competitors with reverse psychology. "...you won't like him, he is ultra detail-oriented to the point that many of his customers come to me."

But when I did close the deal on a customer such as this (Which was more often than not) I would make sure that the customer knew upfront that I am making design and sizing desitions with my customer's best interest at heart. I will not put in equipment that was unnecessary or would be to their disadvantage. If they wanted to watch the price was an additional 5%. If they wanted to comment, the price would go up 10%. If they wanted to help the price would increase by 20% and if they wanted to engineer the job mid-project, we could do that for double the price.

After all the discussions are done, at the end of the day, the system would operate at less cost than the one that was replaced, and that was my goal and my goal was accomplished.

Down and Dirty comparison of an oversized boiler versed a correctly sized boiler

If on the coldest day of the year, (which usually happens after midnight until 5 AM) If your burner is going off by the thermostat or limit for 10 minutes then the burner comes back on for 10 minutes the then goes off for 10 minutes then comes back on for 10 minutes... and this continues this cycle for several hours (From midnight 'til 5 AM), then your heating system is 2 times larger than the size you require.

If you have a system that does not cycle off during this same period of time, and the indoor temperature does not drop below the setpoint on the thermostat, then the system is exactly the correct size.

It is the educated guessing that must be done by an experienced professional with either a manual J calculation or the Degree day method or the "I have done 30 of these houses just like this in this development" method.

With oil heat, you can sometimes reduce the nozzle size to the minimum manufacturer firing rate. With Gas heat, you can select the Modulating input models to get closer to the actual fitting rate required. With a heat pump, you can select the inverter compressors with variable speeds to dial in the needed heating capacity.

You just need to trust your contractor who is knowledgeable and has your best interest at heart.

Your challenge should be to find that contractor. Let him worry about selecting the equipment that will do the best job for you. If you can find an EK dealer/installer in your area that you feel has the experience needed to d the job right, you found the guy!

I know this because the EK dealer in my area has one of the best reputations in the area for workmanship and reliability. Now that I'm retired, I recommend him for much of the work that my former customers need when they are not satisfied with the company that purchased them from me.

MrMike · November 2020

Thank you EdTheHeaterMan, I've been around the block and can read between the lines, so I appreciate your comments: detailed points are never an issue and I hope I encourage them as no matter what tack they take, they all inform - and on so many levels. Being a consultant for almost thirty years and working with countless contractors in many fields, I would not presume to direct someone who will ultimately be responsible for the success of a installed system/solution. That being said, in order to evaluate capabilities and ascertain reliability, adaptability, follow-through and likely-hood to ultimately take full responsibility and not double-speak/set-shift errors or problems, some of us do follow a process - and part of that process usually requires some knowledge. This being said, when I was young and my dad passed away an older relative stepped-in to help me a bit with direction. He was a master-plumber and took me on countless jobs, but admittedly given the circumstances it was not the area I went into and I focused more on running plumbing supplies and getting those fittings reamed, cleaned and fluxed than worrying about what a BTU was. If my potential client knew nothing (in my estimation) but wanted to play the general contractor of wet-dreams with no responsibility I would decline engaging the project. If my potential client knew "enough to be dangerous" and peppered me with questions I would have a blast responding, but I know that's just me. There is a lot to learn about who you will be working with and it all informs - and because I know what I'm doing in my own field I don't need to punish the inquisitive OCD types by having any kind of punitive pricing schedule or other schemes to silence them.

Some people play solitare, some do cross-words (what are those?), some sit on their sofas and play candy-crush all day, others crunch numbers, constantly retune their cars computers or simply love to know how things work. But I suppose most of us would like to beat-on that candy-crush guy if he were sitting in front of us blocking traffic at a green-light while trying finish his round!

I like your 10-on 10-off rule-of-thumb which indicates possible 100% over-capacity in a system and the 12-5am lowest temp details. That relates to what what I've been referring to as "LPON" in my own stats: Lowest Point Over Night (usually 5am-ish) - which corresponds with my systems AM setback-recovery time which also depends on my installed gph-fire-rate, aquastat setting and how deep that setback was. I learned that when lowering the Aquastat, adding "mass" and better insulating the boiler, deep setbacks were not as important - and could be counter-productive, consuming more fuel during recovery. So infact, I could limit the setback range, keep the house comfortable and still save some CO2 for another day. This all is so interesting and is fun-stuff to experiment with and learn - Heating really is an incredible field especially with all the green-people now running around. I'm thinking all you experts in this field who know how to communicate and build trust with your growing number of "green" customers, (I used to call a similar set of folks "yuppies" myself), will be doing fantastic in the coming years - think of all the inefficient systems these people will want to replace, and guys like you will make it happen!

MrMike · November 2020

Thank you Dave T_2 and Supertech: I will be spending some time looking into the KE units! One of you is open to the Reset and the other Not-so-Much, so I want to understand that better as well.

Like I hinted-at, I'm seeing different results with playing with setback on my own system: In my own experimentation on a really, really inefficient system setback was crucial to stretching out firing-time, as I made the system more efficient (or, changed the dynamic a bit by retaining heat on standby, to be more specific) the range of setback temps that were useful became narrower. Instead of 140-185, 150-170 are far more efficient (more on that later)

Thanks!

MrMike · November 2020

I haven't forgotten about your comments STEVEusaPA - it seems like my fire-rate stats are bearing out your quick assessment.

Don't worry, I won't take advice from some guy behind a counter or someone helping me with a new water-filter - but I will talk to them ...and sometimes I even manage to make a new friend!

MrMike · November 2020

A note on the 1960 Sunnyday-5 Crane boiler in my home and trying to figure out how many BTU's it transfers to water: to be more specific about the changes that occurred over the past 9-10 years, I purchased almost 2,400 gallons of oil the very first year, then insulated much of the piping in the basement and went into a period of incremental home and boiler modifications lowering this into the 2,000 range, 1600, and then 1200. It was so much work (basement alone is 2400sq feet with everything overhead) I could not do everything at once because I was figuring things out and I was trying to figure the impact from the renovations to the home. Admittedly, last years stats have caught me by surprise dropping into the 700-800 range - but it was also a warmer winter.

The Crane is a seven-section unit with 8" diameter stack and a sheet-metal case over the body. With a thermal-imaging hand scanner I was reading 140 degrees on the cover top (supposed to be some insulation under there between the iron and the cover - but clearly not much if any!). Basically this unit was a massive basement radiator. Without taking the casing apart I simply insulated between the cover and body in the clean-out-slats area, and all around that, where I could reach, but more importantly I enveloped the entire boiler exterior in 5.5" R23 Rockwool, including squeezing rockwool under the boiler between the cast-iron base and the concrete floor. Like I mentioned, in previous years I already insulated every pipe, the checks, everything except valves (but eventually made them removable insulated covers because they were bleeding heat too) and, of course, I left the circulators alone - which have no insulation so they don't overheat.

To make clear why I thought this was important: when I first moved in, if the living room thermostat was set to 69 (room right above the boiler) the basement would be 80-82 degrees. I knew I was on the right track as I insulated sections and noted the temp drop in the basement. After fully insulating the boiler and pipes the basement is now about 66-67 at a 5' height (about 69 at the ceiling) when the living room thermostat is set to 69.

The inside of the crane boiler is cavernous - AND there was no interior liner except for a cracked/jury-rigged firechamber, that according to the Beckett manual was too small for the nozzle. I lined the floor with high-temp 1" firebrick and also stacked them like Legos to create a properly sized firechamber (which was also high enough - part of the flame would blow over the broken tiny firechamber was in there). Because the boiler firebox is so large and the passages to the stack above are nice and wide I experimented by adding a small uranium-pile, I mean more bricks, for extra mass/heat-retention (to even-out standby) on the floor behind the "new" firechamber (the unit is not a wet-base as far as I can tell.) The weight/mass of these bricks is 144lbs, but in total I only filled maybe 15% of the entire firebox. On the removable access panel above the burner I used a plaster-like firebrick material and shaped it to the panel to be about 1" thick to protect that thinner iron as well. I also replaced the small cast-iron view-port door with a custom-made drilled-out and very high-temp ceramic-glass "cover" that allows for flame viewing and adjustment without introducing enormous amounts of air esp. when trying to do and initial rough-adjustment of the flame or check out how things are running. Incidentally, after a few minutes of firing, the fire-brick surrounding the flame absorb and reflect enough heat to ignite any remaining un-burned atomized fuel as pre-formed boxes are designed to do, in fact the first hint something is off is if any black carbon forms on the bricks.

With all these modifications I've managed to reduce this boilers stand-by losses to about 3 degrees per hour; 20 degrees in about 7 hours. (I have no idea how many gallons of water this boiler holds, so can't figure a mass-calculation for released BTU's). Also learned that going crazy with the aquastat does not have the same effect it did when it would lose all its heat up the chimney while heating the basement to 82: 150 for fall and spring, generally 160 and more than 170 seems mostly useless (likely because many rooms have more radiation than BTU loss). In this configuration the Crane will short-cycles a lot if the aquastat is 170 or above, unless REALLY cold outside (and now I'm assuming wind also has a serious affect on things).

Side benefit: since I added all the insulation the amount of noise of this unit is well less than half what it was. I have to say one part of me is really wrestling with changing the unit out and at the least I am going to take run-time stats this season before deciding anything. No more home improvements so I think this is a good time to figure things out.

That's the background - a lot of changes over the years complicating getting a good consumption picture for this unit, since it was always changing. I was too busy in previous years to take serious stats and didn't even think of a run-time meter - but I finally have the time to focus on this and it actually is a lot of fun!

Dave T_2 · November 2020

@MrMike, fyi the EK boiler is a cold start, low mass boiler, 2.5 gallons. The burner only runs on a call for heat. When the thermostat is satisfied the system manager continues to run the circulator about 20 mins to purge the heat. So it should really be looked at as a 'heat generator'.

Be sure to go to Energy Kinetic web site and learn about their boiler and why it is better. After you have done your homework I would guess you will choose the System 2000 EK1 or Frontier model. Oh, and the very best boiler available is also made by Energy Kinetic, check it out
https://energykinetics.com/wp-content/uploads/2015/10/specification-EK1-Resolute-Oil.pdf

One additional option you can consider is an injection loop to overcome such a low water content boiler. It will not only help the boiler from being shocked by cold return water, it will also allow the loop temperature to evenly distribute the heat through out the zone and minimize short burner cycles.

I am curious, do you have baseboard heat? How many zones? AND if baseboard how many total linear feet?

Good luck, have fun learning about heating!

STEVEusaPA · November 2020

MrMike said:
I know that Degree Days are used by oil companies to estimate scheduled deliveries, but STEVEusaPA's comment about annual consumption vs. BTU loss made me wonder if there is a formula that combines DegreeDays and Annual Oil use into a BTU solution. Does something like this exist?

That btu 'guess' I gave you was based on @Robert O'Brien 's article. I made a spreadsheet and then a simple app that does it quicker. It’s usually very close.
I think either way (EK or triple pass) you’re most likely getting the smallest boiler.

MrMike · November 2020

@Dave T_2, thanks and yes, I have baseboard heat.

There are four zones: one of them had been combined from two previously separate zones by a 'short-stay' previous owner (in and out pretty-quick because the heating bill) who was convinced to install a kick-heater, in-line, between two spaces. Needless to say, that didn't solve his problem. When I finally replace the boiler there will be five zones with that kick on a side-loop.

Converting the installed Pak80s and Kick Heaters into SF-30 equivalent (580BTU/hr) length, there are 232 equivalent linear feet or about 133-134,000 BTU of installed radiation in the current four zones.

Dave T_2 · November 2020

@STEVEusaPA if your sharing your spreadsheet I'd like to see it. I'm into DDays and Kfactors. What did you use to write the app?

STEVEusaPA · November 2020

Spreadsheet attached.
App was made with FileMaker. Free to download FileMaker Go for IOS device.
For the full version on desktop (to modify) you have to purchase FileMaker. You can download a trial version.
edit: to clarify, FileMaker/FileMaker Go are the programs you need. My solution is a database file that runs on the FileMaker platform, aka Claris.
Can't attach a FileMaker file. Send me a PM and I'll email it to you. All the instructions will be in the Word Document.

MrMike · November 2020

Dave T_2, your curiosity about the linear feet of baseboard in my setup made me think of something that had not remotely occurred to me prior.

According to SF-30 baseboard specs the following would be the max. output of my 232 'feet' of radiation:

190 Aquastat, BTU's of radiation = 146,240
180 Aquastat, BTU's of radiation = 132,530
170 Aquastat, BTU's of radiation = 116,535
160 Aquastat, BTU's of radiation = 102,825
150 Aquastat, BTU's of radiation = 86,830

When I'm running a 1.25 gph nozzle I can generate about 173,750 BTU's of fire but from the efficiency perspective of the modified Crane (which in its original configuration and 2.35gph nozzle had an I=B=R of around .66) I *might* now be getting .70, so my max BTUs might be around 121,600. Since radiation of 121K coincides with a max Aquastat of about 173 degrees, a higher aquastat setting would be a waste and result in more short-cycling. At around 170 this does happen with my system. Coincidence? Or is this way of looking at Baseboard water temps somewhat on-target? Am I misapplying/misinterpreting how all this works?

With a 1.10 nozzle I would make 153,000 BTU of fire and at .70 this would gen 107,000 BTU's and with the Aquastat sitting mostly at 160 during last years cooler periods (103K BTU output max) this line-up might explain some of the better results/lower oil consumption for last season.

This idea may sound nutty, but it would be relatively easy test by maybe installing a 1.0 gph nozzle: 139,000BTU of Fire - 97,300BTU transferred at .70 to the baseboards, which then corresponds to an Aquastat/water-temp setting of around 157. (I'm almost certain that overnight thermostat setbacks would have to be reduced a little to compensate for poorer AM recovery with all that mass and a much lower fire output).

The closer I line up and get to the true heat-loss of the home (and the actual heat-generating capability of the boiler) the more efficient this would all get. Is how I'm looking at this too simplistic for all the variables involved? If you could 'experiment' what would you try?

Dave T_2 · November 2020

I would do a heat loss calculation to determine the best actual heatloss. There are programs that can perform this very accurately. This is the easy part of your hunt for the right boiler, stop trying to do it the hard way.

Connected baseboard load is really not relevant, in fact can lead you in the wrong direction. Your home likely has more baseboard than it needs -so the result is higher implied heatloss than required.

If your choosing a new boiler do the heatloss calc and thats the size you need. If you keep the boiler you have then downsizing the firing rate to what is necessary is always a good idea for forced hot water heat. When I say what is necessary, I mean a firing rate that heats the house in the very coldest weather.

Trying to identify best sizing and models for a new boiler

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