Boiler and burner options

diesels12

I have a 12,000 sq. ft. house (9500 sq ft finished) built in 1914, brick with minimal insulation and single pane windows, oil hot water heater. We are ripping out the old single zone gravity system piping to 14 risers (8" trunk) and replacing with 14 home runs of 1" pex with feed and return on each to manifolds by boiler to create roughly 4 zones of heating (currently has 1 zone). We are also taking out the massive ducts with 19 original heating coils ( no fan, cold air induction)that heated 1st floor with new ductwork and 2-5 ton air handlers and heat coil
My heat loss calculation was roughly 550,000 BTU'S for a hot water radiator system for floor 2 and 3 and 2- 5 ton air handlers with heating coils for first floor hydronic hot air system. I figured 120,000 BTUs for 2 air handlers and the rest for radiators.
I believe I have narrowed down the boiler to a Buderus G315/7 with Riello F15 burner or a Buderus G315/8 with Riello F20 burner.
My question is the g315/7 has DOE of 559k BTU'S and 489k net IBR while the g315/8 has DOE of 663k bring and net IBR of 577k BTU. Which one do I use? I don't want to oversize but also don't want to undersize. Does anyone recommend any other boiler, burner combo for such a big house? Also why is there a 4 week wait time for Riello burners at 2 supply houses I called? Are they that popular?

Cheers
John

diesels12

Forgot to add, current boiler has current net IBR of 657k BTU and DOE of 762k. Considering we are removing current 8" trunk and piping to risers and replacing with pex and also getting rid of 19 old heating coils and ducts, we know we can downsize the boiler.

STEVEusaPA

With that size boiler, and you're current situation, I would look at TRV's, and one zone, and constant circulation. Large, poorly insulates houses, heat moves to cold, and trying to keep a whole section (zone) much cooler or warmer, I feel is just not going to feel comfortable.
Otherwise I think with zoning you'll get a lot is short cycling, with that size boiler.
I would also consider a 2 stage burner

diesels12

I have talked to 3 different heating guys and none are a fan of TRV's. They say they are unreliable, don't last long and a pain to change. Of course I plan on modulating water flow with current valves on radiators which is a manual trv . Anything I do though is better than current situation.

HVACNUT

I would seriously consider constant circulation with TRV's and near boiler piping with the thermal bypass, especially if using a Logamatic and ODR.

The sizing should maybe be reevaluated.
Heating the finished portion of the house equates to 51.5 BTU'S per sq.ft. with the 7 section.
Unless you live in the Fortress of Solitude, that's crazy high.

Riello is the only burner option for the G315. The F20 is a 2 stage.

I love Riello, but only the F3 to F10.
I've never really been satisfied with the F15 or F20, (even set up dead on balls accurate, they tend to have a delayed ignition or safety lockout on a cold boiler) and will use a Carlin or Beckett on larger BTU applications, other than the Buderus, or on a large G215.

Do the heat calculation over. I think you misplaced a decimal.

diesels12

Thanks for your well thought out reply, couple of questions.
1)With constant circulation, that would be with 1 circulator pump and no thermostats using TRV's to control temp? What brand trv do you recommend? The plan is to run 12 -1" feed and returns to each riser and return back to boiler. Will one circulator handle this?
2) As to heat loss calculation, I am terrified of undersizing the boiler. We live in NY on top of a hill with big single pane windows and brick exterior and plaster interior walls. We actually figured roughly 50 BTUs per square foot but also did proper heat loss evaluation which brought us to 40 BTUs which included the 120k BTUs to run heating coils in 5 ton air handlers for 1st floor. We added extra because there are some big radiators in basement which is partially finished. Also the monster we are replacing is 755,000 DOE BTU'S so we are are dropping considerably going to the G315/7.My goal is saving oil, house used 4500 gallons unoccupied between November 15- March 15 last year and I am sure thermostat was low. My question is, if possible can I use the F20 burner in the 315/7 and would it be more effecient than the F15 because it's 2 stage? Do you recommend any other options assuming 500k BTU heating?
3) I also have natural gas and the buderus can be used for either natural gas or oil. I just filled my 2000 gallon oil tank so will use oil for now but may switch to Nat gas is oil goes up? How complicated is it to switch burners and in your opinion what is currently the best fuel to use at today's prices?
3) I am getting the logamatic, what is the ODR? Is that the device to read outside temp?
Thanks!

diesels12

FYI as to heat loss calculations, we have over 1100 sq ft of radiators when we add up 2nd and 3rd floors. 1 at floor is hydronic hot air.

KC_Jones

diesels12 said:

FYI as to heat loss calculations, we have over 1100 sq ft of radiators when we add up 2nd and 3rd floors. 1 at floor is hydronic hot air.

1100 sq ft works out to about 187000 btu/hr (with 180° water) so it doesn't matter if you put in a 10 billion btu boiler your system capacity is 187000 btu/hr. Don't oversize it literally does nothing for you.

If you don't have the emitter capacity it doesn't matter how big the boiler is.

Robert O'Brien

Recheck the heat loss, no way is it that high. I'd go with multiple boilers for a house like that. Redundancy and modulation!

diesels12

I agree that 2nd and 3rd floor radiators are around 200k btu, than add the 120k btu for the 2 5 ton air handlers and the 50k btu for the Hugh basement radiators and I get 370k btu give or take. Than you have to take into account the fact that there is no insulation in brick exterior, plaster interior walls and hugh single pane windows that are drafty when closed so add 100k btu for the heat loss. If house was new built well insulated I would go with the smaller boiler but I don't think I am too far off mark at 500k btu.
That being said, of the 12 bedrooms in house only 4 will be occupied 95% of the time so it would be rare when I have to bring whole house to temp at once.
I am getting various opinions from different suppliers/installers who looked at the house and even had a mechanical engineer say 500k to be safe but I respect the opinions on this board and appreciate all comments and suggestions. This is a Hugh job and only want to do it once.
Question on multiple boiler option, how exactly does that work? First boiler primary and 2nd kicks on when needed??

Cheers
John

Robert O'Brien

> @diesels12 said:
> I agree that 2nd and 3rd floor radiators are around 200k btu, than add the 120k btu for the 2 5 ton air handlers and the 50k btu for the Hugh basement radiators and I get 370k btu give or take. Than you have to take into account the fact that there is no insulation in brick exterior, plaster interior walls and hugh single pane windows that are drafty when closed so add 100k btu for the heat loss. If house was new built well insulated I would go with the smaller boiler but I don't think I am too far off mark at 500k btu.
> That being said, of the 12 bedrooms in house only 4 will be occupied 95% of the time so it would be rare when I have to bring whole house to temp at once.
> I am getting various opinions from different suppliers/installers who looked at the house and even had a mechanical engineer say 500k to be safe but I respect the opinions on this board and appreciate all comments and suggestions. This is a Hugh job and only want to do it once.
> Question on multiple boiler option, how exactly does that work? First boiler primary and 2nd kicks on when needed??
>
> Cheers
> John

What does the amount of radiation have to do with the size of boiler? Multiple boilers are staged as you thought.

diesels12

I by no means am an expert, that's why I am here. Based on my description, what would you recommend size wise for a 1 boiler system and a 2?

Robert O'Brien

You need a proper heat loss calculation, the amount and size of radiation are completely irrelevant. No need to add any fudge to that number

Bob Bona_4

Throw out your assumption that 5 ton air handlers require 60k BTU of boiler each.

diesels12

Well I will definitely be downsizing my boiler, there are also only 3 people in house so we will not need to heat whole space.
I am going to use logamatic 2017 control though and will use constant circulation and TRV's for radiator heated floors. There are 12 risers in house, 2 pipe hot water system and each riser has at least 1 radiator on 2nd and 3rd floor. Do I need to put TRV's on every radiator? All risers are on exterior, uninsulated walls so also worried about pipes freezing if there is not constant flow.

I assume I will also not need thermostats for radiator portion of house, only 1st floor heated by air handlers?

How do I handle the heat coils with the logamatic? I would assume temp would need to be higher for them than the radiators. I read one post where the guy doubled heat coils so house gets warm with 120 degree water temp.

Thanks and Cheers
John

KC_Jones

diesels12 said:

I agree that 2nd and 3rd floor radiators are around 200k btu, than add the 120k btu for the 2 5 ton air handlers and the 50k btu for the Hugh basement radiators and I get 370k btu give or take. Than you have to take into account the fact that there is no insulation in brick exterior, plaster interior walls and hugh single pane windows that are drafty when closed so add 100k btu for the heat loss.

First as has been said the heatloss of the building has nothing to do with your emitters.

I used the example of the emitters to show how oversized you were going to be. The max (by your numbers) the system is capable of is 370k BTU. If you put in a 1 million BTU boiler the system will put out 370k BTU and the boiler will short cycle like mad, if you put in a 500k btu boiler same result to a lesser extent

You can't make use of any extra BTU's because of your emitters.

The heat loss is done based on the building as if it had no heating system, then everything is sized according to the heat loss number you generate. Manual J

diesels12 said:

My heat loss calculation was roughly 550,000 BTU'S for a hot water radiator system

The type of system has nothing to do with heat loss again the heat loss is for the building and then used to derive the heating system. If this was new construction the heat loss is done and the system and design done after the heat loss. It sound like you are basing the heat loss off of the system which is incorrect.

Take the time and do the calculations anything else is a guess.

diesels12

Thanks for explanation KC.Basically than I have to work with the existing emitters in the house regardless of heat loss? If heat loss is excessive or exceeds existing emitters, I would have to add extra emitters, correct? Considering this was built in 1914 and in NY where they over radiated everything in that period, I am positive existing radiators are sufficient, if not excessive.
It amazes me how uneducated about sizing so called professionals are. I spoke to 3 different installers and even an engineer and all of them oversized the system based on existing, doing sq ft equation (50 BTUs per square ft due minimal insulation) or just guessing. Prior to posting my problem, I was going to buy a Buderus G315/8 and now I am leaning towards the G315/6 or lower. Will probably due G315/6 to allow for further expansion if I wish to fully heat basement. A couple of people on the board suggested dual boilers, I was thinking small 1 to run heating coils in 2-5 ton air handlers and bigger one to run radiators if I went the dual boiler route.

Thanks

HVACNUT

@diesels12
Let's hit the reset button and start from scratch.

Find the "Design Day" (the coldest day of the year) for your area. If it's 10 degress, don't use 0 to be safe. The curve of the outdoor reset can be adjusted through the 2107.

If you're not using this, then try it.
Google "Slant/Fin heat loss calculatior", and download the app.
Go room by room with the app and enter sq. ft., windows, doors, exterior walls, construction, etc. There are drop down menus to provide insulation factors. Every room will have its own BTU spec, and you can then size the emitters needed for that room, or rooms, in the case of the hydro coil systems.

You mentioned in your first post that there is 2,500 sq ft of unfinished space. If you're definitely going to finish and heat that space, factor that in as well.

After you enter all the info, it will calculate the necessary BTU'S needed to heat your home on a design day.

That's it. Not one BTU more.

You never addressed DHW needs. Indirect(s)?
Is there a giant jacuzzi, or 12 head shower stall?
Shouldn't be a major concern because DHW will take priority through the 2107. Just curious.

After that's done, post back here and we can help with boiler options, (one, or multiple, as Robert O'Brien suggested, constant circulation, etc).

Did you check "Find a contractor in my area" at the top of the page?
Maybe someone here is close to you and can do the heat loss, and provide an estimate.

In any case, your your going with Buderus, (and rightly so IMO) so make sure any contractor you choose has experience with Buderus and the 2107. More than the equipment, the contractor is going to be your most important choice.

Hope to hear from you soon.

P.S. To answer your question about the hydro coil systems, they should operate to turn on and off from a thermostat heat call, not a "close on temp rise" aquastat with a fixed set point. With the outdoor reset, they won't see a fixed temperature, only what's needed, nothing more. And there are program settings in the 2107 to address that as well.

Good luck.

diesels12

Ok spent 3 hours calculating with slant fin app and it came out to 309,00 btu. 128k btu first floor, 69k 2nd floor and 85k 3rd floor. Basement was 27k. 1st floor will be hydro with exception of kitchen and Butler's pantry which are 35k according to slant fin so actual hydro w/ air handler will be 93,000 BTUs.
Suggestions on equipment ? Thermostats I assume will handle air handlers but for the rest?

Thanks in advance
John

Robert O'Brien

3)G115WS/3 controlled by HBX CPU0550. The HBX will stage and provide ODR.

EBEBRATT-Ed

You may have a 5 ton air handler that moves say 2000 cfm. That has no relationship to how much heat it will produce. Depends on the coil

diesels12

So I request say a 60,000 btu coil per unit if space calls for 120,000 BTUs?
Still confused about the 3 boiler setup. I understand the theory but it seems like 3 boilers a lot of maintenance and takes up a lot of space and costly. It just seems easier with say the g315/5.
I am learning a lot here though and whatever I decide I will save $$$$ upfront and over life of unit for sure.

Bob Bona_4

You'd oversize the hydro coils if you wanted some decent outdoor reset benefits. Multiple boilers start to make sense when loads veer up into the 200k range give or take.

KC_Jones

Take the heat loss you did and plug in 50, 55 or even 60 degree outdoor temp and then the idea behind multiple boilers starts making more sense. Remember that 309k is only on the coldest day, all the other days a boiler that size is actually over sized.

heathead

Natural gas is an option correct. Only have 2000 gal of fuel oil. When natural gas is available unless it is grossly over price, I would choose that any day to oil. Compare costs per therm, vs cost per gallon and bttus of each fuel, and percentage of useable heat from boiler. I find that natural gas is much more reliable in equipment, delivery and price. Also one can get some higher efficient running boilers with natural gas, less maintaince also. Higher percentage of fuel used for actual heat and not up the flue. Read about using multiple boilers staging, big fuel savings by staging multiple boilers. If a boiler goes down you will have some heat vs no heat if something breaks if you stage boilers. You need to find contractor from this site find a contractor section. Your costs are in fuel and comfort if you get this wrong. Think of the 2000 gallons of oil used up by the time new system is up and running. Lots of things you need learn to do this right. You came to the right site. Look at Viessmann wall hung Boilers they should have some case studies, on staged boilers. Everyone is saying not to fudge heat loss numbers because you only need the max heat loss a very small percentage of the year. Some places only a day or two a year or once every five years. Boilers run more efferent the longer they run.

HVACNUT

You'll get never ending recommendations here, so I'm going to steal other guys ideas.

Multiple boilers, C/O @Robert O'Brien
However my choice is, 2- G215/4's with the 2107 Logamatic.

Constant circulation with TRV's for the panel rads, C/O @STEVEusaPA.

Icing on the cake. Deck out the equipment room walls with faux diamond plate sheets.

diesels12

Unfortunately I live in Con Ed territory ( gas utility) and it takes 4 months for them to upgrade meter to switch to gas or that would be my choice. I noticed the Buderus g315/5 is a gas/oil boiler that I could switch to a gas Riello burner next spring. I didn't see that option on the g115 or g215 series.
I can try and make it through the season with this 20 year old 750k btu monster but the extra oil burn might be more than the boiler and burner equipment cost. This system burned 4500 gallons from November 15 to March 15 unoccupied which was probably 50-55 degrees ugh. I will be getting rid of existing 8" pipe trunk and piping to beginning of 12 of the risers with 1" pex home runs on each riser so that should save $$$. Also upgrading hot air system with all new ductwork and air handlers for first floor so if I did take a chance and wait till spring those upgrades alone should reduce oil consumption hopefully.
Curious as to what size heating coils to take advantage of outdoor reset in 5 ton air handlers though, that's interesting. I assume bigger heating coils allow lower temps. Does that mean I can run the logamatic 2017 for both air handlers and radiators with same temp? If not what's the alternative?
You guys convinced me on the TRV's with constant circulation for radiators so no thermostats. What does Buderus use to measure indoor temp for logamatic or does it matter?
Cheers
John

diesels12

Update, purchased 2- Weil McLain G0-5 boilers with Beckett burners. Just need help hardware to buy at boiler such as control for ODR, circulators, etc.
One thing that concerns me is some of the longer runs in the house are 135' runs, how is long and 4 stories. There are 12 risers I will feed with 1" pex and some are only 60' long and the rest in between. How many manifolds (and brand) would you suggest and what type of circulators and how many? I want to make sure I don't overload circulators

HVACNUT

You purchased the boiler's?
Do you plan on doing all the work yourself?

diesels12

No I am not doing any of the work myself. I just want to be educated about my options on setting up the system to minimize oil consumption and relay this to installer. I have a lot of respect for the knowledge on this board and most of you guys know more than the average installer. Any help is appreciated.

Cheers
John

KC_Jones

diesels12 said:

Update, purchased 2- Weil McLain G0-5 boilers with Beckett burners. Just need help hardware to buy at boiler such as control for ODR, circulators, etc.
One thing that concerns me is some of the longer runs in the house are 135' runs, how is long and 4 stories. There are 12 risers I will feed with 1" pex and some are only 60' long and the rest in between. How many manifolds (and brand) would you suggest and what type of circulators and how many? I want to make sure I don't overload circulators

While I admire you ferocity with this project, I think you are going to have an extremely difficult time finding anyone competent to install owner purchased equipment.

I think you might want to slow your roll just a bit. You need to do a complete design before buying anything.

The answer to "what you need" is a question: What does the design say you need?

You need to look at each rooms heat loss, calculate flow, head a whole lot of other things to get this correct.

I also fear you started this project way too close to heating season to get it complete.

diesels12

Actually I have property management company and always buy equipment. This is a week job max so plenty of time before heating season. Just asking for suggestions.