is my boiler to large?

[steelman351]

looking for some conversation on my boiler selection for my in floor heat in my 30 x 40 pole barn.
the spec's

north eastern Ohio. normal winter temps, around 20 deg. sometimes colder, sometimes warmer.

5" concrete, 4 loops of 1/2 inch pex. every 16". just about 1000 ft total.
the building is insulated well.
foundation grade board under floor 3 inches thick. r-15.
6 inch board r-30 on the edges of the concrete. (2 pcs of foam board)
walls have vapor wrap fiber glass r-19.
ceiling is 3 inch board r-19 reflective foil face with blown in insulation for a total of r-30+.

i just got the chimney done. 6 inch double wall stainless steel.
now im ordering the boiler pieces from pex supply and a few from Menard's and hope to fire it up soon.

my question is, is my boiler too large?
i sourced an "A-Maize-ing Heat corn boiler that i plan to run only wood pellets. i have a pellet furnace in my home and love it. so the pellet boiler will be a normal source of fuel for me.
the boiler BTU output is variable at 80,000 to 160,000 BTU's.
i have a 1,500 gal poly storage tank i had planned on using for Solar storage tank to supplement my Barn heat but that will be down the road, if its even needed. if i do use it ill need to spend some money on insulating it as well as burying it. again something i don't have plans on doing now.

after reading the problems of "sort cycling" im wondering if i have too much boiler.
any help would be appreciated.
thank you.
jim

 

[mygarageone]

Yes it's way to big. Your needing something half that size in a modulating unit.

Maybe even a 1/3 that size but with out a heat loss calc , no way to know for sure.

 

[big.jim]

not had a lot to do with pellet boilers but 80,000 btu modulating down would be plenty BUT I HAVE A BIG CAUTION FOR STORAGE OF WOOD PELLETS there have been several deaths through carbon monoxide poisoning from stored wood pellets , they should always be kept in a well ventilated area as when disturbed / agitated they give off carbon monoxide.

 

[steelman351]

Yes it's way to big. Your needing something half that size in a modulating unit.

Maybe even a 1/3 that size but with out a heat loss calc , no way to know for sure.

i realize that the heat in slab is much more efficient then forced air but my home unit is heating a 1700 sqft ranch both the main floor and the basement
with a 70,000 BTU pellet forced air furnace. i feel it is a good size but at times struggles.

the boiler in the barn is variable, meaning adjustable. from 80,000 BTU to 160,000 BTU. so it has adjustments to run at a constant 80,000 BTU.

so your saying that my barn could be heated with a 40,000 BTU or even possibly a 25,000 btu boiler?

yes i understand and have used a heat loss cal. in the past but we are talking leaps and bounds here.

i thank you for your input just find it hard to agree that a 40,000 BTU boiler is going to keep a 30 x 40 barn in the 60 deg range.
but i have next to no experience with a boiler.

hoping for more responses.
thank you.

jim

 

[mygarageone]

i realize that the heat in slab is much more efficient then forced air but my home unit is heating a 1700 sqft ranch both the main floor and the basement
with a 70,000 BTU pellet forced air furnace. i feel it is a good size but at times struggles.

the boiler in the barn is variable, meaning adjustable. from 80,000 BTU to 160,000 BTU. so it has adjustments to run at a constant 80,000 BTU.

so your saying that my barn could be heated with a 40,000 BTU or even possibly a 25,000 btu boiler?

yes i understand and have used a heat loss cal. in the past but we are talking leaps and bounds here.



i thank you for your input just find it hard to agree that a 40,000 BTU boiler is going to keep a 30 x 40 barn in the 60 deg range.
but i have next to no experience with a boiler.

hoping for more responses.
thank you.

jim

You are talking a modulating boiler ,so yes. A modulating range from 40,000 - 80,000.
Would be plenty .

 

[brewchief]

With the limited info I pulled up a 30x40 garage from my load calc files and moved a few numbers around, I came up with slightly under 25,000 btu, that's not counting much in the way of doors and windows however.

 

[Shop Specialties]

That is way overkill. I would ballpark you at about 75,000 BTU for a forced air unit and in-floor heat only takes about 1/3 the BTU to do the same job. So you should only need in the ballpark of 25,000 BTU boiler.

 

[mygarageone]

not had a lot to do with pellet boilers but 80,000 btu modulating down would be plenty BUT I HAVE A BIG CAUTION FOR STORAGE OF WOOD PELLETS there have been several deaths through carbon monoxide poisoning from stored wood pellets , they should always be kept in a well ventilated area as when disturbed / agitated they give off carbon monoxide.

This is only an issue when they are stored unbagged or lose in closed storage bins. When they are bagged it's not an issue.

 

[jvitez]

FWIW, our ballpark figure here in the cold Prairie is 10 watts/sq ft of electric heat for residential construction. So in comparison you're well insulated, your climate is somewhat warmer, it's a garage so no need for 72°F inside temps, and in-floor heat allows you to feel warmer at a lower inside air temp anyway.

10 watt/sq ft= 40,956 btu/hr input for your garage, divided by 0.8 for an 80% efficient boiler (another ballpark estimate)= 51,195 btu/hr input rating.

Yup, too big.

 

[anthony666]

all is not lost .. http://www.boilerbuddy.com/ .. i've used these in a couple of jobs they work by adding more mass to the system .. heat is not lost because it's inside the building

there are also a couple of piping strategys that will help, decoupling/hydronic separator for example

 

[Champ49]

30x36 garage, similar insulaltion,similar floor heat design , located in central Canada and had recent temp to -40. Heating with MC50 modulating 18000-50000 btu propane boiler and have plenty of heat.

 

[hidollartoys]

That is way overkill. I would ballpark you at about 75,000 BTU for a forced air unit and in-floor heat only takes about 1/3 the BTU to do the same job. So you should only need in the ballpark of 25,000 BTU boiler.

Can you explain this. Not sure I follow the logic.

 

[mygarageone]

Can you explain this. Not sure I follow the logic.

We'll this May not make sense but radiant floor heat calc's are different than what's used for forced air.

 

[hidollartoys]

We'll this May not make sense but radiant floor heat calc's are different than what's used for forced air.

Just another general statement without any justification. Could you explain in more detail? Is this some trade secret? Based on my study of heat loss, BTU's are BTU's.

 

[anthony666]

1/3 of the btus is a bit of a stretch, but the btu requirement to feel comfortable is definitely lower .. it has to do with what makes people feel warm

i'm sure you've been in a shop standing in front of a work bench and all of a sudden you realize your feet are blocks of ice, so you crank up the stat til your head feels like it's in a toaster but your feet are still cold and they never get warm again while you stand there, the concrete wicks the heat out of your body because heat travels hot to cold naturally .. if the concrete is warmer you don't get that effect

air based systems create a positive pressure in the structure .. pressure wants to equalize, high pressure rushes to low, which is why we get winds .. you open the door and whoosh, there goes a bunch of heat that must be replaced .. same goes for tiny cracks which are exacerbated by the pressure inside the structure, a house is like a big sieve, which is why people are going nuts for spray foam .. that doesn't happen with radiant based systems, the home is not pressurized by the heating system

that said, when i design a system for a structure i use the same heat loss calcs and btu inputs that someone would use for a forced air system .. the difference is in january is the forced air furnace doesn't shut off, but the next door neighbor's house, with radiant, you check the run history of the boiler and it'll be at 60% or so

 

[Shop Specialties]

This is one of the great benefits of in-floor heat. It takes approximately the 1/3 the BTU to heat the slab as compared to heating the air with a forced air unit.

 

[anthony666]

This is one of the great benefits of in-floor heat. It takes approximately the 1/3 the BTU to heat the slab as compared to heating the air with a forced air unit.

i wish that were true, i wouldn't have such a hard time selling jobs .. the truth is the complexity and amount of equipment & materials involved makes the buy in of a radiant system is double or even triple what a forced air system costs & it's human nature to want to spend less .. i tell folks the real operating saving is about 25%, but the quality of the heat is priceless

 

[Shop Specialties]

It can be a very difficult sale. I only deal with waste oil heaters/boilers so that helps when making the sale but 95% of the work I do is in existing buildings. I have a customer right now who is looking at building a new dealership. I told him we could heat the entire building with snowmelt for the same amount of BTU that it would take to just heat the shop with a waste oil forced air unit. He is estimating his ROI would be 2-3 years which he is happy about but he does not like the initial costs.

 

[mygarageone]

I quit trying to sell radiant heat , I now have all those who are interested come to my shop. And feel the real difference. Don't lose to many sales now days , besides all the satisfied clients.
But like everyone who does this for a living , we have to over come the bad rap they get from poor installations and most times it's because so the DIY who screws his system up and the next thing you know he's blaming radiant heating as not being any good.

 

[mygarageone]

Just another general statement without any justification. Could you explain in more detail? Is this some trade secret? Based on my study of heat loss, BTU's are BTU's.

I am not surprized by your lack of understanding this type of system , most don't.

 

[anthony666]

I quit trying to sell radiant heat , I now have all those who are interested come to my shop. And feel the real difference. Don't lose to many sales now days , besides all the satisfied clients.
But like everyone who does this for a living , we have to over come the bad rap they get from poor installations and most times it's because so the DIY who screws his system up and the next thing you know he's blaming radiant heating as not being any good.

amen brother

 

[hidollartoys]

I am not surprized by your lack of understanding this type of system , most don't.

Really..... Then fill me in. Or is this just some more GJ "professional" hokus-pokus.

I have been researching this for 3 years and have never found a "magic" multiplier. Hell, neither you or anthony can agree on a factor. Are you guys actual designers or just installers? Come on guys give me something that I can sink my teeth in, not just supposition. I do HVAC calcs all the time using industry "rules of thumb". No rocket science.

 

[mygarageone]

Really..... Then fill me in. Or is this just some more GJ "professional" hokus-pokus.

I have been researching this for 3 years and have never found a "magic" multiplier. Hell, neither you or anthony can agree on a factor. Are you guys actual designers or just installers? Come on guys give me something that I can sink my teeth in, not just supposition. I do HVAC calcs all the time using industry "rules of thumb". No rocket science.

Oh , you are one who uses rule of thumb for this kind of thing. Remind me never to use your ideas.

 

[anthony666]

Really..... Then fill me in. Or is this just some more GJ "professional" hokus-pokus.

I have been researching this for 3 years and have never found a "magic" multiplier. Hell, neither you or anthony can agree on a factor. Are you guys actual designers or just installers? Come on guys give me something that I can sink my teeth in, not just supposition. I do HVAC calcs all the time using industry "rules of thumb". No rocket science.

wow .. no need for gauntlet throwing mate

i use regular hvac heat loss calcs .. if you wanna learn more about the technical side of things there are tons of industry journals and design manuals available free from the manufacturers .. pm me i'll give you the names of a few that help me

and as i already said 25% less fuel usage is my rule of thumb on a well designed system .. for the record, a pipe straight out of the boiler right into the slab and back is NOT a well designed system

 

[mygarageone]

Actually , the under slab tubing is pretty straight forward most times , not much deviation from industry norms , how ever it's the boiler and piping that needs much more attention and thats where the real understanding of these systems comes into play.
Pump size , location , direction , primary , secondary pumping , flow control , gpm , etc all come into play when designing a system. No it's not rocket science but then I know some very smart hi tech people who haven't a clue about what they should do with these systems . I get calls from them all the time and they try to pick my brain just enough to avoid a service call. Not happening , It's not what I do thats worth anything , it;'s what I know . I can tell you right now Anthony and myself have not shared everything we know about what we do , it took way to many years to learn and educate our selves to get where we are and I do not think we are just going to blab it out every times some one ask a question.

 

[hidollartoys]

Actually , the under slab tubing is pretty straight forward most times , not much deviation from industry norms , how ever it's the boiler and piping that needs much more attention and thats where the real understanding of these systems comes into play.
Pump size , location , direction , primary , secondary pumping , flow control , gpm , etc all come into play when designing a system. No it's not rocket science but then I know some very smart hi tech people who haven't a clue about what they should do with these systems . I get calls from them all the time and they try to pick my brain just enough to avoid a service call. Not happening , It's not what I do thats worth anything , it;'s what I know . I can tell you right now Anthony and myself have not shared everything we know about what we do , it took way to many years to learn and educate our selves to get where we are and I do not think we are just going to blab it out every times some one ask a question.

Not sure I can afford a service call from MI to KS. Not sure you would want to travel here anyway.

I truly understand the "trade secret" aspect of any craft. I am a licensed master electrician and facility engineer. We are always the first in to diagnosis an equipment failure. HVAC, steam boiler and hydronic systems are just a small sample of the equipment I work on. Mostly all designed and installed by low bid hacks requiring us the reverse engineer the systems and properly apply the technology. We have two in slab systems (both way over engineered) and a building hydronic heating system utilizing forced air over radiators
(way undersized). Believe me I understand the system hydraulics and heat transfer issues.

 

[hidollartoys]

wow .. no need for gauntlet throwing mate

i use regular hvac heat loss calcs .. if you wanna learn more about the technical side of things there are tons of industry journals and design manuals available free from the manufacturers .. pm me i'll give you the names of a few that help me

and as i already said 25% less fuel usage is my rule of thumb on a well designed system .. for the record, a pipe straight out of the boiler right into the slab and back is NOT a well designed system

If you use "regular hvac heat loss calcs" do you just arbitrarily reduce the load 25%? What is your justification?

I have plenty of reading material, none of which supports a 25% reduction. No need to supplement my library. At best there is some reduction based on the slab being a heat radiator in lieu of just a heat sink. At best 2 to 5%. Could be an additional 1% or so if you bothered to calc the U value based on the position of the tubing in the slab.

Not sure 25% less fuel is the same as 25% less load.

Pipe in - pipe out...... give me a break!

 

[anthony666]

If you use "regular hvac heat loss calcs" do you just arbitrarily reduce the load 25%? What is your justification?

I have plenty of reading material, none of which supports a 25% reduction. No need to supplement my library. At best there is some reduction based on the slab being a heat radiator in lieu of just a heat sink. At best 2 to 5%. Could be an additional 1% or so if you bothered to calc the U value based on the position of the tubing in the slab.

Not sure 25% less fuel is the same as 25% less load.

Pipe in - pipe out...... give me a break!

you're not listening to me .. go back and re read what i wrote, where does it say i arbitrarily reduce anything ?? the boiler does not run all the time like a furnace which gives you your saving .. newer boilers have a log that shows their run time, typically during heavy load season (ie NOW) it's 16 hours a day, but i see some systems that run 8 hours a day .. it all depends on the build of the system and how well the rest of the house is designed

dude, no offense, but work on your comprehension skills

btus in x efficiency of boiler expressed as a % = btu's out .. so yes, less fuel is the same as less load

sorry about the offer to supplement your library, obviously you're on the crest of the hydronic technology wave and don't need any updates or refreshers or technical help from the people that spend a bunch of money on r&d and make my miniscule knowledge and personal experience a drop in the hot water bucket .. i'm really not into arguing on the internet, so i'm done on this thread

 

[hidollartoys]

you're not listening to me .. go back and re read what i wrote, where does it say i arbitrarily reduce anything ?? the boiler does not run all the time like a furnace which gives you your saving .. newer boilers have a log that shows their run time, typically during heavy load season (ie NOW) it's 16 hours a day, but i see some systems that run 8 hours a day .. it all depends on the build of the system and how well the rest of the house is designed

dude, no offense, but work on your comprehension skills

btus in x efficiency of boiler expressed as a % = btu's out .. so yes, less fuel is the same as less load

sorry about the offer to supplement your library, obviously you're on the crest of the hydronic technology wave and don't need any updates or refreshers or technical help from the people that spend a bunch of money on r&d and make my miniscule knowledge and personal experience a drop in the hot water bucket .. i'm really not into arguing on the internet, so i'm done on this thread

All basic system design information. Thanks for your help.

 

[mygarageone]

Low bid hacks as you call them are required to adhere to the plan and spec;s that the so called educated engineers have given them. Trust me , the engineer is the bidders worst enemy
( most times ) .
So if the system is over designed or under designed or what ever the case , it's installed as per plan and spec , no real deviation is allowed unless the engineer can be made to look good.
I have installed many , many Steam , Hydronic and Forced air systems. Air Handlers , chillers you name it. Every time we catch something not right , we go to the project super then we talk to the engineer and what do we hear ? install it per plan and spec.
Example , not long ago we did a very larger mechanical renovation job for a high school , new pumps , 16 of them to be correct. and 2 new 1 Million BTU boilers and everything else needed for the job.
We found the engineer called for one of the main pumps to be installed back wards , yes back wards. We brought it to his attention and he said we didn't know what we were talking about , put it in per plan. Ok, we do and guess what 2 days before Christmas eve the one wing of the building won't heat . We know why but he won't have it , but when he finally gets it , he says how much to redo pump ? we tell him $ 8,000 dollars , he blows a cork and says he won't pay , we talk to the school super and he tells engineer he will pay and for us to do the change out . It required a welder and helper , and 4 of my men working into the nite of Christmas eve to get it back into operation , all is well we go home.
Then we had to fight with engineering firm because they said we should have known better than to install a pump that way no matter what engineer said.
So before you start hacking on the contractor who does the install look a little deeper and you ;ll know where the real problem is.

 

[mygarageone]

Not sure I can afford a service call from MI to KS. Not sure you would want to travel here anyway.

I truly understand the "trade secret" aspect of any craft. I am a licensed master electrician and facility engineer. We are always the first in to diagnosis an equipment failure. HVAC, steam boiler and hydronic systems are just a small sample of the equipment I work on. Mostly all designed and installed by low bid hacks requiring us the reverse engineer the systems and properly apply the technology. We have two in slab systems (both way over engineered) and a building hydronic heating system utilizing forced air over radiators
(way undersized). Believe me I understand the system hydraulics and heat transfer issues.

I have never heard of a forced air system over radiators , ? Don't you mean air handlers with coils .
What am I missing ?

 

[hidollartoys]

Low bid hacks as you call them are required to adhere to the plan and spec;s that the so called educated engineers have given them. Trust me , the engineer is the bidders worst enemy
( most times ) .
So if the system is over designed or under designed or what ever the case , it's installed as per plan and spec , no real deviation is allowed unless the engineer can be made to look good.
I have installed many , many Steam , Hydronic and Forced air systems. Air Handlers , chillers you name it. Every time we catch something not right , we go to the project super then we talk to the engineer and what do we hear ? install it per plan and spec.
Example , not long ago we did a very larger mechanical renovation job for a high school , new pumps , 16 of them to be correct. and 2 new 1 Million BTU boilers and everything else needed for the job.
We found the engineer called for one of the main pumps to be installed back wards , yes back wards. We brought it to his attention and he said we didn't know what we were talking about , put it in per plan. Ok, we do and guess what 2 days before Christmas eve the one wing of the building won't heat . We know why but he won't have it , but when he finally gets it , he says how much to redo pump ? we tell him $ 8,000 dollars , he blows a cork and says he won't pay , we talk to the school super and he tells engineer he will pay and for us to do the change out . It required a welder and helper , and 4 of my men working into the nite of Christmas eve to get it back into operation , all is well we go home.
Then we had to fight with engineering firm because they said we should have known better than to install a pump that way no matter what engineer said.
So before you start hacking on the contractor who does the install look a little deeper and you ;ll know where the real problem is.

Would be great to live in your world. Little or no true engineering mainly supplier engineering, followed by award to low bidder, followed with any old way to get it done, followed with no final project inspections.

 

[hidollartoys]

I have never heard of a forced air system over radiators , ? Don't you mean air handlers with coils .
What am I missing ?

No , not air handlers. Shrouded radiators with motor mounted fan blades.

 

[mygarageone]

No , not air handlers. Shrouded radiators with motor mounted fan blades.

Ok, we call them unit htrs .

 

[anthony666]

No , not air handlers. Shrouded radiators with motor mounted fan blades.

he means a unit heater

 

[mygarageone]

Would be great to live in your world. Little or no true engineering mainly supplier engineering, followed by award to low bidder, followed with any old way to get it done, followed with no final project inspections.

My company does a lot of our own design build jobs as we call them here. But we also bid on many Engineered Mechanical systems for schools , water processing plants , boiler , chiller , steam jobs. Etc.
Install per plan , spec , regular inspections by engineer and state of Mich Mechanical inspection division , etc,etc.
So I am totally ignorant of what going on in other states. Michigan Requires inspections on all work performed . Plbg , Htg , steam , anything . And work must meet a set standard and code requirement.
And in order to get. A installers lic here , you have to have several years of experience with a legit contractor and then pass a written and hands on exam and pass both by minimum of 70% for each part of the test.
In other wards 70% for written and 70% for practical.
So we don' t those kind of problems here. At least not many.