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Oversizing boilers
RC
Member Posts: 35
Is it ever going to end? When are half **** people going to get it? I went to two different houses today, and there was no way that whom ever installed the new boiler, did a load calculation. These boilers were ri-damn-diculously oversized for the houses. What the hell goes through people's heads? At one house, that was maybe 1200 sq. ft.
There it was a 187,000 input Dunkirk! Slant-Fin offers the program for free. Stop the Madness!!
There it was a 187,000 input Dunkirk! Slant-Fin offers the program for free. Stop the Madness!!
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Comments
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Oversizing boilers
Is it ever going to end? When are half **** people going to get it? I went to two different houses today, and there was no way that whom ever installed the new boiler, did a load calculation. These boilers were ri-damn-diculously oversized for the houses. What the hell goes through people's heads? At one house, that was maybe 1200 sq. ft.
There it was a 187,000 input Dunkirk! Slant-Fin offers the program for free. Stop the Madness!!
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Oversizing boilers
Is it ever going to end? When are half **** people going to get it? I went to two different houses today, and there was no way that whom ever installed the new boiler, did a load calculation. These boilers were ri-damn-diculously oversized for the houses. What the hell goes through people's heads? At one house, that was maybe 1200 sq. ft.
There it was a 187,000 input Dunkirk! Slant-Fin offers the program for free. Stop the Madness!!
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Our house had a 160,000BTU CI boiler in it. Guy from our town's biggest HVAC company came in, looked around, and after a minute wrote up a quote for a Munchkin 199.
(We're now doing fine with a Munchkin 80, and based on therms/dday we will be fine on a design day.)0 -
i have seen far crazier .....
the home owner pays some renta drunk by the hour and ends up with like 200 3/4 copper "T"'s...i seldom find room for more than three ,unless i go out of my way to add fittings...with some super large boiler every kinda wrong way charlie valve some times the home owner gets lucky and the guy runns off before doing really crule things to their home and materials ...0 -
it wont until
I pefect the anti lazy pill. H.O. believe the "expert" who says "you need this" cuz he's hte expert, Right?
Then we get a bad rep. Because we go in, and say "what the he** are you doing with a 200MBTU boiler when you only need an 80?
They don't remember you did it right (unless specifically asked), only spread the word that "ABCXYZ123 plg" screwed them.( no slight to anyone if you work for a company called ABCXYZ123 plg, just picking a random name).
EDUCATION for both the H.O. AND the salesperson. will slow it down.
M0 -
My favorite subject-when are these people going to smarten up? Probably never. If someday the government regulates this--maybe they already do-this industry will only have itself to blame-Isn't bigger always better?0 -
Check out the International Mech Code..Sizing is required
The 2000 code added 312.1, I believe, which looks to me that equipment must be sized according to Ashrae or an equivalent standard.
Boilerpro0 -
how about undersize?
I'm in this building where the south boiler is a w-m rated at 383. They musta spec'd it on s.f. of space, but there's 11' ceilings and 300 s.f. of glass on the store front. I measured and EDR of 420 AND the main is 180' long from the boiler room (thru unheated pipe chase). That boiler would run continuously from October to April. Bitterly cold temps involved dropping interior temps.
This thing used nearly as much gas as the properly sized north boiler which heats 5 times the space!
There's efficiency!
P.S. did I mention the copper near boiler piping and the fact that when they replaced a section of return they LEFT OUT THE RETURN VENT (on a two pipe system)?0 -
The requirements are there but
who is going to enforce or check? can you see the backlash if taxpayer money is used to verify correct sizing of heating units?
Some may occasionally get caught, but the majority will just put in too big, and tell the HO, "we'll its heats your house right? its not cold right? so it must be right, right?...I don't know why its using that much fuel..call the manufacturer"
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I was talking to an Old F%rt retired boiler guy a couple of days ago about this very thing. He said that he always oversized the boilers. First he did a heat load, then he picked a boiler that was at least 1.5 or even 2 times larger. Then he picked the burner based on 1.0 times the heat load. He usually uses a nozzle 10 degrees narrower than the one spec'd for the boiler to get a longer flame with the undersized nozzle. His own house has a 5 section CI boiler with a .6gph nozzle running at 125psi.
Makes sense to me.
Ron0 -
Back in my
residential days, I did pre-computer heat losses. Don't remember many homeowners who were satisfied w/ my numbers. The almost universal reaction was "that can't be large enough." Back then the enviros were predicting the "coming ice age."
I, and my boss, got tired of seeing the competition taking our customers w/ their "large enough" equipment. Figured if you can't beat them, join them. So we did. Looks like the "large enough" guys are still around.
Want to see "large enough" taken to extremes? Check out the multi-family boiler replacement market. It's real easy. Number of apartments X one (1) boiler horsepower. 150 apartments = 150 horsepower boiler. Who cares if the burner seldom gets out of low fire?
Or. One (1) apartment heated w/ hot water = 150' EDR. Steam is 100' EDR per apartment. Can't miss. Right?
How about the P/E who called to get the existing boiler's rating for a building we serviced? I gave it to him, and reminded him the boiler no longer heated domestic water. He assured me he was aware of that. He just wanted to make sure his specified boiler was large enough. Refused to answer his question about what size boiler I would install. You got it. He spec'd a boiler w/ a net that equaled the old boiler's gross. Money well spent.0 -
I know this topic is like beating a dead horse...But i have to ask what is wrong with oversizing a wee bit.
I have read that ultimatley size for design day and even go 15% below that figure. Sooo what happens when you get the rouge winters, where temps fall below design day by another 15 or 20 degrees fo r a week? Put on a sweater ? Not hardly. I want my system to be covered.
Now even when we talk a modulating boiler, what is wrong with jumping up in size won't the modulation aspect of the burner save in fuel costs and the extra Btus be like extra horse power there when you need it?
Gordy0 -
Yeah buy he can charge more for a 199!!!!!!!!!!!!!!!!!!!!!!
Mad Dog
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
G. Kaske
These guys arent talking about oversizing a wee bit. O.K. you want to cover yourself in the rouge of days thats fine . If you got the money and dont expect a fine tune system O.K. But we do this for a living and approach system design with professionalism I think our customers deserve that, not everyone can absorb outrageous heating bills and dont need a 454c.i. engine sittin in there volkswagon. So go ahead oversize a wee bit thats o.k.0 -
> These guys arent talking about oversizing a wee
> bit. O.K. you want to cover yourself in the rouge
> of days thats fine . If you got the money and
> dont expect a fine tune system O.K. But we do
> this for a living and approach system design with
> professionalism I think our customers deserve
> that, not everyone can absorb outrageous heating
> bills and dont need a 454c.i. engine sittin in
> there volkswagon. So go ahead oversize a wee bit
> thats o.k.
Give me a break!!! I don't care what size boiler is in place, measure the fin tube or cast iron rad. to determine0 -
I don't care what size boiler is in place, measure the fin
tube or cast iron radiation and I'll size my boiler to fit
what the system that will put out, always taking into
consideration the size of the house.0 -
Our heat load is ~65,000 BTU. Putting in a 199,000 BTU is 200% oversizing. That's a lot more than 15%.0 -
And what happens
when the smallest boiler is still way oversized for the home ? I just ran the numbers for my Levitt home , and the heatloss is a little over 33,000 btus . That's with double dormers, which I don't have . The smallest oil boiler I know is in the high 60,000 range . When the Feds come to bust me , they won't get me without a fight !0 -
Sweet, I was not talking in reference to a 200% oversize.
The same thing happend to the home I own 87,000 heat loss and a 150,000 net boiler. Although my fuel bill is less than alot of homes smaller in size.
Sorry if I gave the impression that I was thinking the discussion is out of line. Why is a system boiler considered fine tuned if its running 100% at design day.
When there is a very realistic possibility that temperatures could and will fall below design day at some point in time.
I know the design day in my area is -10* but there have been winters of -30* and no wind chill. If your boiler is fine tuned running 100% at -10* where would that leave ya.
I have seen a few posts on here where temps were below design day on some peoples installs and the old brown eye was twitching a bit waiting for a no heat call.
Gordy0 -
G. Kaske
Its just the original post talked of 1200Sq Ft @187000 btu input . Now thats oversizing. Im just concerned that unqualified contractors are eating away at the superior heating hydronics offers. Just ran into two uncontrollable oversized boilers today. Its not good. Didnt mean to jump down your throat. Good Day.0 -
Heatloss
Does that heatloss take into account your snowmelt for all your walkways yet?0 -
Homeowners humble opinion
As I have been reading this sight for several months now and have found all of your advice to be very professional and helpful let me throw my 2 cents worth in. I had previously posted under the STAY WITH GRAVITY? subject and was trying to make that decision when my boiler sprung a small leak. I called around to try to find someone in this area and was given the same name several times. This 33 year experience HVAC contractor indicated that my 50 to 60 year old 324,000 BTU boiler was too big and then suggested a 300,000 BTU Burnham. When I asked about his reasoning he indicated that he did not like to reduce more than 1/6 from what was prior size. I had already done a heatload.com calc which showed my house at 145,000 without sidewall insulation and 95000 if I get the insulation. No other contractor was recommended for boiler work in my area. What do I do now? (Just a frustrated HO)0 -
As with most things in life, it depends...
... What is a design day? According to ASHRAE and/or Manual-J, it's 9°F in Boston. I chose -15°F for the very same reason you're mentioning: Experience.
However, as others have pointed out also, it appears that ASHRAE has a rather substantial fudge factor built into their equations, as solar gain, thermal flymass effects, etc. are ignored. However, if you run their design-day conditions, our heat loss drops from 88kBTU to 63kBTU. Not a whole heck of a lot in the scope of things.
Either way, there is no reason to oversize boilers to any great extent. More often than not, systems these days are sized to meet the indirect WH demands rather than the heating load because the heating needs have flip-flopped: People want to take drenching showers, yet live in insulated homes. Go figure.0 -
Zurnie, that also will get you into trouble, size wise
My own home came with about 900 EDR hot water radiation, which would give you 900 x 150btu/edr = 135,000 output x 1.15 = 155,000 gross output, using non conservative numbers. Using conservative numbers: 900 x 170 btu/edr x 1.3 = 198,000 output.
The heat load for my home is about 50,000 btu/hr. Sizing by radiation would give you a boiler about 3 to 4 times the size really necessary.
Always do a heat load calc, its the only way to really know what size you need. Weil Mclain has a simple chart for sizing, which tends to be conservative, but gets you in the range, at least. Burnham has a slightly more complex calculation. Or you can look at fuel usage and work backward from there. This takes some sizing experience, but probably is much more accurate than even a full blown ASHRAE calc.
Boilerpro
Boilerpro0 -
Where are you located?
> As I have been reading this sight for several
> months now and have found all of your advice to
> be very professional and helpful let me throw my
> 2 cents worth in. I had previously posted under
> the STAY WITH GRAVITY? subject and was trying to
> make that decision when my boiler sprung a small
> leak. I called around to try to find someone in
> this area and was given the same name several
> times. This 33 year experience HVAC contractor
> indicated that my 50 to 60 year old 324,000 BTU
> boiler was too big and then suggested a 300,000
> BTU Burnham. When I asked about his reasoning he
> indicated that he did not like to reduce more
> than 1/6 from what was prior size. I had already
> done a heatload.com calc which showed my house at
> 145,000 without sidewall insulation and 95000 if
> I get the insulation. No other contractor was
> recommended for boiler work in my area. What do I
> do now? (Just a frustrated HO)
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Where are you located?..NM
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Good points but...
...this only works for hot water systems. A steam system must be sized according to the connected load, no matter how out of balance todays heat loss is compared to the EDR capacity of the attached radiators. However, I suppose you could run a heat loss, then downsize the radiators to allow a smaller steamer to supply the house...0 -
What to do when the smallest boiler isn't small enough.
Hi Ron Jr.
Short cycling is the worst thing when you can't get a small enough boiler. What I do when I can't get a small enough boiler is to install controls that allow a large high limit differential. That lengthens the run time of each cycle improving efficiency.
Interestingly, contrary to conventional wizdom, oversizing to an even bigger boiler when you can't get one small enough sometimes helps. But only if you under fire the oversized boiler. The added thermal mass of the larger boiler will allow longer run times for closer to steady state efficiency.
A buffer tank will also help. A "kill two birds with one stone" solution is an inside out indirect that gives you both the added thermal mass and efficient DHW.
When lower firing rate oil burners come on the market, it will help. I am now testing a burner that will turn down to .15 gph
Ron
Ron0 -
Ah, however,
I and others are finding out that sizing to radiation for steam is not always necessary (the Deadman have shown us this through systems such as the Moline. This especially applies to two pipe, where you can effectively downsize radiators by simply turning the supply valve to balance the system. I've also seen this with one pipe, by balancing the steam with adjustable rad vents.
You may not be able to size right to heat load, but you can go much smaller than radiation if you do some balancing.
Boilerpro0 -
WESTERN WEST VIRGINIA ON THE OHIO RIVER0 -
Any Contractor types near there? .....
Was through Huntington last spring I'm in northern Illinois.
I suspect you tried Find a Professional here.
Boilerpro0 -
YES, I TRIED AT THE 100 MILE RADIUS.0 -
Modulating boiler-wish
My ideal is a small version of something I had a chance to work with before the building was demolished (progress?!):
Kewanee 100 hp tubular forced induction modulating. Kewanee claimed highest efficiency between 20% to 80% of rated output. There's your headroom without sacrifice!
BTW the system was vacuum return, pneumatics throughout the building.
Is there a residential equivalent in a steam boiler today?
Observation: I think there's another reason boilers were so oversized in the coal days. Coal goes out. An entire building at 45 degree interior temp is one heck of a pick-up load!0 -
Waste
All of us can debate the loss of efficiency, comfort problems, lost equipment reliability, etc. but what about all of the wasted energy all of us are paying for, either directly or indirectly? Fossil fuels are really a non-renewable commodity. Read any study and it will estimate a finite time frame when all of us will be desparately searching for alternative energy sources. It only makes good sense to size any equipment correctly. Would any of us as contractors purchase a 500HP diesel to operated a service vehicle just because the purchase price might be lower? I realize this is an extreme analogy but in some cases this is almost what the uninformed or incorrectly informed consumer is doing by always looking at the bottom line delivered cost of a replacement heating system. There will always be someone who can do things cheaper. I have no quarrel with them. I still believe we either pay now or later. Sorry if this sounds like a rant. It is only MHO. Thanks for listening.0 -
taming the boiler.
If your not ready for the reno, you could use "Exquisite Heat" to tame that boiler.0 -
taming the boiler.
If your not ready for the reno, you could use "Exquisite Heat" to tame that boiler.0 -
taming the boiler.
If your not ready for the reno, you could use "Exquisite Heat" to tame that boiler.0 -
Dear Mr. Cockerill,
As useful as your reset manager may or may not be, I think it would be in the interest of everyone that you always disclose that you're the owner of the company that manufacturers this product when you go out and plug it 3 times in a row.
Thank you.0
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