Bad place for a Mod/Con?

Gordy_2

Something sounds array with the comparision, if you are not saving money.

Luke_2

Bad place for a Mod/Con?

I have a well insulated home for a 90 year old home, that is 2000 sq/ft plus a 800 sq/ft basement. Calculations indicate I need 100,000 btu's. I am guessing my 50 year old 160,000 btu boiler is about 50% efficient in this home. I have about 240 ft of copper and fin base boards. I live in MN where it is quite cold. I plan to live in this home at least 25 years.

I have read the great things about Mod/Cons and was looking forward to the savings on the $1,400 I spent last year on N.G. for my boiler last year. I have had 5 contractors out to my house and they all said that Mod/cons won't last as long (7-15 years) and are more $$ to fix. One of them said in my house a mod/con will only run about 90% as it will run over condensing temps most of the time.

I am told cast iron boilers would run at 80-87% eff. and last 30-40 years. I am all for energy efficiency, but at 3-7% improvement over a new cast iron boiler, increased maitinence costs, and having to buy a $8000 boiler 2x vs. a $5000 boiler 1x in the time span I plan to live here, I'm not sure that a mod/con makes sense. Am I missing somthing in my considerations? Thanks.

Luke

D107

who did your heat loss calculation?

I'm just a homeowner who's learned alot from the wall. I'm sure you'll be hearing from the experts soon. One question would be who did the heat loss and how did they do it? Seems high for your square footage. A good heat loss means measuring every room, windows, doors, insulation, cold walls, cold partitions, slab floors, tranmission and infiltration loss, etc. Most contractors don't like to do it--takes alot of time. You can do it yourself with guidance from this website and a Slantfin program available for free linked to this site.

Also the existing radiation should be measured. The more oversized to your heat loss it is --especially if it's cast iron--the more likely a mod/con will work with it.

Also, the advice you're getting may be more to do with what the local contractors are familiar with than with your particular need. How many of them have ever installed a mod/con? Also, while many old boilers lasted 40 years or more, it is unclear if the current generation of standard boilers will last near that long. Some evidence suggests that with proper maintenance mod cons can last 15-20 years.

good luck,

David

Guy_6

ModCon

As a manufacturer's rep, I sell both cast iron and mod/con boilers. For MY money, I would put a mod/con in my own home. Yes it costs more up front, and the life span has yet to be determined, but the overall efficiency will more than make up for that. One point that I always make is that boiler sizing has traditionally been based on worst case scenario heta loss, which , here in New England, is usually 2 weeks out of the year. Outside of that, a traditional one rate boiler is overfired. Every time.

Steamhead (in transit)

How did they calculate your heat loss?

If they didn't do it on a computer it probably wasn't done right. Doing it manually takes lots of time so most installers skip it. A computer makes it quick and easy, especially if you have the program on a laptop that you can take to the job as we do.

You can get a free, easy-to-use calc program from Slant/Fin by clicking on the Heat Loss Calcs button on the lower orange bar at the top of this page.

Once you know your heat loss, you can compare the BTUs needed in each room with the radiation in that room. From this you can determine how hot the water has to be to heat the room at design temperature.

If you find that the house lacks sufficient insulation, storm windows etc., I would upgrade these before replacing the boiler. Doing so might mean you can use a smaller boiler that wouldn't cost as much to buy and operate.

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Ken_40

I too question

who did your heat load calcs.

The numbers seem a tad high.

I live in an area that has a design temp of -30 (northern VT) and unless your notion of "well insulated" is unrealistic, see the basic data required to do any designs, suspect - and therefore so is the remaining conclusions we or you might consider.

Not saying 100MBTU's is impossible however; just improbable.

Mark_46

Luke

Another homeowner here...

But I think David and Guy have hit the nail right on the head.

1) Your heat loss calc looks off if the house is well insulated. For reference, my house which is about 1,850 sqft, without insulation in some of the outside walls (im installing end of September) and old windows currently has a heat loss of about 55,000-60,000 BTUH using a 9 degree outside design temp. You may be well served to revisit the heat loss calc results. It is so imperitive as it dictates the needed equipment size.

2) I recently installed a mod/con, a Munchkin 80M. This winter will be my first heating season with it but with natural gas prices where they are, amortization of the boiler cost goes much quicker! Even if prices come down, it's still always wise to be efficient.

To me, a mod/con makes perfect sense. In fact I dont understand why the technology isnt standard. But think of it this way, do you drive your car at full throttle under all conditions? I will assume the answer is no ). A single fire rate boiler is the equivelant of that.

Perry_2

The heat loss might be reasonable

I ran the Slant Fin program on my house this morning. Design at -15F; 1300 Sq Ft (not counting the basement), half the windows upgraded. This house is considered well insulated for its age (it acually has 2" of insulation in the walls - many of the era did not). 64,800 Btu/Hr (Breakdown 47,735 for 1st and 2nd floor; and 17,071 for basement). What is really neat is that the progam said I needed 100 Ft of Cast Iron baseboard @ 140 F heating water for the 1st and 2nd floor. The house was built with 100 Ft, and now has 97 ft installed (the other 3 ft is laying in the garage attic due to a shortning of the kitchen baseboard sometime in the past).

100,000 for an older 2000 Sq Ft home in Minesota... Might be pretty close.

Perry

D107

his calc could be correct, but

the point I was trying to get across--aware that this site is visited by thousands of homeowners--is that many HOs SAY they had a heat loss done when in fact the contractor might have walked around the house, measured a few rads, rooms etc. Many homeowners have no way of knowing that that's not really the way it should be done unless they're lucky to do some reading or find this site.

Hopefully Luke will respond later and we'll know more.

Mike T., Swampeast MO

Presuming it's "standard" 3/4" copper fin baseboard 240' is good for about 70,000 btu/hr at 140°F average water temperature.

If this is a reasonably accurate Manual-J heat loss of 100,000 btu/hr I would suggest that 70,000 btu/hr would be more than sufficient to maintain space temperature in the coldest weather.

What this means is that a mod/con will be condensing the vast majority of the time and possibly ALL the time if you don't need rapid recovery from deep setback.

Given these assumptions, you have MUCH to gain from a condensing/modulating boiler!!!

Please don't try to compare AFUE efficiency percentages between conventional boilers and mod/cons! They cannot be directly compared in this way!

The contractors you have spoken to are somewhat correct regarding a couple of items. Nobody really expects mod-cons to last as long and with as little maintenance as simple cast iron boilers. Fortunately however, mod-cons in the US are based on (or identical to) those from Europe where THEY experienced the initial problems--rather like the early problems with condensing furnaces in the US.

And yes, many of the parts will be more expensive should they need to be replaced. Routine inspection/cleaning is required (annual to semi-annual is recommended), but it's very fast and easy with some models. Quite frankly all boilers should receive such attention...

Unfortunately many contractors seem afraid of mod-cons. People often get rooted in their old ways and don't want to take the time or expend the effort to learn new and TRULY BETTER ways.

Installation is VERY important. I'd suggest that you find a contractor who is already experienced with mod-cons or who truly wants to learn. You might want to send them to Heating Help...

p.s. If you use a contractor who is both unfamiliar with this class of boilers and unenthusiastic about using them, they unfortunately may not pay proper attention to the installation and setup. Then their prophecy will be self-fulfilling and they'll be happy but you'll be disappointed.

Luke_2

I tried!

No one calculated my heat loss, other than me. They all looked around, and guessed, bet I can tell, the 2 most experienced guys guessed what my calculations said, 102,000.
I have used guys based upon references from patients who used to work in the field and angieslist.com, seem to have good reputations. All 5 of them made no real attempt at true calculations, but I did.

I used a web site that was for students of this profession. Will tell you the site when I get home tonight. Took region, window placement, size, type, room wall area, and direction, sun exposure of the house (trees ect.) door area/type, took me hours, doesn’t sound quite a detailed as the one u guys used though. Thanks for the input so far.

Luke

Luke_2

calc used and more thoughts

I used heatload.com's calculator, mabey I should try again with the one on this site. As I am FAR from an expert on this I may have made an error on this.

I am totaly sold that Mod/Cons are more effecnt and a genrally superior product, but if I'm here for over 20 years (which I plan to be) that means I am buying a mod/con 2 times vs. a traditional one once, at todays prices that's a $12,000 price diffrence.

I spent $1,4000 last winter on gas for my furnace, if a mod/con runs 100% eff. and a traditional at 80%, thats a $280 dollar diffrence a year, and will take 42 years to pay back the diffrence. This does not consider the diffrence in cost of matinece

I would love to buy somthing that that would save scarse natural resourses, but I need to recoupe most of the intial investment. I may be missing somthing obvious here, but is seems like the price diffrence and longevity of a traditional boiler overwhelm the energy savings of a mod/con in my case. Though this statment may seem to indicate otherwise, I am open to any thoughts. Thanks everyone for your input.

Luke

Gordy_2

Efficiency

I'm a homeowner luke, You cant look at your differences in efficiency ratings between the two boilers to use as ROI. Modulation is probably as key as condensing is on these mod/cons.

Think of it as being able to throttle the burner to the load, verses wide open no matter what the load is on a CI boiler. Your savings will be well over the 20% you are using for ROI. If you can perculate in the lower 1/3 of the 5 to 1 turn down for most of the season Cha Ching baby.

Plus you are doing your part to save energy, something we all need to do.

Gordy

Floyd

THE biggest mistake.....

over and over here I hear and see people tring to compare boiler ONLY by the AFUE rating!!! While I understand that that is the only real thing that many people can actually get in black and white to compare boiler and eff., it is by FAR the most unreliable thing that any boiler or heating system can be compared on!!!! The way a boiler is installed is VERY important.... modulation and reset can greatly effect the overall heating eff. of the heating SYSTEM...... the system that is used to heat your house needs to be eff., while the boiler is a very important part, it is ONLY one small part of the SYSTEM....
Another thing.... the Mod/con boilers are continually being trashed here as super touchy and unreliable, will only last ten years blah, blah blah...... I have had a Mod/con running
non-stop since Oct. 03.....in a PIG BARN!!!!! no where on earth would you find those conditions in a house???? Okay we've all seen them.. :-) However that boiler running 24/7/365 for three years has WAY more hours on it than virtually any house would give in ten years.....Oh and it is also running at high fire 75% of the time.... now I expact this boiler to keep running for quite a while yet as I have had no problems with it to date. I expect the boiler in my basement that's been there for 3.5 years to give many years of service, way beyond ten years.....and I'm way more comfortable than I was before with the old bang, bang, boiler that stills sits there,,,,,"just in case".....I was a doubter also....

Floyd

Tony_23

Amen, Floyd

And who says today's CI boilers will last 40 years ? I've replaced many 650 #ers with 340 #ers of the same firing rate. Think they'll last as long ?

My own Ultra was the best thing I did for myself last year and I've NEVER had anyone complain about the results obtained by installing one.

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Mike T., Swampeast MO

BLESS YOU FLOYD!

The pigs can't adjust the thermostat(s)!

Josh S.

MOD CONs and Free consulting

I am a contractor in minneapolis and I believe in MOD CONs. I have installed 10 to 15 in the last 12 months. I will be putting one in my own home this winter. But, that said I have worked with our local gas company and compared therms consumed during the same time period 12 months prior to the new install. This comparision used software that took into account differences in outside temperature. The customer maintianed the thermostat on at the same setting, 68. The long and short of all of this research was that no significant improvement was found. Take into account that this house has a heating bill of around $3,500 per year and it is severly over radiated. I love new technolgy and I love saving the enviroment, but installing a MOD CON to save money is wrong reason, short or long term. A cast - iron boiler, with it's low maintaince will win time and time again. On another note...Luke, I hope you paid all FIVE contractors who showed up at your house and offered you their consulting. Because if you didn't you are cheating the system. The reason alot of contractors get burned out on free consulting and don't take the time to do a proper heat loss is customers like you. I think that the interesting thing is that even without the software derived heatloss most contractors can nail it pretty close.

Perry_2

This is not always true

Josh:

I accept that for a number of cases that there is no significant energy savings from people who installed the early mod-cons.

The biggest problem is that most people run their mod-cons the same way as their old boiler. On and off, on and off, etc. In that mode - there are going to be low savings.

I have been researching this issue for about a month now, and have recieved a lot of help (in private) from people on this forum. Amazingly, there are a lot of engineers and scientist that have meticulous records of what can be done out there. Each heating contractor seems to have at least one example (if not several).

In addition to having a mod-con you also need to have a really good control system to optimize how the boiler works. You also may need to adjust your lifestyle slightly.

The Vitodens 200 has a wonderfull control system built into it to optimize it's fuel efficiency. This is way beyond what many other companies offer as part of their boiler. You can purchase an equivelent control system to run other mod-cons from several vendors in the range of $1000 - $1500.

What most people do not understand; just offering an outdoor reset curve is only the beginning of improving the efficiecies of operation; and may not help much if it is the wrong curve for your application.

To really compare; you need to compare it to mod con boilers that have really good efficiency optimization controls - and the boiler operated in a reasonable manner (and we are not asking people to sacrifice a comfortable house).

However, here again; this is a process of paying for what you did not get up front - over and over and over. Too many people focus on putting in the cheapest boiler and the cheapest (if any) control system. A willingness to spend a little more coin up frong - in a wise way - can pay huge dividends.

Perry

Tony_23

That's funny

My lowest reported usage savings is above 30 %. If you're seeing no savings per degree day, something is wrong with the setup.

In fact, I have one older customer with a basement meter, that I read for her every month. The gas co. has been there twice in the last four months to double check the readings because of the change



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Brendan_2

Perry. with all due respect you seem to think that every house is suited for a VITODENS. from all the time i've spent here on the wall the pro's are saying that one should match the heatloss to the boiler, therfore unless you have close to a 90000 btu/hr heatloss you have too much boiler for your home.( yeah we know it modulates but does one size realy fit all)

I as a ho love my copper tube Laars set up to a 25*DT and matching my heatloss and with no intricate electronic components to mesmerize me when the thing fails to light off.

simpiicity always, spend your money on the envelope (insulate) and some of the lost boiler efficiency will be warming up your basement

Brendan

Mike T., Swampeast MO

That sure sounds unusual Josh. With the house "severely over-radiated" a mod-con should be thriving and definitely reducing fuel consumption.

What type of emitters? Was the boiler reset curve set to properly take advantage of their over-sizing? If the boiler uses "auto-boost" was it set properly for the system and they way the customer operates? If the thermostat is continually left at the same setting, there shouldn't be any need for such "auto-boost" but it's usually the default setting of boilers that have the feature. Did the customer's habits change with the new boiler?

Perry_2

Not really

I do not even think every situation is suitable for a mod-con - at all; and the post are out there to indicate that.

However, the Vitodens is - as far as I can see - the first boiler to include all the right controls within the boiler to achieve the best optimal efficiency.

I'm not saying you can't achieve it with some of the others - if you buy the right control system. I am also not saying the you can't do well with some of the others depending on how things match up (if for example the boiler comes with a single outdoor reset curve that goes to 180 F at 0 F, and you have copper baseboard you might do well).

I am well aware of the matching heat load issues. It is a problem for people like me who have heat loads at the smaller end of the envelope. Most of the smallest mod-cons are too big (and the ones that arn't seems to beg questions on durability). Yet, I'm convinced that a proper mod-con is going to be more energy efficient even if it is somewhat oversized - as long as you can control it properely. The modest extra capacity also helps out with Domestic Hot Water.

In this case, This person has a heat load in the range of 100,000 there are a variety of mod-cons that are sized for that.

In my case; it is undecided what I am going to do at this point. The option for a small conventional boiler is still on the table.

Perry