Dunkirk vs Veissman vs ?

Robert O'Brien

is either a big old house or a absolutely huge newer home.Do a heat loss first,Comparing a Dunkirk to a Viessmann is like comparing a Hyundai to a Mercedes.They're both cars but thats where the similarities end

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Neil Rosen

I'm considering changing out my oil burner for gas. I'm in the 175 - 200,000 BTU range. What's my best bet? Dunkirk, Viessman? Are the 94 - 95% eff units worth the cost over the 90%ers? BTW, how much should I budget for a replacement unit? Is it worth going condensing if I have a chimney(that will probably need to be relined for Gas)
Thanks

Mike T., Swampeast MO

With gas, you'll most likely be at the mercy of a single supplier. With fuel oil you usually have a choice and the suppliers usually provide services (like cleaning/inspection). Gas companies (at least in my area of the country) do nothing of the sort.

If you do switch fuels, make CERTAIN that a heat loss calculation is conducted. Older boilers are very frequently oversized. 2x - 3x oversizing is not at all uncommon.

Condensing/modulating boilers like the Viessmann Vitodens cannot be compared via AFUE to conventional boilers. Properly installed in a suitable system they will achieve fuel reduction MUCH greater than implied by AFUE.

Condensing/modulating boilers use different venting--often plain PVC drain line; others use proprietary components. It may be possible to route through an existing chimney, and it may be impractical. Chimney lining is a fairly expensive process.

The habit here is not to mention pricing as it varies greatly--not only by the area but depending on the system.

In general, the lower the temperature at which your system can operate, the more efficiency you get from a condensing/modulating boilers. Radiant floors (tube in concrete or using heavy conduction plates) are great. Standing cast iron radiators are usually very good as well. Cast iron baseboard usually requires higher temperatures and fin baseboard usually requires higher still. Bare tube radiant floors and hydro-air typically require the highest temperatures.

If you have cast iron radiators, a condensing/modulating boiler is nearly a no-brainer. Also consider thermostatic radiator valves (TRVs) on all radiators. They do add to cost, but their value is exceptional. Standing iron radiators, TRVs, and a condensing/modulating boiler will usually produce systems of exceptional comfort and efficiency and are likely the closest rival to radiant floors.

Ted_9

sizing

yes, that house must be large and unisulated.

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Steve Ebels_3

This is an actual letter which was received by a Viessmann installer and forwarded to his distributor. The distributor sent it along to me. Read it and draw your own conclusions. I have edited out the names to protect the anonimity of those involved. The job was in the state of New York.






"I would like to take a moment to thank you for the fine work you did replacing the boiler system at my home. As you know, my house is 8500 SF and composes 6 apartment units and complex systems of piping. The Vitodens Boiler and indirect domestic hot water tank has been working excellent since you installed the system 1 year ago.

As I studied architecture and building performance at UC Berkeley, I was well aware of how inefficient and ill-installed my previous heating system was. I interviewed almost a dozen heating contractors before I chose your company, as I am very concerned with energy efficiency and long term lifecycle costs. Your knowledge about heating systems impressed me and you were given the contract.

You were able to replace not only the boiler and hot water tank, but improve the efficiency of the piping, pumps, and computerized controls as well. All together, the system you installed made my home much, much warmer than previous years, but also reduced my utility bills by HALF. And that includes the fact that the cost of natural gas was about 30-40% higher last year than previous years.

My home is an income producing apartment building and thus I have maintained accurate records of all expenses for tax purposes. In 2002-2003, my property spent $17,578 on utilities, most of which is always heating fuel. In 2003-2004, it cost $16,789 for utilities. In 2004-2005, after much added insulation and new storm windows, it cost $14,692 for utilities. In the past 12 months, since your work, I have spent only $7830 on utilities. I am simply amazed.

And now, as winter approaches again and many landlords will be worried about outrageous utility bills, I sit back relaxed, knowing that my house/income property will be toasty warm and extremely efficient to heat. Thank you //////////

Neil Rosen

Great info

Waht about efficency? Are the 95%ers worth the extra dollars over a 90%

DanHolohan

Robert,

here's what I read about Dunkirk:

"Dunkirk's new Q95M-200 gas-fired modulating condensing boiler is the only 95% AFUE boiler available today and the only boiler to qualify for the U.S. Federal Government's $150 Homeowner High Efficiency Tax Credit. Ideal for high efficiency replacement jobs, new homes, radiant heating, and domestic hot water applications, Q95M cost saving features include infinitely modulating capacity from 80 to 200 MBH, outdoor temperature reset, and domestic hot water priority. The Q95's electrical operating costs are lower than other high efficiency boilers because no primary/secondary dedicated piping arrangement is required. One circulator can service the boiler and all zones. Intake and flue gasses can be piped with readily available 3" PVC to 60' and the contractor has the option of left, right or rear exit for return plumbing and gas piping. Piping connections on the rear and top of the units facilitate multiple boiler installations with boilers in close quarters and the integral condensate trap requires no field assembly. The unit features a standard 115v convenience outlet as well."

Now what's wrong with that?

Robert O'Brien

Dan

Not a thing,I've been to the class on that boiler and it looks nice.The only drawback is the 200K BTU rating and it's step modulated so it a bit large for most apps. My off the cuff comment was directed at the Dunkirk conventional boilers which are the lowest priced boilers in their class vis a vis Viessmann which are the priciest( and deservedly so) in the categories they compete in. I apologize to Dunkirk for implying their Quantum is the same as a Dunkirk non -condensing boiler which it certainly is not.

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DanHolohan

Thanks for that.

We have tens of thousands of homeowners visiting here each week, and I hate to paint any company with such a broad brush stroke.

Perry_2

I think so

What you need to understand is that the 94% and better modulating condenser boilers operate totally different than the 90% and less more conventional boiler (that perhaps has a condensing coil).

The difference in operation gives you much more EFFECTIVE efficiency.

I am having a vitodens 200 installed in my house right now (day 2 of the install) for just that reason.

I figured that I could install a 89% efficient boiler and save perhaps 15-20% off of my fuel bill; or the Vitodens 200 (94.2% efficient)and have a realistic shot at saving 50% off of my fuel bill.

One caution: You need to properly size the modulating condensing boiler to your system, it must be able to be connected to your system configuration in a manner that allows you to gain the maximum efficiency advantages, and you must have the right controls to provide allow the boiler to operate the most efficient.

I found Viessmann had all the answeres on how to do that with my existing system. The other companies did not, without using 3rd party controls.

It may have been possible that the Munchkin boiler might have worked reasonably well - except the local guy pushing Munchkins was wondering how he would connect to my system with it.

Another vendor offered me a mod/con that was way to large - and would have operated as a normal boiler because the minimum firing rate was higher than all but the worst weather days of the year.

Done right - they are great.

Done wrong - they are a waste of money.

Guess that is true of any boiler install.

Perry

Mitch_4

step modulated?

I took the class in Canada and the trainer says its fully modulating, not step.

Clarify please?

Jim_95

Any comments on the Buderus GB 142 /60 condensing boiler ?

Mikey_3

Robert

In Dans posting about what it says about the Dunkirk Q95 it says "infinitely modulating from 80-200..."

What do you mean when you say step modulating?

Mikey