Hi , all-- I'm a newbie to this forum, but I've done a lot of googling lately on the topic of residential propane heating systems lately, and this site has often been in the top search results. I've learned a lot, but somehow still feel a bit clueless about the best way to move ahead with our plans to retire our 25 year old oil boiler and move to a greener propane system. I live in southern NH in a 25 year old cape.... 2100 sq. ft., with 2x4 construction. Five years ago, I added blown in insulation to our attic to get it to R40... We also recently replaced some indows and the front and back doors, so the house is decently tight, if not fodder for the cover story in Insulation Monthly magazine. Anyway, with the volatility of oil prices, I thought that switching to propane might makes sense, both economically and environmentally. I've looked into modcon boilers, which a couple of local contractors have recommended, including the company that supplies us oil ( they also deal in propane). I like the concept of modcons, tho I do have some concern about their longevity. More to the point, I wonder if our house is well-suited for modcons. I think our downstairs area in particular does not have enough baseboard. On cold days of say zero degrees, our boiler fires away yet the house can get up to only 66 degrees or so. Fortunately, the temps are usually not that cold. If we are "under-baseboarded" with copper/aluminum finned board, that means that a modcon wouldn't do much condensing during most of winter, right?, since it would be heating water to 180 degrees or more. Would we not be better off with a conventional gas boiler, perhaps one with an outdoor sensor that modulated the water temps to align with the outside temp? I have a general question about copper baseboard: does not the efficiency of these convective baseboards drop off with cooler water temps? If so, perhaps the condensing boilers and also even the modulating ones are not suited for copper baseboard. At first I was thinking of a Triangle Tube Prestige Solo modcon, but now I'm wondering if a conventional gas boiler like a Veissmann Vitola (if I can afford it) would make sense. Or should I stay with our oil burner for a few more years? I burn 830 gal/yr with an indirect hot water tank and a wood stove I fire up most winter afternoons. By the way, natural gas is not an option in our semi-rural town, tho one of my neighbors heats with bituminous coal and says it saves him a fortune. Thanks, guys, I really appreciate any insights you can offer!

My first question when consulting on out of state or rural boiler (hydronic) heating systems is about the locally available fuel sources. The second is local support of the boiler being considered.

Here in Minneapolis we are blessed with a nearly complete variety of boilers, both gas and solid fuel, foreign and domestic. Naturally this is not the case in most of North America.

In every case a few axioms hold true regardless of local or continent for that matter as the laws of physics do not change.

First, any hydonic heating contractor worth his salt will perform a computer generated heat load analysis before specifying the boiler he intends to install for you. All else is simply conjecture.
Second, there is no reason to guess about the potential output of your fin-tube baseboard radiation, the output charts are available from all current manufacturers and some of us have the output
of many obsolete lines. This is true of all types radiation, though some of the older forms take some experience to size and even more effort to de-rate for proper weather sensitive controls (outdoor reset).
In fact, we always measure the radiation of any home we plan to replace a boiler for, since it is clearly a waste of money to install a boiler with output (too much) greater than the radiation to which it is attached.

Yours are particularly erudite questions, particularly in the your comparison of condensing versus non-condensing boilers. Each have there merits and as you point out, may be or may not be well
matched to a particular application e.g. load conditions, radiation, climate and user expectations. I think of this question more in terms for degree than absolute comparison.

For instance, a condensing boiler is obviously more suitable for radiant floor heating applications than a non-condensing boiler by virtue of the lower design water temperatures normally used
in such systems (below 140°F lets say). One might assume that a relatively high temperature heating system (emitter) such as your fin-tube (made worse by what you describe as inadequate length
for a given space) might disqualify the condensing boiler out of hand. On the face of it, this is all true.

However, the conventional low-efficiency (combustion efficiency mostly measured by stack temperatures in the 400°F range) atmospheric boiler uses inside conditioned (heated) air for combustion,
and requires outdoor combustion air as well, de-rating overall system efficiency. This is true regardless of installation, radiation or control features. This old boiler will likely operate to 210° if you like, but
it can't be argued that it is efficient in any way save that of short term investments perhaps. A conventional atmospheric boiler will never exceed 86% combustion efficiency for long. A condensing boiler
will never operate below 88% combustion efficiency if properly tuned but has the potential to run at 98% under certain load conditions.

All condensing boilers by contrast will have a maximum stack temperature in the 150°F range, same fuel, same radiation same house, less energy going out the flue. In the real world
closing off the drafty conventional chimney and the combustion air pipe (if no other appliances require it) can save 5% on the fuel bill right from the start. Most condensing boilers available
today can produce 200°F water temperatures though some European models (the Vitodens comes to mind) are limited to 176°F (makes more sense in Celsius at 80°C). Beyond this, one has
to remember the outdoor reset is built in, no outdoor air brought into the house, no chimney to draft conditioned air away, no open flame, no SOX , no NOX, the lowest carbon footprint on the
planet.

Now there is the question of reliability and there is no question that the hundred year old cast iron boiler with standing pilot is reliable. You pay for it with higher fuel bills.
Condensing boilers are reliable if properly sized, installed and maintained by an experienced factory trained professional. Wait til it breaks maintenance is not an option.

If your radiation is too short for the load, it should be supplemented. Short zones are also a concern for condensing boilers as a short zone can call the boiler and cause short cycling if the boiler will
not fire low enough to satisfy the radiant zone without shutting down on high or operating limits. Panel radiators are one of our most used upgrades adding to comfort with real radiant heat (fin-tube is a convector) and
the added output of a sandwiched fin. Like insulation, radiation is a long term guaranteed investment in comfort and economy. Once the head load (the amount of heat the boiler will have to
replace on the coldest 3 days of the year) established and the design temperature determined by the available - or future - radiator output a boiler and control system can be specified.

Propane and electricity compete where oil is not an option, so it pays to look into electric boilers or solid fuel with electric backup. If propane is your choice a condensing boiler is likely the boiler
for you. Propane and oil also compete in many markets and it should be no surprise that the cost per unit output is often very close. I would not be surprised if you find your fuel bill has not
changed much if a non-condensing oil boiler is replaced with a condensing propane boiler.

Maintenance on a propane condensing boiler will most likely be similar to the oil also as propane is not as clean or predicable as natural gas. Natural gas condensing boilers are very reliable and
will - though shouldn't - suffer considerable neglect before failures occur.

One of the problems with propane is ignition, related to outdoor temperature. In cold climate the gas is often "doped" to improve reliability and herein many problems can arise. Viessmann has a new
gas valve that is self-adjusting for fuel quality and type, a feature that promises to improve this old nuisance.

If you have a good service company, with the ability to perform a proper heat load and the radiation is sized to the load as well, the choice should be clear.

The features of a conventional cast iron boiler are generally reliability, low maintenance, and in the case of the new Burnham E-3 an add-on feature of ODR that will improve operating efficiency (more
comfort, less fuel consumption) but cannot improve combustion efficiency as the stack must be hot and the byproducts of combustion condense in the atmosphere instead of in the boiler. If you find
no one in your area that can properly specify the equipment you need, then an experienced designer may be the best solution. Once you know what to do the how is fairly straight forward for
a good local mechanic, be he plumber or heating contractor.

Badger,

Thanks for the detailed response... especially on the day before Xmas. You clearly go beyond the call of duty!

You make a number of great points. I can certainly appreciate the concept that one needs a certain amount of baseboard to generate X amount of heat and that a too-large boiler can't add anything except excess fuel consumption if there's not enough fintube. I measured about 65 feet of baseboard in our downstairs area, which is about 1500 sf, including a 15x15' family room with a vaulted ceiling. Our upstairs (650 sf) is two bedrooms and a bath; we keep it cool up there... it's pretty much heated by rising warm air from below.

I read than fintube yields a max of 590 btus per foot, so that would give us potentially 38,350 btus downstairs. I did a heat loss calc for the entire house and got about 49,000.... but if you discount the upstairs, the baseboard capacity seems to be OK... at least according to my figuring.

Anyway, assuming that we DO have enough fintube, do you think that the baseboards can convect efficiently at cooler temps that a modcon generates?

I infer from your comments that conventional propane boilers squander heat and efficiency via high stack temps, not burning outside air, and other factors. That begs the question: does a conventional boiler with ODR offer any benefits over modcons (except for perhaps being cheaper and less finicky)... or are there some applications in which conventionals would be the better choice?

One more follow-up question (sorry!): Is the ability of the Vitodens 200 to do a combustion test on each fire-up and tailor the burn to the quality of propane very important? I understand that it's the only modcon that does this... yet there certainly are many others out there that are burning propane. Would you personally consider anything else, like a TT Prestige?

One of the contractors I've met with has installed both TT and Veissmann units, but his preferred brand is the Burnham Alpine because of parts availability. He did say he'd be happy to install any one of them and did not seem fazed by programming either the TT or Vitodens. The real question here is: if you know one brand really well, can you program the others competently... or is each brand demanding of its own learning curve?

Cheers and hope you have a great holiday! Wish you installed units in NH!

Were all my clients as smart as you...well most of them are actually.

A man who will install any modcon is my kind of guy (if he also reads the installation manual). His logic for preferring the Burnham
Alpine is also valid (though one of my able colleagues is right now installing a new blower into an old Viessmann 200 that came next day air NH to Minneapolis). Burnham is known for there customer support. I less impressed with their commitment to condensing boiler technology. The Giannanni SS heat exchanger is certainly serviceable and used by several manufacturers, but the Viessmann is a Titanium Stainless mix and superior by most accounts. The Triangle Tube heat exchanger is a fire-tube design and preferred for certain applications.

Fin-tube radiation will not respond reliably at sub-body temperatures like a slab or ceiling will, but lower reset temps will improve comfort and decrease fuel bills.

I rarely see advantages to non-condensing cast iron boilers, save return on investment, since anyone will install them and they cost less to buy with a 30 year serviceable life.I can't make recommendations without doing the math, at which point a retainer would be in order.

Recuperating after a recent fall but fingers still work and house guests not quite arrived yet.

Not propane...but have you looked into the possibilities with geothermal (ground source heat pump)?

Annual service is a must for propane fried condensing boilers. Geo is rarely cost effective in residential applications more especially in cold climates.

I'm not an HVAC professional, so take what I say with the appropriate grain of salt, but I would have to disagree with the above statement.  With the current pricing on propane and oil, geo seems to make a lot of sense, especially the longer the heating season.  At least, in my case it did in upstate NY.  Payback over oil should be about 7 years in our case, after considering the federal tax credit on the system.

Now, the O.P. had questions about propane boilers.  Not to turn this into a thread about economic feasibility of geo...just thought I'd put the suggestion out there in case he may want to investigate that as an alternative.

You will want to make sure the HVAC contractor proposing a $40,000 Geo system does the math for you and further convinces you that you will get "your" $26,000 and change back in its 20 years of serviceable life.


"

IMO, geo (or an air source heat pump) usually pays off in well under 20 years when compared to propane. But every situation is different and geo installs are often not as competitive as they should be.

I'd love to do something more environmentally correct than burn oil. Propane is somewhat better for the environment, but I estimate it would cost us at least $400 and probably more like $500 more per year.

Geothermal sounds great, but I understand these systems are expensive, particularly when being retrofitted. Don't know of anyone local who has one, but I've heard there are a few guys in the area that specialize in installing these systems. Still, $20K+ is a bit out of our range!

Posted By Amazer98 on 03 Jan 2012 01:26 PM
I'd love to do something more environmentally correct than burn oil. Propane is somewhat better for the environment, but I estimate it would cost us at least $400 and probably more like $500 more per year.

Geothermal sounds great, but I understand these systems are expensive, particularly when being retrofitted. Don't know of anyone local who has one, but I've heard there are a few guys in the area that specialize in installing these systems. Still, $20K+ is a bit out of our range!

I'm wondering if you're underestimating propane usage by quite a bit??  You stated in your 1st post that you're using more than 800 gal of oil and using a wood stove currently, and your current furnace can't keep up.  Take a look at the calculator link on this page from EIA.  You should be able to put in your local fuel costs, and get a ball park on how a propane fired boiler will compare to oil.

http://www.eia.gov/tools/faqs/faq.cfm?id=8&t=5

As far as geo goes, don't forget that with the current federal credit, you will get a credit equal to 30% of the system (so a 21k system is less than 15k after the credit).  It may be well worth having an energy audit done on your house (any free ones available where you live?) then getting some estimates and fuel expense estimates from installers / engineers for the various options you are looking at.  This will help in sizing whatever system you plan on going with.  You may find that a geo system is not only affordable, but might be your best choice (as I did).  Either way, and whatever you choose, don't overlook any suggestions that come out of an energy audit as far as air sealing and insulation ideas.  Some of this is easy to do yourself and could lower your heat load a lot.  With the energy audit and a heat loss analysis of the house done, you can compare apples to apples, and make whatever choice is best for you based on real installation estimates, and real heat loss estimates of your place.

The EIA calculator assumed propane furnaces run at 78% efficiency, when modcons actually run at 95%, so I don't think it's as bad as you think. Still, it appears that in our southern NH market with oil at $3.49 and propane at $2.95, LP gas will run about 20% more if you compare an oil boiler running at 85% efficiency vs propane at 95%. Sad to say.

The EIA calculator assumed propane furnaces run at 78% efficiency, when modcons actually run at 95%, so I don't think it's as bad as you think. Still, it appears that in our southern NH market with oil at $3.49 and propane at $2.95, LP gas will run about 20% more if you compare an oil boiler running at 85% efficiency vs propane at 95%. Sad to say.

As to Green energy, where does your electricity come from?

PSNH produces electriciy from 3 fossil fuel plants, one wood burning plant and nine hydro plants. Its web site says that 21 percent of the power it generates comes from renewable sources. Not perfect, but probably as good as it gets in New England.

I read; mostly oil. If this is the case, a well kept oil boiler would be in order and focus placed on
heating system efficiency, e.g. outdoor reset, low-temp radiation and insulation.

Posted By Amazer98 on 03 Jan 2012 07:24 PM
The EIA calculator assumed propane furnaces run at 78% efficiency, when modcons actually run at 95%, so I don't think it's as bad as you think. Still, it appears that in our southern NH market with oil at $3.49 and propane at $2.95, LP gas will run about 20% more if you compare an oil boiler running at 85% efficiency vs propane at 95%. Sad to say.

You can change the efficiencies in the calculator to match up with what you are comparing (ie, change it from 78% to 95%).  Needless to say, I think you're in the ballpark.  When I compared propane to oil, in my case I saw no real saving switching. 

NG maybe, coal maybe, definitely not oil for a power plant.

It is interesting that we found this often the case when installing the first condensing LP boilers back in the late. 80's. It is true that the ModCon will burn cleaner and perhaps with less service, but fuel savings are not guarranteed. The notable exception may be in low temperaure applications where the built-in outdoor reset might lower fuel consumption by 10%. Of course (ODR) can be added to any boiler for a fee.

The free market assures the best use of resources when left unfettered, with the notable exception of over-regulated electricity, even so in market the off- peak rate is very close to natural gas price and three times the cost just across the road.