System 2000 and EK1 - Oil or do Propane Conversion?

We're in a similar size house (4800 sq ft), with similar boilers (two circa 1990 Weil McLain WGO-5's) and similar oil consumption (1200 gal/yr) in similar climate (Boston area). But our DHW is from a natural gas heater.

I'm just a homeowner/engineer, not a heating pro, but I've learned a bit from the generous pros here. I've looked at a lot of new heating system options, and the one point warning I would give about considering a switch to a "high efficiency" condensing gas boiler is that you will NOT get the advertised high efficiency number UNLESS your heating system can heat the house for most of the heating season with supply water temperatures below 130 F. If your supply water has to be hotter than that, it will prevent the water vapor in the boiler exhaust from condensing, and you won't get that heat back. Your "high efficiency" condensing boiler is now not so high efficiency.

You'd need someone who knows what they're doing to analyze your system and evaluate how much of the season your boiler would actually be condensing. From that you can then figure how much fuel you'd be saving. Usually it's not as much as you think, because of the inherent limitations of a heating system that was (probably) designed for higher supply water temps.

If it were me, I'd go for the System 2000 EK1. It's a very nice system, and will probably be as high-efficiency as you can get (with the indirect for DHW) without condensing. Support is excellent, and you will avoid many of the headaches that come with servicing/repairing condensing boilers that cost $$ and eat into your fuel "savings." It will last a long time and work well with minimal problems.

It is possible that you could save in the long run with a condensing boiler, but the key is knowing how much of the time the boiler will be able to condense based on your required supply water temp. A heating pro can calculate that. But the unknown unknown is how much more it will cost you to service and repair a condensing boiler.

Do your sums very carefully… but I think you will find that oil is going to beat LP anywhere in Connecticut., even supposing you can get the extra say 8% condensing all the time. Which you won't.

Haha, yes, you must have missed the last 3 years of my posts discussing this ridiculous oversizing.

I was able to talk our heating oil company into downfiring to 1.0 gph nozzles running at 140 psi for an actual firing rate of 1.2 gph. But even so, we're still oversized by 3x. Outside air temp was 4 degrees last night, and the boilers ran a 33% duty cycle. So our actual building heat loss at near-zero outside air temp is 80-100MBH depending on what you assume for overall boiler efficiency. I use the 100MBH number for convenience and to be conservative. But our design day heat loss is probably closer to 80MBH because we're probably only getting 65% total efficiency out of the boilers.

Your oil is cheaper. $3.29 for oil is about $.0235 per 1,000 BTU. Propane is $.027 per 1,000 BTU. Your 1200 gallons of oil would cost about $4,000; the same amount of heat from propane would be around #4,600.

I don't know about you, but that is NOT the kind of "savings" I can afford…

Great comments all around - it's always encouraging to see homeowners like you ,@ctboiler28, digging into the analysis to make a good long term decision for comfort, efficiency, service, and reliability. Many excellent points have been made already, so I will only chime in on a few.

I come up with the same figures as @Jamie Hall to compare the fuels at 1200 gallons equivalent ($4,000 and $4,600 for oil and LP respectively). A reasonable rule of thumb to calculate the input heat loss is to use 1% of annual consumption on design day and divide by 24. So 1200 gallons would be about 70,000 BTU/hr input (1200 gallons x 138,600 BTU/gallon oil x 1% / 24hours/day). If you are running with an annual efficiency of 80% (generous), that would be 56,000 BTU/hr heat loss. And that covers hot water production as well. The 1% figure is the fraction of heating degree days on design day compared to annual heating degree days (this is a very good approximation everywhere in the Northeast).

In the BNL heat and hot water boiler performance study, the System 2000 low mass with thermal purge design performed with an annual heat and hot water efficiency higher than the 95 AFUE modcon and other condensing boilers tested. Low idle loss is a primary contributor to high annual efficiency - we've discussed this in many other threads, so I won't go into detail here; basically when a boiler shuts off, remaining heat energy is wasted, so finishing "cold" with thermal purge through thousands of cycles is a proven pathway to high annual efficiency. That means you'll get exceptional performance in a 30 year proven boiler. An indirect tank with a coil will provide very good hot water temperature and volume with System 2000, but it will not thermally purge as well as a plate heat exchanger with a stratified storage tank so there is a further opportunity to improve performance when the HTP tank reaches its end of life.

If you decide to stay with oil, Roth and Granby double wall tanks look much more modern and "appliance like" than typical steel tanks, and they have exceptional warranties; maybe something to consider.

Please PM me, call customer service at (908) 735-2066, or reach out to our territory manager from Connecticut, Mark Santangelo (413) 575-0210 msantangelo@energykinetics.com if we can assist with any questions you may have.

Best,

Roger