Tired of Pellet Stove How much To Hook Hi Eff Propane Boiler To Old Hydronics

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Driz

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Hi. I live in Northern NY out in the country. 1995 1400 SF house originally with 2 zone basic simple heating . 4 zone oil Peerless boiler throttled down to 105K. nozzle. I never was thrilled at how it worked even at a buck a gallon when it got over 3 switched it off went to pellet stove and electric supplement in 2004. I only use the boiler when I take off on vacation. I put in an electric tank in 2010 upstairs in a warm closet and ditched the side saddle oil rig.
So pellets have gone high and the usual sick of lugging them ect . A friend tells me of a coop nearby where I can get propane at 34cents over wholesale guaranteed. Pellet stove is old and dirty to use so time is ripe for a change. I'm not interested in instant hot water as there is high calcium concentrations in our area.
All my existing boiler copper is still in place as is the old side saddle piping and controls. I am reluctant to convert the existing boiler since it';s fairly rusty ect. I see units like Rinnai 75 for under 3K. What's the approximate cost to switch something like this out vs convert the gun on the old one and all the other considerations. Thanks
 

Dana

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What is the cost of electricity compared to your discount propane?

It might be cheaper/easier to drop in an electric boiler than any propane burner and is often comparable or cheaper to run. Propane prices are very volatile, but the average retail has been pretty high, even when fracking shale for liquids & propane/butane (which is only really profitable if there is a high market price for those products, not the natural gas.) Electricity is all over the place on pricing depending on which utility.

Even a 105KBTU/hr boiler is ridiculous overkill unless you live in the draftiest house built in 1995 and have no foundation insulation (both of which are things you can fix.) The true heat load at -10F is probably still under 34K, which is about the output of a 10KW electric boiler. If you have any old oil bills from back when you were heating only with oil with a "K-factor" stamped on the slip we'd have a very good shot at your true heat load numbers. Without the heat load numbers it's impossible to know which solutions make sense.

Another important piece when looking at propane burners is the amount & type of radiation is there on each of the two zones. (100' of 2" fin tube per zone? 5o' of cast iron baseboard on one zone, and some toe-kick heaters on the other?)

If you've been heating the place with a pellet stove it means you can probably heat the place with a cold-climate mini-split heat pump, which would have about 1/2-1/3 the operating cost of an electric boiler or propane (again, depending on your electric rates vs. propane pricing), and you'd get high-efficiency air conditioning out of it too.
 

Driz

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Being as I am on the infamous NYSEG New York State Electric and Gas at 17 cents/ KW electric boilers aren't the norm around here. The lucky ones are getting Nat Gas but that ain neva gonna happen out where I am.
 

Dana

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At 17 cents/kwh heating with cold climate mini-split air source heat pumps is about the same cost as heating with natural gas, and less than half the cost of heating with oil or propane.

Like pellet stoves, mini-splits are point-source heating (unless you get a ducted version, which is more expensive and somewhat less efficient.) With a better handle on your actual heat load (which can be determined via fuel use, or K-factors) we'd know if that's a possibility here. A typical 1990s vintage 1400' house would have a heat load at -5F of about 25-30,000BTU/hr. A single Fujitsu AOU-15RLS3H or Mitsubishi MSZ-FH18NA can put out 20,000 BTU/hr or more at -5F with a seasonal efficiency coefficient of performance of about 3 (it uses 1/3 the amount of electricity of an electric boiler) which means you'd be fully covered down to +5F with just the mini-split.

In the meantime the most economic thing is keep the Peerless as the "Hail Mary" backup system, then swap it out for an electric boiler as the backup when it eventually croaks. Even if it doesn't cover 100% of the load at your 99% outside design temp, from return on investment point of view, a mini-split would be a better investment than swapping out the boiler (at any boiler efficiency) since the 90% of your heating energy use covered by the mini-split would effectively be half-price compared to oil or pr0pane.
 

Dana

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Probably true, (especially if only using it as back-up for a mini-split), but be careful what you wish for, eh?;)

There's no financial payback in buying either new propane boiler or new oil boiler to replace the Peerless, since the small difference in marginal operating cost gained via higher efficiency will never recoup the installed cost of the new boiler. But there is financial payback from installing a high-efficiency heat pump to take on most or all of the heating load, since the operating cost is dramatically lower. You also get high efficiency air conditioning with that solution.

Then, if/when the boiler gives up (or you get sick of looking at it), an electric boiler would have the cheapest up-front installed cost back-up solution for the heat pump.
 

Tom Sawyer

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System 2000 will save him 20% minimum! maybe as much as 40%. Same for the Firebird. The problem with the mini splits is distribution. Unless the home is fairly open even a three off has problems with coverage, especially if there's a 2nd floor. And then there's the esthetics of three evaps hanging off the walls.
 

Dana

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He's been heating with a pellet stove, which has an even greater distribution problem than a wall-coil mini-split. If that was a satisfactory solution, 1.5 ton single-head mini-split in the same location would probably be good enough. But there are now some pretty good cold-climate ducted mini-splits that are nearly as efficient as the wall blobs that still have decent capacity at -5F to -15F.

A 3-head cold climate multi-split is almost certainly going to be oversized for his loads, taking significant hit in efficiency & comfort. This is a 1400' house built in the mid-1990s. The heat load at -5F or -10F or whatever isn't likely to be more than ~20-22,000 BTU/hr. (If it's more than that it has some serious air leakage or insulation installation problems.

A better oil boiler only saves money relative to heating with oil. It's still way more expensive than heating with a mini-split with 17 cent electricity. If the Peerless is only needed for 3% of the total annual heat, saving 40% from that isn't going to pay for anything.

A 1.5 ton ducted mini-split like the Fujitsu AOU-18RLFCD has an HSPF of about 11, but in the Adirondacks the annual average will likely be more like 9.5, or an average COP of 2.8. At 17 cents/kwh that comes to:

2.8 x 3412 BTU/kwh = 9554 BTU/kwh, or 1,000,000/9554= 105 kwh/MMBTU. At 17 cents that's $17.85/MMBTU.

Even with a perfectly sized oil boiler that uses no electricity and has no standby losses you're never going to get more than 120,000 BTU/ gallon of heat into the heating system, or 1,000,000/120,000= 8.3 gallons/MMBTU. To break even with a ducted mini-split the price of oil has to be less than $17.85/8.3= $2.17/gallon, have zero standby loss, and use no electricity for pumping or operating the boiler. The last time the average price of oil was that cheap in NY state was in February 2005. The average price since then has been well north of three bucks.

This week's retail price of heating oil in NY is $3.10. That's 50% higher than the break-even price even with an ideal oil boiler, and lower than the recent 5 year or 10 year average price of heating oil. To buy a Firebird or System 2K instead of a ducted mini-split is to bet that the average price of heating oil will be under two bucks for the next couple of decades, or that the average price of electricity is headed toward 30 cents or higher, neither of which seems like a good bet, in fact the converse is more likely.

The price of oil is down from the 5 year average, and may stay down for awhile longer if China's demand growth stagnates and Iran's oil industry gets back into the market. But at current prices the North American shale & oil sand boom is dying fast. Those shale companies who had hedged with insurance policies to guarantee $90/bbl for this years production are cashing them in to stay afloat, but those policies are not being renewed at $90. The current price of oil doesn't pay their expenses. (My in-laws in the oil & gas exploration biz just moved back to Seattle from their Calgary operation after 3-4 years of boom times, and are now trying to sell the project to a company with deeper pockets.) When that oil is no longer on the market, price volatility will resume. Whether that's in 3 years or 5 years, it'll be well within the lifecycle of a boiler or mini-split.

At 30 cents/kwh it's financially rational in NY to un-plug from the grid at current solar & battery pricing. (In sunnier Australia it's rational at 20 cents/kwh, and the current residential retail rates there are in the 30-35 cent range- the utilities are in an existential struggle to stay solvent.) Prices on solar and wind are still on a fairly steep learning curve, and are already putting downward pressure on wholesale electricity pricing right now, and that pressure will only increase over time.
 

Tom Sawyer

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No argument over the operating cost of the mini vs the boiler but s lot depends on how the house is laid out and yes, the pellet stove presents the same problem. The advantage of the mini is that you don't have to be the to feed it. Don't get me wrong, we install a lot of mini- splits but I'm pretty careful to be sure the home lay-out is suitable, especially when getting 8 to 15 grand to install the thing. Customers are not always all that willing to have the evap's hanging in their living spaces and many don't particularly like the air movement issue which is why I have one in my office so that they can see, feel and hear what they will be getting. If it's a two story home, the second floor always presents challenges too. Yes, relative to oil is correct but it sounds like he doesn't have a nat gas option and propane would be insane.
 

Dana

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His primary objection to the pellet stove is lugging the fuel and price trajectory, which makes me think distribution isn't much of a problem and he'd be OK with higher efficiency wall-blob version. The noise of a pellet stove is louder than a 1.5 ton mini-split too.

But the ducted version the operating cost projections were done on would take care of the distribution issue too, even if it's a 2-story (though at a fairly modest 1400' it's probably a single story.)

If you're getting $8-15KUSD to install a 1.5 ton mini-split I'm in the wrong business! I've never seen it break $5K for single head, or more than $7K for a ducted version (retrofitting the ducts.)
 
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