Cracked boiler
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There are two flavors of Versa (Flame and Hydro) with multiple sizes within each flavor. The smallest of either would work just fine with your loads- which ever comes in cheapest is the "right" one. The Hydro has a bigger turn-down ratio for space heating and may be ever so modestly higher efficiency than the Flame at your modest loads. The min-fire input of the Flame is 35,000 BTU/hr which is going to be well above your peak heat load, but given the high thermal mass it doesn't much matter- it would be hard to short cycle it.
I don't know how easy or hard the conversion from propane to natural gas would be on these models. It's worth asking somebody at HTP (not your local installer, who may not have the details right) on whether that's something reasonable to do. Some of HTP's modulating condensing boilers have standard conversion kits, but not sure if they have similar kits for the Versa to make it super-easy.
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Tom Sawyer
In the Trades
Whatever you do, do not go with propane
Why do you say that? Our thinking is that with a propane boiler, if natural gas does come to my street, it would be easier to convert.
The cost per source-fuel BTU is higher than oil, often substantially more. But a 3-4x oversized 87% efficiency oil boiler that's short-cycling won't even deliver 80% average efficiency, maybe not even 75%. A condensing HTP combi reliably delivers mid-90s efficiency (if you tweak the outdoor reset curve correctly) which shrinks the difference in delivered BTU cost a bit, but it's still more. Prices for both fluctuate a lot, but in general heating with propane costs 10-25% more than heating with oil at the recent 5 year price averages.
Oil has a source fuel heat content of 138,000 BTU/gallon.
The amount going in to the heating system if 87% efficiency: 0.87 x 138,000= 120,060 BTU/gallon. That's (1,000,000/120,060=) 8.33 gallons per MMBTU (million BTU.) At 87% efficiency at this week's $2.28/gallon that's 8.33 x $2.28= $18.99/MMBTU
The amount going into the house at 77% short-cycling efficiency: 0.77 x 138,000= 106, 260 BTU/gallon, which is (1,000,000/106, 260 =) 9.41 gallons/MMBU, which is $2.28 x 9.41= $21.46/MMBTU.
Propane has a source fuel heat content of 91,600 BTU/gallon.
Burned at 95% efficiency the amount going into the heating system is 0.95 x 91,600= 87, 020 BTU/gallon, for (1,000,000/87, 020 =) 11.49 gallons/MMBTU. At this week's price of $2.68/gallon, it then cost $2.68 x 11.49= $30.79/MMBTU, which is still substantially more than heating with a ridiculously oversized oil boiler (this week, at least.)
Oil boilers need annual maintenance which comes at a cost, which for very small heat loads may more than make up the difference on raw fuel cost. If you use 60 MMBTU of space & water heating per year that's 500 gallons of oil @ 87% efficiency , x $2.28/gallon is $1140/year. If 95% efficiency condensing propane that's 690 gallons/year x $2.68/gallon comes to $1850.
The $700 difference buys quite a bit of annual maintenance. How much are they charging for the oil tank replacement?
But you might also factor in what it might cost to heat the place with a mini-split heat pump. A right-sized ducted mini-split would deliver a seasonal coefficient of performance (COP) efficiency of about 3.0, and a wall coil type would deliver something in the low 3s. The average residential retail electricity price in NH is about 17.25 cents/kwh. Converting kwh to BTU, each kwh is good for 3412 BTU if used in a resistance heater like an electric baseboard, but at a COP of 3.o a mini-split delivers 3 x 3412= 10,236 BTU/kwh, or (1,000,000/10,236=) 98 kwh/MMBTU.
At 17.25 cents/kwh that's $16.90 MMBTU, which is quite a bit cheaper than this year's decade-low oil prices. At 60 MMBTU/year heating needs that would cost $1014, or 12% cheaper than the best-case heating with oil (not even counting the annual maintenance or power used by the oil-fired system.)
And it air conditions at high efficiency too.
Oil has a source fuel heat content of 138,000 BTU/gallon.
The amount going in to the heating system if 87% efficiency: 0.87 x 138,000= 120,060 BTU/gallon. That's (1,000,000/120,060=) 8.33 gallons per MMBTU (million BTU.) At 87% efficiency at this week's $2.28/gallon that's 8.33 x $2.28= $18.99/MMBTU
The amount going into the house at 77% short-cycling efficiency: 0.77 x 138,000= 106, 260 BTU/gallon, which is (1,000,000/106, 260 =) 9.41 gallons/MMBU, which is $2.28 x 9.41= $21.46/MMBTU.
Propane has a source fuel heat content of 91,600 BTU/gallon.
Burned at 95% efficiency the amount going into the heating system is 0.95 x 91,600= 87, 020 BTU/gallon, for (1,000,000/87, 020 =) 11.49 gallons/MMBTU. At this week's price of $2.68/gallon, it then cost $2.68 x 11.49= $30.79/MMBTU, which is still substantially more than heating with a ridiculously oversized oil boiler (this week, at least.)
Oil boilers need annual maintenance which comes at a cost, which for very small heat loads may more than make up the difference on raw fuel cost. If you use 60 MMBTU of space & water heating per year that's 500 gallons of oil @ 87% efficiency , x $2.28/gallon is $1140/year. If 95% efficiency condensing propane that's 690 gallons/year x $2.68/gallon comes to $1850.
The $700 difference buys quite a bit of annual maintenance. How much are they charging for the oil tank replacement?
But you might also factor in what it might cost to heat the place with a mini-split heat pump. A right-sized ducted mini-split would deliver a seasonal coefficient of performance (COP) efficiency of about 3.0, and a wall coil type would deliver something in the low 3s. The average residential retail electricity price in NH is about 17.25 cents/kwh. Converting kwh to BTU, each kwh is good for 3412 BTU if used in a resistance heater like an electric baseboard, but at a COP of 3.o a mini-split delivers 3 x 3412= 10,236 BTU/kwh, or (1,000,000/10,236=) 98 kwh/MMBTU.
At 17.25 cents/kwh that's $16.90 MMBTU, which is quite a bit cheaper than this year's decade-low oil prices. At 60 MMBTU/year heating needs that would cost $1014, or 12% cheaper than the best-case heating with oil (not even counting the annual maintenance or power used by the oil-fired system.)
And it air conditions at high efficiency too.
We've scratched the idea of the heat pump. Although the heat pump's ability to cool is appealing, it won't solve the problem of how to heat the bedrooms and second bathroom. That problem in addition to the already incurred expense of the 4 new radiators and we want to stick with hot water heating. The question now is how to make the water hot.
We got a couple another quote with 3 options , a 90% efficiency System 2000 EK1 Frontier Premier floor mounted, non-condensing boiler for $10,830, a System 2000 Accel CS floor mounted, propane fired condensing boiler for $11,720 Viessmann Vitodens 100-35 Combi $8,835. All those quotes included removal and disposal of the oil tank.
We got a couple another quote with 3 options , a 90% efficiency System 2000 EK1 Frontier Premier floor mounted, non-condensing boiler for $10,830, a System 2000 Accel CS floor mounted, propane fired condensing boiler for $11,720 Viessmann Vitodens 100-35 Combi $8,835. All those quotes included removal and disposal of the oil tank.
The EK1 Frontier puts out about 82,000 BTU/hr with the smallest (0.68 gph) jet installed. Your radiation adds up to about 125' of baseboard equivalent. That's a ratio of ~650 BTU/ft-hr, so with the high-limit temp cranked to ~190-200F it should balance reasonably with your ~125'base-boardheat emitters. Being more than 3x oversized for your likely load you won't get 88% efficeincy out of it, but due to it's fully integrated heat-purging control system it'll do better than 80%, maybe bumping on 85%, despite oversizing. See Table 3, System #3 in this document. System 3 was a system 2K oil-fired beastie. At 3 x oversizing in an ideal laboratory setting it delivered 85.3% efficiency. You'd be at a bit more than 3x oversizing, and not in a laboratory, but still. It's easily convertible to natural gas, which would run at ~86% if right-sized, but at your house, low-mid-80s due to the oversizing factor, call it 83%.
The smaller EK-1 System 2000 Accel CS has a max BTU output of 115K, which is on the very small side for serving two bathrooms simultaneously, but should handle 1 just fine. It's minimum output is about 23,000 BTU/hr. At 125' of baseb0ard equivalent that's 200 BTU/ft-hr, which means it balances with ~120F average water temps, and should hit the mid-90s on combustion efficiency without cycling when it's tweaked in. That 23K output is about where I'd expect your design heat load to come in. So if you can tolerate the less than stellar hot water performance this might be OK. The EK-2 version's min-fire output is 38,000 BTU/hr, which would be 304 BTU/ft-hr on the radiation which balances at 135-140F average water temp, which is outside the condensing range. It would deliver 87-88% efficiency in space heating mode, but would have much better hot water heating delivery. Buffered by 5-6 gallons of internal tank they get around most of the quirks of tankless hot water heaters.
The min-fire output of the Viessmann Vitodens 100-35 Combi is about 34,000 BTU/hr. With 125' of baseboard that's 270 BTU/ft-hr, which would balance at about 130-135F average water temp (140F out, 125F return), which is the edge of condensing. You'd get something like 90% efficiency out of it if tweaked in, maybe even 92%, but it will never modulate when serving a space heating load (but it would when serving domestic hot water.) It's a glorified tankless hot water heater, with some of the tankless quirks when serving hot water.
It's hard to make a case for the Versa Solar due to the high upfront cost, complexity/reliability & maintenance of solar-thermal systems. I know of one person in MA who recently scrapped (rather than repairing for the third time) his ~15 year old solar thermal system, devoting that roof real estate to photovoltaic panel, and installing a GE GeoSpring heat pump hot water heater. Rooftop PV is essentially maintenance free, and even if he replaces the GeoSpring every 10 years the lifecycle cost will be lower than what his solar thermal system was costing him to maintain & repair. Rooftop PV + heat pump water heater may make more sense than heating hot water with an indirect using expensive fuels. The financial analysis of the PV and the heat pump water heater should be able to stand on their own, and need not be considered as a package.
The smaller EK-1 System 2000 Accel CS has a max BTU output of 115K, which is on the very small side for serving two bathrooms simultaneously, but should handle 1 just fine. It's minimum output is about 23,000 BTU/hr. At 125' of baseb0ard equivalent that's 200 BTU/ft-hr, which means it balances with ~120F average water temps, and should hit the mid-90s on combustion efficiency without cycling when it's tweaked in. That 23K output is about where I'd expect your design heat load to come in. So if you can tolerate the less than stellar hot water performance this might be OK. The EK-2 version's min-fire output is 38,000 BTU/hr, which would be 304 BTU/ft-hr on the radiation which balances at 135-140F average water temp, which is outside the condensing range. It would deliver 87-88% efficiency in space heating mode, but would have much better hot water heating delivery. Buffered by 5-6 gallons of internal tank they get around most of the quirks of tankless hot water heaters.
The min-fire output of the Viessmann Vitodens 100-35 Combi is about 34,000 BTU/hr. With 125' of baseboard that's 270 BTU/ft-hr, which would balance at about 130-135F average water temp (140F out, 125F return), which is the edge of condensing. You'd get something like 90% efficiency out of it if tweaked in, maybe even 92%, but it will never modulate when serving a space heating load (but it would when serving domestic hot water.) It's a glorified tankless hot water heater, with some of the tankless quirks when serving hot water.
It's hard to make a case for the Versa Solar due to the high upfront cost, complexity/reliability & maintenance of solar-thermal systems. I know of one person in MA who recently scrapped (rather than repairing for the third time) his ~15 year old solar thermal system, devoting that roof real estate to photovoltaic panel, and installing a GE GeoSpring heat pump hot water heater. Rooftop PV is essentially maintenance free, and even if he replaces the GeoSpring every 10 years the lifecycle cost will be lower than what his solar thermal system was costing him to maintain & repair. Rooftop PV + heat pump water heater may make more sense than heating hot water with an indirect using expensive fuels. The financial analysis of the PV and the heat pump water heater should be able to stand on their own, and need not be considered as a package.
I'd run the room by room heat load calculations on the house (or hire an energy nerd to do it, not an HVAC contractor) for both the rooms that would be easily reached by a ducted mini-split and those that couldn't, to see if there isn't a mini-split solution. Ideally this wouldn't be happening at half-past December- the time to do it would have been last spring, but the boiler doesn't always want to fail on YOUR schedule... (Murphy's Law says that it never does.)
Also note, Maine's average electricity cost is about 15.6 cents, not 17.25 cents, as in NH. (I can't say why I had it in my head this AM that you were in NH... not enough coffee?) so a mini-split would would have an even lower marginal operating cost than quoted. It's cheap- as cheap as natural gas in some New England markets. I can't say for sure what YOU are paying for power.
If most of the house can be heated with a 1.5 ton ducted mini-split (probably can) I'd mothball the hydronic system, or micro-zone it using a cheap electric boiler to serve the rooms that aren't served by the mini-split. An electric boiler tolerates short-cycling well, and runs at the same efficiency even when short-cycled. At 15 cents/kwh an electric boiler's output is ~35% more expensive heat than propane at current MA prices, but if it's only a small portion of the house it doesn't really much matter. If you run the electric boiler micro-zones with setback thermostats &/or occupancy sensor controls you can reduce the heating costs of those rooms considerably, and let the adjacent heat-pump heated zones heat them passively much of the time at 3x the efficiency. But it may be hard to find the design and installation talent for this approach on short notice.
If you're sticking with the existing heat distribution, the EK1 Frontier with an 0.68 gph jet still gets you there quickly (specify that jet- the boiler has higher firing rates with other jets that you absolutely DON'T want) , and you can hope/lobby that the gas-grid eventually reaches you before the price of oil spikes again. It looks really cheap this year, and probably next, but the US shale oil can't even be pumped profitably from most existing wells at today's $35/bbl WTI price point- that oil is coming off the market.
John Molyneux
Member
Nothing wrong with propane from the fuel side, but one thing to keep in mind is that propane dealers are able to lock you in as customers much more than in the heating oil market, meaning that you can't shop around to get the best price - unless maybe you buy your own tank(s). There's much less fuel price transparency because of the way the industry is set up. I was a long-time propane customer (in Maine, also) and I'm really happy they finally brought natural gas down our road. I have one neighbor that is paying $1.90/gallon because he owns his own tank, while the same company was charging me $2.75. When I called the fuel supplier to see if they had any incentives to keep me from converting to gas they offered me a price of $1.50. So I guess they were making a healthy markup. In contrast, the local heating oil market is cut throat competitive and you can always see whether you're getting the best price.
I spoke again with our current plumbing/heating guy, who said I do not need to replace the oil tank at this time. Thus, having thought carefully on all the options and listened carefully to all your terrific advice, we've decided we will go with his quote for a Biasi boiler, but will size down on the boiler to the Biasi 3. His quote comes to $6325.
You'll do just fine with the Biasi B3. (That too can be retrofitted with a gas burner later if gas becomes available.) It'll do measurably better if it's fitted with a heat-purging controller like an Intellicon, since the burner is still more than 2x over-sized for your actual load.
If you decide to air condition the place, DO consider a modulating mini-split heat pump rather than an oversized single speed AC-only system., since that will give you some options when (not if) the price of oil spikes again. Even people who hated noisy drafty forced hot air furnaces, or have experienced the misery of the tepid wind-chill output of old school ducted heat pumps have been able to get comfortable with modulating mini-splits.
If you decide to air condition the place, DO consider a modulating mini-split heat pump rather than an oversized single speed AC-only system., since that will give you some options when (not if) the price of oil spikes again. Even people who hated noisy drafty forced hot air furnaces, or have experienced the misery of the tepid wind-chill output of old school ducted heat pumps have been able to get comfortable with modulating mini-splits.
Tom Sawyer
In the Trades
The Biasi is a fine choice. Less money than the System 2000 and a reliable unit. Be sure that it has the Riello burner.
