Upgrade advice for aging system

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Raybo

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Hello All,

I am seeking the advice of experts as I'm a bit lost in which direction to take. I currently have an Oil Fired 26-year-old Energy Kinetics EK-1 boiler (120K btu) and am considering upgrading, but also switching to LP as I have a 500 gal in-ground LP tank.

The current system is operating just fine, but am getting concerned with its age and efficiency, along with the same-aged tandem 330-gallon oil tanks in the basement. The only issue I've had with the system has existed since new; Flue gas condensation as a result of being a cold-fired boiler. I have an insulated stainless liner and the burner up-fired a bit, but that never resolved 100% of the issue. The top of my masonry chimney looks like hell as a result.

I haven't run heat loss calculations, but since the 120K BTU system has been sufficient, I'm assuming that's the ballpark the replacement unit should be in. 3600 sqft 2 story house, R36+ in the attic, 2x6 walls R19 and in Connecticut.

The system is 2 Hydro-Air zones and heats domestic HW with a plate exchanger that utilizes an 80 gal storage tank. I also use the boiler to heat my in-ground pool, using a large plate exchanger which tends to really push the boiler, but is effective and works well, albeit slow. I don't think I'd go that route for the pool again although it's nice not to have to maintain a separate heating unit.

I am giving serious consideration to switching to a high-efficiency LP condensing boiler as a replacement, with the potential benefit of wall mounting and getting rid of the 2 oil tanks in the basement. I realize the cost of doing this will be a premium over upgrading to a newer oil fired conventional system but I am thinking the added efficiency and space gained in the basement will balance the equation over time.

I already have a 500 gal in-ground propane tank, which is currently connected to my standby generator (20KW), Gas fireplace insert, outdoor grille, cooktop, and an 11000 BTU Rinnai wall furnace in an outbuilding. My only concern there is if my 500 gal tank is sufficient. I'm thinking I'll be OK in that regard as my scheduled deliveries currently are every 3 months, with usage approx. 60 gallons per month in winter which would be peak usage, not accounting for power outages.

If you got this far, thanks for reading this rather long post! Any advice, thoughts or input appreciated!
 

Fitter30

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Oil comes in high efficiency 90% and lp 95%. Your boiler 80-82%. Don't know if you burn #1 or 2 heres a list of btu content of both and lp. Then you can figger how much cost of fuel delivered and see what a btu cost. Lp 500 gallon tanks hold 400 gallons not knowing what generator you have ask yourself what happens if i loose power for a week with no deliveries if i need heat to.
https://www.engineeringtoolbox.com/energy-content-d_868.html
 

Dana

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I haven't run heat loss calculations, but since the 120K BTU system has been sufficient, I'm assuming that's the ballpark the replacement unit should be in. 3600 sqft 2 story house, R36+ in the attic, 2x6 walls R19 and in Connecticut.

That's a really bad assumption. Most reasonably tight 2x6/R19 house with clear glass double-panes will come with a heat load of around 12-15 BTU/hr per square foot @ 0F (or for a 3600' house 43- 48,000 BTU/hr). A tight 2x4/R13 type house might be as much as 20 BTU/hr per square foot, and even that wouldn't call for anything like a 120K boiler. If your house has an insulated foundation it's likely to come in even lower.

The 99% outside design temps in CT are all in positive digits F, many locations north of 10F, so your BTU/ft^2 ratio is likely to be even lower still. ASHRAE recommends an oversize factor of 1.4x the load at the 99% outside design temperature, not more. That is sufficient to cover the coldest hours of a Polar Vortex disturbance cold snap, while maintaining a higher, more efficient & more comfortable duty cycle on the heating system.

Since you have a heating history on the place, run this math on wintertime oil fill-ups. This is a way to measure the heat load (including all standby and distribution losses.) If you are on a regular fill-up service that stamps a "K-factor" on the billing slips, a few wintertime K-factors and a ZIP code (for design temp estimate) is enough.

BTW: What is your recent average price for propane? What are your all-in fully delivered electricity rates? What are the BTU/hr specs on the hydro-air handlers (or the model numbers)?
 
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