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|01-03-2012, 07:27 AM||#1|
Join Date: Dec 2011
Location: Southern NH
Gaining efficiency with oil boiler
I've greatly enjoyed reading through numerous threads and learning a lot of the ins and outs of home heating systems.
However, it seems that the more I learn, the more dangerous I become.. to myself. I had started off pretty sure that when we retire our aging oil boiler this spring, we'd install a propane tank and a hi-tech modcon boiler.
Now I'm thinking that I'll just stick to oil and install the smallest Buderus G115WS boiler (74K BTUs) with a Logimatic ODR. I'm not convinced that oil will become cheaper than propane per btu in our market (NH). Propane is currently 50% more expensive per btu than oil... and even with the added efficiency of a modcon, it's at least 25% more expensive compared to oil, even when the latter is burned in a good cast iron boiler with ODR.
Nobody knows what the future holds when it comes to energy pricing, but oil would have to take a big jump (with propane prices holding relatively steady) for it to become comparatively expensive compared to LP gas. Current pricing in our part of New England is $3.49 for oil and $2.95 for LP.
Anyway, the proven longevity and relative maintenance simplicity of CI compared to modcons is appealing, and we already have an indoor oil tank and a decent chimney, so those are further reasons for staying with oil. Still, the environmental benefits of burning LP are points in its favor.
Anyway, our 1986 2100sf cape has two zones-- downstairs with 66 feet of copper fintube and upstairs with just 30 feet. Ooops, make that 3 zones, counting an indirect water tank.
Since our upstairs is such a small zone, I was wondering if I should insist that a buffer tank like Boiler Buddy be included as part of all our bids. My understanding is that this buffer would prevent the short cycling that we get from our current boiler situation (the tag on it says 124,000 BTUs).
Is a buffer necessary or beneficial in our situation or can short cycling be adequately addressed by how the boiler is plumbed?
Is there anything else I should be aware of when this goes out to bid? I've done my own heat loss calcs using an online calculator, and came up in the 47,000-56,000 range. Obviously, the 96 total feet of baseboard in the house yields 56,600 at 180 degrees water temp... but when it's colder than, say, 10 degrees outside it takes forever to warm up the house if I've set back the thermostat to 62 or 63. I can't figure out why, except perhaps when the baseboard is so exactly matched to the heat loss, you have to expect a very slow recovery process.
We've insulated our attic to R40 and replaced some exterior doors and windows, so the house is tighter than before. This week I'm having foam sprayed into the joist boxes in our basement to seal any air infiltration down there-- maybe that will help baseboard performance a bit.
Anyway, I'm hoping that a smaller boiler with ODR and (perhaps) a buffer tank will prove more miserly with fuel burning than presently at 830-840 gal/ calendar year.
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