You have alot of questions - and they are all good questions.
As you've gathered - most of us do this type of work for a living. I'm an Engineer, and our firm specializes in energy efficient design - although mostly commercial/small commercial. We do some residential stuff, including audits, paybacks on equipment changes, and MEP design.
That all being said - I'm not going to lay out a 10,00 word post telling you what to do and with what specific equipment, and what it will all cost, and how soon it will pay back, and how it will all improve your life.
Here are some general ideas I suggest you research further and run with:
Since you do not have natural gas, you are left to choose between oil, propane, or electricity. Electricity can be used as straight resistance electric -which is technically 100% efficient - but the fuel cost is very high.
Heat pumps work like this (really simplistically): for every one watt of heat you put in - you get around three out -this is a Coefficient Of Performance, or COP. This example heat pump is essentially 300% efficient, and would have a COP of 3.
Further - there are three main types of heat pumps - air-to-air (looks like a traditional AC condensing unit, but has the ability to reverse the refrigerant cycle and bring heat INTO the home instead of OUT OF the home.) ,water-to-air (commonly used in a geothermal set up) or water-to-water.
The big advantage of geothermal: Heat pump performance suffers as the ambient (outside) temps get extreme - really cold or hot. A geothermal system uses the earth as a heat sink - which essentially keeps the "source" of the heat (in heating) warmer. The source is actually water that is pumped through wells or a field loop. It's like this - an air-to -air heat pump needs to work in the outside air - ranging from say -10 deg to 100 deg. A geothermal heat pump works with source water from the ground heat exchanger/wells that ranges from say 35 deg to 90 deg. Therefore, the geo system can work more efficiently with the narrower temp band - the average COP will be higher. Water-to-air heat pumps are also generally more efficient than air-to-air anyhow, but this is beyond the scope of this conversation...
Ok - now the disadvantage of geo. Sinking wells cost a ton of money. A ton. Triple the budget of a normal heating/cooling system. Plus, knowledgeable installers are not on every corner. A system can be installed that "works" but it may bot save as much money as the numbers would lead you to believe - for a variety of reasons from poor design to short-cuts taken during the install - to just plain not knowing any better.
Here's what I suggest for you:
If you are going to put in central air - do the ductwork right, and get a heat pump instead of a condensing (cooling only) unit. The air-to-air heat pump will save you money over the cost of oil or propane. But remember - the efficiency of this type of heat pump suffers in extreme cold - and so does its capacity.
Ah-ha - dual fuel. Below a certain temp - usually around 35 deg, your system will switch from the heat pump to the boiler/radiator system.
OK - now onto boilers.
A modulating and condensing boiler is the best you can do. This almost always means gong to gas. A regular boiler has a cast iron heat exchanger and needs high return temps (160 deg+).
A condensing boiler can run at lower temps - which allow the unit to condense the flue gases - and RECLAIM THE HEAT from the water vapor that would normally go up the stack.
The best case scenario would be to "reset" the boiler supply temp according to outside air - in this case the boiler starts running at 35ish deg. At 35, the boiler supplies at say 130. On design day (maybe -10 deg), it supplies at 160 (or whatever is needed to balance the heat load in the home - I doubt it needs 180 - systems are usually sized for 180 - but I should say systems are usually OVER-SIZED for 180.)
Using this reset strategy allows the condensing and modulating boiler to run lower temps - where it is much more efficient. At 180 - a mod/con boiler is really no more efficient than a regular boiler.
We covered condensing - modulating refers to the boiler's ability to run at lower capacities. This is an advantage because longer run times means the system reaches steady state efficiency much more than a boiler firing a t full capacity would - which short cycles and has large losses because of the short run times.
As far as domestic hot water - on demand heaters are good - they eliminate standby losses that are inherent to storage tank types. The disadvantage - they have a min flow to "kick on" - meaning no drooling of hot water into the tubby and it's hard to get a little hot mixed into the water on a hand sink, but these issues are small...
The hot tub:
The best would be to use a heat exchanger off of your mod/con boiler loop - but no-one ever really does this... heat exchangers are pricey, and the warranty on the hot tub is likely voided, etc. Like beenthere said, hot tubs are energy hogs, either enjoy it and pay - or sell it...
OK - that's close to 10,000 words - I'm punching out!
Geoth., vs. tankless, & pro EK
Your questions & larobj's answers show what I've been discovering: there are many more questions and topics than one initially would guess.
1) Geothermal is a big commitment with potentially a big return. Not a casual decision; are you ready for a big job?
2) We tried a tankless here in CT, near New Haven, and we are ditching it. Problems include: a) as stated, no off-on bits of hot water -- when you turn it off then on, there's a chunk of cold water that will come through; b) poor modulation (newer units may be better), so one cannot balance the temperature well; and esp. c) our local water is too cold in the winter for the unit we got. Perhaps the last was an installation question, but in any case the sum of the problems made this trial a failure. For your hot water in CT, I'd say a good indirect would be nearly as efficient & much more usable. Whatever, make sure you know how cold your cold water is in the winter.
3) Since you already have oil (e.g., the tank in the ground, &c.), look into the E.K. System 2000, as has been suggested. Its efficiency is slightly better than mod-con's (when measured more comprehensively than AFUE -- check their site).
(There are many partisans pro & con; from what I can tell, much of the opinion is not based on science so much as personal style and experience. One contractor who spoke against EK, on questioning showed that it was his experience with an oil co. that rankled.)
Good luck getting it all straightened out; from what I can tell, good luck is crucial, along with good planning.
I am not a firm believer in that system - or the info they present on their literature.
Originally Posted by LakeWhitney
The thing is their general argument may be true that their system can save you money - but this is what I think they are doing:
They basically compare a properly sized and installed (duh) system 2k boiler to the "average installation" of other boilers - including mod/cons.
Well, most boilers are WAY oversized - and MANY mod /con boilers are put in and are essentially not utilized to their full potential because the outdoor reset isn't used, or isn't used argessively enough. In a nut-shell - they're not set up right.
The system 2k is a low mass boiler, with a strategy that continues to cycle heat out of the boiler after it is done firing/cycling with some timer mechanism.
Their science is sound (and good, I might add). But a properly sized, installed, and set-up gas-fired modulating and condensing boiler will out-perform it in my opinion.
However (and this was your point, I believe), if the OP is set on keeping oil, the sytem 2k is something to look at. Expensive though, and I wouldn't expect the savings they promise...
Sizing: criteria? Includes IWH?
Question on sizing: here in our ca. 1200 sqft condo, we've had suggested 80,000 btu units by some contractors, with minimal analysis. The old unit (original, I think, 1950's) is 125,000 (& previous neighbor got a 125/104 Utica in the early '90's). I think part of the sizing is to be sure to be big enough for the indirect water heater -- true? Given that the sizes are standardized, for a small condo unit, is sizing fairly obvious.
Originally Posted by larobj63
Opinion on EK: Yes, their literature highlights comparisons with out-dated systems, but with what seems independent research, EK beats a good mod-con by a slight amount -- of course, granted that each is put in correctly, a warning to us all. Some more good testing, and an agreement on what is being tested (AFUE seems too limited), would be helpful.
How did you type so many words without timing out and have to log back in? I'm impressed.
Originally Posted by larobj63
Check the "remember me" box when you sign in and you won't have that problem.
Originally Posted by mlstark
Government is a disease...
...masquerading as its own cure…
Ecclesiastes 10:2 NIV
Thats a funny joke.
Originally Posted by bt1
No one would say that and be serious.
Actually the national oil heat council had verified the costs per unit and nobody disputes the fact that oil has beaten gas, 12 years over the last 15 years in terms of unit costs.
Originally Posted by beenthere
Since energy usage (any fuel) is measured in unit value...Oil is pretty consistent in being a better value.
Also, the latent heat gain over gas across the same casting is additionally 10%greater in most all cases....sometimes as much as 15%.
Where oil gets beaten is typically in the maintenance of that heating equipment or design of that equipment chosen.
If you are referring to most U.S. manufactured burners...you are going to get beat by the sooting that occurs by either basic set up or simple simplistic design which aids in this sooting.
Updraft castings add to this dilemma and when combining any updraft with any non-positive pressure burner....gas will do better due simply to the effect across the casting.
That being said....a scotch marine casting with a positive pressure burner (most) will out perform a comparative gas match.
I give money back guarantees on my conversions and (as of today) I have never had to offer a refund when recalculation the degree day to find gains/losses over any of my gas/oil conversions.
Generally, I find that people who are backing gas do so because they cant/wont build/tune a proper oil appliance.
I service and install both.
Oil does not out right beat gas, everytime. And it is foolish to think it does in all areas.
I'll put a mod/con NG gas boiler up against a oil fired scotch marine design (of any brand) anytime. (In MY area)
Do the math.
Oil, 4 bucks a gallon.
NG a $1.71 a therm.
No one would seriesly say that oil beats NG everytime. Since you can't know the prices of all fuels in every area, at all times.
Well, the national oil heat council says its so - so it must true.
Originally Posted by bt1
Your problem is comparing "the same casting" when comparing the fuels. A mod/con gas boiler will usually employ a heat exchanger that is much different than a oil-fired casting. The argument holds no water.
No one I think has commented on the safety aspect. I would guess that oil is safer, against both explosions and leaking fumes. Can anyone establish the relative safety of the two with evidence? (& his choice is propane, not gas, right?)
Originally Posted by ItsSortOfYellow
Last edited by LakeWhitney; 08-31-2008 at 07:43 PM.
Reason: minor re-focusing from last posts, which go off topic.
Nope. ANY appliance that burns fuel will produce CO. Wood, coal, oil, gas, propane.
Originally Posted by LakeWhitney
Any appliance that is subject to delayed ignition can go boom.
Never heard of coal or wood going boom, but I do know how they could in theory.
I love my job, but paydays Thursday