Hi,

We will begin our search for our radiant components to finish our radiant install. The main question right now is how to determine which type of boiler to go with?

The fuel sources we have available are propane and electric. I suppose wood or corn pellets could be an option, as well as firewood if that's possible to use.

As of right now propane is $1.68 per gallon, but that can change since contracts for winter aren't signed until August. (e.g. this last winter we almost went broke since contract price went up to $2.20 per gallon). Electric rates if used in a separate meter for heating only is $.05/kwh plus $5.00 per month fee for delivery.

So, how can I choose between which fuel option to go? I have load calcs done using Siegenthaler's book.

Thanks for the help.

Might want to consider an outdoor boiler , see www.woodgasificationfurnace.com as I have some that will burn wood and or corn, we also have crete-heat and the barrier products to assist you. know all options to assist you in your project. good luck

Thanks radiant. I looked at the website, but not much information there. How does it work? It would heat up the water to the radiant floor through a heat exchanger? I'm not sure that I am a fan of having to go out in bad weather to load the unit.

YES most people use a water to water heat exchanger and hook into hot water tank. Burning wood is renewable resource.

Well putting your numbers in this is shows at your current rates assuming 1 million BTUs per season

propane at $2.20 = $2900 yr
propane at $1.68 = $2214 yr
electricity at $.05 = $1391 yr

Looks like electricity is a no brainer, especially at $.05 / kw, that is REALLY low.

Propane burned in a non-condensing 85% efficiency unit delivers 91000 BTU/gallon x 0.85=77350 BTUs/gallon into the radiant floor. So @ $1.68/gallon that's

about 2 cents per 1000 btus.

Electricity delivers 3412 BTUs per kwh @ 100% efficiency into the radiant floor, or about 1.5 cents per 1000 BTUs.

In your case electricity would be 25% less than with propane. With a condensing propane boiler you can do slighly better, but not 25% better (110% combustion efficiency just isn't possible.) If you anticipate that propane price inflation will outpace electricity price inflation on average for the foreseeable future, you'll be better off with electricity. (If you can use either an air-source or geothermal heat pump, even more so.)

Me, I'm paying 18 cents/kwh, vs. $1.60/therm (a therm is as much heat as 1.1 gallons of propane), so my economics differ considerably from yours (and are in the opposite direction.) Even for me it would be operationally cheaper to go with ground-sourced/geothermal heat pump, but the up-front installation costs kill the deal. Air-sourced heat pumps are somewhat marginal in my climate, but air-sourced heat pumps can make a lot of economic sense in climes milder than New England.

Outdoor wood burning boilers might make sense for people/businesses with large heat loads, but my needs are too small to be able to use them efficiently. (Indeed even the tiniest woodstoves and fireplace inserts exceed my design-day heat load.) The output the woodgasificationfurnace.com products are 210 & 320KBTU/hour, which is 8-10x my design-day heat load. see: http://woodgasificationfurnace.com/outdoor-furnaces.php

I'd need one helluva buffer tank for storing heat to be able to use them efficiently- the 160/250 gallons in the boiler wouldn't quite cut it alone. YMMV Whether (efficiency be damned) it ends up being CHEAPER to run than with electricity/naturalgas/propane is a function of it's actual operating efficiency as-used, and the price of the fuel. I know a dairy farmer in NH who swears by 'em, but his loads for space-heating & hot water are enough to require multiples of even bigger wood boilers than these.

May also want to try:
http://www.alternateheatingsystems.com/index.htm
They may offer a size suitable for the project.

I very much doubt corn is competitive to use as a fuel source wood yes its renewable but unless you have your own bush and dont mind the work the cost to buy wood might be too high

Thanks for the information.

Brock, those numbers look nice.

Dana1 - is Iowa milder than New England? I am looking into air source heat pumps to heat upstairs since my DH is not sold on doing the whole house radiant (though I will try to change his mind). But I see air heat pumps aren't such a good deal below 32ºF since you have to have a back-up to keep up. I did see this new electric heat pump (can't remember brand) that is supposed to have better efficiencies at lower temps. Ground source up-front costs are too much to consider it at this point.
I a heat pump was a viable option, could one heat pump be used for radiant and air heat? Or would I need two?

I do have a friend who uses corn in his wood/corn stove and it's amazing how much heat he gets out of a bag of pellets. He buys the pellets in summer when they are cheaper, but not sure what the economics are for real. He claims he's spending less to heat with corn than he did with propane. Wood is plentiful in my acreage, so I wouldn't need to buy, but it would involve a lot of labor. Mmmmh, may be excuse for nifty log splitters and new gator to haul wood around.

Thanks Zircote, I'll take a look, though oil and coal are not readily available around here.

Iowa is roughly comparable to southern & central New England, somewhat warmer/milder than northern New England. 

But IA utility prices (especially electricity prices) are much lower than in most of MA/CT/RI. 

A good cool-region air-source heat pump can still deliver a COP of better than 2 down to about +5F or so, and can hit a COP 3-4 when it's above freezing.   Even though it's efficiency performance will SUCK when it's 0F and lower, that isn't very many operational hours out of the heating season, and don't add hugely to the operating cost (still some):

http://www.wunderground.com/NORMS/DisplayNORMS.asp?AirportCode=KDSM&SafeCityName=Des_Moines&StateCode=IA&Units=none&IATA=DSM

If you spent the difference in up-front cost between ground-source heat pump and an air-source heat pump on a tighter & better insulated building envelope, the size and operating cost shrink to the point that it's usually cheaper to super-insulate and reap a larger operating cost benefit than going with the GSHP.  (Even in retrofit situaions the economics often tend to tip toward air-source, even in milder parts of region 6. http://www.madico.com/images/climateZoneMap.gif  )

I'm sure your friend gets many more BTUs delivered per dollar (even in the typical ~70% efficiency stove) with wood & corn pellets than he could with propane. Propane prices track oil prices, since most propane in the US is an oil-refining product. (Not so for natural gas.)  I know someone in central MA who switched from heating oil to a corn-boiler about 3 seasons ago who remains happy with his choice despite some volatility in the corn prices.  If you're local to the fuel sources, biomass boilers can be very economical to run.