Insulate insulate insulate, glycol 25% or what ever is right, use a proper boiler not a water heater move on.
I cant see how a freeze alarm will do any good on a second home when there is a blizzard and your normal residence is 150 miles away?
who's going to help then? You guys know the drill out there though, not me I have never lived in that type of climate.....
Dan

I agree with Dan @ Blueridgecompany. In my opinion boilers are the way to go for any heating situation. Any of the small wall hung boilers eg; Munchkin Contender 50-80MBH will supply more than enough heat for your application. I usually also install an Indirect fired hot water storage tank when I do these systems. This eliminates the need for more than one fuel burning appliance thus reducing your operation costs. I am not a fan of using Hot water tanks to supply heat for the slab. The most inefficient way to do it. A typical HWT will only get 60% efficient at best. The Munchkin is a condensing boiler which gets 94% or better efficiency. Also make sure the slab is insulated with 2" styrofoam and also there is no need to raise the pipes into the slab. I typically charge out about $2/sq. ft for insulation and tube installed. Oxy-PEX is the preferred pipe (orange in colour) 1/2" and try not to exceed 250' in any loop.

rob, with all due respect, you're wrong on your estimation of hot water tanks. they have 60% efficiency ratings for domestic... which is based on usage for DHW, which is tiny usage compared to heating. standby loss accounts for more than 10% of the efficiency drop in that case.

in heating mode, they run mid to high 70's..... standby loss is a much smaller percentage of total load at that point. which is why they are ok for low load situations. there are many places in the country and heat loads that 10% to 20% efficiency gain will never make economic sense on the install cost of a water heater and HE vs mod/con and indirect. In those situations, regular water heater tanks are the optimal economic solution.

it's a very particular kind of situation. but there is more to it than just "always use boilers for heating", IMHO.

Rob NRT is right,

An energy factor of .62 is not 60 percent efficiency. It is a number specific to DHW only applications. I find the combustion efficiency of many conventional hot water heaters to be in the 80% range - just like a tank-less WH.

For heating small loads - a basement for instance - the domestic hot water heater serves very well given the reduce load.

When loads are smaller than the smallest ModCon - about 40mbtu - I look to a condensing water heater for large domestic loads and low heating loads. As Rob points out, in mild climates my favorite combination is the same as ROB t p,

ModCon with indirect.

I like a dual purpose WH with plate and ODR subsystem for heating radiant floors, walls, ceiling or steel Europanels like Myson.

The "gain” for a ModCon is nearly always 15% plus as AFUE does not accurately reflect the fuel consumption of a properly sized and controlled ModCon or condensing combi domestic water heater.

Now don't get me started on the nearly worthless tank-less combination di

If your going to design a combi system than start with the domestic load. Do you have a whirlpool or soaking tub? How many shower heads total? whats the rest of your domestic hot water load? Now what are your electric and gas costs per therm? What is the heating load for you radiant. Cant really recommend anything without a little data....Eric