I'll try to give as much information as I can.

I had an electric boiler installed 3 weeks ago, first time electric boiler install for my subcontractor.  The boiler ran full bore for 3 weeks because I had no insulation in my attic, and I set the thermostat at 70.  Very expensive mistake.

There appears to be sediment in my lines.  I'm using well water, from a new well, and we filled the radiant system after running a hydrant outside for 4 hours to clear the chlorine from the lines.  There is no filter on my radiant system.  

The first night the system ran with air in the lines.  I returned the next morning and discovered the upstairs zone was almost entirely air (we thought we had all the air out of the system, but we were wrong)  So I added more water and cleared the air from the system. 

Most of you know this is my first install, but I understood my sub knew what he was doing.  I think their may be a few holes in his understanding of radiant.  This is beside the point now as I need heat for the remainder of the winter.  Temp's in the single digits in 2 days, and I've only got 1 good element.

My unit is a 2 element, 10kw, Thermolec electric only.  I can get electric at 5 cents, or propane at $1.95/gallon, so I chose to heat with electric.

We tested the elements for continuity Wednesday (Feb 6) and found one element burned, the other running 20 amps.  I ordered 2 more elements and we will replace them this morning (Friday, Feb 8).  I am a little uneasy as there are no instructions, and if it doesn't work right away we will get cold.  Anyone replaced these elements before?

My number is 319 936 5636, feel free to call with advice.

Thanks,
Ben

They normally should last 5 years some 10 years. 3 weeks is way too soon. I believe you should send it to the company for replacement. It's probably a fluke thing that after 3 weeks it's history. If it happens again then you have either:
too long a run of BX wire from your main/ or undersized gauge wire causing voltage drop at your heater/ or loose breaker in the main/ loose connection on breaker. When in doubt always use a heaver gauge (lower number) Bx wire 2(120) or 3(240) . Always use the rated Breaker but you can use a heaver wire gauge which will have less resistance or voltage drop. You should not have this problem if an electrician did the wiring. I had voltage drops from a loose breaker which will fry everything eventually by sky high resistance. Try power tools with 100' 16 g cord........ history in 5 mins. lets hope your replacement last years.
Mike

Mike,
The warranty on the elements is 10 years, but I doubt I can make a claim... I suspect I caused  the boiler to dry fire in my ignorance. 

All my wiring was done by a licensed electrician. 

I also need to get a water softener system installed, then flush my radiant system, and refill with softened water.  There was already 1/16+" buildup on my elements.  I already know too much about the insides of my boiler canister.  Hopefully I don't go through any more elements.

Thanks for your help thus far,
Ben

Maybe guys like geodean and tuffluck have a different perspective based on experience, but I'm skeptical about needing to use soft water for your hydronic system. The reason I say this is because it's a closed system and once it's filled you will have very little fresh water coming in. It's the constant supply of fresh water that causes fouling problems in any open water system because you keep replenishing the supply of minerals and oxygen. With a closed system the oxygen and minerals get depleted and then the water will become soft and oxygen free on its own. Thirty-five years ago I had a house with hot water heat and cast iron radiators. I opened up the system to reroute some of the piping and relocate a radiator. I expected the pipes to be plugged from 50 years of circulating water. What did I find? A light coating of black sludge and no corrosion.

It sounds like the boiler was air locked. Do you have an air scoop (eg. Spirovent) in the system? If so you could try running the circulating pump, without the boiler running, for a few hours to eliminate air. Keep an eye on your pressure guage to see if it goes down. It is possible to have an air bubble somewhere in the system that won't move. It pays to have a manual vent at the highest point in your system manifold so that you can purge air from the system. Many boilers have a diagnostic led or beeper that will indicate what is going wrong with your system. It is usually under a cover, so you need to be qualified or very informed before you take this step on.
We filled and tested the system with distilled water @ $.50 a gallon. This might be unnecessary, but I bet my $10 worth of water that it is not. Especially when you have a new well and hard water. We fill one loop at a time and circulate each loop until there are no more air bubbles (using a bucket and transfer pump). Finally open all zones and circulate through the entire system until the water returns without air bubbles.

We are in a cooler climate and add heating-system grade propylene glycol after the system has been brought up to temperature and leak tested. We can then pump in the correct amount of freeze protection, because we know the true volume of liquid in the system.

Make sure that your problem was an airlock and not an electrical problem or you will be replacing elements again.

Can you say what brand and model of electric boiler that you are using??

Thanks for the advice, I only wish I'd learned this stuff 2 months ago. 

I am using a Thermolec boiler.

Ben

Ben : I am no heating guy, but what Dtel is saying about using glycol is good advice :-)
I'm sure you run coolant in your pick-up and notice no scaling when you open your rad cap.
Same for your boiler and loops, and you can rest easy if the power goes out and you're far away from home ,
cause your lines won't freeze.