TG; I don't remember anyone saying this was metered water. Is it?
Is natural gas available as well? They go hand in hand in my area. If so gas would be least expensive to operate.
One other thing mentioned was the requirement was for 4 months. You would have ~$1,000 into a sidewall vent water heater which would buy you a lot of water.
OP; What sort of municipality delivers water at 34*? You are right though, that would be a deal breaker. But please never suggest open loop geo "wastes water" that is a political position not a reality.
Good news though we do know the size heat pump you need. In hydronics your heat plant size is determined by the amount of radiation. So see what the btu capacity of your radiant floor system is and you can design your house and heating system around it. 
Not trying to sound harsh just trying to make the point that you are going about things backwards and it will cost you money. Get a pro involved now. You are already behind the 8 ball. 
j

Only true for steam! The heat source for hydronic systems is sized to the load, not the radiation. For geo the more radiation the better, within reason. You want to drive the water temps as low as possible.

Perhaps you would prefer I said desired operating temp, load and radiation, but does that change my point about the cart being ahead of the horse?
Have you never run across the bigger is better mindset where HO installed twice the required radiation?
Design of radiation and heat plant should be done in concert is the real message.
j

That sounds better - I know I tend to be pedantic sometimes! I can't think of any case for hydronic geo where more wouldn't be better if cost is no object. Of course if you spend 10k doubling your loop spacing to get a 0.1 improvement in COP that doesn't make sense. So I agree completely that the radiant system needs to be designed, not guessed at especially with geo.

When you're guessing there is one really bad outcome and 1 less bad outcome:

1. The radiant system won't keep up with load at the max geo temp (most quote 120deg but in reality this is stretching it for many units)

2. The system is undersized or oversized relative to cost. I.E. you could have spent another 10% and gotten a 30% COP improvement, or you've spent twice what you have to for a very minimal COP improvement.

I really dont see how oversizing the radiant a little especially when using a GHP can be a bad thing? i have run/am running 9" on center in a tight brand new ICF house, i know that is overdoing it but the cost of the extra tubing in minimal, having larger radiant than needed would just allow me to run at a lower temp which, correct me if im wrong is better for a GHP, within reason. Undersizing the radiant would be a different story admittedly. Im working with an extremely limited budget, i decided it was more important to have the heat pump/load sized accurately than the spacing on my radiant, not having the money to do both.

As far as domestic water temps in MN, 34 degs is not unusual in a cold winter when we have a lot of ice, coming out of the river, i dont see how a municipality would have any control over that.

I see what i was missing running an artificial loop inside the house means what ever energy is consumed inside the house gets converted directly to heat inside the house. Being internal it is not bringing anything in, i.e. heat from an external ground loop.

So heating the water for my radiant directly (electric or gas) would seem to be the way to go, my next thought is, is there anything i could use to generate domestic and heating water that could be utilized later in my GHP install or do i try and find the cheapest way to do this knowing it will be temporary?

I really do appreciate the suggestions and advice, this isnt a 'one size fits all' scenario, yes id love to hire the best local contractor to design and install my system, just as id love to have had someone build my house for me but then id still be dreaming about it 10 years from now. So far, respectfully collecting advice from people more knowlegable than myself in their respective industries has worked out extremely well, spending my money where it is most needed to make my project halfway possible. I dont wish to offend anyone and as i said, i do appreciate the conversation!

Im very familiar with wall hung instantaneous combination boilers from working in Europe, which would be ideal for my situation (small, flexible, easy installation, relative economy etc), however they seem to be rather rare and expensive here, cheapest one i found the other day was $1,600. Bummer.

It appears that you are on metered water (though it has not been directly stated), still wondering about nat. gas.
J

>How is 100% efficiency maintained

You use more electricity but also get more heat. So efficiency stays right at 100% in an electric, no external input system.

Where does more heat come from in this case, from the compressor running unnecessarily? Does the heat generated make it into the living space for comfort? If this was a toaster running in the kitchen, I might agree with you.

Yes and "it depends". But the latter is a practical matter.

Pete, it might be a long shot but if your heat load is small enough you might get by with an electric water heater wired so both elements run at the same time ( a tank with two 5500 watt elements would get you roughly 34,000 btus). Then when your loops are in you could replumb this tank with your desuperheater as a buffer tank fprior to your domestic water heater.

Another factor to consider is that if this won't be installed for another 4 -6 weeks your btu requirements will drop off rapidly. Spring will be here before you know it.

The part you are missing is that the "ground source" heat pump exchanges heat with the earth.  Without a connection to it, any setup you have will be horribly inefficient.

Does your heat pump have an electric coil for auxillary or emergency heat?  That is likely your best bet. 

Ed   

Huh?  Running treated water through a geo system and onto the ground or into a drain is a waste.  How is this political and not reality?  If the water comes from a treated municipal water supply and dumps into a municipal waste-water system, the water must then be be treated twice.  If treated water runs onto the ground, it is still a waste.

The only open loop setup that gets my vote is the standing column well.  I have this setup and made sure my wells were drilled deep enough so that we almost never need to invoke an emergency bleed (we haven't yet).

Ed

I do have gas available and my water is metered. Where i work (downtown Minneapolis) the incoming water temp is monitored which is where we see it go as low as 34-36 degs, perhaps the proximity to the river and treatment plant and very high usage/flow accounts for the low temp. The point about city water effectively being a ground loop as far as temperature goes is very valid and somethimng i hadnt considered, my house though still using treated city river water is in the suburbs and the neighborhood probably sees a much lower flow rate so maybe the temp is closer to the 55 deg ground water, ill have to check.

Does no one see the irony that OP with admires a $1600 water heater but wouldn't consider a couple $200 water bills?

I respectfully disagree and certainly do not see it as ironic. I see it as being wasteful dumping treated water down the drain or to ground, yes i know where it goes but i happen to consider that irresponsible. Plus it would be more than a couple of $200 water bills which again i personally see as wasteful when i could spend the same money on equipment that i might be able to re-use or sell (though admittedly there would be higher operating costs) and i dont recall saying i admire $1600 water heaters, just that I am familliar with them and they would be a good solution if the cost were lower.

The reason i consider my heat loss calc and heat pump sizing more important that the sizing of my emitters (tube spacing) is that you can compensate for slightly overdoing the emitters by lowering operating temp which has no negative effect on the GHP. Not having an accurate heat loss/load calc though could result in an oversized GHP which is bad news for a whole bunch of reasons correct?

Can you just use electric radiant or "space" heaters temporarily? I would think it would be the cheapest way to go in the short term; it should take the same amount of electricity as using an electric hot water heater and circulating that. I guess it depends on the state of the structure. Are you trying to keep it from freezing, or is it finished and is an occupied space?

If people are in it I would just go with an 80 gallon tank running both elements if necessary and circulate that water though the system. Then later I would reuse that tank as the DSH buffer tank.