Minnesota Happy Thanksgiving and the start of my testimonial thread!

Tough to beat the 143F degree water going to your radiators....when the LLT is 143F. The magic Tee is working the magic....

 

Good show! Only one thing beats Geo, and that's Geo with cast iron rads! So are you 100% radiant now? Seems you started with a mixed system, as I recall.

 

Hi Frank! Yes, we are 100% radiant heat. We have a 7 ton W2W, and our loop is not big enough to also run the 5 ton W2A split, so we only use that for AC in the summer.

 

143 water temps are very nice from a geo unit. I was heating my house with 160 degree water temps from my gas boiler. 143F you can do a lot with.

 

154F degrees from a geo unit is even nicer.

 

How is the recovery rate with 154 F ?
Is it enough to make DHW, radiant, & heat base boards?

When I was researching it 5 years ago, I was told the recovery rate is so slow, it's not enough to melt snow, or do whole house base boards.
I would need to over size the unit, and it wouldn't be worth it.......

 

You don't want to run it at 154 all the time.....
Define recovery rate? For your hot water? This is a 7 ton heatpump as an example, rated for about 70,000 BTUs/hour, probably a bit less when making 154F water.
With snow melt, geo does not pair well. You need a very large capacity for a short period of time, very expensive to put in, and higher efficiency does not pay back quickly due to the short run time.

Tell customers to get a boiler for snowmelt.

 

Tamar, I see that the supplemental heat does not even turn on, that's excellent!

How do you heat you domestic hot water?

 

I just added R-30 to my attic. Complete blanket over the existing R-19. Spent over $1000, but it'll be worth it, even if it take years to recover the money.

 

Not sure what your post has to do with Tamar's thread?

 

Chris, we have a gas hot water heater. For the period ending Dec 28, our total gas cost was $18.64.

 

We don't get quite 154 this time of year because our source water is a bit lower (at least I assume that's the reason). Gas starts injecting some heat at about 148. That's plenty for most of the time, even in January. Right now it's 11 degrees and the house is very comfortable with 136-ish degree water.

 

You certainly do not want 154F from the geo, only when you need it, since your efficiency drops with hotter load temps. I was just saying that high temp units are able to do this. But you want an outdoor reset control so you increase your efficiency and reduce your stress on your heat pump during warmer than design conditions.

 

Tamar,
could you display you Xcel bill trend from the website like you did before? Just curious how your annual consumption was ,,,,

 

Doc, Here's the Usage off the Geo Meter in 2016.

Our overall electric bill can't be compared to previous years because we've had an electric car for the past 18 months and put 20K miles on it at a cost of (we think) around $70/month in the summer and probably closer to $95-$100 in the winter. Our current bill (December 2016) is $536 including all electric and gas, so including charging up the car every night, and the car is quite the battery hog when it gets below about 10 degrees.

Our worst bill during our winters with the poorly designed geothermal was well over $600 (without needing to juice up an electric car). Our largest bill pre-geothermal and pre-electric car was around $520. We are significantly more comfortable than those years where I never let the thermostat get above 67 degrees.

As predicted, the shoulder seasons are where the geo really shines and saves us a lot of money.

 

Tamar,

$$$ are not really telling since electrical rate might went up. The key is the KWH comparison. You posted it, but no comparison the previous years.

Yes, electric cars use some juice, I have sold all my regular cars, and have 3 electric once now.....but no comparison the gasoline.
AND certainly the outdoor reset is key. Why hydronic geo is getting less efficient at lower ambient temps due to older homes requiring higher supply temps, you can mitigate this with an outdoor reset when it lowers the supply temps at lower ambient temps, which you see the benefits of...

Do you have before and after comparison in KWH?.......

 

Ah, you're looking for the bill trend. Last year was a laugher of a winter, so the trend for 2016 doesn't look good, but really is, especially when compared to 2013, which I'll pull in from earlier in the thread. You can see July 2015 was when we got the electric car and electric usage went up (but trips to the gas station are now almost nonexistent since they're only for out backup car).

 

oops, not bill trend either, as I re-read the request. Is this what you want to see (this is KWH for just the geo meter)? Xcel lonly lets us go back 24 months. Outdoor reset is in use.

 

Looks good!

 

Incredible to hear you at long last got the framework working. You can't beat brilliant warmth, and in principle, Geo and cast iron ought to be an upbeat blend