ASHP connected to WSHP
Last Post 29 Aug 2014 10:05 PM by engineer. 8 Replies.
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bacUser is Offline
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23 Aug 2014 08:37 PM
Hi Folks,

My 130000 BTU oil-fired Boiler has died.  We're in Massachusetts.  I have 100% radiant heat with 4 good sized water to air air handlers for cooling.  The main hydronic loop is oil-fired for heat, and geothermal direct heat exchanger for cooling.  I've calculated around 4Ton of cooling output by estimating the flow and temperature gain/loss from the main loop and the return to the well.  Water from the well is 40-50 degrees F. depending on the season.  I don't have the exact drinking well spec, but its something like 20gpm recharge 30gpm flow 280 feet deep.

The geothermal contractors want to dig another well.  That ran over $40k with everything.

Has anyone ever done a ganged ASHP to a WSHP?  I need 110000 BTU max heating.  Maybe 2 5 Ton units?  Is this just a bad idea?  Is getting 2 ASHP something I should look at?  Should I just pay the $9k and put in a new oil boiler?

Thanks for any suggestions.
 
jonrUser is Offline
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23 Aug 2014 09:40 PM
So your existing geothermal system is available for ~4 tons of heating in the Winter and you need ~4 more? - what you have is unclear. In any case, I'd consider mini-splits and/or open loop geo using the existing well.
Bill NeukranzUser is Offline
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23 Aug 2014 09:52 PM
Here's how it's done.  See this picture diagram: http://www.welserver.com/WEL1000/ .

Hope this helps.

Best regards,

Bill
Energy reduction & monitoring</br>
American Energy Efficiencies, Inc - Dallas, TX <A
href="http://www.americaneei.com">
(www.americaneei.com)</A></br>
Example monitoring system: <A href="http://www.welserver.com/WEL0043"> www.welserver.com/WEL0043</A>
bacUser is Offline
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26 Aug 2014 03:23 PM
Thanks for the ideas.

Upon further reflection a.k.a. speaking to my wife, she's not happy using the domestic well for heating.  When we use it for cooling we get pinkish residue on the fixtures and grit etc... She thinks using it for 3 season heating will degrade our water.

New tentative plan is 2 5Ton ASHP.  Giving up the Direct heat exchange from the well.  I think 1 5Ton will be adequate for 90% of the time, the second unit will energize at the temp extremes.   More investigations have to happen.


jonrUser is Offline
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26 Aug 2014 04:36 PM
I'm curious - what model is your geo HP?
G.O. JoeUser is Offline
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27 Aug 2014 05:26 AM
More questions. You describe you're existing geo system as "direct heat exchanger for cooling". Do you mean a DX with refrigerant or "free cooling" using well water through air handlers? Or something else? Either could have detrimental effects if you are rejecting heat to your drinking water well. A typical open loop with proper discharge should have no effect on your drinking water quality.
G.O. JoeUser is Offline
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27 Aug 2014 05:40 AM
If you want the least expensive first cost just throw a boiler in however if you want the least expensive operating cost a good geo contractor can show you the operating cost benefit as a comparison over time. In most cases you will end up with more money in your pocket at the end of the month even if you borrow the money. You can compare fuel cost and efficiencies on your own based on your input of fuel prices and expected efficiency here. http://nhclimateaudit.org/calculators.php
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27 Aug 2014 09:28 AM
I agree - while there can be some effects from warming drinking water, I'm not aware of any from cooling it (ie, Winter use). Rarely seen is excessive iron bacteria growth in the well from increased flow (open loop).

It would be a shame to have radiant heat in the floors and not use it.
engineerUser is Offline
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29 Aug 2014 10:05 PM
"I need 110000 BTU max heating. Maybe 2 5 Ton units? "

Great Guns!...Is this "need" based upon an actual load calc?
Curt Kinder <br><br>

The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
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