DX Geo for pole building/apartment
Last Post 26 Mar 2009 10:47 AM by tuffluckdriller. 29 Replies.
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emjayefUser is Offline
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12 Mar 2009 09:58 PM

Having already brought up the subject of DX Geo in another thread comparing Geo with the Acadia, I thought I should start another thread before taking my questions any further.

I have a 3,000 sq. ft. Morton pole building with a 12' ceiling.  It is insulated with 6" fiberglass blankets in the walls, and 17" of blown fiberglass in the ceiling.  Inside this building, I am putting an apartment of about 850 sq'.  Two of the outside walls of the building are used by the apartment and the remaining two walls inside will be insulated with 6" fiberglass and the ceiling with 10' of fiberglass.  I also installed 1-1/2" of Foamular Rigid Foam insulation (pink) around the perimeter of the building to a depth of about 16".  This foam is below grade. 

I would like the heat both the building and the apartment, but the building area would be set at around 50 degrees most of the time during the winter unless I am working out there and need to raise it.  I am not particularly concerned about cooling the building but would like to cool the apartment.

Presently, while I am constructing the apartment, I am heating the building with the air handler unit from an old air source heat pump I replaced a number of years ago.  The unit contains the 20 kw backup resistance heat coils from that old heat pump and they easily heat the building to whatever temperature I set it at, although I drop it back to about 48 when I'm not working.

I would like to install a DX geothermal system but would like some input as to the best way to go with this, or even if this is the best way to go.  I am assuming a two-zone system but any other advice or suggestions would be greatly appreciated.  I just recently found a DX dealer within a reasonable distance of my place and will be contacting him shortly to get his input on my idea.  Thanks for you help.      

tuffluckdrillerUser is Offline
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13 Mar 2009 01:55 AM
This setup is a bit challenging...
I'll have to think on this one for a day or so...time to get to bed, anyway...
Clark Timothy (clark@pinksgeothermal.com)
Geothermal Heat Pumps: Heating and Cooling that's Dirt Cheap!
www.pinksgeothermal.com
joe.amiUser is Offline
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13 Mar 2009 05:59 AM
When dealing with zoned systems, I prefer multistage heat pumps. Geo (like any refrigeration systems) do not perform well with restricted air flow.
If you insist on DX, I would suggest that it be sized sligtly larger than the apt. demand and be set up to prioritize apt then heat pole barn once apt is satisfied. This set-up will probably use more resistance heat, but again zoning single stage systems isn't a great plan in my book.
Option two is to use the DX to condition water for a buffer that circulates to hydronic fan coils in the various zones. This would be very effective, but not cheap.
If you had me design it, I would use a 2 stage water source, that offers low capacity operation for low demand situations.
You are not far from the Earthlinked distributor (he's just west of Ft. Wayne), so you likely have more than a few DX dealers around you in MI and IN as well as OH, so I'm sure you'll get lots of disparate input on this job. Now you have mine to add to the mix.
Good luck,
Joe
Joe Hardin www.amicontracting.com We Dig Comfort! www.doityourselfgeothermal.com Dig Your Own Comfort!
geo fanUser is Offline
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13 Mar 2009 03:27 PM
2 system or dump zone
If it where me I would look first at a two system set up ,DX
second option would be a two zone system and dump damper bypassing the the pole zone
considering the size difference in the zones the pole zone would rarely turn on at all except when it called
I would also only wire the aux heat to the large zone
best option 2 systems sized for the load , second best 2 zone dumping into the large zone for bypass
the only hitch to this option is the large zones ductwork would have to be sized to handle the intire system as there would be no dump when that zone called by itself , so when both zones where to go at once the static pressure would drop off , but it doesnt sound like that would happen to often considering you keep the temps very low in there exept when used , hopefully this makes sense

         apartment                      dump              pole
                ]                                  ]                    ]
           damper                       bypass           damper
                ]                                  ]                    ]
--------------                                 -----------------------------------



tuffluckdrillerUser is Offline
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13 Mar 2009 07:41 PM
The EarthLinked product handles half capacity duct really well, so if the zones are fairly well balanced, a 2 zone setup would be recommended.

That being said, I'm exploring on my own home an option with the EarthLinked using a 2 stage compressor. Design says it should work without problem with their drilled loop... not getting terribly far into detail right now, though, as I'm still in contemplation stage. Looks like I might have a couple weeks of downtime with my drill...I can finally get my own loops in!
Clark Timothy (clark@pinksgeothermal.com)
Geothermal Heat Pumps: Heating and Cooling that's Dirt Cheap!
www.pinksgeothermal.com
emjayefUser is Offline
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13 Mar 2009 08:40 PM
Okay, let me see if I understand all this. Joe, you would recommend a water-souce geo rather than the DX?

Geo-Fan, you recommend using DX but size it for the building, then when the apartment calls for heat/cool, dump the excess into the building to keep the pressures in line?

And Tuffluckdriller, you say Earthlinked has a 2-stage compressor that will alternate between stages depending on which zone is calling for heat/cool? If this is true, and it works, I think I would prefer this option.

I was about to ask about a 2-speed compressor, when I got Tuffluckdriller's answer. I don't know all the technical aspects of heat pumps or geo systems as far as pressures, circulation speeds, etc., but I was going to ask about that. If the refrigerant circulates through the ground loops slower, would it not pick up more heat? If so, then faster circulation would pick up less heat? I may be way off base here, but if this is correct, it would seem a 2-speed compressor coupled with a variable speed blower would solve the problem with the zones not being the same size. By picking up more heat and using a faster blower speed, the system would be able to heat the building. By picking up less heat and using a slower blower speed, it would heat the apartment. Or am I an idiot for even thinking this way? I have a lot to learn and that's why I found this site. I've already learned alot and hope to keep adding to it. Thanks to you all for your time, knowledge, and hopefully your patience.
geo fanUser is Offline
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13 Mar 2009 09:00 PM
tuffluck private sent
emjayef you are correct in my recomendation
joe.amiUser is Offline
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13 Mar 2009 11:57 PM
As always, many methods to skin the cat, what is most important is what your installer wants to do.
Two systems would be most expensive. Dumping is wasteful and contrary to geo in general. 2 stage earthlinked is not in general distribution yet and as Clark points out, zoning single stage works okay if areas served are "fairly well balanced" which doesn't appear to be the case here.
Not every system is best for every application. Nor does every dealer/distributer handle multiple systems.
If you are pre disposed to DX and find a good dealer I'm sure it will work well for you. If you want a multistage unit with the ability to serve disparite zones and a multi-year performance record water source fits the bill.
The main thing really is the contractor, the warranties, the references; as long as these are all good, the brand or even type, doesn't matter much. Let's see what the local guy suggests.
J
Joe Hardin www.amicontracting.com We Dig Comfort! www.doityourselfgeothermal.com Dig Your Own Comfort!
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14 Mar 2009 09:50 AM
No, EarthLinked doesn't currently have a two stage system.

What I'm saying is that I'm going to try an application of it with a two stage compressor. This is something I'm going to try myself that I have EarthLinked's approval to try. If it works, they may develop it further. Just an R&D situation...Not something I'd recommend you be a guinea pig with. In theory, with a drilled loop system, and ground temp 60 deg. or lower, it should work without any problem.

Right now, I'd suggest doing what geo fan is recommending.
Clark Timothy (clark@pinksgeothermal.com)
Geothermal Heat Pumps: Heating and Cooling that's Dirt Cheap!
www.pinksgeothermal.com
joe.amiUser is Offline
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15 Mar 2009 07:55 AM
Emj, I always admire Clark's advice, and again will tell you that while DX will work okay in your situation, even Clark suggested that 2 stage would be best. Earthlinked however doesn't have one to sell you. We could argue that Earthlinked may or may not be more efficient, but if it is not a good fit for the job (choking or dumping) then the argument is moot.
Instead pick a 2 stage unit. That's appropriate for your job. If you insist on DX then Nordic is the one available. If you can't find a dealer in your area, then you may want to check out water source (virtually every brand has a 2 stage system). Or buy multiple units to make your own 2 stage Earthlinked (if money's no object).
Your other advisors here have told you how to make Earthlinked work in your situation which is not suprising as it's all they sell. I won't present DX as the most efficient anything when choked or dumped.
Most importantly, again, as long as you do your homework you'll likely be satisfied with anything you put in.
J
Joe Hardin www.amicontracting.com We Dig Comfort! www.doityourselfgeothermal.com Dig Your Own Comfort!
geo fanUser is Offline
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15 Mar 2009 09:02 AM

Thanks for trashing me there
the reality is even a 2 stage unit would have to dump in your situation , The only difference would be they would likely dump back to the return
which which has its unseen drawbacks with heatpumps , or they would ( trust the fan and staging )
and people wonder why there systems are noisy
do ductwork right and dump your zoned systems if you dont you are giving warm air a bad name
I realy hope you dont zone systems with out the use of barometric or preferably an electronic , static pressure operated bypass damper. The only difference between the right way to do what you asked and what Joe is pushing is the amount of air that would get choked/dumped and where it would go chances are it would just temper a room that you keep conditioned anyway

PS I dont sell earthlinked .
If he asked the best way to do a water source unit with 1 system I would have the same recomendation

geo fanUser is Offline
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15 Mar 2009 11:18 AM
Im going to modify my recommendation
geo the apartment
fossil the pole
my reasoning is two fold
1 considering roughly 70% of your return air would be coming from the pole which you want to keep at 50degrees in a zoned system the supply air
first stage of the water source would only produce 75 degree air which if the duct work is not perfect might not be comfortable
DX would be around 80-85 which is fine but
2 you say that basically you only want to heat the space when you are in it
either system would take more then a few hours of constant running to raise the temps
emjayefUser is Offline
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15 Mar 2009 07:06 PM
Okay, you've all given me alot of to think about. If Earthlinked doesn't have a two-stage system, I'm certainly not qualified to cobble one together. I am going to check into the Nordic as suggested although I've never heard of it.

Other than that, I was under the impression that if I had a two-zone system, the air supply would switch from one zone to the other depending on which one was calling for heating/cooling. I just assumed there would be a damper to close off the supply from the zone not being served. That would eliminate the issue with the colder air from the building being used to heat the apartment. It would also keep any fumes that might be in the building from entering the apartment along with the supply air.

I didn't think it would be this difficult, but I always seem to come up with something to throw a wrench in the works. I was really hoping to use the DX system, but perhaps that is not feasible unless I just go with the DX to heat one side or the other. But I doubt it would really pay for itself for heating/cooling just the apartment since it's only about 850 sq. ft. Seems like overkill to me. Not sure how small a system they make, but the cost probably wouldn't warrant it.

On the other hand, using it to heat just the building also seems a bit ridiculous because most of the time it would only be keeping it at 45-50 degrees. Sure don't need a DX system to do that. I'm keeping the building and the apartment area at that now with an old air-handler with 20Kw resistance strips. I've done that all winter and the highest electric bill I've had while doing so has been $119 and that includes jacking the heat up to 60 while I'm working on the apartment. The building is really well-insulated. Morton does a nice job with that.

I also don't like the idea of trying to use a DX system by dumping the excess off when heating the apartment because that sort of goes against everything the system is trying to achieve, namely efficiency. Why heat the building if it's not calling for heat?

I hate to say it, but maybe I'd be better off with an air-source for the apartment and just using the old air-handler for the building. The apartment isn't going to take much to heat it. It will be very well insulated and with two of the four perimeter walls along with the ceiling being inside a 45-50 degree building, the heat load should be pretty small. If I ever got to the point where I'd like to keep the building warmer, I could always put in a geo at that time.

I like the idea of the DX system because of its efficiency. I remember thinking years ago when they came out with the water systems, why not just circulate the refrigerant? Now they are, but for my application, it may well be spending a dollar to save a dime.

I love this forum. You guys really make me think. I need that so keep the idea coming. Thanks to you all.


geo fanUser is Offline
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15 Mar 2009 08:22 PM
OK to start
zoning does close and open supply ducts
what it doesn't do is close and open return ducts hence my concern
another option available with dx and a good compromise cheaper then 2 systems better then any zone setup for your situation
geo radiant the apartment warm air the pole 1 unit can handle by just about any manufacturer DX or other
No load concern or airflow/temp
My thinking for fossil in the pole is "if it doesn't run its not saving you money "
My thinking for staying geo in the apartment is , a small space doesn't require much heating, this means a smaller unit , which almost proportionatly decreases install cost . Of course standard inputs would be required but your ROI likely would go from 7 to 8
in you situation it would be my guess that it would decrease the number of years considering you dont use the majority of the space most of the time
but a longer ROI on a larger investment isn't always a bad thing either
so to recap
Mikes top choices
1 2 DX air systems / or 1 system radiant heat apartment ,air to pole ( no a.c. in the apt. but you said that was ok )
2 DX the apt cheap over sized unit to flash heat on demand the pole
3 Im going to end there because in your specific situation I dont think zoning any system would work well
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17 Mar 2009 08:56 AM
GF, sorry if you feel trashed (and if you don't sell Earthlinked), but you really are trying hard to make your system work here and it is not the best one for the job. That's my opinion and it comes from a contractor with DX and water source systems available to him. You mentioned you only do DX, fine. It's always your answer, I get it. Is it always the best answer? Isn't it folly to suggest that one product is the best fit for every application?
I mentioned hydronic circulation in my first contribution to this thread as the best way to employ DX. I simply didn't suggest radiant as it is more expensive and doesn't provide cooling for the apartment. Water source is still less expensive in this application.
You are obliged to work with whatever your boss carries. I would encourage him to take a look at Earthlinked.
Emj,
Your mention of the electric bills suggests that geo may not offer you a very good ROI at all. You'll need a good heat load and operating cost calculation to know.
After that, if you are still looking at geo, it is not true that the 2 stage would have to dump if it is properly designed, the whole point of the first stage is less btu's exchanged so less airflow is required (fewer CFM-smaller duct system).
The common installation of zone systems is not to damper returns, but there is no reason you couldn't and in your design we'd have to, for reason that GF points out. Further when you mention fumes and such, the inspector in me neglected to mention that if you call the rest of the building a "garage", you would find the code very un accomodating to your plans.
So to sum, get a good operating cost projection, don't be afraid to consider electric baseboards or some sort of ASHP. If geo is still indicated, a water source 2 stage is absolutely the best fit for a building with significant disparity in zone size (though for another day's discussion, we could argue wether your zones have different btu requirements due to the 20* disparity in set point- we need a manual J for that).
J
Joe Hardin www.amicontracting.com We Dig Comfort! www.doityourselfgeothermal.com Dig Your Own Comfort!
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18 Mar 2009 07:04 PM
GF you say that zoning doesn't open and close return ducts. That was an eye-opener because it seems only logical to me that you would only want to pull in the air you're trying to condition, not air from another zone that isn't calling for heat or cooling. I know the technology is there to do it, why it isn't done is beyond me. Please explain...

Joe, I notice you are from Howell? I nearly called a dealer in Howell awhile back about the DX system because there was no one closer to me. That may have been you. Now there's a dealer quite a bit closer, but whether he has the experience you have remains to be seen. You mentioned the possible problem with building codes. Fact is, the area where I am building is behind the times as far as the codes are concerned. I'm really very surprised at how easy everything has been up to now. My previous experience with building codes was a nightmare. I've gone from a county that was way ahead of their time to one that is way behind the times. The county I live in now was stricter 35 years ago than the one I'm building in now. Just the same, I was an industrial electrician for about 30 years and I absolutely go by the national code for any of my electrical work. In fact, I am stricter than they are about it. Drives some people nuts, hell, it drives me nuts sometimes, but that's the way I am.

Getting back to the heating system. I'm totally not sure what to do now. I will probably get a price for a small geo system for the apartment, but I expect the payback wouldn't warrant it. Just the same, I'm going to find out. As for the building, I will probably hold off on any heating system for that. I can heat it with the old air-handler for now and that will give me more time to convince myself of what I should do. That brings up another question. I was told by a water systems dealer that putting the loops in a pond is not an option if you use the pond for fishing. The way it was explained to me was that the plastic gets soft as the water circulates through it and makes it susceptible to fish hooks. Is this true? I originally thought about using my 1 1/2 acre pond for the loops of a water system, but discarded that idea after hearing this. Soon after I found out about the DX system.

Anyway, I checked out the Nordic as you suggested, Joe, but the closest dealer to me is in Virginia. Not too close. I believe they have recently switched their entire line of DX systems to the 2-stage option. I can't imagine that Earthlinked wouldn't soon offer it as well. Like I said in an earlier posting, I never thought this would be so difficult. But that's why I sought out this forum.

All in all, I keep learning more about these things and that's a good thing. Thanks again.
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18 Mar 2009 07:31 PM
Normally no need to damper return ducts since the zone being supplied will be the one with excess air which will tend to pressurize the returns nearest to it.
Curt Kinder

The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill

www.greenersolutionsair.com
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18 Mar 2009 08:23 PM
I'm not sure if i'm the only DX guy in Howell, but I'm probably the only one that grew up in NW OH and likely the only one that's been to Fostoria. We're actually working a water source job just North of Jackson right now which is the closest one to you in the near future (I'll be there Sat. and have permission to invite spectators). I would suggest that you send me building plans and let's both see if you could get payback in the next 20 years for your investment. I also have a trip scheduled to Swanton for some vandalized equipment evaluation.
I'll send you a private message through this site with my website that has a cost calculator if you fill in the information on the info request page. Please include propane and KW prices.
Joe





Joe Hardin www.amicontracting.com We Dig Comfort! www.doityourselfgeothermal.com Dig Your Own Comfort!
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18 Mar 2009 08:32 PM
Oh and while it's not typical to damper return ducts, in situ's with a 20* differential between zones, i think it's a must.
Joe Hardin www.amicontracting.com We Dig Comfort! www.doityourselfgeothermal.com Dig Your Own Comfort!
geo fanUser is Offline
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18 Mar 2009 09:15 PM

 

 if your design cant handle worst case ( smallest zone calling for max ) its not good enough

modern ecm motors factory program 70% W1 80%W2 

If ( and not here ) your zones are close in size you could oversize ducts allow static pressure to bump up because ecms will maintain cfm up to .5 ( which if you get near your doing something wrong) and allow it to drop off when both call . lets now say you have a large difference in zone sizes , the problem is clear pushing 70%  of the air into 25% of the ducts

( which is better then the 80% a single stage unit would push but) your static pressure still goes through the roof and best case you have noisy ducts , worst you go over .5 and your cfm drops allong with your eff. ( number one complaint of warm air systems noise ) 

Which is why we dump , and normally I dont have a problem dumping into the return unless its a large amount of air .

On zoning returns ( I was taught never put any dampers in returns as there is risk and little return ha ) but this is the least of your problems over size the returns so either can fit the needs of the system alone , I would only damper the one in the garage/pole minimize the risk of mod motor failure causing problems

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