Thermal - PV and diff controller + dump control... [RE-wrenches]

Conrad Geyser conradg at cape.com
Sat May 6 16:11:29 PDT 2006


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Geoff et all,
We like to run ~ 12' of baseboard off the antifeeze loop using a three way 
zone valve.  This helps act as a high limit and does some 
heating/dehumidifying in the basement.  About half that basements that we go 
into have some dinosaur dehumidifier running.  The idea is to help reduce 
this load.  I'm not sure if this makes as much sense in a house with AC, but 
maybe.  A double throw aquastat set to about 140 degree F acts as control.
We also happen to have some 120 VAC three way zone valves that Taco made for 
us when we were working on our draindown project(currently shelved).  These 
get you around needing the transformer that you would need for normal zone 
valves....
happy heating
Conrad Geyser
Cotuit Solar

----- Original Message ----- 
From: "Geoff Greenfield" <Geoff at Third-Sun.Com>
To: <RE-wrenches at topica.com>
Sent: Tuesday, May 02, 2006 9:46 AM
Subject: RE: Thermal - PV and diff controller + dump control... 
[RE-wrenches]


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>
> Thanks Tom-
>
> I also like the el sid's and have had no failures.  I am also curious 
> about
> their variable speed injector control.  I wish they had more "solid" 
> looking
> stuff rather than exposed boards.
>
> I am now knee deep in a much better version of Tom Lane's book - my 
> earlier
> edition was rough, this is more polished.  It is still a lot of info (all
> things to all applications) but I can focus only on freeze region 
> technology
> now, as well as res HW and larger approaches.
>
> Here is a further question I have about my future system and a 
> customer's -
> \
>
> D U M P    L O A D S!
>
> I am looking forward to a system sized for radiant heating assist, and 
> plan
> on a combined dump load/secondary storage/rejuvination station:  An
> insulated hot tub (concrete stock tank) with a big copper coil HE under a
> bench seat!  The added complexity of being able to store and remove heat 
> may
> or may not be worth the effort.
>
> My question is:  are motorized valves reliable?  worth the electrical load
> (I'm off grid) Or would I be better off with dedicated pumps and check
> valves?.
>
> Second question:  is there an easy way for existing GL-30 to kick in this
> dump load at storage tank high temp or do I need a seperate GL 30 or
> aquastat?  A-stat or control Recomendations (I don't have an immersion 
> well
> available so prefer a thermister approach).
>
>
> Date: Mon,  1 May 2006 12:21:04 +0000
> From: Tom DeBates <habitek83 at yahoo.com>
> Subject: RE: Thermal - PV and diff controller?
>
>
>
> good day Geoff,
> ...sorry about the delay in replying.
>  This Winter I installed a PV-powered solar thermal system for my
> residence.  I have a 32 watt Unisolar powering 4 ElSid pumps. Currently
> there are only 3 pumps installed as I have not completed the small
> radiant heating loop. There is a 10 watt pump on the collector loop, a 5
> watt on the storage tank loop, and a 5 watt on the heating loop (HX
> side). The other 5 watt pump will be on the heating side of the HX.
>  Although I need to do more insulating and fine-tuning, so far I am
> satisfied with the performance of the system. Initially I felt that I
> was "missing" some late afternoon gain as the collectors had more
> "thermal inertia" than the PV could extract during that period. I
> considered adding a small module facing west, but have decided that the
> storage tank and collectors are almost at equilibrium at that point
> anyway and I am not losing much gain.
>  ElSid does make a differential controller. It is a small board that
> attaches to the side of the pump. It is set for ~ 8 to 10 degrees
> (non-adjustable) and seems to work well....nice and simple. I inquired
> as to a set-point controller and Dan (ElSid) said that he could do this.
>  I can send a schematic and pics if you want.
> good luck,
> Tom
>
>
> geoff at third-sun.com wrote:
>>
>> I like the PV direct approach for typical residential solar thermal...
>> nice
>> 20 watt panel and an el-sid and away we go.  Flow rate increases with
>> sunlight (and collector temp in theory?). Usually an 80 gallon with
>> built in
>> HE.
>>
>> My question - how may of you add a differential controller to the
>> system?  I
>> didn't have a good answer for a savvy customer who asked the somewhat
>> obvious question... "What keeps us from dumping heat on a sunny but
>> super
>> cold day?"
>>
>> For a brighter energy future,
>>
>> Geoff Greenfield
>> NABCEP Certified Energy Practitioner
>>
>> THIRD SUN SOLAR & WIND POWER Ltd.
>> 340 West State Street
>> Athens, OH 45701
>>
>> www.third-sun.com
>> (740) 597-3111
>>
>>
>
> For a brighter energy future,
>
> Geoff Greenfield
> NABCEP Certified Energy Practitioner
>
> THIRD SUN SOLAR & WIND POWER Ltd.
> 340 West State Street
> Athens, OH 45701
>
> www.third-sun.com
> (740) 597-3111
>
> -
>
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