Second hand EOS thermal system

[Thirstymate]

I've been searching through and I can't directly find the information I'm looking for.

As a background, I am an architectural engineer turned commercial pilot, who has for a long time desired to dable with solar heating. This system is located in southern Maine US.

I found a complete second hand EOS solar set up consisting of 2 thirty tube manifolds, a 60 and 80gal storage tank and all the pumps, heat exchangers and and IMC solar eagle 2 controller. For a very low price I am now creating hot water. The 60 gal tank is a preheated for DHW and the 80 gal will be the storage for the single baseboard heat loop in the house.

My question is in regards to normal operating parameters.
With this setup on a full sun day I am seeing an average at the output of the collector of 165 degrees, and by the end of direct sun around 4pm the bottom of my 60 gal tank around 115 degrees. The high limit for switching to tank 2 is 120, so far so good on that end. 165degrees at the collector by 10 am is much more than I was expecting. I certainly did my homework with sun angle and facing 195degrees on a compass... But if that's what I'm seeing in January, I'm going to have a serious amount of heat to displace this summer. Does this sound correct? Is the collector operating too high? I have the documents for installation, but EOS is long gone and I have no "normal" operating parameters to go by.

System is charged with Dowfrost HD

[Mike90250]

seat of the pants, I'd do something to increase the transfer of heat from the collector loop to the potable. Either faster pump rate, or larger exchanger in the the storage tanks.
165F water just "seems too hot"

In summer, you HAVE to shade much of the collector system, or it will overheat. Start saving refrigerator cardboard cartons !

[Thirstymate]

The system is charged with dowfrost hd. So it's not water, but my brain is telling me the same thing. What's confusing to me is that I have a small drill pump, running that for just a few minutes when I was bleeding the system gets the collector temps down sub 100. I suppose I could call IMC. They are still in business.

[LucMan]

Is That temperature with the pump running?
That doesn't seem like a problem to me, your 1 tank storage is at 115 degrees. You could speed up the pump to increase the gpm through the collector or if you have a balancing valve in line with the collectors make sure it is full open. I'm going to guess that you need 3-4 gpm through your manifold or maybe more. This can be changed up or down to give you the delta T that you want to achieve. Usually between 10-20 degrees. I have my flat plates adjusted for 10 degrees delta T.
115 degrees isn't going to give you much heat in the 1 zone of baseboard radiation. If I remember correctly most manufacturers do not rate baseboard below 130.
Evacuated tubes=low volume high temp.
Flat plated = high volume lower temps.
With 60 tubes, in the summer to prevent over heating a dump zone will be required.

[J.P.M.]

The collectors sound like evacuated tube type. For starters, any chance for a data sheet for the collectors ? Without data or a data sheet on the collectors, it's not possible for me to suggest an answer to your question. However, if they are evacuated tube type, the collector loss coefficient will usually be low enough that the temp. differential between collector and the ambient air will not have as great an effect on efficiency as if the collectors were flat plate types. Also, if this is a heating application, increasing the collector tilt to be closer to vertical will increase the winter collector temps. and tend to decrease the summer ambient to collector temp. some due to increased/decraesed w winter/summer collector irradiance levels.

[Thirstymate]

Lucman.
pump running.

J.p.m
I'll check but I'm 99% certain I don't have a data sheet. They are evacuated and I believe 72". For my location I had a minimum sun angle of 30* in January and I believe 70 some odd in the summer. I set the panels for approximately 35* as that gave me the best collection for November through March.

[Thirstymate]

I suppose it may well be that my time on the math for orientation is paying off, and certainly being 40* off angle in the summer is going to help quite a bit.

I have read that the heat exchangers can require regular replacement to due efficiency loss, does that also seem to be the case? I was considering putting in a second exchanger to assist in heat removal from the glycol.
I believe they are currently Duda B3-12a 20 plate.

The temps I'm referencing in the tanks are bottom measurements, so I'm assuming the upper portion is a bit warmer.

[J.P.M.]

Lucman.
pump running.

J.p.m
I'll check but I'm 99% certain I don't have a data sheet. They are evacuated and I believe 72". For my location I had a minimum sun angle of 30* in January and I believe 70 some odd in the summer. I set the panels for approximately 35* as that gave me the best collection for November through March.

Thank you.

What's the dimensions of the collector and also the tube dimensions ?

FWIW, I'd think that the latitude in So. ME would make the 70 deg. tilt more favorable for winter collection and the 35 deg. tilt more favorable for summer collection of heat. Do you have the sense of your winter/summer tilt angles reversed or are you measuring the tilt of the panels from the vertical rather than the horizontal plane ?

Also, being a pilot I'm sure you took this into account, but did you correct for magnetic declination for the compass reading ? So. ME requires about an 18 Deg FWIW, So. ME requires about an 18 deg. westerly compass correction.

Are you attempting to provide DHW or space heat ?

[LucMan]

You can try going to the SRCC rating web site and look at a similar 30 tube array (Apricus) that will give you a pretty good idea what your daily BTU output would be in your climate zone. Then you can calculate what size HX you need.
To calculate your array output 1BTU heats 1 pound of water 1 degree

[Thirstymate]

Thank you.

What's the dimensions of the collector and also the tube dimensions ?

FWIW, I'd think that the latitude in So. ME would make the 70 deg. tilt more favorable for winter collection and the 35 deg. tilt more favorable for summer collection of heat. Do you have the sense of your winter/summer tilt angles reversed or are you measuring the tilt of the panels from the vertical rather than the horizontal plane ?

Also, being a pilot I'm sure you took this into account, but did you correct for magnetic declination for the compass reading ? So. ME requires about an 18 Deg FWIW, So. ME requires about an 18 deg. westerly compass correction.

Are you attempting to provide DHW or space heat ?

I am using angles from vertical or zenith. so you and I are referencing the same thing just speaking it in opposites. I know it as magnetic variation, but yes it was considered. I actually tracked shadows from first light to last light on the roof and set the middle, then I found a tool online that provided 195 for a magnetic heading and it was near-as-makes-no-difference.

The closest system would likely be the Duda solar sc5830, which being that some of the parts are marked Duda they may very well be Duda collectors. if I'm reading it correctly I have 84k btu/day summer and 40k btu/day winter.

[Thirstymate]

Thanks so far for the information. I'm able to reference that my heat exchangers were sufficient at new and will be making some calls to see if I can get a grasp on their age. I appreciate you all pointing a new comer to the areas to find the needed information.

Ideally, I'd like to get the unit to supplement heating. Currently, as I got it, it is setup for dhw and to discharge additional heat to radiant floors. I do not have radiant floors, but do have forced hot water and tied the over heat discharge into the heating loop. I have a tankless coil on my boiler and so the cold water I diverted from the coil, via an H pattern manifold with valves so I can return to direct to coil if needed for servicing, to the 60G tank and the back to the coil inlet. This setup works very well as in the afternoon when the 60G tank is up to temp the boiler does not come on for atleast 1 shower, some hand washed dishes and a run of the dishwasher, so far that's all the load I've put on it, I consider that a win. hopefully I can convert my wife to evening showers as well, though I hardly have anyone to impress when I'm home from trips and showering in the evening is a necessity after a day working on the house or in the garage.

My house faces approximately 200* sse. I have installed approx. 60sf of skylights and have another 50sf of south facing windows. In all but January so far, the sun heats half my house to 80*. The upper skylights are operable and with windows open, do a good job of evacuating excess heat in all but august.

[peakbagger]

I am surprised all your tubes are good, lots of evac tube owner's have replaced more than few that failed within a few years. Usually, the company that sold them eventually goes out of business and that is the end of it until the owner gets a new roof and yanks the system.

[Thirstymate]

Only one tube had failed in.... 15 years? And the system came with three spares.