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Posts: 720
Reply with quote  #11 
Yes I have the one hot water panel. I'm guessing at the total pex footage but 450' is close. I bought 2 250' rolls & have a little bit left over. I also have 12' of radiant baseboard connected to a pex loop. Last year it worked (95 degrees at exit). Since my panel isn't producing as good as heat as last year's I have bother to check the baseboard temps. I'm sure someone will mention about trying to use radiant baseboard with a low heat supply.

Yes I am feeding all pex loops, baseboard (inline via 1 loop), & storage tank. I have a separate circulating tank & guessing it has 10-15 gallons of anti-freeze (not water). I circulate the heated AF thru the system, BUT I'm not heating for Domestic Hot Water.

I installed my Pex differently than most installs because it was cheaper. Most have pex pipe under the floor & connected a manifold, generally at the pump location. I used 3/4" CPVC pipe (on-sale) for the hot-cold lines going to & from the solar panel. The individual pex loops feed from this main pipe. The CPVC was on sale & cheaper than buying additional PEX pipe to terminate all loops at the pump location. Pex isn't easy to install for a one-person project as CPVC.

I included edited-labeled pictures so it's easier to understand. The picture also shows the pre-heat line that goes direct back to the circulating tank. The pex loops all connect to a 3/4" cpvc return pipe that goes back to the circulating tank. The return pipe is not shown in the picture, but located on the back side of the support beam that the heated pipe is mounted on. I snapped this picture last year as I was installing the pex.

I haven't really used my storage tank yet, but agree on the value of having it.

Central IL

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Posts: 1,845
Reply with quote  #12 
Thanks Jeff,
   That's interesting, I have been thinking of adding more than the 6o feet I originally planned to my long horizontal, maybe I should do both.  I also have ceramic tile in the kitchen that sure would be nice to have heated.  -20 this morning and that kitchen floor felt kind of cool on my bare feet.
   I have listened to the theory of keeping the panel temp rise to only about 5 degrees but don't understand it, therefore do not like it.  Logic to me seems like a greater increase, colder in but limit the temp out by flow, would be more efficient, so I do not understand the whole circulating tank thing.  I guess I need to do some more reading.  I guess if temp coming in is warmer it easier to get higher usable temps when cold, like with hot air systems.
   Yes I have read the radient baseboard heaters work better with hotter air but many people have used the with good results.  Probably best to put it first though. 
Thanks, Dan

Posts: 720
Reply with quote  #13 
I was impressed wioth my radiant baseboard last year. The baseboard was installed onm the north side of the room & you could physically feel the warmth. Of course the parabolic panel last year produced a lot better heat.

Yes the baseboard is fed at the beginning of a pex loop by using a tee-connector. That way, both the pex tubing & baseboard receive the heated water at the same temps.

I know exactly what you mean about the cold floor. That's why I pursued hot water with pex tubing. I have a vinyl foyered area at the base of the staircase & doorway. It has always been cold! It's a good thing the rest of the room is carpeted or my floors would be unbearable during the winter.

Once I get a good-working-reliable solar water panel I plan to change to hardwood floors. I didn't mention it but that manifold piping in my crawl space also exits the north side of my house. It connects to an old wood-burning stove that I converted to heat the same water (anti-freeze). By opening/closing valves (manually) I can build a fire & heat the house with the same water at night or re-generate the storage tank. It's not connected/working right now. I robbed the copper tubing from it & placed it in my storage tank. I intended to build a better copper system for the burner-boiler but it took longer getting the parabolic panel together. I doubt I will bother getting it working this winter.

I found an old picture (2 yrs ago) of the wood burner, shortly after I got it moved outside.

Central IL

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Posts: 303
Reply with quote  #14 
Solar hot water collection lends itself VERY well to under/infloor radiant heat.

A few things to remember and think about:
  • Solar is usually at lower temp than what most under/in floor radiant was originally developed for. ~90F for solar as compared to 110-120 for fuel-heated.
  • If you need more "heat" in your radiant floor, experiment with closer spacing. There have been installs with the PEX having 4" spacing between 'runs', instead of the standard 6". Higher heat density seems to be the thing in this approach.
  • Use heat spreader plates. Think "flat-plate solar collector" in reverse. The more contact you have with the heat and flooring material, the better. (Check out this link)
  • Usually, lower flow rates works very well thru the PEX/spreader combo. 
  • In-wall PEX radiant heat. Wrap your mind around that. Better if your walls are already open, tho...
  • Warm your doghouse (floor and walls). Fido will love you, and when the wife gets too mad, you have a warm place to sleep.
  • Deice/melt snow on your porch/sidewalk/steps

Basically, test and see what kind of temperature drops you get in your storage tank overnight while heating, and see if you have 'extra'

I've been thinking of many uses, because my "roof over" project has the capacity to easily do all the above, plus probably heat the neighbor's home, too. And an enclosed garage. And a swimming pool. Or two...


Posts: 243
Reply with quote  #15 
Hi Dan,

"Radiant floor heating questions,
   One of the early things I read that really got me thinking about water was something Scott Davis has on his website.  He states that if you don't want to build a tank just build a collector and hook it up to a pex tubing radiant loop directly.  It seems like the more I read the more I stray from this most basic heating concept.  My questions are:
1. Is anything else needed for safety etc, other than a panel, a run of pex with flashing, a pump, a snap switch? 
2. Could it overheat and how can that be prevented.
3. How much collector for each 10 feet fun of flashed pex? (any other guideline will work)
4. Using the tank drawing attached, what's the best way to keep from overheating, or would it with say 60 square feet of collector.

I think that at a minimum you need to have an expansion tank and a temperature pressure relief valve in the circuit.  And, fill valves.

For the overheat, why not just have a thermostat that senses the water or floor temperature and just have it shut the pump off when it gets as hot as you want things to get?  Some of the differential controllers have a setting for this.  That still leaves the possibility of the collector itself over heating, but if the tilt is vertical or steep, I don't think this would be a problem.

This guy has a collector direct to slab solar heating system:
You might have to search around his site for the whole series he did on implementing this system, but its pretty good.



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Posts: 283
Reply with quote  #16 
While i was browsing through that blog i saved the links for anything solar related i found, will save some time finding them.Hopefully its all here.
I tried putting the links in here one by one but kept getting the text you entered is too long?
Heres the links in a word doc instead.Sorry if someone aint got word its the only way i could get it working for now.
Just highlight them first then right click and select open hyperlink.
Regards Mattie


Posts: 243
Reply with quote  #17 
Thanks Mattie,

It looks like there are a couple more posts on their site:


They have some more on their newer site:

Hard to find stuff on their site.

Its their solar project with the bank of collectors mounted on the side of the shipping container that has the direct circulation to a slab.
It appears to be working for them.



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Posts: 1,845
Reply with quote  #18 
   An answer to a question I'd forgot I asked but useful info still the same.  Timely also, as I have been thinking about how I can keep my sunspace warm enough at night for planting soon.  A deviation of this guys project may be two use a couple of smaller existing collectors I have, (The ones from testing last year), and feed them though pex buried in sand under paving stones or gravel.  This way I can use the heat of the day in the sunspace to heat the stones but also to supplement it with water heating from the collectors.  Since it is still likely to freeze I could have the collectors so they drain into the lower pex at night or maybe a small insulated tank so the air will stay at the top of the tank or be vented from there.
  I was thinking about circulating air from the sunspace through the ground but my floor space is probably not deep enough for that, or using water to heat my 55 gallon drum and just let it radiate through the night.  Probably a tank or the drum keeps it simpler and cuts down on the expansion tank and release valve requirement.

Lots of options, running out of time.

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Posts: 2,319
Reply with quote  #19 

Will you be adding a more permanent floor to your sunroom at some point?

Greg in MN[wave]


Posts: 243
Reply with quote  #20 
Hi Dan,

Just to add another option [smile]

I tried a system where I had an air to water heat exchanger mounted in the peak of the greenhouse with a fan pushing air through it.  The water side of the heat exchanger was plumbed through the 5 water barrels I have along the back of the greenhouse with a Topsflo pump to circulate the water.

Basically it takes the excess heat at the top of the greenhouse and uses it to get more heat stored in the barrels. 

It was pretty simple, and it appeared to do well on collecting heat.  The problem I had with it was freeze protection.  I thought I had the heat exchanger setup so that it would drain back to the water barrels when the pump turned off, but it did not and froze up badly.  

I have another heat exchanger ordered and will try to work out a way to protect it from freezing.

It seems like a good way to go if the freezing problem could be solved.  

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