Solar Panels

RAD

I want to tie a baseboard system to solar hydronic panels. I am looking for some creative ways to divert flow to and from each system separately, and control excess heat on a closed loop solar system. Thanks

Jack_23

not the best system for solar

Solar collectors work best on low temp systems. Collector efficiency is much better/higher with low temps. Confirm with manuf of the collectors. solar works best with radiant and hydro-air. Low temp solar is great.

RAD

Low temp

That makes sense, and I'd like to run the heating at lower temps on warmer days. Where are all the "Sunheads" hiding out these days?

Bob Gagnon plumbing and heating

Jack's right

solar works better with radiant than b.b. because your floor is a lot bigger than your b.b. 70 to 80 degree floors would be great, but 80 degree b.b. you would hardly notice. why not run a seperate radiant floor heating system dedicated to solar? i'm about to add a collector to my system. i think i'm going to use either Thermomax tubes or Heliodyne flat plate collectors. does anyone have any comparision between the two? bob

Jack_23

Check your radiation output tables

At low temps you will have to line the wall with baseboard element to get enough out of it. How big is the space? Heat loss? How many sq ft of collector. How big a (very well insulated)storage tank? Have you done this before?

RAD

I understand...

I get you on the low temps/convection. I am planning on switching some of the system to panel rads on a separate zone. Floor heat is not an option in this house. I have never used solar with heating systems, only many DHW and hot tubs. I would love some pointing in the right direction.

RAD

Low temp

I understand why you guys are directing me towards radiant, and there will be some panels added to the system. What I dont understand is why the low temp/efficiency correlation? It seems that the collector returns would yield some pretty high temperature water.

hr

Calc your loads

then determine how many panels and storage capacity you would need. Takes a bit of panel square footage to do much heating.

Winter time temperstures would be kinda low for much heating, unless you go with the evacuated tube type. they get quite a bit hotter, but at a much higher cost.

For heating, you will need some insualted storage. typically night time is when your loads are highest. Not a lot of sunlight, unless you bottle and store it

Contact various panel manufactures for their output in your location. They could give you a range of btu/ square foot output for their panels. See how this matches up with your loads. www.heliodyne.com is one place to try.

By far your best solar "bang for the bucks" id DHW generation. This is a year 'round load.

Solar for just heating leaves you with a bunch of free energy and no place to go with it, in the summer months. Generally one 4X8 or 4X10 panel will generate all your DHW.

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Jack_23

Collector efficiency

Solar coll are subject to the law of physics and this is simply a matter of heat loss. If you pump 120f fluid thru a Heliodyne collector it will loose less heat tahn if the temp is 180F. BTW, Heliodyne was an excellent company and they made a great product in the 70's and early 80's, when I was in the business and using them. I would assume that if they are still owned by Tom and Jurgen that would not change. The T-max is a better hi temp collector in that it is an evacutaed tube. I did not have experinece with then. I tried some ev tube units but the tracking mechanisms always ended up looking at the moon when I needed them to look at the sun. but that was 20 yrs ago....

David Woycio

solar heating

You guys are correct when realizing the heating limitations of a solar thermal heating system. B.B. heating with solar heating is inherently flawed due to the temperatures needed at the B.B.'s. Radiant heat is DEFINITELY the first choice beause a Radiant heated floor system works very well with the mean temps. (our systems usually run around 130 deg. F.) that you'll see out of the system in the winter months. If infloor w/solar is not an option then what we have had very good luck with is using McQuay heaters. These are fan convertors and heat the air as opposed to radiant. Either one of the floor models work good, or what we really like, are the TSF ceiling mounted units. You have the option to duct to various rooms distributing with a floor registar while keeping the heating unit (and the noise) in the utility room where it belongs, This works well when you have an open ceilling space to run the ducting. Temperatures can be as low as 90 deg F. and still able to keep up with the heat loss of the room(s). We usually tell customers to run the fan speed at the lowest setting. Slower consistant heat is better than a quick hot blast.

As far as flat plate solar collectors go we have used them all. Really like the old Novan solar collectors because of the riser/header configuation and ease of mouting. Generally speaking, any solar collector with a copper black chrome or quality black painted absorber plate, good riser tube to plate connection (more the plate wraps around the riser the better), good insulation, extruded aluminum frame, and textured glass will give you years of reliable service. These collectors are low tech and forever repairable. Look for common sizes 4' x 8', 4' x 10',and 3' x 6'. Have had some issues w/evac tube types. They don't hold up at all to hail which we have in abundance in Denver. The glass in a flat plate will hold up very well. Some of the older units had issues with the controls. If they're temps increased too rapidly (a cloud passing overhead) and the system's pump was slow to pump water to the solar collectors, they would shut down because the tubes could be damaged from the cool water entering an extremely hot tube. They do have high temperture gain charactaristics. Usually install these on a car wash where there is no storage tank and you need to get the water up to temp with one pass via a good heat exchanger. When cost and reliability are concerned it's hard to beat a good flat plate.

By the way we have lots of used pressure tested flat plates for sell. Although shipping could be an issue. Hope this helps.

RAD

Thanks All!

You guys kick butt. Thanks for all of the feedback. Looks like Metro Man is right in my backyard. You'll be getting a call from me on Monday. Thanks again gang.

Mark Eatherton1

Radiant floors are NOT the only solution...

when choosing radiant heat. What about walls, ceilings and counter tops? Everyone gets so focused on the floors that they forget about all the other radiant opportunities staring them in the face...

The key is LARGE surface radiators. Floor is but one option, and the more expensive option at that.

Many people don't realize it, but if you're doing a ceilings, you don't HAVE to cover every square foot of the ceiling to make the system work right. You only install the necessary square footage required to heat the room.

With radiant floors, the consumer EXPECTS warm floors, so regardless of demand, we put a minimum of one linear foot of pipe per square foot of walkable surface, just so the consumer doesn't have to set foot on a cool surface...

Look around. There are MANY flat surface opportunites right in front of you, just waiting to be turned into a warm, friendly surface, and making the dwelling "radiantly warm".

ME