Solar Facelift

Ron Huber_2

I agree, but you can have the best design, and human error or bad installations can still have negative results. I installed many drainback and draindown systems in the past with no failures. But around here there were many goofups who got into the solar install business and did not have a clue, and I am afraid we will be seeing it all over again with this current surge for solar. The system has a high limit set for 160 degrees, it is an atmospheric tank so it cannot blow off on high temps or pressure, if the heat dump fails the large expansion tank on this system should back us up. It is what it is, but going back to drainback here was not an option. And two feet from the closed loop PT blow off is a 3sq. ft. floor drain that can handle the 20 gal of non toxic anti freeze should worst case happen and every drop of glycol dumps, not likely.

Ron Huber_2

Solar Facelift

Before and after pictures of 28 year old system that had froze and burst last winter(drain back). Thanks to insurance, we replaced it with new Heliodyne Gobi panels and an external heat exchanger, never to freeze up again.

scott markle_2

nice system Ron

Looks like you opted for closed loop.( I see the glycol pails and the panels don't appear to be pitched.) With so much collector area what will you do with all that spare capacity when there is no heating load?

Also what's up with the u tubes going in and out of the bottom of the exchanger?

Ron Huber_2

Extra capacity

Using a fan coil to extract heat from the storage tank in the summer, it is ducted to the outside. Not the best setup, but had to work with what was there and customer and insurance company had been convinced to stay away from going back to drainback. The "U" tube is a larger version of the Heliodyne exchanger that we use for domestic hot water systems, it is the same exchanger that was used by Grumman and is 24% more efficient than a typical exchanger in tank setup, it is counterflow and inside surface is rifled like a gun barrel.

Ron Huber_2

28 years

On the tank and heat exchanger/fan box combo, controls where inside the hot air plenum! C-30s and relays and they where still working. System is now being controlled by the Heliodyne Delt T control that is mounted inside the new exchange module(HelioPak)

Metro Man

Too bad

Too Bad a 28 year old drain back had to be converted to closed loop and now using more energy than needed for heat dump.

This is why you design a drain back system with inexpensive redundant freeze protection controls to prevent this from ever happening.

The next call from the insurance company is going to be when the heat dump fan failed, storage heated to beyond high limit, blows P/T off pot. storage tank, and floods the basement. This usually happens when homeowner is on vacation according to Murphy.

Me thinks THAT bill is going to be higher than frozen solar collectors on the outside of someone's house.

Anything can fail anytime. Just have to remember the 7 P's...... Proper Prior Prevention Prevents Piss Poor Performance.

Metro Man

scott markle_2

So that system uses an open tank for storage and an air handler for distribution.

To bad you couldn't go a bit further. Forced air and solar seem like a week combo. I guess there were some interesting things done with rock beds and air in the seventies, mostly interesting because they sought to utilize natural convection instead of fans or pumps.

Perhaps if you crunch the numbers the energy used by fans in this system is reasonable by comparison to the energy collected from the sun. However If we are going to involve electricity so much in our design maybe a ground source heat pump would be a better way to go. Is running an efficient scroll compressor so bad compared to all that copper and glass pumping the suns energy at it's most productive period- through a bridge to nowhere. 28 years is good run, I'm surprised the insurance people didn't insist on having it redone exactly as it was built!

Colorado and other cold high insolation areas of the country might make
sense for high fraction solar heating. lesser endowed regions?

In the winter it will be interesting to see if there is any change in performance from the original system, there is probably not enough of a record to determine this, but if there was, it would make a good test of the notion that glycol limits solar efficiency. (something I'm not fully convinced of)

Ron Huber_2

Heliodyne

Anyone else using Heliodyne panels?

ScottMP

Nice work Ron

But then thats what I have come to expect from you.

Nice to see you posting pictures again.

Scott

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Metro Man

Still too bad

You have a superior system design in the drain-back system that was there. Sounds like you have enough experience to have reinstalled a "new" drain back system that would have been redundantly freeze protected in the place of the old. And if I remember correctly you could have re-plumbed better than the original.

I would have fought the insurance company who has zero technical experience in deciding what type of system should go back in.

Not knocking the install. Just think it is our job a solar professionals to point out and educate those who don't know all of the options.

Metro Man

Ron Huber_2

Weighing the pros and cons

One of the other issues I have come to find out during the process of quoting this job, was that there are more flat plate manufacturers that will not warranty their panels in a drainback system in northern climates. Heliodyne is one of them, Viessmann does not even make a panel that can be used for drainback, seems like this is the direction the business is headed as far as northern climates are concerned. And electrical issues are kind of a wash. The pump on the original system was a high head shallow well pump (and noisy) that draws a lot of juice compared to the Wilo circulators in the new system. Antifreeze loss in efficiency and overheating problems was a concern. But just this week I found that the original system had a heat dump that I did not notice until I started looking at ways to dump some heat in the summer. Off the main supply trunk to the house is a 12x20 trunk line that went out through the top of the foundation. About 14 years ago the the original owner built an addition off that part of the house and blocked off the louver that was part of the dump zone. Inside the supply plenum is a set of dampers, one covers the trunk line to the house, the other covers the trunk line to the dump louver. So on the original drainback system they must have wanted to dump some heat in the summer to prevent the panels from getting stressed all summer with no flow through them. Ideal system, two or three panel DHW system on a passive solar house with condensing boiler on a radiant system. Oh Ya, and under 2,000 sq. ft. of living area. I think it is time to downsize.

Metro Man

Collector Man.

In 27+ years of being in the solar business I have never seen a solar collector stressed from stagnating temps in a drain back system. I have let collector arrays stagnate to 270*F and pumped 60*F water through. Makes a hell of a lot of noise then runs smooth. The new controllers have an option to protect the pump in a glycol system. I guess if you where worried you could set the same function down.... although I wouldn't.

I have seen poorly made collectors have they're absorber plates release from the risers. But these where glycol and drainback systems.

I know what you mean in talking with some of the collector reps. Not sure where when or why that term (collector stressing) came about but think alot of it is to save they're own butts. Also many collector mnfc sell complete systems that include mixing blocks, heat exchangers, x-tanks, and etc.. that is all part of the system package. Easier to train installers to install a complete prepackaged system. Think you mentioned earlier about a lot of the newbe's coming out and potentially freezing systems. I agree... the last thing Heliodyne (or anyone manufacturing collectors) wants to see is they're collectors freezing on some big array.

Wilo (if your listening) needs to step up to the plate and think through the drain-back scenario completely and come up with a high head pump that will work. I've talked M.Hunt about this and they still have issues that need ironed out.

HIgh head pumping (over 30').... there are options... like stacking 2 pumps.

Anyway... it is a very nice looking install. How do you like hanging off of those 12-12"s?

Metro Man