Solar Hot Water

[Doug Kalmer]

I`ve taken several older, non working systems from other folks homes, and used the components to make more modern systems. Here`s two links to two systems Ive put together. Doug
DIY Solar Hot Water Articles can be found here:

http://www.solarfacts.net/articles/diy/diy_solar_hot_water_heater_-_doug_kalmer.html

http://www.solarfacts.net/articles/diy/diy_solar_hot_water_heater_two_-_doug_kalmer.html

[Rob Beckers]

Hi Doug,

Very interesting info! I like the idea of having one's own stainless steel water tank built. If you have a bit of time, could you post more about how it's made? Maybe you have drawings of the tank, or pictures (especially of the inside while it's being made). The link you published doesn't really give enough information for someone that would want to do the same. I'm interested, and I'm probably not the only one.

-Rob-

[Mark Parsons]

Hi Doug,
Nice work. How has Bob made out offsetting his heating bills? Some data to share would be great. Where did you get your heat exchangers for the DHW tank? Looks like you went thermosyphon through the exchangers?

Question for Rob,
I recently refurbished a 3' x 8' Norsun flat plate solar collector made by Nortec Solar Industries of Manotick, ON circa early 80's. Heard of them? I can't find any details - suspect they went out of business in the 80's. The unit was originally designed as a thermal diode type using a refrigerant. The structure, glazing and absorber were in great shape so reconfigured for direct function by passing water through instead of the refrigerant thermosyphon system which didn't work anymore. Added some high tech duct insulation and painted the faded absorber with a new coat of flat black stove paint. Tests show good btu production now, 1200 - 1600 btu per hour of direct sun exposure. An estimated range due to lack of continuous sun during 2 test periods to date. Been a cloudy winter down here. I'm going to use as a solar drainback DHW assist for the cottage.

Thanks.
Mark

[Rob Beckers]

Hi Mark,

Only having been in Manotick for the past 1 1/2 years, I'm not too familiar with what was and is around here. I called a buddy of mine who has lived in Manotick since the early 60's, and he does remember Nortec. According to him they most definitely no longer exist. He says he knows some of the people involved with that company, but he's not in touch with any of them.

By the way, this guy (my buddy) is into making bio-diesel. He collects waste oil from the restaurants around here and turns it into diesel in his garage.

-Rob-

[Paul Bailey]

:) now that Feb is rolling along starting to see more sun on all fronts and lots more hot water finally. Paul

[Rob Beckers]

Hi Paul,

Where is this collector located? And how is hot water production?

-Rob-

[Paul Bailey]

I'm in Prince Edward county . 100 miles east of Toronto.. Still trying to get all of my system integrated with Domestic hot water (DHW) and some low temp radiant applications. Unfortunately things are never simple and proper design and application is crucial to the sucess of the install in order to maintain proper efficiency. ..This bank of 60 thermomax heats my 120 gallon tank to 150+ in a day if is sunny. . More details to follow .Paul

[Mark Parsons]

Greetings Paul,

I would love to get a feel for system costs of your evacuated tube system by the time it is installed and operational. How much of your heating are you figuring to offset? If memory serves me you should be in about 15 MJ per square meter per day annual average insolation. Maps are at - http://atlas.nrcan.gc.ca/site/english/maps/archives/5thedition/environment/climate/mcr4076

Any data on your system and personal experiences would be great.

Regards,
Mark

[Rob Beckers]

Paul,

In addition to Mark's questions here's another one: Do you have any problem with snow coverage of the collector tubes in winter? As part of my 'going green' plan (a very loooong term plan) I've been pondering the same evacuated tubes, and would have a good spot for them high up on the roof. It's completely inaccessible though in case they get snow covered. So I was wondering about that.

-Rob-

[Paul Bailey]

My collectors are 55 degrees Versus my 45 deg. N. latitude. ? Why??? I wanted optimum production for spring and fall and some self limiting factors of being off angle by 35 deg.tilt so I do not overproduce in the summer which can Happen.. To answer the Snow question I will say yes It will and can bond and does take longer to come off but my extra steep tilt does help with this sheer. I'LL add some pics. Now as far as cost. Most of you are aware these are premium priced products.As far as production I think you'll see at least 25 to 40% more output. There are other ways to increase the overall system Efficiency regardless of who's collector you buy. !!! I'll elaborate on this later if you wish. Paul:)

[Wilco Vercoelen]

Here is a flat plate collector in winter for comparison.

[Paul Bailey]

At noon my panels are self clearing but its taking some time. Paul

[Mark Parsons]

Thanks Paul and Wilco.

I'm aware of the improved performance of the evacuated tube type collector over flat plate. I've just refurbished a flat plate collector to use for partial DHW. I guess I'm still looking for some data on the ROI and heating capacity from an unbiased individual with direct experience.

My cottage is located 45.2 degrees north. It bothers me to burn propane (read pay$$) to keep the place slightly above freezing in the winter between my visits. Could I get solar collectors to replace this base propane heat for freeze protection? Is this even a reasonable supposition? Fears of unattended operation? Possible too many days without sun causing a large frozen tank and split lines?

Questions, questions...:confused:

Mark

[Paul Bailey]

Hi Mark ..I'll return with a detailed reply on this tomorrow since I'm off to work shortly. I'm at 44.11 N .Do you know your heat loss in BTU's versus you degree days????? Paul

[Mark Parsons]

Hi Paul,

I do not know my btu loss per degree day. I know how many btu's my propane stove is burning based on refueling data and interval. For instance, from December 16, 2006 to January 9, 2007, a daily average of 7.3 litres per day of propane was used. At 24,200 btu per litre the average was 176,660 btu per day. Looking at it now, is see the propane bill is full of other information.:o I think it shows the number of degree days for this interval to be 735. Hence math is (174.8L x 24,200 btu) / 735 = 5,750 btu per degree day. Does this number sound right? Bear in mind I keep the propane stove at minimum thermostat setting so my degree day balance point is at about 45 degrees.

Thanks for making me think through this mental excercise.

Regards,
Mark

[Paul Bailey]

Hi mark RE your above post Haven't run your numbers yet but I did find degree days for nearby Sarnia...Heating deg days for the Year

l
Heating Degree Days (base 65) 6174 Total
Cooling Degree Days (base 65) 137 Total
Growing Degree Days (base 50) 987 Total

Paul

[Mark Parsons]

Thanks Paul.

My degree day numbers and propane use are for my cottage located near Barry's Bay, ON. north of Bancroft.

Mark

[Paul Bailey]

oooops sorry Mark. Bancroft numbers are;)


Degree Days
Heating Degree Days (base 65) 8816
Cooling Degree Days (base 65) 334
Growing Degree Days (base 50) 1905

[Mark Parsons]

Hi Paul,

Thanks for the degree day references.

Do I need an annual calculation or is the one computed over the 3 week period posted earlier sufficient? The 5,750 btu loss per degree day.

An annual calculation will be difficult since this is the first winter with the propane back-up. Wood heat is difficult to quantify the btu value accurately.

Using your table for Bancroft of 8,816 heating degree days times 5,750 btu per degree day I would require about 51 million btu's for a season. (About 2100 litres of propane - sounds about right.)

How do you get from this value to a solar heating solution?:confused:

Regards,
Mark

[Wilco Vercoelen]

The heating degree days for Bancroft are just over 5000 according to:
http://atlas.nrcan.gc.ca/site/english/maps/archives/5thedition/environment/climate/mcr4033
18C as a standard.
On average +/- 1175 Litres per year.

[Paul Bailey]

That NR canada map is whacked. I'm 100 miles south of Bancroft. And I'm in the 7000 dd range yet the map says i'm around 4300. I Have over 10 years data to prove this. . Oh ,Mark call a few heating oil companys in the Bancroft area for some real world numbers as they track this right to the actual d.d. to base there fuel deliveries upon this. Paul. ;)

[Gary Reysa]

Thanks Paul and Wilco.

I'm aware of the improved performance of the evacuated tube type collector over flat plate. I've just refurbished a flat plate collector to use for partial DHW. I guess I'm still looking for some data on the ROI and heating capacity from an unbiased individual with direct experience.

Questions, questions...:confused:

Mark

You can compare the actual performance of evac tubes and flat plate collectors on the SRCC site. Just download the "Directory of SRCC Certified Solar Collector Ratings" from this page:
http://www.solar-rating.org/RATINGS/RATINGS.HTM

Here is a little info on how to use the compare collectors from the ratings:
http://www.builditsolar.com/References/Ratings/SRCCRating.htm

The differences between good flat plates and good evac tubes are actually quite small.

Gary

[Mark Parsons]

Greetings Gary,

Let me first say, I love your web site and check it frequently. I assume you must be back from your fishing excursion.

I have seen the SRCC Rating reference data you refer to linked from your site. Great info.

I understood the main advantage of evac tubes was to get hotter water in winter. Not so necessary for heating, but necessary for SDWH.

Regards,
Mark

[Ralph Day]

Hi Paul

I'm designing a rack to increase the angle of my shwcollecter. It's presently at 15deg. What is your compromise angle on your tubes? I'm aiming at about 50 deg or would that be too steep for summer collection. Now, the system doesn't even run from dec to feb (i don't clean the snow even, not enough collection).

Angle? THanks.

Mark...I think i need glasses at the computer. I know your picture is of you and your undershot whater wheel, but evrery time i look at it i see an old tyme prospector leading his pack mule accross a creek! The eyes see what they think the brain wants to see.

Ralph

[Mark Parsons]

Mark...I think i need glasses at the computer. I know your picture is of you and your undershot whater wheel, but evrery time i look at it i see an old tyme prospector leading his pack mule accross a creek! The eyes see what they think the brain wants to see.

I'm flattered - I think.... :rolleyes:

I would comment on yours, but I see I am in the small minority posting an Avatar. :D

Mark

[Paul Bailey]

Veiw all the pics at .

www.pbase.com/ericjeeper/solar

[Gary Reysa]

Greetings Gary,

Let me first say, I love your web site and check it frequently. I assume you must be back from your fishing excursion.

I have seen the SRCC Rating reference data you refer to linked from your site. Great info.

I understood the main advantage of evac tubes was to get hotter water in winter. Not so necessary for heating, but necessary for SDWH.

Regards,
Mark

Hi Mark,
Thanks for the kind words on BuildItSolar.
We are back from the sunny and 80F vacation to 20F and snowing Montana:)

Gary

[Wilco Vercoelen]

Hi Everyone,

I have done some research on Evacuated Tubes and Flat Plate Collectors.
As far as I can see: yes, the efficiency per m2 is higher for evacuated tubes, but the costs are higher too. I have done some calculations among different brands and models and found out that it is more cost-effictive to install more m2 of flatplate compared to less m2 of evacuated tubes, even in winter! It really depends on the brand and model ofcourse but I think it worth while doing some research before actually purchasing panels or tubes. They don't tell you the whole story...;)

[Paul Bailey]

Hi Wilco the data says they both perform the same in the summer. All other times of the year the Evac. tube would of course clearly outperform a flat plat. . MY DATA( 15 years experiance with solar thermal) says.... My array of thermal has decreased by 30 % and my tank size increased by more than 50% and I'm getting about the same temp as the flat plates. SO I'm definately producing alot more with the evacs. I'll get even more by upsizeing to more tank or dumping to low temp radiant. Remember every 3 degrees is 1% more efficient...Paul:)

[Gary Reysa]

Hi Wilco the data says they both perform the same in the summer. All other times of the year the Evac. tube would of course clearly outperform a flat plat. . MY DATA( 15 years experiance with solar thermal) says.... My array of thermal has decreased by 30 % and my tank size increased by more than 50% and I'm getting about the same temp as the flat plates. SO I'm definately producing alot more with the evacs. I'll get even more by upsizeing to more tank or dumping to low temp radiant. Remember every 3 degrees is 1% more efficient...Paul:)

Hi Paul,
I'd say the winter performance is very close to equal, depending on which particular collectors you have.

Here is some data from the SRCC certification document for a Heliodyne Gobi and two evac tube collectors.

Clear Day 2000 BTU/sf-day
---------------------------
Gobi Flat Plate: 713 BTU/sqft (ie you get 713 BTU per day for each sf)
Apricus evac: 688
Thermomax evac: 521

Mildly Cloudy -- 1500 BTU/sf-day
--------------------------------
Gobi Flat Plate: 403 BTU/sqft
Apricus evac: 469
Thermomax evac: 293

Cloudy -- 1000 BTU/sf-day
--------------------------
Gobi Flat Plate: 124 BTU/sqft
Apricus evac: 282
Thermomax evac: 98

So, the Gobi (flat plate) always does better in sunny conditions, and it does better than one of the evac tubes in cloudy conditions.

These numbers are for "Service D", which is a 90F difference between the collector fluid temperature and ambient -- this is what the SRCC calls the "Winter Heating - Cold Climate"
These results are part of the SRCC certification test, and are done in the same way for all collectors. They are from this document:
http://www.solar-rating.org/RATINGS/OG100DIRECTORIES/OG100DIRFULL_20070313.pdf
All I did was to divide the collector output by the collector square footage to get the collector output per sqft.

I've noticed that there is more variation between the different brands of evac tubes than there is between different brands of flat plate.

---
To me, how much you spend per BTU of heat output makes more difference than a point or two difference in efficiency.

For example, all of these collectors do a good job of heating, and are likely within a few percentage points on efficiency, but look at the difference in the cost per sqft:

A simple (home made) thermosyphon air collector -- $2.20 per sqft
(this collector pays its full construction price each year in propane)
http://www.builditsolar.com/Projects/SpaceHeating/solar_barn_project.htm

A home made water heating collector -- $7 per sqft
This uses a commercial absorber plate with selective coating and double glazing.
http://www.builditsolar.com/Projects/SpaceHeating/SolarShed/collectors.htm

A Heliodyne Gobi Flat Plate collector -- $30 per sqft.

My thoughts (for space heating):
-If you are going to buy a commercial collector, check the SRCC ratings, and see how well it actually does.

-If you can muster the time, building a collector can save a lot of money.

-A system that can use simple air collectors instead of water collectors will cost much less, and have a better return (but is less flexible on storage etc.).

My 2 cents -- I'd be interested in hearing what others think.

Gary

[Paul Bailey]

I think the srcc ratings are or were origionally done in florida. All of my OLD data from books( that would be solar books) stated evacs producing up to 50% more for the year average more than any flat plate out there including thier own brand based on a per square footage basis.. Also some tests were done with water and others with glycol, not a good comparison at all.Real world testing is where its at for all energy technologies.. I can only speak for my case having tracked hot water performance for 13 years before upgrade and retrofit to evacs with a 50% larger tank and the 30 % smaller array of collection area. So they really produce substantially better than the flat plates...Oh I also increased angle by 10 degrees to help control summer overheat by clipping the output. But the SRCC data does not tell me this but I have the proof...Paul:)

[Paul Bailey]

Oh ... thermomax makes the Viessmann tubes for viessmann yet on a couple of the test data sheets they seemed to produce 2X and in some cases 3X the output.If that were the case I probably would have bought that particular collector (brand X) for my upgrade.I guess what I'm getting at here is in this day and age you don't have 2 types of evacs with one putting out triple the btus. This is similar to PV's where most All put out within 15% of each other per meter Square.As stated just to much smoke and mirrors Paul

[Wilco Vercoelen]

Hi guys,

Apparently I did not get the message across.
I am not talking about the efficiency, we all know the difference.
I am talking from a price-point of view.

Let’s assume you want to deliver 60% of domestic hot water needs with Solar (theoretically using the same loads).
How much collector area would you need from evacuated tubes, brands A, B, C?
How much collector area would you need from flat plate collectors, brands D, E, F?

Obviously you need less square meters from the evacuated tubes compared to flat plate collectors because of the fact that the overall efficiency is better in most cases.

But what price do you pay for each system A-F to accomplish that 60%!

[Gary Reysa]

Hi guys,

Apparently I did not get the message across.
I am not talking about the efficiency, we all know the difference.
I am talking from a price-point of view.

Let’s assume you want to deliver 60% of domestic hot water needs with Solar (theoretically using the same loads).
How much collector area would you need from evacuated tubes, brands A, B, C?
How much collector area would you need from flat plate collectors, brands D, E, F?

Obviously you need less square meters from the evacuated tubes compared to flat plate collectors because of the fact that the overall efficiency is better in most cases.

But what price do you pay for each system A-F to accomplish that 60%!

Hi Wilco,
Well, not to belabor the point, but I think your basic assumption is not correct. The SRCC data (an example in the post above) says that good flat plates and good evac tubes are just about equal in performance in the winter.

The SRCC is a non-profit organization whose sole function is to fairly test the performance of different brands and types of collectors. They have a multi million dollar facility to do this, and collector manufacturers pay them about 10 grand to perform the testing. They specifically state that their test numbers can be used to compare collectors performance -- thats why they do the numbers. They give collector outputs for both summer and winter conditions. I'm a pretty skeptical engineer type and I believe their numbers, and I know a lot of other very experienced people in the field who believe their numbers.
If you have found good engineering data that says their performance numbers are wrong, I'd like to know where I can get hold of it.

So, to find out which collector is the best deal 1) look up its output in SRCC tests for the usage class that best fits your use (I would think "D" in your case), 2) divide this by the panel area to get the output per sf, 3) divide the BTU output per sf by the cost per sf. The panel with the highest number wins. This does not count issues of durability, life, appearance, ... which might be important as well.

Gary

[Wilco Vercoelen]

Hmm, let's put it this way.

All year average for a given location e.g. wind conditions, HX..bla..bla:
Solar Fraction 60%, Load is 300 Litres p/day, temperature 60C.

With Viesmann Flatplate you would need 6m2 to achieve 60%.
With Viesmann Evacuated Tubes you would need 6.2m2 to achieve 60%.
With Apricus Evacuated Tubes you would need 8.7m2 to achieve 60%.
With Thermodynamics G32 you would need 6.8m2.
With Thermodynamics S32 you would need 8m2.
With Mazdon 20 you would need 6.5m2.
With Mazdon 30 you would need 6.6m2.

Find out the prices per collector per m2.
Then find out what standard systems sizes are and their prices.
There we go.;)

[George Craft]

I bought my evacuated tube solar water heater about a year ago. I broke my foot last year and never got around to hooking it up.

Next week, I'll be off for a couple of weeks vacation. So, it looks like as good as a time as ever to get a few projects completed. I'm in the middle of building a Sevtec Vanguard hovercraft at the same time.

References:
I bought my collectors here, http://www.s101470521.onlinehome.us/6901.html
My new homebuilt toy, http://www.amphibiousmarine.com/images/download_videos/download_videos.html

[Doug Kalmer]

Hi Doug,

Very interesting info! I like the idea of having one's own stainless steel water tank built. If you have a bit of time, could you post more about how it's made? Maybe you have drawings of the tank, or pictures (especially of the inside while it's being made). The link you published doesn't really give enough information for someone that would want to do the same. I'm interested, and I'm probably not the only one.

-Rob-
Sorry it`s taken me so long to get back to you on this, I`ve not been aware of the questions posted about my system, I`ve had computer problems, and been very busy. Rob, the tank was made from a 10'x4' sheet of 16 gauge non-ferrous stainless. A welder friend rolled it up, and I made a coil of 3/4" copper tubing to go into the lower half of the tank. He also welded two extra bulkhead fittings thru the tank wall to attach a loop from my wood burner directely to the domestic water. The tank sits in my attic, directely above the masonry stove, so gravity does a good job of circulating water thru the tank. It`s well insulated. Although the heat exchanger (HE) is single walled, there is no problem, since I use distilled water and proplyene glycol mix in the closed loop, and keep loop pressure below househopld water pressure. No one in my home ever drinks from the hot water tap, either. Unfortunately, I have no pics of the coil in the tank.
My friend Bob`s system has been working well, but he keeps a cookstove burning most of the winter, so it`s hard to say how much heat the solar slab provides. I think I`ve changed the settings to email me when new messages are posted on this subject, so I`ll try to do better answering questions.
BTW, I just had 21 2" x4' evacuated tube solar collectors donated to me, I`ll be experimenting with installing a heat pipe in the, and I`ll post my results. Doug

[Doug Kalmer]

[QUOTE=Mark Parsons;720]Hi Doug,
Nice work. How has Bob made out offsetting his heating bills? Some data to share would be great. Where did you get your heat exchangers for the DHW tank? Looks like you went thermosyphon through the exchangers?

----------------------------------------
Mark, I replied to the question about Bob`s above. The tube-in-shell Heat Exchangers were ours for the taking from, I kid you not, a rocket scientists home in Huntsville, AL because they couildn`t get their large, older system to work! We got 4 40 sq ft panels, two 120 gallon tanks, many yards of piping, fan coil units, 3 HE`s, pumps, etc, all free for the taking. Yes, Bob`s two He`s have the domestic water flowing thru them by gravity, and the antifreeze is pumped by PV. Doug

[Mark MacEwen]

Hi Mark
I seen your post where you said you rebuilt some Nortec Solar panels. I have 4 of these panels and I was wondering if you could tell me how to rebuild them.

[Rob Beckers]

Hi Mark
I seen your post where you said you rebuilt some Nortec Solar panels. I have 4 of these panels and I was wondering if you could tell me how to rebuild them.

Mark, I assume you're addressing Mark Parsons? Unfortunately he is no longer with us. He passed away in 2008 due to cancer (http://www.greenpowertalk.org/showthread.php?t=6074).

Best regards,

-RoB-

[Mark MacEwen]

Sorry to hear that it looks like he was a great contribution to this forum. Probably a great person also.

Do you know of someone that can help me get my Nortec Solar panels working again?