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Crazy solar idea....?

Started by DeerMeadowFarm, June 10, 2014, 11:40:30 AM

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DeerMeadowFarm

So, here is the set-up. I have a barn/workshop detached from my house. Behind it is my OWB. Aside of it is my above-ground pool. The roof of the barn (flatter portions of the gambrel) would be a great spot to have some solar panels to pump water through to heat my pool. Then I started thinking....
I have a line plumbed from my OWB to the barn that I haven't used yet as I need to insulate a little more of the building. I plan on eventually using a modine style heater in there. Anyway, I was thinking, what if I back fed the OWB from the panels on the roof as well as the pool during the summer when I'm not burning it and ran the circulator pumps to the house. Maybe I wouldn't use any oil at all for domestic HW during the summer....?
Thoughts?

Ljohnsaw

My experiences:

I have a soar water setup for my pool.  The last 2 days have hit 105 air temp.  My solar puts out 92-94° water with the input water at 88° (pool temp).  If I stop and restart after it sits for a bit, I'm looking at 100-104° water for a short while.  These are just the black rubber/plastic mats with no glazing.  If you are looking to heat domestic water, I think you will at least need glass panels.  What is your day temps and roof angle?  You are at about the same latitude as me so your "preferred" angle on your panels would be about 36° (IIRC) for the summer.  You've got a bit more moisture in the air so I would expect less solar heating capacity then out here.

Good luck!
John Sawicky

Just North-East of Sacramento...

SkyTrak 9038, Ford 545D FEL, Davis Little Monster backhoe, Case 16+4 Trencher, Home Built 42" capacity/36" cut Bandmill up to 54' long - using it all to build a timber frame cabin.

Thehardway

Not crazy but how hot do you like your DHW and your pool?
Norwood LM2000 24HP w/28' bed, Hudson Oscar 18" 32' bed, Woodmaster 718 planer,  Kubota L185D, Stihl 029, Husqvarna 550XP

DeerMeadowFarm

I'd like the pool to be around 78-80. DHW...160?

Thehardway

IMHO, for DHW temps that high you would need to go to evacuated tube or flat plate collector type system.  I don't think you will achieve those temps with a plastic based collector and if you do it would be for a short period of time when you have full sun.  Of course just using a solar collector as a preheat system with second stage gas or electric DHW heater would be a huge energy saver for you and a huge improvement over nothing. 

I think the pool heat temps are very realistic if you have a thermal blanket to prevent night time /rainy day heat losses.  A lot of folks have moved to using PV panels and then powering a Heat Pump type water heater like the Geospring unit.  It is not quite as efficient at producing hot water as there are additional conversion losses but it does allow you to use the electricity generated for other purposes once you water heating needs are satisfied.
Norwood LM2000 24HP w/28' bed, Hudson Oscar 18" 32' bed, Woodmaster 718 planer,  Kubota L185D, Stihl 029, Husqvarna 550XP

Gadrock

Supposed to be about one kilowatt per square meter in energy...so converting it into BTU's efficiently and economically is the issue. If you look farther into this field you will see that heating your house is quite well a doable thing. In the house multistaging heat exchangers keep the correct temps in the correct zone, so your hot water temps can be near 200 f yet usable house water heat remaining at 130f or so.

A big barn with the correct direction could indeed heat a pool, or help it. More square feet of collector equals more thermal transfer, but remember heat loss can occur if the system is not shut down at night.

David G


carry on
LT40 G18,   bent Cresent wrench,   broken timing light
Prentice 280 loader, Prentice 2432 skidder, Deere 643J fellerbuncher, Deere 648H skidder, Deere 650H Dozer

LittleJohn

I would be interested to know if you could pipe the underside of the barn roof, like you would for joist heating; but steal heat from roof, not add???

P.S. I am not 100% sure of your boiler, but if its open you might have to add in some heat exchangers, so you can run pipes up to roof/solar application

Ron Wenrich

I have a hot tub that I heat with solar.  I only like it to about 97°, but it can heat to well over 100° during the summer months.  The size of the collector is about 4 x 8 and heats well during the late spring to early fall. 

I've seen solar collectors for pools that were made from coils of 1/2" plastic tubing and put under tarps to trap the heat.  I use the plastic tubing because its cheap and durable.  It won't blow out if there is a freeze and some water is left behind.    The pool collectors used the filter system to move the water.  You would have to watch you don't get the water too hot.
Never under estimate the power of stupid people in large groups.

Thehardway

Quote from: LittleJohn on July 18, 2014, 09:43:28 AM
I would be interested to know if you could pipe the underside of the barn roof, like you would for joist heating; but steal heat from roof, not add???

P.S. I am not 100% sure of your boiler, but if its open you might have to add in some heat exchangers, so you can run pipes up to roof/solar application

Don't want to hijack the post but there is a commercially available system to do just this.

http://www.englertinc.com/blog/09-2013/solar-thermal-and-standing-seam-metal-roof-systems-perfect-together/

As I posted before, the key is how to provide hot water WHEN you need it after the sun goes down and before it comes up.  Most folks don't use a lot of hot water during the mid-day so storage becomes the biggest issue for domestic hot water.  Your solution has the pool heating covered well but I think you will need to supplement the domestic side a little depending on time and volume of use and how much storage capacity you have based on a 160F target temp.   The higher the temp of the water being stored, the more rapid the heat loss so you can see where trying to store hot water made at 4PM in the evening to take a hot shower the next morning before the sun comes up might be problematic.

Norwood LM2000 24HP w/28' bed, Hudson Oscar 18" 32' bed, Woodmaster 718 planer,  Kubota L185D, Stihl 029, Husqvarna 550XP

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