Wondering if anyone has DIY'd one. I've scrounged all the materials I need other than maybe a few fittings and some spray foam for free. Getting ready to start the project. Have a huge coil of 2" poly water line I'm using for storage. Math sez it holds about 44 gallons. Basically gonna build an 7x7' box. Insulated. Foil bubble wrap backing. Have a double pane tinted window for the lid. Does tinting hurt, help or non issue with heat production???? Any tips would be appreciated.
I would think you would want the tint on the inside to help keep the light in the box instead of keeping it out. I'm not sure if that's an option, but worth considering.
Thats a good question. You'd think the glass when it's clear would magnify the suns rays better and the tinted class would hold it better, not sure what would work in this situation.
I made one for my pool - a bit differently. Used black garden hose. I coiled the hose on three pieces of unistrut mounted to the roof of the garage and had boxes of surplus 5/8" tubing clamps. It would raise the return temp ~2F depending on the supply temp, but I'd have to really throttle it down to <5gpm to achieve that result. A lot of this has to do with the distance from the solar collector to the end use source. In your case an occasional demand system like a hot water heater could benefit from a setup like this - just plan on a bypass and drain fittings as this thing will freeze in the winter - the real preheaters use a glycol filled collector and heat exchanger near the water heater. All the tubing leaving the collector will need to be insulated to avoid losses Ran the thermodynamics on the rise/gpm and figured it would take running it consistently for ~6hrs/day to warm the ~40,000gallons 2F would taken a bout a week. I then contemplated going down the rabbit hole of installing a heat exchanger and transfer medium with a coil around my HVAC condenser gaining that heat and helping the condenser operate with a cooler ambient inlet... decided against it, the thermal transfer efficiency of stainless(to prevent corrosion from the pool chemicals) would make it kind of useless - poly tubing has even worse transfer coefficients.
Are you running an electric/gas/wood hot water heater? Most of these can benefit from a simple timer and flow switch to greatly reduce running when they aren't in a demand mode, set the timer(they sell two a day timers) to kick on ~4am - 7/8 depending on when you wake they will still only turn on by the thermostats and a flow switch (sized appropriately) will kick it on when demand is present.
Back in the 80s I hooked up a timer for the electric hot water... timer then cost about $30. It paid for itself in just over one month. Had it come on at 5 AM off at 7AM... on at 5 PM off at 8 PM. Crazy how much money is spent heating water we don't need. I'll bet the much more efficient hot water heaters today would save even more.
The on demand units do save a ton of operational money that is ultimately spent upfront - not to mention the electrical panel sizing, they pull some serious current. Gas OD units are really the way to go - but again how long it lasts is up in the air - and the average homeowner is going to make a service call when things don't work, nullifying any "savings" I bought a 2-pole timer a few years ago - ran about $90 ...depending on your rates could pay for itself in ~2-3months
Electric. Fairly new, maybe 6 years old. I have tried shutting the breaker off to the tank for 12,24, and 36 hours. After 36 hours I can still take a quick shower and have hot water. 48 hours I had room temp water. It was just me up till a month ago. Now theres 3 more heads and clothes to wash . All materials were sourced free otherwise I may not attempt this project. I may wait to see what the first months electric bill is before I start.
show us what you got. i have been contemplating building a solar pre-heater but wont mess with it until i get new roof on. i heat DHW with wood boiler and storage now, but any increase in temp over ground temperature that goes into my DHW would keep the pull from storage cycling less. no pumps and drain it for the winter.
If you are just now adding three members to the household...brace yourself When it was just me I could run $40-60/month(non-summer), added the GF and it stays ~85-90 non summer. Running a 1981(stills kicks cold) whole house AC and pool pump a few times a week depending on the summer temps runs 120-160. Everyone I talk to has $2-300 powerbills. The timer option may help out by just setting it to cut on during the daytime hours if that's your and the new additions' lifestyle. Hopefully your power company offers an online graph that can show you historical graphs of usage and cost....Or make you scratch your head a few months from now I'd stay away from the tinted glass - it's preventing solar gain/heat from entering the box, regardless of its installation orientation
http://www.builditsolar.com/Projects/WaterHeating/Metal1K/Metal1K.htm Here is the system I built a few years ago. I have 2 4'x8' panels heating 100gl of water. In the summer with good weather it will supply the majority needed hot water( 2 persons) Lots of good info in the build it solar site. I don't think a timer will offer much savings unless you have off peak rates. The standby losses are not that much. Also, I tried turning the power off on my water heater off, it would stay hot for a few days ( 80 gl) but when I turned it back on, the temp would overshoot by about 15*, probably offset any savings. From what I have read the on demand units will not offer a payback on the increased purchase price and added electrical service needed. A heat pump water heater probably would be a better bet.
Mine has been $53 and $45 April/May. June was $67. They were here the last 10 days of June. I'm expecting $100/month minimum after Junes bill GF showers 6am . Daughter between 10am- 2pm. Me and the boy back to back at nite usually with a load of laundry morning and nite. I usually shower with room temp or cooler water just to get my body temp down at nite in the summer so I can sleep better. I have a new in box timer I found at a yard sale for $1. IMO I don't think in this case it will help due to the spread of HW usage. The girl will be going to college in a month so that will help. Capacity in my case is what is gonna help the most. 44 gallons on top of the tank and with all the 2" insulboard I have I can super insulate the box. Should be able to heat water as it enters system fairly quick .
I think anything to preheat the water before it gets to the hot water tank is worth it. An old man I knew had a tank in the attic that preheated the water. He swore by it and wanted me to do one but I'm lazy and never did.
I'm considering plumbing the HW tank to the outside of house and just letting this 44 gallon coil just bake in the sun till I get the box built . I'm curious to see what temp it will generate. I'm thinking 100 would be attainable easy.
Ya, anything above the ground temp is a plus. Also hvac guy I know wrapped his tank with one of those blankets to hold the heat in once it's warmed up.
