Retro fitting solar Hot water collectors

[Wombat2]

OK this is not about rebates and town supply - we are on tanks.

I want to retrofit some collectors to an existing HWS - I realise it won't be as efficient as a properly built solar system but past experience with another house in Victoria there will be days when the water will be so hot effeciency is irrelavant.

As we have a house that is effectively 3 storeys on the North side I plan to put the collectors in the supporting poles and braceing at the same level as the tank and assist circulation with a solar powered pump designed for the job. My main concern is fed and return. Does the take off and retun have to be right at the tank or would it work tapping in anywhere along the house supply? I ask as the HWS and tank pump are at one end of the house and all the main use areas are at the other end ( great design - NOT) and both the hot and cold water "mains" run with a few meters of the propossed location of the collectors. If I put one way valves on the solar circuit it will stop back flow - Just writing this I realised there would eventualy be hot water in 2/3 of the cold water supply to the house so the feed should come from the bottom of the HWS but is there any reason why the hot can't return to the nearest point? - All the hot water piping is lagged with black foam lagging 1/2" thick.

[Bloss]

Oops - didn't read your post properly! :-

The solar work can be done cheaply enough and using evacuated tubes of course. Talk to these guys - I reckon they are helpful.SolarVox :: Home (http://www.solarvox.com.au/) and these guys too: ultimate products direct items - Get great deals on items on eBay Stores! (http://stores.ebay.com.au/ultimate-products-direct?_trksid=p4340.l2563)

I am pretty sure the return line connections into existing plumbing lines won't work - the solar circulation system needs to work independently of the hot water draw off - all the conversion systems I have seen installed use a 5-way way adapter fitting - see pic.

You can buy them from Solarvox & others.

This guide might help: http://www.dlgp.qld.gov.au/resources/guideline/plumbing/plumber-reference-guide.pdf (~3MB file)

and the SHWS Training Manual too is a good source doc: http://www.cleanenergycouncil.org.au/resourcecentre/Consumer-Info/SWHguide/mainColumnParagraphs/0/text_files/file1/SWH_Installation_book_online.pdf (NOTE: a 10.4MB PDF - Admin - maybe a good one for Library?)

Note too that for best winter performance tilt angle (at North +/_ 15 degrees) should be latitude +15 degrees which in colder climates is really worth doing. So in ACT the latitude is 35 degrees so solar tilt angle would be 50 degrees. In Melbourne at 38 degrees tilt would be 53 degrees and in Hobart at 43 degrees the tilt angle would be 58 degrees. The reason is simple - in summer there will be more than enough heat even at the common roof angle of 22.5 degrees or the 35 degrees often achieved with standard brackets, but by tilting for winter optimisation you are getting the greatest heat input when you most need it - to offset the shorter days and the much lower water temperature which requires a larger temperature lift. The more solar you use the less other energy you use.

Worth reminding too that how you use your water will make a huge difference to how much advantage you get from solar HW - or if you get any at all. The idea is to use as much of your water in the early morning (showers, baths, washing machines, dishwashers) - so that the cold water replacing the hot in your tank can be heated up using solar during the daylight hours. No need to be obsessive about it, but a general change to those hours will make a big difference. If you stay as an afternoon or evening/night time hot water user then you will be boosting using gas and electricity at night and all just to store it and have hot water in the tank in the morning (of course if you use a wood boost or are solely on renewable power then who cares - although silly to waste energy at any time). The general rule is - your stored water should be at its coldest in the morning.

[cyclic]

OK this is not about rebates and town supply - we are on tanks.

I want to retrofit some collectors to an existing HWS - I realise it won't be as efficient as a properly built solar system but past experience with another house in Victoria there will be days when the water will be so hot effeciency is irrelavant.

As we have a house that is effectively 3 storeys on the North side I plan to put the collectors in the supporting poles and braceing at the same level as the tank and assist circulation with a solar powered pump designed for the job. My main concern is fed and return. Does the take off and retun have to be right at the tank or would it work tapping in anywhere along the house supply? I ask as the HWS and tank pump are at one end of the house and all the main use areas are at the other end ( great design - NOT) and both the hot and cold water "mains" run with a few meters of the propossed location of the collectors. If I put one way valves on the solar circuit it will stop back flow - Just writing this I realised there would eventualy be hot water in 2/3 of the cold water supply to the house so the feed should come from the bottom of the HWS but is there any reason why the hot can't return to the nearest point? - All the hot water piping is lagged with black foam lagging 1/2" thick.

When you get your plumber, ask to see the solar accreditation on his licence, then ask him to explain why you cannot link the return line from the solar panels into the existing hot supply at the nearest point.

[SilentButDeadly]

HW return from the solar has to return into the cold water inlet of the storage system. Otherwise your circulation pump will have conniptions.

I've had a bit of time with the bloke from Run On Sun in the past...he's got a pretty good retrofit system going. Convert an existing electric hot water heater to solar and save 10% off all kit prices for June 2012. Will end June 30 (http://www.runonsun.com.au/www.runonsun.com.au/Retrofit_an_existing_hot_water_tank_to_solar_with_ a_PV_pumping_system.html)

He's also got a ghetto version of the valve that Bloss pointed out

http://www.runonsun.com.au/www.runonsun.com.au/Retrofit_an_existing_hot_water_tank_to_solar_with_ a_PV_pumping_system_files/Retrofit%20valve.jpg

[Wombat2]

That retro fit valve is a great idea - would it reduce the water flow much? - the 12mm return pipe takes up about half the opening of cold water inflow into the tank. Our pressure pump sensors when addition taps turn on and increases speed and hense pressure to compensate do you suppose it would just see the drop in flow as an extra tap and speed up?

[SilentButDeadly]

That retro fit valve is a great idea - would it reduce the water flow much? - the 12mm return pipe takes up about half the opening of cold water inflow into the tank. Our pressure pump sensors when addition taps turn on and increases speed and hense pressure to compensate do you suppose it would just see the drop in flow as an extra tap and speed up?

Not at all. We basically have the same setup on our solar HWS and it's fed by a similar pump system to your own. Works a treat...

[stpea1]

Not at all. We basically have the same setup on our solar HWS and it's fed by a similar pump system to your own. Works a treat...
I am in the process of installing a solarvox system to a 315 Rheem Optima tank. It is recommended that an S bend be made in the hot water return via the retrofit 4way fitting. I have a problem in that a S pipe will not wriggle through the cold inlet. Have tried different radious etc but the curved dip tube will not allow entry; other than a short, 60mm single radius bend. Can I remove the dip tube without damage to the liner/tank?
Cheers, Steve

[SilentButDeadly]

I'm a deer with no eyes on this one. What does Solarvox suggest?

[stpea1]

Thanks SBD, I talked to Stewart (solarvox) and he suggested "food grade plastic" to extend the copper through the dip tube bend and at least be past the cold inlet so as not to mix cold and hot too much. I have another idea to drill through the dip tube bend, to allow the copper return to pass through and into the middle of the tank. I am after info re the dip tube : is it plastic, brass etc, ideally can it be removed.
Cheers, SteveP

[Wombat2]

I purchased the bits to make the DIY inlet valve - I guessed I would have to drill out the end of the 12mm fitting to let the pipe pass through the 20mm T . All the compression fittings came with both nylon and copper olives - do I assume that copper is for hot and nylon for cold?

[stpea1]

Using two tees ( I used two 3/4, all female, with a male nipple to join them ) no drilling required. Not sure what you mean here.
I have only used the copper ferrules; seems to work ok.

I have posted a problem with an inlet dip tube -- further investigation after extracting the 3/4 extension into the tank provided a better view and a dome bottom to the tank !! A little more appropriate pipe bending and the hot water return was advanced 200mm up and into the tank. Hopefully fire it up tomorrow. Pity about the rain !
Thanks for the reply, SteveP

[SilentButDeadly]

Well done on the HW inlet pipe.

Wombat...I've no idea why you'd need to drill anything. The half inch pipe for the hot water return should go straight through the 3/4" T fitting (with room to spare for the cold water to go in and out of the cylinder around the 1/2' pipe) and be held in place with the half to 3/4 coverter nipple on the other side of the T