Alternative Technology Assn Forums

1. 

   Greg
   Member

   I searched the forum but did not find anything so hence this post. Has anyone seen or used a solar system with a heat pump as the booster?
   I could not find a product online premade for this so I was thinking...
   1. Evacuated tubes
   2. Stainless steel tank with mid height exchanger that could be used by the booster. I know everlast make such a tank.
   3. Maybe something like the sanden Heat pump as the booster.

   Issues
   Will the built in heat exchanger work with the sanden?
   Does the sanden unit need temperature probes in the HWS as the ports would be used by the solar controller?

   So fellow forumites, what say you?

   Posted Saturday 8 Mar 2014 @ 12:57:25 am from IP #
2. 

   Lance
   Key Master

   NuEnergy do a heat pump boosted solar system although the dedicated site for it is missing, see http://www.nuenergy.com.au/for_your_home/integrated/natural_heat/

   Edson does one as well, at least they used to, worth contacting them...

   Posted Saturday 8 Mar 2014 @ 1:28:08 am from IP #
3. 

   Greg
   Member

   Woo hoo. Thanks Lance!

   Posted Saturday 8 Mar 2014 @ 1:33:03 am from IP #
4. 

   Greg
   Member

   Sad but neither company could help. Looks like a DIY project if I can find the time

   Posted Tuesday 18 Mar 2014 @ 6:40:28 am from IP #
5. 

   munter
   Member

   Is there any particular reason for choosing a heat exchanger tank rather than direct heating the water? There would be many more options if you used direct heating. It shouldn't be too hard a diy job to retrofit a solar circuit on to an existing heat pump/tank unit though I don't know how many of those tanks are stainless.

   Fwiw, I'm just at the final stages of building a system like you describe but mine is for floor heating. It has a 400l tank, a 7kW heat pump and evac tube collectors totaling about 60 tubes. It's all diy because factory systems are rare and expensive. Diy is also good fun though the missus tells me to get it all working before winter...

   Posted Tuesday 18 Mar 2014 @ 9:25:31 pm from IP #
6. 

   Greg
   Member

   How effective is direct heating when there is little or no sunshine? Its the rainy or overcast days (get several in a row) that I need the booster for. That's why I thought the most efficient use of electricity would be.

   Posted Wednesday 19 Mar 2014 @ 8:20:54 pm from IP #
7. 

   munter
   Member

   Apologies, I misread your first post. I thought you wanted the heat exchanger for the solar circuit. Now I understand you want the booster to heat via the hea exchanger. Maybe an alternative would be the new drop-in heat pumps that pump water from the tank through a separate box containing the heat pump and return it to the tank. Lance had links to these I think.
   Ours setup has the heat exchanger external to the tank and relies on a pump to circulate water out from the tank, through the hea exchanger and then back to the tank. I'm not sure which would be more effective but I suspect that external heat exchange will give you many more equipment options.

   Posted Wednesday 19 Mar 2014 @ 9:41:28 pm from IP #
8. 

   Benny
   Member

   What about getting a standard solar HWS with extra ports on the tank (for wet back etc) and then one of these "bolt on" heat pumps....

   http://www.skylineenergy.com.au/SX-05%20Bolt-On%20Heatpump.php

   I'd never do this I admit. Spending a few thousand dollars for a heat pump to be used only 1month per year. Our solar HWS is 25yrs old, still needs little boosting (about 30kWh/year) but just use electrical in tank boost and buy green power.

   Posted Thursday 20 Mar 2014 @ 9:39:46 am from IP #
9. 

   Greg
   Member

   Appreciate the responses.
   I suppose I thought of a heat pump as it produces more heat for less input energy than an electrical element (both can use green power). If there is a better way (for the environment and my hip pocket) I'm interested.
   I get quite a few overcast days and with just two in a row the tank is down to 30C or even 15C in winter (top of tank). We're on a rural block no reticulated gas as an option. In winter I use a wetback to provide hot water and heating but starting the fire when its 22C in the house does not appeal during the rest of the year.
   Would I be maybe better off getting an additional "standard" HWS with electrical element and using the "direct heating" method, thereby doubling the amount of Hot water stored to get me through those cloudy periods?

   Posted Thursday 20 Mar 2014 @ 9:18:05 pm from IP #
10. 

    sun2steam
    Member

    Greg, most solar hot water systems have already an electrical heater element installed in the tank. No need for purchasing and installing an additional hot water system.

    In regard of the environmental impact you also need to consider the embedded energy in an additional heat pump or an additional hot water system. That is quite significant and it may be a long time to recover that with 'environmental savings' from using a heat pump as booster.

    Also with a heat pump sitting idle for most of the year there is a good chance that it will fail when you need it.

    If you want to do something for the environment and save money you can install a solar PV system. A PV system is also producing some electricity on cloudy days and you could use it in winter for direct boosting of the hot water tank and use it on other days to replace electricity from the grid.

    Posted Friday 21 Mar 2014 @ 9:26:30 pm from IP #

RSS feed for this topic