Solar water heating

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robfish

683 posts

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#2087437 11-Sep-2018 11:46

Our house and our rental property both have solar water heating with large storage cylinders "topped up" when necessary by "off-peak" power at nights.

Only twice in 13 years has the water cooled below shower temperature.

Even with my son's family living with us for 19 months our power bill only just went over $300 once.

In Christchurch we still have sunny days in winter so we still get the benefit then.

Rob

tdgeek

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#2087444 11-Sep-2018 11:59

robfish:

Our house and our rental property both have solar water heating with large storage cylinders "topped up" when necessary by "off-peak" power at nights.

Only twice in 13 years has the water cooled below shower temperature.

Even with my son's family living with us for 19 months our power bill only just went over $300 once.

In Christchurch we still have sunny days in winter so we still get the benefit then.

Yes, and even though solar doesn't cut it in Winter, and the shower will only be hot due to the grid topup, getting 40C added in a day reduces grid kwH's used

Summer, pull all the plugs! Collector and the 300L cylinder all at 84!

MikeAqua

7773 posts

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#2087550 11-Sep-2018 14:50

tdgeek:

Yes, and even though solar doesn't cut it in Winter, and the shower will only be hot due to the grid topup, getting 40C added in a day reduces grid kwH's used

Summer, pull all the plugs! Collector and the 300L cylinder all at 84!

In Nelson on sunny winter days (no wind) we would routinely see 55 - 60.

Mike

Aredwood

3885 posts

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#2087574 11-Sep-2018 15:04

wratterus:
Good info here. Sorry for the incoming hijack....

We'll be making some changes to our hot water system soon - currently it is low pressure, header tank on roof. Want to get rid of header tank and get a higher pressure system (would probably be re-plumbing the whole house too as it's currently all old copper and dodgy as hell).

Have been considering wetback & possibly solar too. I've not looked into this too much, what is the general consensus on wetback these days? I assume this can be run with a higher pressure system? Thanks.

Mains pressure with wetback can be done, but you need a cylinder with a heat exchange coil. Consider a pumped wetback system, as that gives you regulation of the cylinder temperature, as well as flexibility on where to put the cylinder. And if you get solar later, the wetback can also be used to manage excessive cylinder temperature during the summer.

A wetback is a better fit than solar hot water. Simply because the colder the weather, the more you will be using the fire.

tdgeek

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#2087581 11-Sep-2018 15:11

MikeAqua:

tdgeek:

Yes, and even though solar doesn't cut it in Winter, and the shower will only be hot due to the grid topup, getting 40C added in a day reduces grid kwH's used

Summer, pull all the plugs! Collector and the 300L cylinder all at 84!

In Nelson on sunny winter days (no wind) we would routinely see 55 - 60.

Cylinder temp or day increase?

MikeAqua

7773 posts

Uber Geek

#2087585 11-Sep-2018 15:15

Aredwood: Mains pressure with wetback can be done, but you need a cylinder with a heat exchange coil.

Does HP also work with an external heat exchanger - pump out of HWC into HE and back again?

Mike

Aredwood

3885 posts

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#2087597 11-Sep-2018 15:27

MikeAqua:
Aredwood: Mains pressure with wetback can be done, but you need a cylinder with a heat exchange coil.

Does HP also work with an external heat exchanger - pump out of HWC into HE and back again?

@MikeAqua Assuming that you are referring to heatpump hot water?

MikeAqua

7773 posts

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#2087628 11-Sep-2018 15:42

Aredwood:
MikeAqua:

Aredwood: Mains pressure with wetback can be done, but you need a cylinder with a heat exchange coil.

Does HP also work with an external heat exchanger - pump out of HWC into HE and back again?

@MikeAqua Assuming that you are referring to heatpump hot water?

Sorry, poor choice of acronym. I was wondering if you can use an external heat exchanger with a high pressure HWC?

I've used stand alone heat exchangers with low pressure cylinders

Mike

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