Modern 609m2 house with 4.5kW photovoltaics, solar hot water, wetback powering energy efficient appliances. Come and see!

Contact us today to visit the solar energy house and get extensive hints, tips and notes for free as part of the tour...



Space Heating In The Solar Energy House In Meadowbank, Auckland

Solar Energy House C/- Simon & Kristina Cope | 19 Manapau Street, Meadowbank, Auckland 1072  |  New Zealand  |  Contact us now to arrange your tour

We have solar hot water collectors on our roof that feed our hot water cylinder. In summer this combination provides sufficient hotwater for baths, showers, the dishwasher and washing machine needs...


However in winter our demand for hotwater increases significantly as we then pump it throughout the house for underfloor heating in the bathrooms, and through radiators to provide us with space heating. We have decided to used radiators as they are easy to regulate the temperature on, blend in to the decor and we have beautiful native Matai wood floors due to the house originally being a NZ State built house. We then purchased additional Matai tongue & groove flooring from the local house wrecker for the extension of the lounge...


If we were building from scratch on a concrete slab floor then we would have embedded underfloor heating tubing to provide the space heating that way.




LookingAtWetback PLumberSolderingRadiatorPipes PlumberUnderHse_RadiatorsEtc Simon_HWC_pipes SUNcomfort%20Solar%20Hot%20Water%20System%20Produc Main_bdrm_looking_North_West

So What Is A Condensing Boiler Then?

A condensing boiler preserves energy by using heat exchangers designed to remove additional energy from the gases of combustion before leaving the stack.


The flue gases produced from condensing boilers are at a much lower temperatures than those of non condensing boilers to the extent that the water vapor in the flue gases condenses, thus releasing their latent heat and increasing efficiency of the boiler.


Condensing boilers have efficiencies of 95% or greater as compared to the normal 70%-80% for non-condensing boilers.

Above: wetback / heat exchange connected to fireplace.


Below: Uncontrolled heat source (wetback) then comes into the HWC to be distributed throughout the house...

Here the apprentrice plumber is about to braze / join up the radiator pipes... when we extend the system in 2009 we will NOT be using copper as there are now plastic pipes with a thin shealth of aluminium tubing (not touching the water) encapsulated inside available at 1/2 the price of copper specifically made for radiator runs (ie HOT HOT water).

Important to lag (wrap) the radiator pipes up. Here the plumber is doing just that!

It is unrealistic to put enough solar hot water panels on the roof to provide sufficient hot water to use for bathing needs as well as space heating in winter. (What on earth could we use the EXCESS hotwater in summer if we did?).


The sensible more economic thing to do is use a booster of some description to heat this extra hotwater requirements... in our old house we had a gas booster to provide sufficient hot water for bathing.


However in this house we have 2 solar hot water boosting systems:


(1) Wetback / heat exchanger on our fireplace - see the diagram and the photo below over on the   RHS of the page where the boy is pointing at the heat exchanger / wetback pipes.. AND,


(2) Condensing boiler. This is enable us to programme the space heating system so it will wake up at 6am in the morning, measure the temperature in the HWC cylinder & outside and then turn on the radiator pumps. If the temp in the HWC is too low then the condensing boiler will fire up, boost the temp of the water to ensure we wake up to warm toasty house, heated towels, warm tiles underfoot - ready to step into the piping hot shower... hmmmm! No excuse to get up!

What Is A Boiler?

A boiler (item 5 in the diagram below) is an enclosed vessel in which water is heated and circulated, either as hot water, steam, or superheated steam for the purpose of heating, powering, and/or producing electricity.


The furnace of the boiler is where the fuel and air are introduced to combust; fuel/ air mixtures are normally introduced into the furnace by using burners, where the flames are formed. The resulting hot gases travel through a series of heat exchangers, where heat is transferred to the water flowing though them. The combustion gases are finally released to the atmosphere via the stack of exhaust section of the boiler.

What Fuel Will You Burn In The Boiler?

We are still looking at what fuel we will burn in the condensing boiler.


We originally looked at using a WhisperGen boiler which burns CNG gas - however they are not ready to commercialise this unit in NZ yet (under trial in the UK (very exciting NZ designed & made product). LPG / CNG is not economical (too expensive per kW of energy) enough in my opinion either.


We have also been looking at modifying an off-the-shelf condensing boiler to run on bio-diesel, however there is not enough surplus fishn' chip oil around to purchase at a cost effective price - and processing it looks messy!


We have an idea 'we' are developing - "the royal 'we' " - in actual fact I am less than 1000 hours into my hot water apprenticeship compared to grand master -  David Howell - the heating 'genius' we are working with (he designed the overall heating system we are using) and he is the one with 'the rabbit up his sleeve'  - as soon as we have commercialised his idea - I will tell you. Til then...



So what do we do with all this wonderful heated water? We have lots of radiators throughout the house that 'radiate' the warmth outward :-) In the photo above (the 'master bedroom') you can see the radiator underneath the main window. Notice how they 'blend in'.... For the first 5 years in the house we didn't have a wetback on the fireplace to boost the solar hot water system and then we installed it. Our daughter Isabella when she walked into her bedroom said "I didn't realise we had heating in the room  just like we do at school..." which goes to show how they blend it - the radiator had been there all along...