We are considering building a new home, on a slab, in the upper Blue Mountains NSW, and I would think that hydronic heating would be very suitable here (we've been known to have a fire going all day Xmas & Boxing days.....).
We intend to install a lot of Solar Panels, and use as much of that energy as possible until we put a battery or two in, in a few years time when they are economically viable.
After a couple of calls today to research Heat Pumps, I'm hearing that they really have to have cold water going into them to work properly. I was kinda hoping that we might be able to use a wetback on a slow combustion wood burner to get the most of the energy out of that, and then top up the required heating of the water with a heat pump. I would also have liked to use a system like Swim pool style solar heating on the roof to get the same sort of thing happening. That way the pool solar heating would supplement during the day and wood heater would supplement in the evening.
So for this part I'd be interested in hearing if you think any of that is possible, or are the sales people actually telling me the truth - no go.
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If I can't put other water heating systems in tandem with a heat pump, then how can I make use of the wasted heat from the wood burner?
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The other part of the HWS that I would like to improve upon is the first 5-10 litres of wasted cold water when running HW in places a long way from the HWS. This is a waste of energy and water, and time.
I had been thinking to have 2-3 smaller HW tanks/heaters because of the wasted water and energy piping hw across vast tracts of house. These would be located right near the points of use. However, because Heat Pumps are a large initial cost, it is not cost effective to have 2-3 of them scattered around the perimeter of the house.
Then I started thinking about the quantities of HW that the different places require:
Kitchen - small quantities but very frequent on any day,
Laundry - not much, and infrequently, so don't worry about it
Ensuite - large qty (shower/bath) 1-2 times per day, small qty for teeth cleaning etc (only Superman cleans his teeth in cold water up here :roll:)
Second Ens and/or bathroom - only really on demand (just the two of us plus visitors), but would be larger quantities. Just have to suck it up on the waste I guess.
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So that got me to thinking about using an instant HW service right at the location to boost the temp of those first litres of cold water to save all the waste. This would just be in the high demand areas like our Ensuite and the Kitchen. Actually, the Kitchen could probably just be run on an instant electric service only (largely free because of the solar panels). The logic there is that for manual dish washing it is only a relatively small amount of HW required, perhaps 10 litres, and for a dishwasher they have their own heating element anyway. Most other HW uses in the kitchen are fairly small qty.
In the plans that I've been designing there has always been either the bathroom or the laundry right next the ensuite in any case, so it could still run just off the Heat Pump without much waste.
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So what that boils down to is:
~300 litre Heat Pump right at the Ensuite, with no instant booster
hopefully either bathroom or laundry immediately adjacent to the ensuite, with no booster
perhaps put a booster in the bathroom if it is a long way from the Heat Pump
Just run the Kitchen off an Instant Elec HWS
I rang Stiebel Eltron to discuss a few things, including this boosting idea, and they said that the only HWS that could receive already heated water was their 3 Phase jobbie which is $1100 - probably not economically viable, given that I won't have 3 Phase power. I suppose I could consider 3P because I will be putting in a machinery workshop, and 3P machines are desirable.........but not sure how easy or even possible that is with Solar Panels (sans battery at this point)
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What does the Brains Trust think please? Sound logic, or needs some work?
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One other question on Hydronics - what about the minerals in the water - are the pipes in danger of choking up if the mineral content is on the high side (which I suspect it is here). Does the water get changed or is it always the same? If the latter, can demineralised or distilled water be used?
and either the laundry or the bathroom which might be only 6-8 metres from the heat pump. In fact I may be able to move it right up next the main Ensuite, so there would be Ens/Bath/Laundry all next to each other.
