It may be of interest to others in the community to point out some examples of products. From publications such as Renew or the Manufacturer/Brand supplier.
Yes, here is an example from Stiebel Eltron
of a heat pump. And this was the article about using existing ductwork.
I would need 3 of them to heat my home*. I did a web search to find a 30kw heat/cool/water unit and the first hit is from the EU. It requires 3 phase 380~420v power.
It is good to look behind the curtains on installation requirements vis a vis the target premises and infrastructure. Electric is good but perhaps ‘we’ may have read how fragile some claim our grid operation is in these times?
* I have a 30kw condensing gas fired hydronic boiler but did not take up the water option since the hot water service was only 2 years old when the boiler needed replacing.
How much will it cost me to ditch gas entirely?
A view from the SMH including a summary of government subsidies.
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I’d go for it except the rebates are sbstantial for those of us who are truly low income. and I will be long gone before I derive benefit from the current options in NSW. I was going to get the bottom mount LG fridge they are/were offering as a cheap replacement for the fridge I have… at the time I looked into it first your fridge had to be a minimum of 6 years old. Went back to the site and found that it had changed to 10 years old. Mine will be 10 years old next year, by which time I expect that the scheme will have stopped, or the fridge would need to be 15 years old. Cant beat city hall, so to speak.
The place to go for information on all issues about transferring off gas to electric is My Efficient Electric Home Facebook group (currently over 67,000 members).
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Just reading page 15 of the excellent November 2022 issue. Re sound levels: you can easily install a phone app to measure & record dB sound levels. I used them regularly in my physics teaching and I think they are pretty accurate. I also have a Sanden heat pump HWS, now nearly 9 years old. It is almost silent, less than 40dB when standing right in front of it. Any heat pump that is more than about 55dB should have the installation checked! Thanks for the great work 
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And now for something completely different…
Leave the gas on: Company offers cash to plug electric exodus
The gas company Jemena is offering NSW customers a $500 cashback to people who dump electric appliances for new gas ones in a program that flies in the face of state and federal government policies to support the transition from the fossil fuel.
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Jemena, being even more generous. Depending on how you spin it.
This year, Jemena is offering customers a cash back eftpos card of up to $1000 value on a range of quality heating and hot water natural gas appliances.
The T&Cs allow for two claims per residence.
The related news release. Caution before reading. It may leave you ready to pick up the phone and convert, or something else …
‘https://jemena.com.au/about/newsroom/media-release/2015/turn-it-on-and-go-natural-gas
I’m not suggesting one should change to gas. When it’s time for replacement it’s an opportunity to convert to electric at a reduced total cost. More encouraging if the government has a supporting scheme in place at the time. The offer for Jemena customers will be attractive for those with aging gas appliances. The current Jemena offer is what it is.
Edit - Footnote: The Guardians and some further comment, mostly criticism of the strategy.
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Funny not funny that I am still in the same situation as when I started this topic! I had someone come and look at my house and the problem that they saw was (1) Very limited space underfloor meaning unable to put an electric heater underneath, and (2) Very high ceilings meaning heating in the roof space would be inefficient. An option was hydronic from scratch, which would be a large initial cost due to the age of the house putting in everything. Seems its not so easy to retrofit some older housing stock.
I don’t understand that. High ceilings can make a difference to heating as there is a tendency for hot air to rise and sit up near the ceiling which doesn’t warm you and this is worse with higher ceilings.
What is this heating in the roof space? You don’t ever heat the roof space as that is a complete waste of energy. Perhaps the idea was that heating, such as warm air from aircon, that goes via the ceiling space would not work as well but that doesn’t sound that important.
Take those public spaces that are air-conditioned like shopping malls and theatres, these can have huge ceilings compared to a house but they manage to do it. Also I would think that heating with a fan behind it (like aircon) would overcome much of this problem by causing mixing.
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Yeah the heating & cooling guy said putting a system in the roof and heating through vents into all the rooms through the ceilings would not be efficient. Yeah I don’t quite understand either. Perhaps he was comparing the costs to heat once installed? Vs the gas heater through underfloor ducts. I do have fans so I can control the air movement somewhat.
Having high ceilings always makes heating/cooling more difficult as you have to deal with a greater volume of air for the same floor space. I don’t see what that has to do with putting the ducts in the ceiling.
Unless you stick to a radiant heater like a bar or oil heater (which are way less energy efficient than aircon) all your heating is going to involve moving warm air around in some way. I think you are likely to find your answer in some kind of aircon or heat pump (the principle is the same the name different). If this is beyond the ken of one installer I would be asking for another opinion; for an explanation of how the high ceilings will affect the outcome and how much.
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We use our ceiling fans plus RC split aircons for heating in winter. It does improve how the warm air is circulated. Typically we leave them blowing down as in summer on the lowest setting. It appears to warm the room faster than switching them to blow towards the ceiling. Our ceilings are insulated - wool batts and the ceilings are 3.2+m. We purchased extension rods for the ceiling fans which hang approx 1m off the ceiling. It works well for us.
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It does sound possible, although somewhat painful since I already have ducts in the floor throughout the house. Would a main split system sit outside where the current gas heater is and pipe up the wall into the roof? Then I would need to create ceiling vents into every room (not an open plan house). Would probably need quite a big system to generate the same amount of heat (I think this is what he was saying it would take a long time to heat to the same temperature compared to the gas heater).
There is a degree of flexibility where the outside equipment can go, it should not be too far from the internal heat exchanger and fan, that goes in the ceiling, which is generally near the centre of the house.
It is standard for ducted aircon to have an outlet in all major rooms, this is part of the price. You can turn off some rooms if not in use or control the temperature of rooms separately in some installations. Also you can alter the direction of the outflow from louvres in the internal vents to some extent which may assist with getting hot air where you want it.
Possibly but the fact is aircon (unlike gas and resistive electric heaters) produces much more heating than the amount of energy it consumes by a factor of 2 1/2 to 3. Aside from the relative price of gas and electricity per megajoule this is the major difference in running cost.
In my mind there is no doubt that for running costs and flexibility aircon beats gas hands down. Whether the upfront cost of the change is worth it and when you will get your money back is something you need to consider.
Should you make the change and discover that the hot air sits too high (which I think unlikely unless you live in a cathedral) you can always put in fans in the bigger rooms as Mark suggests. How high are your ceilings?
I am not an aircon expert, I think you need to talk to some more people who are and who can explain to you how their system would work in your particular setting. Ask pointed questions!
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The option of an electric heat pump replacement for the gas air heater of a ducted gas heating system does not come up in any of the searches I’ve made. It seems illogical not being able to reuse what one has if all you require is to heat in winter. It appears at least in Australia suppliers are focused on installing new ducted or multiple split system air conditioning (electric heat pumps) to provide heating in winter and cooling in summer.
Possibly it’s that there is much greater value to a supplier/installer to offer a total replacement. It may also be what the majority of their customers are asking for, looking to the following example of relative running costs.
Worth a read if you are looking at the options,
Note the gas heater for your ducted system will have a nameplate or manual and a specification of the maximum rated heat output. (MJoules if newer, or likely BTU if quite old). Homes with large ducted gas heating systems may need an upgraded household electrical supply. Worth ensuring you know the answer to when looking at the options. An 8kW heat output split system delivers approx 29MJ of heat energy while consuming approx 2kW of electricity every hour. For a ducted gas heater the same output requires approx 40MJ (70% nominal efficiency) or greater consumption of gas.
Note: Common models of flued gas heaters suitable for ducted systems include models with heat outputs from 20-30kW (72MJ -108MJ equivalent).
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Thank you both, I can ask the right questions when I get quotes.
Yes @syncretic - I agree such a system in the roof should work fine in terms of heating efficiency. I already have fans installed. Not sure where the outside system would go though to reach the roof but that shouldn’t be a problem.
I agree @mark_m - I still don’t really understand why I can’t just switch a heat pump for the gas heater that sits outside and ducts under my floor. Thats a question I will ask.
Cheers!
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We recently (12 months ago) replaced gas ducted heating with reverse cycle ducted heating and cooling in Canberra. The ducting for the gas heating was under-floor, with one or more vents in the floor of each room.
We could have retained under-floor ducting and positioned the aircon under the floor, roughly in the centre of the house, but decided we preferred in-ceiling.
But we had enough space in both places to have a real choice.
If we had kept it under-floor, it would’ve been new ducting replacing all of the old. The aircon cannot be positioned outdoors where the gas furnace had been, so the ducting would have had to be re-routed to the aircon’s central location under the floor. That probably would’ve involved replacing a good deal of the ducting, and because of the age of the existing ducting, it made sense to get all-new (with better insulation) anyway.
To answer your question about the location of the aircon: going by our experience, it’s very unlikely that the main split system could be installed outdoors. Maybe commercial ones can, but not domestic units. It would either go under the floor, with underfloor ducting, or in the ceiling, with in-ceiling ducting.
If you have enough space under the floor for the aircon unit, stay with under-floor ducting, but be prepared to replace all the actual duct to get the best results.
If there isn’t a lot of space in your ceiling, you don’t really have the ceiling option anyway. Those well-insulated ducts take up a lot of room.
With high ceilings, I think you’d find ceiling fans a worthwhile investment. They’ll distribute the warm (or cool) air more efficiently than the vents can, regardless of whether those are in the floor or the ceiling, and fans cost very little to run.
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Thanks @isopeda . Interesting to hear your experience. Also interesting to hear that your external unit needed to be under the floor (which is a problem for me as there is not enough space). The latest guy I spoke to thought I could potentially use the same spot/pad outside that the gas furnace is on. The previous company said no. Perhaps it depends on the type of heat pump. I got a quote for an entire system plus installation that was around $10k. He said maybe wait for the new round of Victorian incentives.
The latest guy explained that the gas ducts are too big to be reused for electric. It would be good to be honest to get the ducts out from under floor as they seriously restrict air circulation and I have damp problems. Switching to ceiling ducts would have the bonus of improving ventilation below.
