House Central Heating - Reverse Cycle Aircon

[101RRS]

My house is fitted with an early 80s commercial grade Braemar Reverse Cycle Aircon central heating system - it runs 7 floor vents and one wall vent. It uses 3 phase power.

It is so old that it requires a fair amount of maintenance each year - is exceptionally noisey both inside and outside and the outside fires up with a huge bang as the fan is not soft start.

When it finally gets up an going it can maintain 20 degrees in minus degree Canberra winter nights but takes about 4 hours to get up to temp.

It is time to get rid of it and get a new system - so looking at a new modern inverter style A/C central heating system to replace what I have and that can provide reasonable heat on cold winter nights.

I have no idea what is good or bad and what sort of prices I can expect to pay so anyone (or aircon installers) who has modern central heating provided by reverse cycle aircon please let me know what is good or bad.

Thanks

Garry

[kiwirich]

Hi Garrycol,

I'm not sure how it's done here ..... But make sure that whoever you end up selecting, they come around & measure it up properly. Include things like Night zone options & measuring the Return Air flow.

It's all a bit of a pain but you won't enjoy spending 15-20 K to do it all twice if it doesn't work how you want.

You'll have it for a long long time
Richard

[101RRS]

Well I went window shopping yesterday to about 6 companies. They all recommended Daiken and depending on model needed cost will be between $8.5 and $11K. The cheaper price is for a 15kw single phase unit and the higher price is for a 20kw 3 phase unit (my current unit is only a 5hp, 5kw 3 phase unit). Prices were basically the same at all installers but obviously I will need quotes.

Interestingly they all said that even though these all have premium inverter technology these units still take a while to provide heat when turned on in very cold consitions - hence they are designed to be on all the time which I do not want.

I don't have gas at the moment but I also asked about it - $5k but a gas unit is a lot more expensive to run and the price of gas is going up - will also have to continue to pay the gas supply and admin fees in summer when the heater and gas is not being used. To get gas to my house would be another $500-$1k.

Looks like it is time to see if I have any personal contributions in my super fund before I freeze - though the little fan heater does a great job.

If anyone has any personal experiences please let me know.

Cheers

Garry

[kiwirich]

HI Garry,

I think that maybe they weren't explaining it properly .......
The logic behind leaving it on all true time is that the Walls, furniture, Carpet, ceilings etc, etc all "Soak" up heat.
If you leave it running, everything in the zone is eventually heated & de-humidified meaning that it doesn't need to be done again & the Unit isn't working as hard all the time.

You can still choose to switch it on & off manually or even better, you can program the timer & thermostat so it only runs when you're home.
EG start at 15 Deg & turn off at 21 Deg. Start at 17:00 & stop at 06:00 etc.
If you're looking at a unit of that size, I'd go 3 Phase if you can. It'll provide better balance for your power supply Billing.

Richard

[dromader driver]

I have lived a couple of times in Melbourne both in rented townhouse and own home. The townhouse had a bovis ( spelling ) buffalo underfloor gas heating system which was relatively quiet and very effective.It was run under the floor with outlets in each room. the house had ducted heating via a burner in the ceiling with outlets in each room. This system was marginal as i believe it had been originally installed prior to an extension being done and they may have just bumped the fan airflow.

Both systems were thermostat controlled and we turned it down overnight then up in the morning. main problem was with the ceiling mounted system sounding like a B707 on takoff power when the fan kicked in, usually at 0300 hours.

We also lived in Orange for 3 years with ducted heating in the front of the house and and a wall furnace in the back. both worked well.

Depending on wether you need cooling in summer I would be seriously looking at hydronic heating with a high efficiency boiler. warm and quiet. Electrickery is going to get much more expensive and gas although rising will be better for heating.

don't believe reverse cycle works well below 5C and tends to ice up. positioning of the return air grill is critical both for noise and heat distribution.

If you can score a good wood supply I would go with a Coonara tile fire. Had one in Camden and it was the best solution of the lot. They have a duct available that can draw air from a remote part of the house which is very good for heat distribution with a 3 speed fan. pretty cost effective and just nice to live with.

My preferred solution for a house we were considering near Cooma was for a coal fired boiler and hydronic. Mackenzie boilers in NZ make a very good unit that has been sold into the Bathurst district. They also have a cost comparison model on their website. Coal boilers Dunedin, Coal hoppers manufacturers Christchurch (http://www.mckenzieheating.co.nz/coal-boilers-dunedin)

hope this helps.

[101RRS]

I think that maybe they weren't explaining it properly .......
The logic behind leaving it on all true time is that the Walls, furniture, Carpet, ceilings etc, etc all "Soak" up heat.
If you leave it running, everything in the zone is eventually heated & de-humidified meaning that it doesn't need to be done again & the Unit isn't working as hard all the time.

You can still choose to switch it on & off manually or even better, you can program the timer & thermostat so it only runs when you're home.
EG start at 15 Deg & turn off at 21 Deg. Start at 17:00 & stop at 06:00 etc.
If you're looking at a unit of that size, I'd go 3 Phase if you can. It'll provide better balance for your power supply Billing.

Richard

Thanks Richard - I would leave my current system on overnight but it makes such as racket and it lives (suspended) under my bedroom floor giving me a cheap thrill when it runs.

I know of the issues of a/c in cold - my system has electric boosters but they have been disconnected because of the fire danger. I understood that the new high powered inverter systems were far better - I was just surprised that they took a while to warm up that was all.

Cheers

Garry

[scarry]

I would also look at Mitsubishi electric,we use it in preference to Daikin.

But your temperatures are a lot different than ours here,we only need heating for a few weeks a year.

The modern units are very good,extremely quiet,but as they are full of electronics,make sure you do your best to keep the geckos,rats,etc out of the units or you will have issues that may not be covered by the manufactures 5 yr warranty.

I would also go for the larger 3 phase unit.

[101RRS]

I don't believe reverse cycle works well below 5C and tends to ice up. positioning of the return air grill is critical both for noise and heat distribution.

If you can score a good wood supply I would go with a Coonara tile fire.

hope this helps.

Thanks for all those comments - apparently the new reverse cycle systems work well below zero but just take a while to build up heat.

When I first moved down to Canberra it was impossible to go outside at night in winter and breathe - indeed wood heating is now banned in some suburbs, so wood is definitely not an option.

Thanks for the input - I appreciate it.

Garry

[Dougal]

Pretty much all heat pumps are rated at 7c outside in heating mode. They can really plummet in efficiency and capacity add it gets colder.

I am running a 7kw output heat pump upstairs and a fire downstairs. Costing me about $2 a day to power it, averaging around 600w when I look. That's the great part about inverter models, they slow down to suit the load. A few good frosts here so far.

[scarry]

Mitsubishi ducted,the 12.5Kw and the 20Kw will operate on heating down to -20 degrees ambient,as per the specs.

Dunno what Daikin run down to without going to the office and checking,guessing somewhere close to that as well.

Not an issue up here,as it rarely gets lower than 5 degrees,but something that garrycol needs to check.

The issue we have up here is that Daikin will not cool if ambient is lower than 10 degrees,which means that they are no good for some applications such as server rooms.They also have NO warranty in these applications as the unit is not 'comfort cooling'.
Mitsubishi will cool at lower ambients and have a 12 months warranty in a server room.

Both brands have good parts availability,5 yrs warranty,and good tech support,but i recon the Mitsy is slightly better quality.

A bit like Holden verses Ford.

Just my 2 cents worth,we are more in the A/C & Refrig.repair industry than installs.

[101RRS]

Thanks Paul - every one of the six installers I visited recommended Daiken and no other. I am assuming (and we know what happens when you assume) that as all the installers are local they would be recommending one suitable for the climate - but before I proceed I will ask a few more questions.

Cheers

Garry

[Dougal]

Depending on your house layout and usage it may be better to go for several smaller systems to be run individually rather than one large.

Also remember there is no substitute for insulation to increase comfort, reduce heating/cooling costs and even out the temperature throughout the house. If you have a wooden floor then underfloor insulation makes a massive difference.

[Kev the Fridgy]

I would second what Paul has said, last project I ran we installed roughly 200 Mitsubishi systems, current project has about 15 Daikin systems, in the past Daikin was considered the leader but to be honest Mitsubishi give them a good run for the money and given the costs I would most likely select Mitsubishi.


One of the reasons for the delay in heating is that with modern control systems they delay the fan for a while to allow the coils to achieve desired temps before circulating air, after all you don't want cold air circulating for 10 minutes before the warm air starts.

[Bigbjorn]

I don't have gas at the moment but I also asked about it - $5k but a gas unit is a lot more expensive to run and the price of gas is going up - will also have to continue to pay the gas supply and admin fees in summer when the heater and gas is not being used. To get gas to my house would be another $500-$1k.

Cheers

Garry

I worked as a fitter at Brisbane Gas Co. in the days before it was taken over and asset stripped by Boral. It was a good place to work then. I can tell you that hardly anyone who worked there would have considered having gas hot water or space heating. Far too expensive. Even worse now with the "service charge" first and foremost on the account.