Ducted or seperate split system

[Williamstown]

I'm in Melbourne and currently looking at replacing an old email aircon/heating and gas wall furnace in our Victorian house.

Had a few people out to give quotes; however had various and difference advice. I ideally want a solution to head/cool the whole house; however heating is probably more important that cooling as I will only be cooling living areas for a week or so a year.

Of the 3 companies only 1 suggested a ducted system. Because we have high ceiling (3.6m in front part and standard height in the extension) they dont want to install a ducted system in the roof - as they said heat wont circulate properly/reach the ground. One also said they would not want to install vents in the roof due to potential damage to the original (old) plaster on the roof. The one company that said they would do a ducted system said they would install it under the floor; however would only be suitable for heating and not cooling as there is only enough clearance under the house for heating ducting and not cooling (cooling requires larger ducting). Price for quote seemed good at only $3500 for gas 4 star heating with 8 vents.

They all gave me quotes to install multiple splits as an alternative. It varied from 4 single splits to 2 multihead systems with 2 heads each. 1 7.2KW split for kitched/dining and adjoining bedroom, 1 x 5.6kw for living area, 1 x 2.5kw for study and 1 x 3.5kw for another bedroom.

Splits obviously have the advantage of cooling as well as heating, heating/cooling part of the house (in practice probably how wil be used); however disadvantage of not having whole house heated/cooled and multiple ugly condensers outside and box on wall inside. Multi-head systems only means 2 boxes outside which isn't bad.

Does anyone have any advice?

Questions:
What is the cost of running seperate interters/splits compared to gas heating.
Does it matter if ducting is on ground under house, will it degrade?

Thanks in advance.

[munruben]

The house we moved into about 6 years ago had no air conditioning so we had 3 bedroom air conditioners installed. (Did that myself) and one split system air con downstairs in the lounge. This does the trick for us and we can have the rooms cool that we want to and not waste power that way.

My son had ducted air conditioning in one of his homes and he said he would never have ducted air conditioning again. Too expensive to run and not really effective on real hot days. I remember one day when it was really hot, the air conditioning until stopped working and when he rang the manufacturers, they told him this was a normal cut out procedure for the unit to stop it overheating. Maybe he picked a bad brand. Can't remember what it was now. Anyway when he sold and bought another home, he installed 3 split units and his house is kept beautifully cool in summer and warm in winter.

[juan]

All my experience with both systems makes me agree totally with munruben.

Cheers

[GraemeCook]

... only 1 suggested a ducted system. Because we have high ceiling (3.6m in front part and standard height in the extension) they dont want to install a ducted system in the roof - as they said heat wont circulate properly/reach the ground. One also said they would not want to install vents in the roof due to potential damage to the original (old) plaster on the roof. The one company that said they would do a ducted system said they would install it under the floor; however would only be suitable for heating and not cooling as there is only enough clearance under the house for heating ducting and not cooling (cooling requires larger ducting). Price for quote seemed good at only $3500 for gas 4 star heating with 8 vents.

I'd be wary of the competence and integrity of this company:

*** Virtually all airconditioning in commercial buildings is installed in the ceiling and they generally throw more than 3.6 metres.

*** Aircons in Tasmania are installed primarily for heating, with the bonus of cooling for the two days a year that is required, and they do not need larger ducts for cooling.

*** The possibility of damage to lathe and plaster ceilings is real, but easily repairable, so essentially a non event.

With heat pumps the inverter technology is so much better than the older units that you should not consider them. Inverters are now marginally more expensive to buy, account for about 90% of sales, are cheaper to operate, and operate virtually continuously at low power rather than cycling on and off, and giving a cold blast as they warm up.

The quoters should give you an estimate of operating costs tailored to your life style. Assume the equipment will last 10-12 years and just work out the life time costs. It will be illuminating.

Please keep us posted as you explore the options and refine your thinking. It is a complicated and expensive part of our lifestyle.

Cheers

Graeme

[Williamstown]

Thanks for the input. I'm now starting to think a RC aircon with splits is the way to go. We can install 1/2 now and if they work out well install more later as required. Daikin make a 18KW model that allows you to run upto 9 heads, I'm planning on getting pricing.

[tricky4000]

You may need 3 phase power in your house to operate an 18kW unit. Gas heating is much cheaper to run. I have a similar house in Melbourne and we have gas floor ducted heating and ceiling ducted reverse cycle inverter air conditioning and this seems to be the best option. Also, my AC guy strongly steered me away from Daikin and said go for Mitsubishi. He said Diakin used to be good but something has changed in their manufacturing over the last couple of years and they're newer range of ACs have gone downhill. He said he has lot of customers calling back with problems. I hope that tip helps you out.

[Buggermedumplings]

The house we moved into about 6 years ago had no air conditioning so we had 3 bedroom air conditioners installed. (Did that myself) and one split system air con downstairs in the lounge. This does the trick for us and we can have the rooms cool that we want to and not waste power that way.

My son had ducted air conditioning in one of his homes and he said he would never have ducted air conditioning again. Too expensive to run and not really effective on real hot days. I remember one day when it was really hot, the air conditioning until stopped working and when he rang the manufacturers, they told him this was a normal cut out procedure for the unit to stop it overheating. Maybe he picked a bad brand. Can't remember what it was now. Anyway when he sold and bought another home, he installed 3 split units and his house is kept beautifully cool in summer and warm in winter.

I'm guessing it was. I have ducted (Brivis Gas heater with refrigerated add-on unit) and no issues to speak of- Simply because it's top-shelf gear and was installed/balanced/sized correctly. Extremely efficient too- will generally add $30-40/quarter to the bill during summer and that's cooling 31 squares.