AC cooling to adjacent room idea

We’ve got two bedrooms that are adjacent. Both share a northern facing exterior wall and as a result, get very hot in summer (old house, not insulation, and too costly to put insulation in).

However, room B has AC (split system) already installed and given we have solar, we are happy to crank it on hot sunny days. The other room (room A) faces west and gets very hot in the summer afternoons.

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I was thinking about a way to pipe some of the AC-cooled air from room B to room A, but don’t know if this would work. Basically, something like:
- Create two holes between the rooms, one near the floor and one near the ceiling
- Put a fan of some kind in one hole to draw/push air in the right direction

I think in principle this could work but I’m trying to figure out how big the holes would have to be and how much power the fan would need. Eg if I used 150mm pvc and then something like a computer fan, would that work? I’m sure there is some relevant maths here that someone might be able to help with.

There are calculations for HVAC and the number of air changes per hour required, pretty sure a computer fan is not going to cut it unless it is one used in large servers or network devices. Ever worked in a data centre to understand how noisy these type of fans are ?

I suspect you would fluff around trying out ideas and never be happy with the result.
Small split systems are cheap, my recommendation is install a second one in the other room.

Extra info
https://sigristdesign.com.au/what-ai...re-recommended

Thanks will have a read.

I agree about small split systems for individual rooms.

We've basically converted over to electricity for cooling and heating. We're in Melbourne where gas heating is the go; or has been.

Continually seeking ever better efficiencies in air conditioning units, I gravitated towards Mitsubishi Heavy Industries and their Avanti range; which is pretty much the most efficient 2kW split system on the market, or was back then.

We have two 2kW units, one in our bedroom and one in the kitchen. We have a 3.5kW in our back extension room, 7.5m x 4.5m with one long wall facing north and almost all window. All of these work extremely well and their power drain is very low.

The two 2kW units usually draw around 150W to 300W once the temperature has stabilised and as for heating, they are more efficient by about 10% over their cooling power draw.

Currently it is around 37ºC outside, while it is around 24ºC in the back of the house extension where I'm typing this. The approximate draw of the 3.5kW unit oscillates somewhere between 250W to 480W to maintain around 24ºC.

https://www.mhiaa.com.au/products/se...i-plus-series/

Believe it or not, the big green shed was the cheapest place to purchase these air conditioners. They were a special buy, but that wasn't an issue. We were told by the electricians from the company doing, among other things, our air conditioning installation; that for this particular sub brand of Mitsubishi Heavy Industries split systems, the green shed bought the most and received the best price in Australia.

Whether or not that was correct, or even correct today, their prices were certainly the best I could find 4-5 years ago. They were also bolstered by using my trades card through my Men's Shed for an extra 5%(?) discount.

Mick.

Quote:

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Originally Posted by Optimark

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The two 2kW units usually draw around 150W to 300W once the temperature has stabilised and as for heating, they are more efficient by about 10% over their cooling power draw.

Currently it is around 37ºC outside, while it is around 24ºC in the back of the house extension where I'm typing this. The approximate draw of the 3.5kW unit oscillates somewhere between 250W to 480W to maintain around 24ºC.

...

Mick.

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I'm very interested in how you measure this, as I assume they will all be hardwired ?

Probably better off just using a bathroom style exhaust fan and just pumping it over using ducting.

A mate of mine does this with his firr place in the lounge room, uses an exhaust fan to suck hot air from above the fireplace and pumps it down to a far bed room to warm it.

Quote:

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Originally Posted by havabeer69

Probably better off just using a bathroom style exhaust fan and just pumping it over using ducting.

A mate of mine does this with his firr place in the lounge room, uses an exhaust fan to suck hot air from above the fireplace and pumps it down to a far bed room to warm it.

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Further to this method, using ducting and an inline fan in the roof space would be almost silent

Quote:

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Originally Posted by r3nov8or

I'm very interested in how you measure this, as I assume they will all be hardwired ?

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Yes, they are all hardwired.

Our house is pretty much an off grid house at this time of the year and sort of off grid in the winter period. We have 5 separate rooftops with solar panels that are coupled to 20kWh of useable battery energy. Even though we are very close to 38º latitude, we currently sort of get by with minimal power draw from the grid. In the new year we are looking at putting more solar panels on the garage and possibly the darkroom and upping our battery to close to 30kWh of useable storage and more or less a possible near off grid situation for the entire year.

Effectively the entire house, shed, darkroom and sauna all run through the battery system. This system has a live power display in Watts, which over time and with only one item powered on, I can see any items actual power draw live with each items nominal/actual power draw shown in Watts.

The live display is hardwired to the inverters, so it is a direct readout and within reason it is about as good as you can get without spending squillions for ever diminishing returns on accuracy, which aren't needed.

Fun fact. We purchased an Aldi portable induction cooker, it switches full power (1600W) on/off at longer intervals the lower the cooking temperature you select, and the higher the cooking temperature you select, the shorter the on/off cycles. I assumed it would draw less power at lower cooking temperatures selected on the display and higher power at higher cooking temperatures selected. Nope, just alters the gap between full on, or full off, power draw.

Mick.

Thanks. Very efficient split systems, given you can measure in real time.

Re induction cooking, yes, I've heard the same. Which is why every chef (and decent cook) prefers gas

Yes, with the cheaper units one does expect simplicity in execution of design.

However these days, dual induction units now provide a constant power delivery compared to single induction units. I first heard of these through the rellies in Germany when using a Siemens induction cooktop some years ago. I think it was state of the art back then (2017) but is now available for caravanning and the like in Australia.

https://safiery.com/product/smart-rv...-indoor-and-o/

Mick.

You should check the specs of the unit and make sure it can manage the new air volume.