Cooling upstairs bedrooms

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13684 posts

Uber Geek

#1424955 11-Nov-2015 08:42

What about Velux skylights? Automatic self-closing with rain detector, double insulated glass, shades, insect screens etc. Probably expensive up-front cost vs a heat pump, but might offer an effective passive solution. Fresh air is nice too - supposed to be good for you (and kids).
I know that on occasions where it's >30 deg (Chch) a small heat pump which is adequate for heating our living areas on a cold day, is fart1ng against thunder on cooling cycle. If going that route then I'd be calling an expert in - if the heat pump is going to be used for cooling, then capacity might need to be much larger - and running costs much higher - than expected.

xontech

268 posts

Ultimate Geek

#1424987 11-Nov-2015 09:01

With regards to the window film questions - yes they are pretty large bedrooms with quite a bit of north facing single glazed window area in each room. So quite a bit of window area to get covered.

As to effectiveness, the 3M product that has been recommened to us (Prestige 40) states a solar heat energy rejection of between 60 and 66% on single glazing. So we are hoping for a reasonable reduction in heat coming in via the windows.

Thanks for the tip on Velux skylights, that is something I will look in to as well.

I'm not fully against heat pumps, I have had them in houses the past, though not a fully ducted system. Installation costs aside I would suggest that when getting quotes to ask the installer to give you an estimate as to what your running costs will be for your installation.

andrew027

1286 posts

Uber Geek

#1426013 11-Nov-2015 10:38

+1 for going ducted, if there is any way you can afford it.

In the 1990s I was asked to move to Adelaide to work on the whole of (state) government IT outsourcing project. Outdoor summer temperatures regularly hit the mid-40s and at that point having windows open doesn't help. I bought a two storey house and walking upstairs in the afternoon was like opening an oven door in your face - the master bedroom faced east and was hot, and the two secondary bedrooms faced west and were like hell. Apparently the previous owners dealt with it by carrying the kids' mattresses downstairs every night to sleep in the family room. Bugger that!

I put a ducted air conditioning system in, with the fan unit installed through the roof over the garage so we didn't get much noise or vibration in the bedrooms. One vent in each of the three bedrooms and another over the stairs which also kept the lounge cool - there was already a reverse cycle heat pump in the family room/kitchen but this area had tiled floors so tended to be cooler anyway. The second summer we were there my wife was pregnant and she would not have coped without the air con, and of course the third summer we had a 9 month old baby.

Shanemc

76 posts

Master Geek

#1426288 11-Nov-2015 15:28

That 4.5k price doesn't seem too bad, for the amount of room coverage you are getting. I'll look into getting some quotes. I can suffer through February, but with a 9 month old, extending the mortgage might save our sanity.
Any recommendations for installer/suppliers on the North Shore.

Shanemc

76 posts

Master Geek

#1443312 9-Dec-2015 08:47

Well the quotes are in. The air conditioning options are a 1. 'whole floor' ducted system. at around 6500 less a couple of discounts. This is a 4 vent system. Or 2) a mini multi split system with heads in all three rooms at high 6000. Getting conflicting advice from different companies.
I'm a little concerned that the ducted system would be wasteful as we would only really need to cool the baby's room during the day. Then the baby's and 4 year old during the early evening. And only occasionally the master bedroom. I also worry a bit about it over-cooling rooms with air running down the stair well and having the doors closed. The temperature sensors are in the intake, which would be in the hall way.

The mini split system would seem to give us complete control.

However the ducted sales guy seemed to say that the efficiency of running the ducted system, compared to the mini split system was significant and meant that cooling the whole floor wasn't that big a deal.

Any experience or thoughts on these issues from others?

MadEngineer

4271 posts

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#1443367 9-Dec-2015 10:05

Ducted units are supposed to be less efficient.

Multi head would let you set the desired temperature per room.

You're not on Atlantis anymore, Duncan Idaho.

ben28

190 posts

Master Geek

#1444395 9-Dec-2015 11:24

For 6K you should be able to get 3 x small heat pumps, one for each room, including installation. Advantages are the smaller units are more efficient , more reliable. We have a 3.2kw Fujitsu unit in our bedroom and its great, quiet. Only had since July so only used to heat so far.
You could also stagger the install, just do one room and learn from the experience.
Position so avoid getting a draft on you when in bed if possible. The smaller units sometimes dont have horizontal control of air direction , so check out carefully.
Our unit is positioned so it can blow out the door down the hallway to the toilet/bathroom. About 10 m, and it actually works . I suspect helped by the stairwell creating a large volume, so the air 'pressure' is less than the bedroom. Also heat rises so the heat stays upstairs.
We used Kiwi Heat Pumps in Auckland, I'd recommend getting a rep from a company that has done this kind of thing before.
Let us know what you choose and how it works out

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jonathan18

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#1444566 9-Dec-2015 15:07

Shanemc: (cut) The temperature sensors are in the intake, which would be in the hall way.

Based on my experience of having a ducted system installed, be very careful about such a system that relies solely on a sensor in the return duct - indeed, I'd recommend you avoid this at all possible.

Despite strong indications to the contrary, that's how our system was initially installed (I think the installer believed there was a sensor in the controller as well, which many models have), and its performance was a total disaster. We experienced a five degree variation in temperature - two degrees below, three above the set temp. Then there was the other major issue that the sensor wasn't necessarily in the area being heated (given ours was a two-zone system), which led to the farcical situation of the heater heating one space based of a temperature reading in another space! We basically had to order the installer to put in additional sensors - we put one in the lounge and one in a bedroom, which can be user-selected. These problems were solved overall, though we still have the problem of them having used the wrong air vents for the higher-stud rooms.

The other key thing to consider is whether you really want the ability to control whether individual rooms are heated. It's possible with a ducted system to shut off the air flow in certain rooms, whether it be by using zoning via dampers or manually shutting off particular air vents. Some vents are easier to do this than others (eg those using a lever compared to ones that have to be screwed in), but how easy this is to do can depend on the stud height (even getting a chair to do this could be considered a too big a hassle on a daily basis).

Personally, I'm happy with our ducted arrangement which while two-zoned means we must heat multiple rooms at one time, meaning even if only the 'bedroom' zone is going we are cooling/heating all that half of the house including an unoccupied bedroom and the hallway. I also prefer the lack of noise, less obvious airflow, and the minimal aesthetic disruption that a ducted system has over a split system, but there are many advantages to the latter.

Kickinbac

427 posts

Ultimate Geek

#1444576 9-Dec-2015 15:25

I have the same dilemma in my house... ducted or hi-walls! I've just bought a new (old) house and it's two storey and built in the mid 80's. It gets hot upstairs in our kids rooms so want to put some cooling. They have ceiling fans but don't help enough with the heat. We are upgrading the insulation in the roof and putting in air conditioning.

I've basically decided to use hi-wall split systems in each room because wall mounted heat pumps are cheap, very efficient (compare the COP figures 4.8-4.9 for a 2.5kw hi-wall vs. ducted with COP's around 3.8-4.0). I can turn each room on/off as required and don't have to heat or cool the hallway that is open to downstairs via stairwell (a good place to lose heat). So I will have four heat pumps, a 6.0kW unit for kitchen/lounge /dining and a 2.5kw in each of the bedrooms. The hallway will have nothing.

A ducted system would do the whole of upstairs, can't turn lounge/kitchen/dining off when we go to bed (could be done with extra zone controls but more cost). I'd have to heat/cool the hallway with all its heat loss. It's hard to get ducts to and from downstairs bedroom and no temperature control. The other problem in my house is that there is only a small ceiling hatch in a wardrobe. To install a ducted system we'd have to cut a hole in the ceiling or take some of the roof off to get the indoor unit in.

For the hi-walls we have to conceal the pipework and drains. We are going to open up a wall to conceal the pipes in the wall down into our garage below so that it will be neat and tidy with no surface mounted capping. We can also do two now for kids bedrooms (the hottest in summer) and do the other two next year, mainly for heating next winter.

MadEngineer

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#1444580 9-Dec-2015 15:34

Weird. Thermostat install instructions that I've seen advise to place them at head height

Regarding the sensor in the controller, some require this function to be turned on, for example some require that you hold the thermostat button down which unlocks the change, then you press it once to toggle between the cassette sensor and the controller sensor. This same one has a dip switch in the back to set the default behaviour.

You're not on Atlantis anymore, Duncan Idaho.

Kickinbac

427 posts

Ultimate Geek

#1444593 9-Dec-2015 16:01

MadEngineer: Weird. Thermostat install instructions that I've seen advise to place them at head height

Regarding the sensor in the controller, some require this function to be turned on, for example some require that you hold the thermostat button down which unlocks the change, then you press it once to toggle between the cassette sensor and the controller sensor. This same one has a dip switch in the back to set the default behaviour.

Thermostats are generally mounted 1200 - 1500mm above the floor. You want the sensor in the area the humans are at. Ducted systems have a sensor in the return air duct which gives an average of the space.

I think from memory jonathan18 had a new Daikin Skyzone controller which is basically an android tablet mounted on the wall working via Wi-Fi to indoor, there is no internal temperature sensor.

E3xtc

773 posts

Ultimate Geek

#1446940 10-Dec-2015 09:30

It sounds like it's going to come down to personal preference in this situation. The cost differential between the 2 isn't that much. We decided on the ducted solution primarily because we couldn't actually install a split solution due to the configuration of the house (with the only wall in one of the bedrooms being a 3 storey+ drop - so scaffolding/osh requirements mean cost is prohibitive). BUT if we were able to do that, then I think we still would have gone with the ducted solution, just because I really dislike the look of the high wall units - in larger areas they don't seem so dominant, but in smaller areas like bedrooms I just really dislike them :(

Re the heating the whole floor - and getting the temperature variance. We didn't find this to be a major issue. We found that we could adjust the vents for each room, ie smallest one has less air, largest one has more air...or if one room is vacant/spare, just close it off altogether. So while it's not a process of just going "oh I want each room to be at X degree's", you can with a bit of adjustment (or both the temp, fan speed, and/or vent opening) get a feel for what the optimal settings are.

FWIW most of the time in summer we just want it to rapidly take the temp of our son's room down (ie blast the room with cold air), so his room has his vent opened up the most, with the spare room closed off, and the master bed getting only about 15% opening. In winter, we had it so that his room had less air volume going into it, because we had the unit on for longer periods and wanted to maintain a comfortable temp across a longer duration - so relied on the system managing the fan on/off in combination with the sensor in the intake. Worked well.

jonathan18

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#1446955 10-Dec-2015 09:46

MadEngineer: Weird. Thermostat install instructions that I've seen advise to place them at head height

Regarding the sensor in the controller, some require this function to be turned on, for example some require that you hold the thermostat button down which unlocks the change, then you press it once to toggle between the cassette sensor and the controller sensor. This same one has a dip switch in the back to set the default behaviour.

Yeah, it really doesn't make sense to me that ducted systems would have the sensor mounted in the return vent, but that's the way they are apparently (or at least some?). As our experience proved, reading the temperature at that point ensured it had little relevance to actual room temperature, and led to mis-readings apparently due to air stratification and movement etc.

The controller that came with our unit is totally different to all other Daikins; it's simply a cheap Android tablet (my earlier post links to the earlier thread where I discuss the problems with this system!) in a white Daikin casing. There is no sensor included in this and can operate only wirelessly, hence it can be placed anywhere with only a power plug needed. It should have also been proof enough to the installer that additional sensor(s) were required. My recommendation regarding this fancy-looking system is that it's all smoke and mirrors, and best avoided; stick with a hard-wired controller with a sensor included.

Both sensors we had installed were put in at head height. Our remaining problem is that one of these sensors reads 2 degrees cooler than the actual room temperature! This can be a hassle in that the lowest we can expect the room to warm to is 18 degrees, when it is set at its lowest of 16 - this is warmer than need be for maintaining a level of warmth when out of the house...

bfginger

1267 posts

Uber Geek

#1448258 10-Dec-2015 16:13

The downside of having multiple external units is you have multiple external units using electricity in stand by mode and you have to have somewhere to situate them. The best single split systems will be more efficient than multi-splits and ducted systems when running as new technology goes there first.

You can have multi-split systems supply into a room through a duct connected to a box in the ceiling. They should be slightly quieter but more expensive.

All but the smallest ducted systems' external units are high dB rated units when running at high power. Some multi-split external units are rated as quiet at high power.

What colour are the concrete tiles? If they're dark that will be contributing to the heat build up.

lapimate

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#1448388 10-Dec-2015 20:49

Kickinbac: ... So I will have four heat pumps, a 6.0kW unit for kitchen/lounge /dining and a 2.5kw in each of the bedrooms ...

Doesn't this increase the possibility of thermostatic "hunting", unless all the control units are somehow interconnected?

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