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Paul1977

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#253070 24-Jul-2019 12:27
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We are building a new house and looking at ducted heat pumps and had a question for those of you who know how these systems work.

 

We are being recommended to upgrade to an "AirTouch 4" controller that has wireless temp sensors in each room to allow electronic dampers to adjust airflow to be able to ensure all rooms are at the appropriate temp. It would be set up as 6 zones. Living & dining being a single zone, then every other room with a vent being it's own zone.

 

We are also looking at the possibility of incorporating a heat recovery fresh air ventilation system, but are undecided on that.

 

Being a bit of a geek, I wanted some opinions from fellow geeks in the know, rather than just relying on what the suppliers say is best.

 

Below is a sketch I did of what I have discussed with a supplier (I haven't got his actual plan through yet), and was wondering if this is a good way to do it.

 

I was also wondering if we should look at having a cavity slider to the left side of the main entrance. I thought this might better allow us to just heat/cool the living areas during the day without it being siphoned into the bedroom side of the house. Since there are return vents in each hallway, would there be any times when having a closed door in this position would be a problem for air flow?

 

 

Thanks in advance.





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jonathan18
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  #2282800 24-Jul-2019 13:10
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I like the sound of wireless sensors in each space - I assume that provides for real-time adjustment of airflow into each room to maintain an even temp throughout the house? (Or can you even set different temps for different zones?) Are the sensors battery powered?

 

Have you had a price back on the job yet? It'll be interesting to see what the heat recovery component adds to the cost, but personally I'd be strongly tempted to go for this (and compromise elsewhere if necessary).

 

I assume you've also going to have more than one company quote for the job? Even if it's just to get the ideas of multiple people. As per my comments on other threads on ducted systems, I learnt the hard way and next time would be 100% sure of the competence of the designer/installer in regards to ducted systems (vs basic back-to-back etc) given the relative complexities of such installs.

 

In our case it's ok shutting off and heating a zone that doesn't have any return vents in it - we sometimes only heat the lounge/dining side and have the doors shut, but I can certainly feel the air being sucked under the gap of these doors and all installers we had quote for the job said this would be ok. That said, it could be a different matter with a modern build, if gaps are far better managed. Have you been advised whether bedroom doors etc need venty things (yes, that's the technical term!) on them to ensure airflow is ok when the doors are shut? It could be a similar matter with that sliding door, even if it's as simple as keeping the door open a crack. But, yeah, if you're going zoned there's a clear logic in being able to restrict airflow to the areas you want to heat - let alone would you not benefit noise-wise from a door in that location?

 

 




Paul1977

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  #2282809 24-Jul-2019 13:32
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He's given a ball park estimate on price, but nothing concrete yet.

 

I assume the sensors are battery powered since they're wireless, and he commented that you can move them easily. You can also set different temperatures in different zones (but obviously you can't heat one zone while cooling another). He said they use 5-position inline dampers (fully open, 75%, 50% 25% and closed) to each zone which automatically adjust to maintain the set temperature in each zone.

 

This is the supplier/installer the building company normally uses, but I have had a couple of independent quotes as well. They are coming out about the same dollar figure, but this solution appears to give a lot more control.

 

What I have noticed is that every installer has a different idea on what's best - hence posting hear for some more advice.

 

I forgot to include it in the above sketch, but would likely also have a small return vent or jump duct in the lounge. This will be a media room and will have the door shut when in use. For light and sound control I won't want this door to be undercut or have a vent in the door for return airflow.


openmedia
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  #2606982 19-Nov-2020 14:31
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Hi @Paul1977 some great detail here and on your other threads.

 

Can you let us know what the final configuration was and do you have any recommendations/guidance.





Generally known online as OpenMedia, now working for Red Hat APAC as a Technology Evangelist and Portfolio Architect. Still playing with MythTV and digital media on the side.




mdooher
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  #2606986 19-Nov-2020 14:39
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can you get those returns down to floor level in any place? thicken up a wall and create a duct... It will improve the efficiency no end... otherwise you are returning all the hot air and leaving the cold stuff at the floor

 

 

 

you will also need a small return in  Bed1...unless you want to sleep with the door open in which case don't worry





Matthew


Paul1977

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  #2607055 19-Nov-2020 16:18
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mdooher:

 

can you get those returns down to floor level in any place? thicken up a wall and create a duct... It will improve the efficiency no end... otherwise you are returning all the hot air and leaving the cold stuff at the floor

 

you will also need a small return in  Bed1...unless you want to sleep with the door open in which case don't worry

 

 

I'm sure you could get return vent at floor level, but it would need to be incorporated into the house design from the beginning probably. We just stuck with the ceiling returns.

 

We do sleep with the door open a little, but also had a slightly bigger undercut on the bedroom 1 door.


Paul1977

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  #2607069 19-Nov-2020 16:39
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openmedia:

 

Hi @Paul1977 some great detail here and on your other threads.

 

Can you let us know what the final configuration was and do you have any recommendations/guidance.

 

 

We pretty much went with how it's drawn, except the heatpump and Lossnay share the the main return vents/ducts with the heatpump and then Y branch off to the Lossnay in the roof space. In retrospect I'd probably suggest keeping the return ducting completely separate (like the diagram in the first post).

 

We also put a small return grill in the lounge (which is used as a media room, so often has door shut).

 

I think we should have gone the next size heat pump larger as well. What we got seems fine for heating, but on a very hot day struggles a little with cooling. To be fair we haven't got all the curtains and blinds up yet so do get significant solar heat gain on a sunny day - this will hopefully be more controllable once the curtains are up.

 

Another argument for going the next size up is with all zones open, even on the highest fan speed, we don't get a great amount of airflow out of the ducts (i.e. if we want to rapidly cool the house). This might be normal, I just expected higher airflow on the top setting though. If we close some vents down then the flow increases to the remaining ones.

 

If the temperature outside is cooler than inside, putting the Lossnay in summer bypass mode and cranking to full speed is still no comparison to just opening a couple of windows which will cool the house way faster. 

 

We did put the cavity slider in, which I think was a good call as a few times we have closed off the bedrooms and concentrated all the cooling into the living area to drop the temp faster.

 

 


jjnz1
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  #2607212 19-Nov-2020 20:17
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Looks like a great system.

Would you recommend to others, and what was the ballpark figure price wise?

Do you have any indication yet of how much the system is costings to run or KWs used?

 
 
 

Shop now on AliExpress (affiliate link).
Handle9
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  #2607215 19-Nov-2020 20:37
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jonathan18:

 

I like the sound of wireless sensors in each space - I assume that provides for real-time adjustment of airflow into each room to maintain an even temp throughout the house? (Or can you even set different temps for different zones?) Are the sensors battery powered?

 

 

Temperature controlling branch dampers (rather than on/off zoning) requires a much more sophisticated control than a domestic unit can provide. What you are suggesting is Variable Air Volume (VAV) control. A domestic unit is a Constant Air Volume (CAV) Fan Coil.

 

To work properly the dampers need to be volume controlled based on demand and then the unit has it's temperature setpoint reset based on the unit that has maximum demand. You also need to pressure control the fan to provide a constant pressure up the back of each damper.

 

This is well beyond the average domestic unit and certainly well beyond a domestic installers capability.


Paul1977

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  #2607323 20-Nov-2020 09:23
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Handle9:

 

jonathan18:

 

I like the sound of wireless sensors in each space - I assume that provides for real-time adjustment of airflow into each room to maintain an even temp throughout the house? (Or can you even set different temps for different zones?) Are the sensors battery powered?

 

 

Temperature controlling branch dampers (rather than on/off zoning) requires a much more sophisticated control than a domestic unit can provide. What you are suggesting is Variable Air Volume (VAV) control. A domestic unit is a Constant Air Volume (CAV) Fan Coil.

 

To work properly the dampers need to be volume controlled based on demand and then the unit has it's temperature setpoint reset based on the unit that has maximum demand. You also need to pressure control the fan to provide a constant pressure up the back of each damper.

 

This is well beyond the average domestic unit and certainly well beyond a domestic installers capability.

 

 

I'd imagine you're correct that for a perfect system it would require VAV control on the heat pump itself - which as you say domestic systems don't have. What it does is open and close the dampers in 5% increments to control the air flow to each zone (and thus the temperature), and each zone can be set to a different temperature with the temperature setpoint dynamically changing to the the target temperature of whichever zone still requires the most heating/cooling to reach target (as read from the sensor in that zone). That's my understanding from observing it anyway.

 

So it does reset the setpoint automatically as required, and "kind of" does VAV to each zone (with the big caveat that the total air volume is constant, which means it relies on spill/dump zones to presumably prevent a blowout).

 

I'm not an expert, but in theory it seems as good as you'll get for a domestic unit I would have thought. In practice I think there a quite a few options missing that I'd like to see added in future firmware revisions to make it smarter. One example being that the it triggers a spill/dump zone based on the damper positions regardless of the fan speed, where I would have thought it would make more sense to have different thresholds for the different fan speeds/total air volume. There are several things like that where I feel the logic could be improved, and this is a good reminder to email the developers with my suggestions.

 

Most of the downsides seem like things that could be improved in software, it's just a question of whether it will happen.


Paul1977

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  #2607346 20-Nov-2020 09:44
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jjnz1: Looks like a great system.

Would you recommend to others, and what was the ballpark figure price wise?

Do you have any indication yet of how much the system is costings to run or KWs used?

 

Cost wise I think the AirTouch zoning control was something like $5000-$6000 on top of the heatpump. I'm not sure exactly as it was all quoted together.

 

I'm unsure as to whether I'd recommend it. I like having it fully zoned, but not sure if it was worth the cost. I've never had a ducted system before, so I have no comparison to say how much value/comfort it's added.

 

I'm not sure on cost to run it yet, as we shifted in on the tail end of Winter and aren't yet in the full height of Summer. But from looking at power usage, if you had it running all the time (actively heating/cooling) it would cost a fortune - but no more than any other ducted heat pump. The AirTouch Controller and dampers would use negligable power, as does the HRV. Heat pump uses negligible power when in "Fan Only" mode. The cost is when you're actively heating or cooling. We up-specced insulation and glazing to minimize how much we need to us it.

 

In theory it should be cheaper to run than a non-zoned system since it minimizes overheating or overcooling parts of the home, but in practice I really don't know. I doubt it will ever come close to paying for itself through power savings.


Handle9
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  #2607777 20-Nov-2020 18:13
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Paul1977:

 

Handle9:

 

Temperature controlling branch dampers (rather than on/off zoning) requires a much more sophisticated control than a domestic unit can provide. What you are suggesting is Variable Air Volume (VAV) control. A domestic unit is a Constant Air Volume (CAV) Fan Coil.

 

To work properly the dampers need to be volume controlled based on demand and then the unit has it's temperature setpoint reset based on the unit that has maximum demand. You also need to pressure control the fan to provide a constant pressure up the back of each damper.

 

This is well beyond the average domestic unit and certainly well beyond a domestic installers capability.

 

 

I'd imagine you're correct that for a perfect system it would require VAV control on the heat pump itself - which as you say domestic systems don't have. What it does is open and close the dampers in 5% increments to control the air flow to each zone (and thus the temperature), and each zone can be set to a different temperature with the temperature setpoint dynamically changing to the the target temperature of whichever zone still requires the most heating/cooling to reach target (as read from the sensor in that zone). That's my understanding from observing it anyway.

 

So it does reset the setpoint automatically as required, and "kind of" does VAV to each zone (with the big caveat that the total air volume is constant, which means it relies on spill/dump zones to presumably prevent a blowout).

 

I'm not an expert, but in theory it seems as good as you'll get for a domestic unit I would have thought. In practice I think there a quite a few options missing that I'd like to see added in future firmware revisions to make it smarter. One example being that the it triggers a spill/dump zone based on the damper positions regardless of the fan speed, where I would have thought it would make more sense to have different thresholds for the different fan speeds/total air volume. There are several things like that where I feel the logic could be improved, and this is a good reminder to email the developers with my suggestions.

 

Most of the downsides seem like things that could be improved in software, it's just a question of whether it will happen.

 

 

The problem you have is you will never achieve good control with what you describe. Without constant pressure behind the dampers the system will go dynamic and never hit dead band. Basically you end up with dampers constantly fighting against each other, only slowed down by the 5% increments you are talking about.

 

If you're having to "spill" you're going to end up over heating / over cooling the spill zones. At that stage what is the point of this system? You are still heating/cooling the same volume of air so you won't save any money on energy and you've invested a fair bit of cash to do so.

 

In ideal conditions you might get something acceptable but at that point just commissioning the airflows correctly using manual balancing dampers will you much the same results for far less money. Most domestic installers, and many commercial contractors, aren't even capable of this TBH.

 

 


Paul1977

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  #2607845 20-Nov-2020 20:53
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Handle9: The problem you have is you will never achieve good control with what you describe. Without constant pressure behind the dampers the system will go dynamic and never hit dead band. Basically you end up with dampers constantly fighting against each other, only slowed down by the 5% increments you are talking about.


If you're having to "spill" you're going to end up over heating / over cooling the spill zones. At that stage what is the point of this system? You are still heating/cooling the same volume of air so you won't save any money on energy and you've invested a fair bit of cash to do so.


In ideal conditions you might get something acceptable but at that point just commissioning the airflows correctly using manual balancing dampers will you much the same results for far less money. Most domestic installers, and many commercial contractors, aren't even capable of this TBH.


 



I still think it has to better than a non-zoned system or simple on/off dampers - especially if most installers can’t properly balance them as you suggest.

The main spill zone is the area that will always require the most heating or cooling, so will normally be the last one to hit it’s target temperature. This should (in theory) minimise over heating from spill zone activation.

And since it’s installed and paid for I’d like to carry on believing that it has some benefit!

Is it worth the cost? Perhaps not, but it’s done now so will make the most of it and try to use it as optimally as possible.


EDIT: I had to look up what dead band meant. We don’t put the system on auto mode, not sure that applies for our use case. We either have it on heating, cooling, or fan only. Never on auto.

  #2607905 21-Nov-2020 08:39
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We have a ducted system with multiple zones and heat recovery, etc in our new home. It works well and means that the whole house is useable unlike the 'one heat pump per room' solution we had in our previous home, no more being confined to one room at a time.

 

We spent weeks thinking about how we wanted to live in our new home. Very rewarding when we got it right and intensely annoying when we didn't or couldn't. Fortunately, we managed to get most things right for our budget.  

 

Looking at your floor plan (and others I've seen), why wouldn't you combine your garage with the laundry? this will save overall space and eliminate an external door. And do you really want to access the Garage via the Office?

 

 

 

Have you missed the door to Bed 2?


Paul1977

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  #2607914 21-Nov-2020 09:30
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rogercruse:

 

We have a ducted system with multiple zones and heat recovery, etc in our new home. It works well and means that the whole house is useable unlike the 'one heat pump per room' solution we had in our previous home, no more being confined to one room at a time.

 

We spent weeks thinking about how we wanted to live in our new home. Very rewarding when we got it right and intensely annoying when we didn't or couldn't. Fortunately, we managed to get most things right for our budget.  

 

Looking at your floor plan (and others I've seen), why wouldn't you combine your garage with the laundry? this will save overall space and eliminate an external door. And do you really want to access the Garage via the Office?

 

Have you missed the door to Bed 2?

 

 

@rogercruse We just dislike laundries in garages, and a separate laundry was on our "must have" list. Personal preference I guess, as I noted you often suggest having it the garage as being better. Plus for us the laundry was the preferred place for a cat door.

 

The room that was originally labelled "office" is actually a home hair salon for the missus to work from home full time, but we added a wall to create a defined salon entrance area which doubles as a thoroughfare to the garage. That was a trade off we had to make for everything else to work. After being here a few months there are a few things I'd change if I did it again, but the floor plan isn't one of them as it works really well for us. We don't have children so bedroom 2 and bedroom 3 are used respectively as a sewing room for the missus and a home office/computer room for me (I don't work from home though).

 

We ended up doing a separate hi-wall heat pump in the salon to keep it isolated from the ducted heat pump and HRV servicing the rest of the house.

 

The bedroom 2 door was just me having drawn something wrong.

 

Below is the as built plan (click to enlarge).

 

Click to see full size

 

 


timmmay
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  #2673747 13-Mar-2021 13:45
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Hey Paul, how are you finding the Airtouch? We have a ducted heat pump and I'm finding I have to get up into the ceiling quite often to adjust the dampers. On sunny days I need a lot of airflow to the small bedrooms down the side of the house that gets a lot of sun. On cold or cloudy days I need to reduce the airflow so when we have the system on heating the smaller rooms don't end up super hot.

 

The same company also has the Zonetouch which looks like it's a simpler way to adjust dampers without as much automation. That might do me ok if it's cheaper. I could probably just adjust the smaller 200mm ducts, rather than at the plenum which have larger 300mm ducts.

 

Anyone else seen any other solutions?


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