Ducted heatpump advice sought

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jonathan18

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#175823 13-Jul-2015 09:38

Hey there

Apologies for yet another heatpump-related thread!

We’re planning on having a central heating system installed in our 1920s house; while it’s got ceiling and underfloor insulation it’s still too cold for us in winter, and we’d like an easy-to-use, all-of-house solution (as this is the only thing we really dislike about the house). We’ve considered gas (having read though earlier threads on GZ extolling its virtues), but have decided on a ducted heatpump. Where we live (PN) doesn’t get too cold, so I’ve not got a big concern regarding the system’s failure to operate fully in low temperatures (but will avoid brands/models known for not operating well in such situations). Anyway, thus far we’ve had three different companies visit; the first two to provide quotes are significantly different in cost but also level of detail, brand and model used etc (all three companies agree for the need for a unit of about 16kW heating capacity). I was hoping I could ask the knowledgeable community on here for some advice; apologies for the length of post, but thanks heaps in advance for your responses.

Brands
We have totally contradictory advice on this; two companies like Panasonic ducted systems, the other doesn’t; the third company recommends Daikin, one of the others doesn’t. Between these two brands, can we go horribly wrong, or should we be going by features/COP figures etc? We are definitely set on being able to have full control via smartphone, so we are limited to those that provide for this (whether built-in or additional module). Interestingly, all agreed on not recommending Fujitsu.

Zones
We like the idea of zonal control, but are not sure whether it’s necessary or workable. Our preference would be for two zones: one in the living side of the house, the other for the bedrooms and hall (diagram attached). This would allow us to keep the bedrooms warm all night, and have the living side switch on to warm just before we get up. Similarly, in summer the living side of the house can get really hot (due to big east-facing windows), so it would be useful to cool only those rooms.

If we went with zones, we’re planning on going with the Daikin FDYQT125L model, which has zone control built-in so is fully controllable by the unit (and therefore also via smartphone) and can manage the fan speed (reducing by up to 40%) when not all zones are operating. My concern is, though, would the living side heat up in time, given we’d want the fan speed set to low during the night (to keep the noise down), or would we need to either run a faster fan speed before using that space or turn on the living zone way before getting up, thereby negate some of the savings/advantages of having the zones in the first place?

Location and number of vents I’ve attached one installer’s plans for the house. Do we bother with a vent in the hall, given both returns are going to be located there? One company didn’t think they were needed. The company which provided that diagram proposes to put a duct in the entrance to have that inviting for visitors; another suggests putting one of the returns there, and having a duct part way down the hall. One company suggests we can put up to 10 ducts, but this doesn’t seem to match the information in any of the brochures (that talk about up to 8), so are they just trying to split that air into too many locations? (They also suggested only one in the kitchen/dining, and haven’t made any mention of using a wider ducting, so I’ve some concern they’re not approaching it with the same level of detail as that which provided the detailed plan and quote).

Vent type
One installer suggested there may be issue getting warm air down to a meaningful height with a high stud. Much of our house (all bar the kitchen/dining, both bathrooms and one bedroom) has a 3m stud. His concern is with the standard vents much of the warm air will hang too high. He suggested using those vents with the holes that allow the air to be ‘shot’ down to a lower level. Others said these can produce considerable air flow directly under them, and the high stud can be managed fine using the standard vents. Can anyone offer advice regarding whether this is something to worry about?

Thanks for your thoughts and advice!

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#1342034 13-Jul-2015 11:11

Sorry I don't really have anything to contribute but this interests me a lot as well, I also have a 1920s bungalow with 3m studs, lots of insulation under the floor and in the ceiling - although I'm in Dunedin so I think it gets a bit colder down here :) I've started retrofitting the windows with double glazing (including the leadlights which I didn't know they could do) which seems to have made a bit of difference.

An option I'm looking at is a hot water heat pump with radiators, I currently have a woodburner with heat transfer to the bedrooms but I'd like something a bit more automated.

livealittle

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#1342058 13-Jul-2015 11:33

Hi

We have a 2 year old house in CHCH 318m2 (inc 3 car garage) we have a ducted Fujitsu heat pump running 3 zones.
We haven't had any issues with it not heating the house in fact at night we have to turn it either right down or off as it get to hot to sleep. We have higher studs sorry can't remember the exact height.

Zones didn't seem to be an issue. Ezibreeze here in Chch configured and installed it.
We have 5 bed rooms with open plan dining kitchen and sep lounge so in total we have either 9 or 10 vents with 2 intacts ( one in hallway and the other in the dinning area).
Only difference I would do is re configure the zones esp the bedrooms but hey its not a major.

timmmay

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#1342059 13-Jul-2015 11:34

I can't much help with brand, but I can say I like our Daikin single unit over Fujitsu. No idea of Panasonic, hopefully someone will have used.

My lounge is around 4x4m, and connects to a 4x2m hall leading off sideways, and a 4x4 bedroom around a corner. We have a 10kw heat pump in there an I wouldn't want smaller. The house is old, but has some double glazing, great ceiling insulation, good wall and floor insulation. With only 2kw of heat it would take ages to heat up.

In your diagram I don't think I'd be heating the hallway, I'd treat that as exhaust, but I'm not an expert in any way.

stevenk

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#1342091 13-Jul-2015 12:33

I've had Panasonic heat pumps in the past and haven't had a problem with them. To be honest, I think that getting the unit size and vent locations right is going to be more important that the differences between Panasonic and Daikin.

Right now I've got gas-fired ducted central heating (which is great!) with the unit and ducting in the ceiling space, and a 2.7m stud throughout the house. My vents all fire the hot air horizontally across the ceiling and I don't have a problem with heat distribution, but the return air vent is at floor level rather than in the ceiling. If you go with vents that push air downwards, then I'd make sure that they're not located where you're going to be sitting underneath them - having an air conditioner blowing straight onto you isn't that pleasant, especially when they cycle on and off.

It could be worth asking where the temperature sensor for the thermostats are going to be located - if the sensor is located in the return air vent, the system could behave very differently to how it would if the sensor is on the wall at eye level, especially if you end up with short-cycling, where newly heated or cooled air is sucked straight back into the return air vent.

I wouldn't bother with a vent in the hallway. It's going to be heated and cooled by air circulating from the other rooms, and how much time do you spend in there anyway?

timmmay

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#1342109 13-Jul-2015 12:52

jonathan18:
joker97: How many kW will your ducted unit put out

All three installers are looking at units around the 15 kW size; the one we're likely to pick, given its ability to fully control zones and that it comes with built-in wifi access (Daikin FDYQT125L), is cooling 12.5 (EER 3.4) heating 15 (COP 3.96).

Can you target just one room for all of the heat from the heat pump? Say you want the lounge warm right now?

jonathan18

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#1342115 13-Jul-2015 13:00

Thanks for the feedback thus far.

We too have a wood burner (and a gas fire - all main options covered!), but TBH I'm totally over the hassle of stacking wood, bringing it in, starting the fire, waiting for the damn thing to produce some decent heat, putting up with the loud fan needed to distribute the warmth [it's built in to the fireplace], cleaning the fire, and dusting off every surface due to the stuff left everywhere as a result of running the fan. And still only heating half the house!

The logic behind thinking of putting a vent in the hallway is because the hallway will be heated over-night, but only two of the rooms in that 'zone' (one empty bedroom and our own bedroom, at opposite ends of the hall) would have doors open at night; it'll be pulling air from under the doors from two other heated rooms (the kids' bedrooms) and of course the cold air from under the doors of 'living' zone (which won't be heated at night, assuming a two-zone solution).

Given we keep our bedroom door open at night, wouldn't there be a risk of our room being fairly cool if there's no additional vents in the hall? (and the plan is to have the vent in the hall just near our bedroom). Or could that be managed by following one installer's suggestion of having the return vent just by the entrance way (ie, also near our bedroom door), therefore the air being sucked into that return will all be travelling past our bedroom, negating the lack of a vent? I just don't want to end up with a cold bedroom, despite spending big bucks to avoid this very thing, so want to get this aspect right!

Any thoughts re location of the other vents? I'm tempted - if I indeed don't need a vent in the hall - to put one in the laundy (unlabelled room in the bottom left of the picture). It gets #$@# freezing in there, and while it's not a 'living' space, the ability to warm it would be a nice-to-have and make it less dire to work in there (plus not make it so bad when the rest of the family leave the door between the kitchen and laundry open!).

I've spoken to the installers re location of thermostat; apparently, some (I think it was the Daikin) use an averaging between the temperatures at the location of the controller and of one of the returns, and the installer claimed they'd never had to change this default, but said there's just a systems tweak required if we want it to measure solely off the controller. Speaking of which - should this affect where we have the controller placed? I'm thinking in the kitchen/dining or lounge, and not too near the back door into the laundry (as that would be relatively affected by change in temperature due to cold air coming in when people use the back door.

jonathan18

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#1342141 13-Jul-2015 13:15

timmmay:
jonathan18:
joker97: How many kW will your ducted unit put out

All three installers are looking at units around the 15 kW size; the one we're likely to pick, given its ability to fully control zones and that it comes with built-in wifi access (Daikin FDYQT125L), is cooling 12.5 (EER 3.4) heating 15 (COP 3.96).

Can you target just one room for all of the heat from the heat pump? Say you want the lounge warm right now?

Depends on how the zones are set up. Given there are up to eight vents and up to eight zones, I'm assuming it can be a 1:1, ie each vent can be a different zone. Our plan (unless we're advised of a better one) is to stick with two zones, essentially dividing the house along the hallway. That means we could run just the lounge/kitchen/dining zone (so through 3 x 200mm vents, as per that diagram). That whole space is fairly open-planned (the partial dividing wall is actually a fireplace with gass on one side and woodburner on the other), so there would be no point splitting this space into further zones.

My understanding, from discussions with installers, is that most zoning is an after-market feature, with such systems working independently of the heatpump (essentially they're just controlled dampers that cut the airflow to particular ducts). This means on such 'dumb' systems running only the kitchen/dining/living zone would result in the unit using the same fan speed as if it were heating all zones. As such, the air pressure builds up resulting in additional noise. The solution here is to reduce the fan speed, but that would need to be done separately on the heatpump. Zonal changes couldn't also be done remotely or via timer (or, if they could, it would need to be done on an independent system), so it would be difficult to do what we want to do which is start up the living zone at a different time to the bedroom zone.

My sense is all these problems are fairly effectively managed by that specific Daikin series (which also come with some flash-looking colour screen - see http://www.daikin.co.nz/sites/default/files/2015-Daikin-Ducted-Heat-Pump-Brochure-NZ.pdf). Given the difference between the single-zoned and fancy multi-zoned system is less than $500 [partly as we'd have to pay an additional $674 for the basic model to get the wifi control) it seems a no-brainer. It therefore comes down more to the best way to set up those zones, and the location of the vents.

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#1342142 13-Jul-2015 13:16

Meesham: interesting they double glazed your leadlights. Did they fit into existing suround. If they were using original window frame, are there no issues of added weight on hinges?

re ducted heat pump, i dont get the 3m stud issue. Surely your current ground level heating makes hot air rise to roof and then it falls as it cools with no assistance. In this case, the heat starts at the roof.

bfginger

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#1342321 13-Jul-2015 15:51

I'd sort out the wall insulation and double glazing before installing a ducted heat pimp. Ceiling and underfloor are half of the heat loss but heat will still be streaming through those windows and walls. Many underfloor and older ceiling insulation installations are ineffective too. If you read this forum often you'll know standard NZ windows joinery is poor quality and won't be much of an improvement over old wooden single glazed windows.

An installer will want to install a bigger system than what would be necessary if it was fully insulated. 16kW is big and most 1920s houses are modestly sized.

Some ducted heat pump systems aren't very efficient so look at the coefficient of performance (COP) rating in the model specifications.

timmmay

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#1342445 13-Jul-2015 18:00

Wall insulation didn't make a different I could feel when I had it done. I had that foam stuff put in the walls, which these days isn't considered great.

timtait

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#1342497 13-Jul-2015 18:43

Where in NZ are you? We're in Dunedin in a similar house, early 1930s, 4 br, 2 lounges - ceiling + floor insulation. We looked at the ducted heat pumps but for the size of our house / number of rooms it wasn't so economical. We've been leaning towards a coal or diesel boiler + about 9 radiators over the house.

We're waiting on quotes for the boiler units but running costs wise the coal is pretty cheap, burning kai coal works out around $120 a month over winter, this includes your hot water bill too. Diesel is more expensive but there's next to no maintenance where with coal you have to clean out the ash once a day and muck around with it.

If you're close to Dunedin and want to see a ducted heatpump working there is one installed in the Lockwood show home out Mosgiel. (I think it was Lockwood, can confirm if anyone wants). But this is in a new fully insulated home so may not be the most ideal demo.

timmmay

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#1342518 13-Jul-2015 19:46

Coal or diesel are both dirty fuels, you really want to burn that around your house? Won't that destroy any air quality in the neighbourhood? Check out if there are any upcoming pollution laws, you don't want to buy it then have to junk it. Heat pump and Flick Electric = win.

timtait

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#1342523 13-Jul-2015 19:55

timmmay: Coal or diesel are both dirty fuels, you really want to burn that around your house? Won't that destroy any air quality in the neighbourhood? Check out if there are any upcoming pollution laws, you don't want to buy it then have to junk it. Heat pump and Flick Electric = win.

The boilers you put in these days are pretty efficient, wouldn't be worse than a coal burner inside. I wouldn't mind going electric but the size / layout of our house doesn't really make it economical.

But yeah I do have pollution laws in the back of my mind but I doubt these would change around Dunedin anytime soon though.

dgashby

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#1342561 13-Jul-2015 20:45

We have a similar setup and are pretty happy with it. It has struggled a bit the last couple of mornings when we've had -6 degree frosts and the efficiency has probably suffered as the outside unit spends time defrosting. We have other heating options as well in case of power cuts, but the ducted system is great at getting the entire house warm.

One thing we would change is in our kids bedrooms. Each bedroom has an outlet, but the intake for that end of the house is in a hallway. The problem is if you close their bedroom doors at night the airflow can't circulate from the outlet back to the intake and the rooms quickly overheat. The obvious solution is to leave the doors slightly ajar but kids will sometimes find the tiniest excuse for climbing out of bed, and if you're running the heatpump on a timed cycle then the rooms cool down much faster once the heatpump shuts off if the doors are ajar. Currently we have the heatpump programmed to come on twice for an hour each night. I've got an Arduino with a temperature sensor logging the temperature at cot level in our youngest's bedroom to Xively every 60 seconds and review this every now and then to see if we need to adjust the programme.

jonathan18

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#1342569 13-Jul-2015 21:04

timtait:
timmmay: Coal or diesel are both dirty fuels, you really want to burn that around your house? Won't that destroy any air quality in the neighbourhood? Check out if there are any upcoming pollution laws, you don't want to buy it then have to junk it. Heat pump and Flick Electric = win.

The boilers you put in these days are pretty efficient, wouldn't be worse than a coal burner inside. I wouldn't mind going electric but the size / layout of our house doesn't really make it economical. But yeah I do have pollution laws in the back of my mind but I doubt these would change around Dunedin anytime soon though.

The use of renewable sources to generate most of NZ's electricity was one of the reasons we're going with heatpumps as opposed to gas as a non-renewable that releases CO2. My sister's recently bought a house on Banks Peninsula which has a diesel furnace, but can't say I'd go that way myself.

We are also with Flick for power, so the lower prices we pay over night line up well with our intent to heat the bedrooms at night.

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