Ducted heatpump /Lossnay system, still getting condensation

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33coupe

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#288738 20-Jul-2021 08:54

Hi there,

New build in Christchurch with ducted heatpump and Lossnay system. I thought the Lossnay would eliminate any moisture in the house, but over the cold nights we still get it on one window (our bedroom)
It's being run 24/7 at the highest fan speed.

I've spoken to the installers who said due to the size of the ducting Being bigger it would be best to use the fan only mode on the heatpump.
The only issue with that is that it's a bit noisy on its lowest fan setting, don't think I'd be able to sleep.

Other than the above, or turning on heatpump on heat setting for couple of hours in the morning (not really budget friendly), can anyone suggest any other tips that can help with the moisture?

Thanks

timmmay

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#2746953 20-Jul-2021 09:09

Condensation is caused by warm, moist air inside hitting cold glass. Cold air can hold less moisture than warm air, so the moisture ends up on the windows.

Heating the house makes condensation worse, but you have to have a livable house. You can take the humidity down to 40 - 50%, but there's always going to be moisture in the air.

The next step would be double glazing. The inner glass pane ends up warmer than with a single glazed window, the lower temperature differential results in less condensation. I used the cheap plastic films one year and found they ruined my window frames and I had to repaint. I then did a second pane of plastic which worked well, but looked ugly. I went to proper double glazed PVC windows.

I have a well heated, well ventilated house, with double glazing, ground sheet under the house. Before I did all this my windows were so wet in winter I used a towel on each one. Now we get a light mist on the bedroom windows on maybe the 10 coldest days of the year. About five times a year I use a tea towel to give them a very light wipe.

Not much point having a ducted system if you don't use it. Weekdays ours goes on 3pm and turned off 7am, weekends we leave it on 24/7.

johnmo

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#2746968 20-Jul-2021 09:35

Quite a lot of info below as have not found a lot on internet so thought you may be interested

Have a new installed Mitsubishi Central ducted heatpump system and Lossnay (Feb this year) and in Waikato country with many cold mornings (-3 mornings). House is double glazed and well insulated and definitely well sealed. Work from home, lots of cooking plus dry clothes inside in sunny room. Windows all shut.

Lossnay runs 24x7 on slow speed. No condensation on any windows anywhere. Used to open windows a crack before bed every cold night and still wipe up in the morning. Run extractor fan in range hood while cooking and an hour for one in bathroom after showering in morning.

247sq m house. Two returns and bigger rooms have two outlets.

We have fresh air all the time this way and some rules to turn on heat from 6am to warm house a bit before getting up at 7am and again 7pm to 9pm so warm when relaxing after dinner. Took a while to work all out as well.

Not sure of your setup but we only have one controller for both heatpump and lossnay so we are always running on fan mode 24 x 7 which circulates around house from north facing rooms to south rooms so constant temp through house. Lossnay output of fresh air feeds directly into heatpump which with fan mode circulates all the time so house is now at 52% rel humidity while outside is 95% and a lot cooler :) House exhausts from two ceiling vents via lossnay which we have even partly closed which has saved a little power. Cannot hear the Heatpump fan in any of the rooms of the house even on quite nights (country is real quiet) but in hall under unit and one of the big return grills there is a faint noise. Heatpump and lossnay are bolted together and suspended from roof so not touching ceiling or wall top plates.

Installer recommended big ducts and vents every where plus positioned for maximum flow across all rooms.

Could not be happier.

Used to have a couple of wall mounted heatpumps. On in office and one in main room / kitchen and always had condensation and cold rooms. Power bill went up about $50 a month but changed suppliers and it is now less than before.

Dry warm house all the time and end of summer was also great with cool house.

That's my story.

33coupe

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#2748069 22-Jul-2021 11:18

Thanks for the replies. Yeah it does seem like I will need to either use the heatpump or fan a bit more.

I couldn't find any info online either about the Lossnay, thanks for sharing your experience.
We have a separate control panel for the Lossnay and heatpump, but the Lossnay ducting feeds into the Daikin heatpump.

Our house is 180sqm with 2 returns, and both units just on the trusses etc. Double glazed

I just wish the fan only mode on heatpump wasn't so loud (louder than on heat mode medium level), but can't do much about that.

I turned my heatpump on last night at 6pm to 21 degrees but when I turned it off at 10pm it still hadn't reached temperature. It got to 19 degrees which was ok.
Would that be normal not to get to requested temperature after 3 hours?

I have to set it to 21 due to the kitchen / lounge seem to take a while to be comfortable, I'm guessing due to the 2.7m ceiling.
The bedrooms get warm no problem (2.4)

Thanks

Spyware

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#2748073 22-Jul-2021 11:24

Yes it is normal to not have reached temperature, for that you run your heating 24/7, that is what a thermostat is for. Try it for a week, you'll be shocked by the warmth. Christchurch can be cold during winter with -4 at night and 8 max during day.

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Fred99

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#2748078 22-Jul-2021 11:29

timmmay:

Condensation is caused by warm, moist air inside hitting cold glass. Cold air can hold less moisture than warm air, so the moisture ends up on the windows.

Heating the house makes condensation worse, but you have to have a livable house. You can take the humidity down to 40 - 50%, but there's always going to be moisture in the air.

Only if there's a source for increased and ongoing water evaporation indoors. Heating a house "allows" more water per M3 air, but if moisture sources are adequately controlled, RH will fall with increasing temperature, water that does condense on glass will evaporate more quickly, so it will reduce condensation.

Some things are easy to eliminate (ie with adequate capacity kitchen bathroom exhaust fans) others you're stuck with (ie a lot of people in a small space) and others may be building faults that need to be sorted.

billgates

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#2748094 22-Jul-2021 11:41

We got a separate Lossnay controller installed for no extra cost in our new build last year after the company we used promised and sold us on the fact that the 2 x HVAC Mitsubishi PAR40 controllers can control both ducted Mitsubishi unit and Lossnay. Turned out when we moved in that the Lossnay controls are extremely minimal via PAR40. You cannot switch between manual summer bypass or heating for Lossnay and lowest fan speed I think was 3 our 4? The mode is always auto.

I pushed due to what they promised us and they installed a separate Lossnay controller. We still leave the Lossnay on auto but it means we can turn off main HVAC and the auto has been right 95% of the time setting itself to heat. We get condensation sometimes in our guest toilet and kids bathroom mainly due to not having a big enough gap under the entry doors or both these rooms. Not a biggie. We just leave the doors open tiny bit or I might ask the builder or do it myself by trimming the doors a little bit. Every other room is perfect. Toasty warm and fresh air! The HVAC WiFi module is also very handy. You cannot control Lossnay controller/unit though via Wifi module.

Do whatever you want to do man.

33coupe

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#2750137 26-Jul-2021 19:33

Sorry for the delay, and thanks so much for the replies, great info.

This is my first ducted heatpump (and only used a high wall heatpump a few times), so have no idea if it was working properly or not lol.

I was also a bit surprised that there is no control over the Lossnay, only fan speed, and direction mode, so have this on auto, highest fan mode.
(We thought there would be some control like a hrv, then turn on heatpump when needed extra heat etc.)

I'm wondering if I should be using the fan only mode on the Daikin heatpump during the day, then change to heat at night or whenever too cool.

Does anyone know if the fan only mode would assist with bringing warmth into the house, or just more fresh air from the Lossnay system (eg probs wouldn't use fan only while at home in winter)?

Or am I getting it all wrong? Lol

Sorry and thanks

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timmmay

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#2750146 26-Jul-2021 19:56

Did you ask your installer? I don't know anything about Lossnay in practice.

If you want fresh air in the house during the day then fan mode sounds like it might work, but not sure if the Lossnay has its own fan. With my ducted system I have a completely separate positive pressure system, I just turn that on at the same time as the ducted system on fan. Seems to work, not as well as the Lossnay of course but it's ok.

33coupe

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#2793236 11-Oct-2021 13:40

Sorry I've just realised I didn't reply to this.

I have spoke to the installer who will come around to fix the temperature imbalance, and discuss the fan options.

I'll let you know when I hear back. Thank you