Random defrosting? Without ice?

[Xringer]

Today's Extremes
High Temperature 16.4°F__12:40pm
Low Temperature 7.4°F__7:21am




At 8:30 this morning, we noticed both Sanyos were doing Defrost cycles.
(The Living-room was first with the Den cycling 10 minutes later).
There was no ice seen. The dew-point was way too low for icing.

The cycling stopped within a few minutes, and the units went back to normal heating.
The room temperature never changed. 21C with 22C overshoots.
(Setpoint was pushed from 20 to 21C at 7AM)

It was odd, never seen this occur before.

I'm wondering if the temperature increase after 7:21AM, somehow tricked the Sanyos into thinking they had frost?

[Xringer]

I guess my theory about rising temperature causing false frost was wrong.

We just got another Defrost cycle in the Den, at 18:15 this evening, as the outdoors temp was dropping..



Currently, 9.3°F and starting to get chilly. The forecast is for 0.0°F at 6AM.

This sure looks like we will be using some backup heat tonight!

This evening, I did notice the Den had dropped down to 20C while the defrost
was cycling. Maybe it cycled a few times, don't know.
On the ramp back up, the output vent was 102 F.

[Mikesolar]

Which output vent?

[Xringer]

The heat output vent on the bottom of the indoor unit (HX).

It got down to 1 deg F this morning and the Den Sanyo was still putting out a lot of warm air.
But the living room Sanyo had too many sq ft to heat and it went over 10A and reset about 5AM.
After it restarted, I checked the output and it stayed around 70 to 80F. (Den was doing 98F).

Dropped to 19C in the living room during the 10A reset, so I turned on a 900W (3000 BTUh) space heater.
That seemed to work with the LR Sanyo and the main areas stayed at 20C all night.



WOBURN WEATHER CENTER - WU Station History

The Den is small (18x16) http://i46.photobucket.com/albums/f1.../9784_9784.jpg
but has a window and wide French doors into the main house.
So, the heat from the Den flows into the rest of the house.
Still, I was pleased to see the DIY repaired unit pouring out nice heat when it was between 1 & 9 deg F outside..

[warmwxrules]

At what temp will it stop working? At 1F how efficient is it (watts in to watts out?)... Pretty cool it is still pulling that much heat from such cold air.

I had -4F here this morning, my 95% efficient nat gas furnace was running a lot last night. Coldest we've seen so far is -10F and a total of 5 nights have been below 0F (we avg 26!)... One issue here is lack of snow cover, which drops temps an avg of 12F or so... so typically the temps would be a lot lower here.

[Xringer]

-4F ?? I don't think these would run at all. The spec ends at Zero..
http://i46.photobucket.com/albums/f1...CL/heatcap.jpg

When it was 1F, the unit in the Den was working great. Since both units run about the same when it's around 15F,
it's got to be the smaller area of the Den, that's allowing that unit to really crank out the heat.

I have no accurate way of knowing how well the units are working at 1F.
When I see 3kW on the meter, I know they are using around 1.5kW each.
That's when I can just hold my hands out and feel the warm air, and feel how they are working.
If it feels really nice at 1.5 kW, I know it's working somewhat normally.

A 1500w space heater will give me 5,000 BTUh. So, I have a good idea
what 5k BTUh 'feels' like on a cold morning.
The Den Sanyo felt like I had 2 or 3 space heaters running.

The living room Sanyo, felt like was putting out a little bit more than a 1.5kW 5000 BTUh space heater.. Not real good.

[poleikleng]

Xringer,

At zero degrees F the air handler air temperture was 108F. Very happy with the way the heat pumps operated Wednesday and Thursday. We did not have to use any supplemental heating.

Poleikleng

[Xringer]

Yeah, I think most of the Inverter models that will run okay at 10F, are going to be fine down to Zero..
But once it gets colder? Not so sure.. I'm keeping my little 1200w space heaters, just in case!

[warmwxrules]

That is good to know. Even around here a heat pump could be used a lot during winter.

[Xringer]

Originally Posted by warmwxrules

That is good to know. Even around here a heat pump could be used a lot during winter.

Your average temperatures aren't crazy off the scale.. Compared to Woburn MA.


If your average temp is above 10 deg F during the cold months,
a good Inverter Mini-Split will be able to pump in a lot of heat.

If you were burning oil or other costly fuels, it might be a good way
to greatly assist your heating system during the warmer parts of the day.

Wow, the daily low around here is about the same as your daily average in January.?.