Mini Split heat pumps

luvrbus · November 21, 2015, 05:33:29 AM

I am posting for a friend that has 2 -9000 btu splits ? is how often are they supposed to recycle or purge I guess you could call it.

They are in Idaho City and freezing their @$# off it got down to 10 degrees last night and is in the 20's now and the heat pumps are not doing the job they are recycling more and more as the temp drops.

He is a little upset told me he was better off with the heat strips in roof airs any of the mini split people have a answer for him will a low or high Freon charge cause that ?

chessie4905 · November 21, 2015, 06:02:38 AM

http://www.energyvanguard.com/blog-building-science-HERS-BPI/bid/36683/Finding-Balance-Heat-Pump-Heating-Load-vs-Capacity

I wouldnt expect a heat pump to work well at those temps in an rv. Too much heat loss with a low output temp from the heat coils, probably 55 to 60 degrees at that temp after some degrees of loss from ducts or housings. He would be better off with a few electric heaters in those situations. Jmo

Darkspeed · November 21, 2015, 06:08:18 AM

The cheaper mini splits will not have a an effective heat absorption cycle below 30ish.

The good brands will get you heat down lower , for example the Fuijtsu's will go down to -5F, but I consider anything below 20-10F a need for supplementary heat.

What brand? What humidity level? Exchangers frozen over?

luvrbus · November 21, 2015, 06:34:27 AM

Quote from: Darkspeed on November 21, 2015, 06:08:18 AM
The cheaper mini splits will not have a an effective heat absorption cycle below 30ish.

The good brands will get you heat down lower , for example the Fuijtsu's will go down to -5F, but I consider anything below 20-10F a need for supplementary heat.

What brand? What humidity level? Exchangers frozen over?

Fuijtsus, humidity around 15% and they are new,he solved the problem he didn't remove the rv furance but did the mounted tank so it cost him 100 bucks for propane tanks and fuel, they are warm now she told me and are headed south Monday

Oonrahnjay · November 21, 2015, 07:28:00 AM

Quote from: chessie4905 on November 21, 2015, 06:02:38 AM... I wouldnt expect a heat pump to work well at those temps in an rv. ...

I was in Norway back in the summer and noticed that many homes and businesses had mini-splits. Those units usually had a special name plate on them -- like "Fujitsu/Arctic" or "Panasonic/Polar". I had never seen any nameplates like this on N American heat pumps. I'm guessing they're talking about $$$-sucking (or Kroner sucking) electric strips but obviously they've seen a need and fixed it.

Darkspeed · November 21, 2015, 07:38:12 AM

If they were Fuijtsu's and the were installed with the correct ventilation around them they must be undercharged or defective in some way.

If they dont have enough ventilation = no heat at low temps.

pvcces · November 22, 2015, 06:35:29 PM

Hi, folks.

Those Fujitsus have a BTU rating, and if they use R410A, then they ought to go down into single digits. However, if the BTU rating totals 18000, they will only provide about 2 1/2 portable electric heaters worth at that temperature. As they found out, that isn't enough heat.

The builder made a good choice in leaving the propane furnace in place. I'll bet that they were glad to warm up.

People buy these units for their high efficiency thinking that they are getting more heat, but they are buying less electricity. For cold weather, they need more heat.

One other thing is that sometimes the output air can circle around and come inside as input air. If that happens, you get frequent defrost cycles, which the friend is complaining about.

At outside temperature of 32F, those Fujitsus should have no trouble keeping up, IMO.

For what it's worth.

Tom Caffrey

bobwoo · November 23, 2015, 01:58:51 AM

We can't fool Mother Nature or beat the Laws of Thermodynamics no matter how we try

robertglines1 · November 23, 2015, 02:39:43 AM

have the Invert-er type mini split in bus and home. They work fine down in single digits . first installed in 2012. We live in SW Indiana and temp run from slightly below zero to occasional 100 plus. was careful to not recycle condenser air. Bob

luvrbus · November 23, 2015, 02:52:42 AM

I spoke with him a few minutes ago it's 24 degrees in Idaho City they work ok down to around 30 degrees @ 24 degrees they are blowing 52 degrees air and cycling the old rv propane is blowing 105 degrees he is headed south today.He too thinks 18,000 btu is not enough,he said don't expect any help from Fijistu their customer service is worthless

TomC · November 23, 2015, 03:11:48 AM

I have three roof airs all with heat strips that will get the interior like a sauna. Also 40,000btu propane furnace. Along with the engine run original heater, could be in a blizzard and be fine. Like having three roof air conditioners, you can't have enough heat. We sometimes just fire up the stove top burners to take the chill out. Good Luck, TomC

luvrbus · November 23, 2015, 03:18:04 AM

You run the heat strip in roof tops on low fan they do a good job it is equal to cube heaters in BTU's but they will use some power and are useless on hi fan BTDT I am keeping my @$# in AZ in the winter

digesterman · November 23, 2015, 03:45:30 AM

I like my hot water heat, either on diesel or electric always nice and cozy

wg4t50 · November 23, 2015, 03:50:02 AM

No sperience with heat pumps, but the Aqua Hot 600 series does the toasty thing. Not cheap but sure is comfy. I set thermostat ar 72 and smile. With bthe LP gas & electric base board heat, that worked too, not as comfy but sure did work.
DaveM

luvrbus · November 23, 2015, 04:00:55 AM

Quote from: wg4t50 on November 23, 2015, 03:50:02 AM
No sperience with heat pumps, but the Aqua Hot 600 series does the toasty thing. Not cheap but sure is comfy. I set thermostat ar 72 and smile. With bthe LP gas & electric base board heat, that worked too, not as comfy but sure did work.
DaveM

Aqua Hots are nice Dave but most people don't want to spend 10 grand + on a heating system in a $10,000 bus