Reply
 
Thread Tools Display Modes
 
Old 11-26-2013, 03:43 PM   #1
Guru
 
River Cruiser's Avatar
 
City: UMR MM283
Country: US
Vessel Name: Northern Lights II
Vessel Model: Bayliner 3870
Join Date: Jan 2013
Posts: 1,226
Winter & heat

I was interested in the water temp here in the harbor so I dug out my temp gun & found it to be 38f. Then I decided to check the output of my reverse cycle units because I've read they aren't efficient below about 40f water temp. I thought this was pretty good, better than I expected.

Click image for larger version

Name:	image-2191846152.jpg
Views:	106
Size:	57.9 KB
ID:	25064
__________________
Advertisement

__________________
Ron on Northern Lights II
I don't like making plans for the day because the word "premeditated" gets thrown around in the courtroom.
River Cruiser is offline   Reply With Quote
Old 11-26-2013, 03:53 PM   #2
Guru
 
djmarchand's Avatar
 
City: East Greenwich, RI
Country: USA
Vessel Name: Bella
Vessel Model: Mainship Pilot 34
Join Date: Aug 2012
Posts: 2,878
Check your IR gun against a known thermometer at the 38 deg temps. My Fluke IR gun is off about 10 degrees at those temps, but right on at 75 deg F.

And unless the return air was 80 or more, I would suspect the 104 deg reading as well. Heat pumps rarely have more than a 20 deg temperature rise particularly at low outside air temps.

And finally, not to be a smart&*%, it is not the efficiency that drops off. My home heat pump works down to about 15 degrees outside air temperature. But the seawater will freeze in the condenser of a marine unit at much below 40 degrees. That is why Dometic and other marine heat pumps have a sensor that cuts off at that temp.

David
__________________

djmarchand is offline   Reply With Quote
Old 11-26-2013, 05:53 PM   #3
Senior Member
 
magicbus's Avatar
 
Join Date: Nov 2010
Posts: 460
So my heat pumps are gonna shut down when the temps hit under 40? That happens I'm in big trouble in December when we finally head south. I'm not going to tell my wife...

Dave
__________________
Barnegat Light NJ or Nantucket MA
magicbus is offline   Reply With Quote
Old 11-26-2013, 10:02 PM   #4
Guru
 
boatpoker's Avatar
 
City: Port Credit
Country: Ontario
Vessel Name: DIRT FREE
Vessel Model: Benford Fantail 38
Join Date: Sep 2012
Posts: 2,011
Re-read the manual for your gun. I think you'll find that they warn against aiming it at a reflective surface as that can make it wildly inaccurate.
boatpoker is offline   Reply With Quote
Old 11-26-2013, 10:45 PM   #5
Guru
 
City: Carefree, Arizona
Country: usa
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 6,363
My reverse cycle units worked while we were anchored in front of Reid Glacier in Glacier Bay Alaska. Water temp around 39 - 40. With heat strips they work at temps below that I'm told.
sunchaser is offline   Reply With Quote
Old 11-26-2013, 11:29 PM   #6
Guru
 
River Cruiser's Avatar
 
City: UMR MM283
Country: US
Vessel Name: Northern Lights II
Vessel Model: Bayliner 3870
Join Date: Jan 2013
Posts: 1,226
I know last Saturday it was 12f with a stiff north breeze and it was 67f on the boat & today the temp in the bilge was 41f, water checked at 38f. Last weekend the water temp was 44f at St. Louis so 38f here today isn't that far off seeing as how we're about 70 miles upriver. The air coming out of the grill is nice & warm on my 98.6f hand;-)
__________________
Ron on Northern Lights II
I don't like making plans for the day because the word "premeditated" gets thrown around in the courtroom.
River Cruiser is offline   Reply With Quote
Old 11-27-2013, 06:11 AM   #7
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,524
>With heat strips they work at temps below that I'm told.<

Heat strips are what is in a toaster or any portable heater.

As long as the electric doesnt blow a portable heater (or 5 ) works fine, and there are no losses heating ductwork.

Reverse cycle stops working in air source models when the unit ices up.

Water cooled , the same , the heat exchanger ices.

The new Mini splits work down to real cold and are all over northern Europe.

But none are made for boats yet , sad as they are 400% to 500% more efficient than the toaster wire .
FF is offline   Reply With Quote
Old 11-27-2013, 06:35 PM   #8
Guru
 
River Cruiser's Avatar
 
City: UMR MM283
Country: US
Vessel Name: Northern Lights II
Vessel Model: Bayliner 3870
Join Date: Jan 2013
Posts: 1,226
Had some skim ice in part of the harbor this morning. Back home in Kansas now & the lake behind the house had some ice in the cove.

Click image for larger version

Name:	image-2838344292.jpg
Views:	56
Size:	75.4 KB
ID:	25082
__________________

__________________
Ron on Northern Lights II
I don't like making plans for the day because the word "premeditated" gets thrown around in the courtroom.
River Cruiser is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 07:45 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012