Sprinter-Forum    
 

Go Back   Sprinter-Forum > Sprinter-Based RV's & Conversions > Sprinter-Based RV Brands > Winnebago / Itasca

Winnebago / Itasca Itasca Navion, Winnebago View.


 
Thread Tools Display Modes
Old 09-14-2019, 01:50 PM   #31
billbo
 
Join Date: Feb 2010
Location: NW Georgia
Posts: 143
Thanks: 11
Thanked 51 Times in 39 Posts
Default Re: Air Conditioner with Heat Pump

The simple answer. Heating air increases it's capacity to hold water vapor which lowers the relative humidity. Relative humidity is simply the ratio of the current amount of water in the air at a given temperature relative to the maximum amount of water in the air at that same temperature. Then you can get into saturation vapor pressure which increases as temperature rises and on an on about pressure inside the house, outside the house, equalization of saturation vapor pressure and what the heck?

Bottom line, heat pumps decrease humidity in heat mode by a combination of effects. Those of us who are impacted use reliable measurements to keep humidity around 50%.
__________________
Bill and Brenda
Traveling with Mobius the Big Dog
2018 View 24D
billbo is offline   Reply With Quote
Old 09-14-2019, 03:18 PM   #32
TJLee089
2013 Itasca Reyo 25R
 
Join Date: May 2012
Location: Lehigh Valley, PA
Posts: 1,385
Thanks: 307
Thanked 679 Times in 466 Posts
Default Re: Air Conditioner with Heat Pump

Once again you are 100% wrong. Warming the air with a heat pump reduces relative humidity because warmer air can hold more moisture. It does not remove ANY moisture. It does nothing to absolute humidity, which is the actual moisture content of the air. Heat pumps in AC mode actually remove moisture from the air.

Life is too short to continue this discussion. Talk to the folks that service your home heat pump and LP systems. They will enlighten you.

To Summarize:
1. Heat pumps in heating mode (that simply recirculate inside air) and vented combustion heating sources (oil, gas) that pull the combustion air from the outside (RV LP furnaces) neither add nor remove moisture from the heated space.

2. Unvented combustion sources, such as gas stoves, gas fireplace logs, and freestanding kerosene heaters add moisture to the heated space.

3. The air in heated spaces becomes dry because of the exchange of cooler, drier outside air with warmer, wetter inside air by such things as vented bathroom fans, clothes dryers, and stove hoods; by opening doors and windows, AND vented combustion sources (oil, gas) that pull the combustion air from the heated space (inside) and vent the combustion gases to the outside.

I will stack my credentials against yours: B.S., M.S. Chemical Engineering. 30 years as a licensed professional engineer.


Quote:
Originally Posted by billbo View Post
OK, absolutely ludicrous response. Of course the air circulation is removing the moisture. But then, I am only a patient who has studied this for the past 47 years or so, with professional help from physicians and from HVAC folks.

Given the fact that I also have extensive knowledge of HVAC and one son who has done it most of his working life - I don't need any further education from you.

I also decline to an ongoing running argument/debate. My complete statements are 100% correct. Everyone I know has a humidifier installed on their heat pump in the home. Yes. It is necessary to protect health, home and contents.

Just for grins I remember when we purchased our second Tiffin DP while speaking to Bob Tiffin we were discussing travel to some of the Western states. He stated to always run a humidifier while in those arid areas to prevent the wood inside the RV from being damaged. Me? Heck, I'm more concerned about my health.

The average healthy male gives off about 200 milliliters of water during an 8 hour sleep period, breathing. Yes, that is true and two people and a dog will definitely produce moisture on the windows in some conditions, temperature drop at night outside etc. You can actually call those functional bodies humidifiers. Normally opening a vent and allowing the air exchange will prevent the moisture accumulation.

As far as debating the technical reasons for a heat pump lowering the humidity in a home lets just admit it happens, which it does. I completely understand the technical functions of a heat pump and using one will lower the humidity in the home - enough said, whether you want to admit that or not does not matter it is just a known fact. It is not removing humidity the same way the unit does in cooling but it is drying the air to desert levels. It is certainly the exchange of air and air movement.

As far as using an unvented LP heater inside the coach - some are actually doing that but unless they got buried they opened a window. The debate is over.
__________________
2013 Itasca Reyo 25R

Last edited by TJLee089; 09-14-2019 at 03:32 PM. Reason: edit
TJLee089 is offline   Reply With Quote
Old 09-14-2019, 06:30 PM   #33
NYBobbo
 
Join Date: Nov 2015
Location: NY
Posts: 292
Thanks: 66
Thanked 118 Times in 98 Posts
Default Re: Air Conditioner with Heat Pump

My 2 cents:

Heat pumps are used when temps are warmer (above 40), the warm air circulates making the entire rig more evenly heated then a cube heater. I believe, due to lower temp differentials when using HP (inside/outside ...perhaps a dew point issue) and air movement helps reduce condensation.

When much colder outside the furnace is needed - the output from the furnace is more localized and not circulated evenly around the rig, with the increased temp differentials and lack of even air flow I've noticed condensation on the windows to increase - usually when the propane heater is used.

I could be wrong, I may be wrong but I stand by my observations and subsequent thunkin on the subject.
NYBobbo is offline   Reply With Quote
Old 09-14-2019, 08:40 PM   #34
Hosh
Navion 2018 24J
 
Join Date: Jun 2017
Location: Denver
Posts: 272
Thanks: 31
Thanked 88 Times in 68 Posts
Default Re: Air Conditioner with Heat Pump

Well this thread is pretty lively. Anybody want to discuss the virtues of composting toilets, compressor fridges, bio diesel?
Hosh is offline   Reply With Quote
Old 09-14-2019, 09:26 PM   #35
TJLee089
2013 Itasca Reyo 25R
 
Join Date: May 2012
Location: Lehigh Valley, PA
Posts: 1,385
Thanks: 307
Thanked 679 Times in 466 Posts
Default Re: Air Conditioner with Heat Pump

IMHO, thumbs down on all three.

Quote:
Originally Posted by Hosh View Post
Well this thread is pretty lively. Anybody want to discuss the virtues of composting toilets, compressor fridges, bio diesel?
__________________
2013 Itasca Reyo 25R
TJLee089 is offline   Reply With Quote
Old 09-14-2019, 10:21 PM   #36
rollerbearing
 
Join Date: Jan 2015
Posts: 1,775
Thanks: 590
Thanked 914 Times in 632 Posts
Default Re: Air Conditioner with Heat Pump

Quote:
Originally Posted by Hosh View Post
Well this thread is pretty lively. Anybody want to discuss the virtues of composting toilets, compressor fridges, bio diesel?
Quote:
Originally Posted by TJLee089 View Post
IMHO, thumbs down on all three.
Ok - we get it. You two have by choice, or inability, decided to keep your rigs more or less stock. Fine. You've also expressed your opinions regarding other's mods. Fine & great.

I agree with Winterbagoal:

Quote:
Originally Posted by Winterbagoal View Post
Sometimes it's expeditious to cut to the chase, and make your point. Then move on.
Of course, you'll be accused, by some, of being "uncivilized" if you choose this route.
The key point is to "move on". Continuing to taunt, one up, beat a dead horse, etc. shuts down the discussion that others may be interested in. So ......time to contribute or move on.
rollerbearing is offline   Reply With Quote
Old 09-14-2019, 10:38 PM   #37
TJLee089
2013 Itasca Reyo 25R
 
Join Date: May 2012
Location: Lehigh Valley, PA
Posts: 1,385
Thanks: 307
Thanked 679 Times in 466 Posts
Default Re: Air Conditioner with Heat Pump

My last response to billbo included "Life is too short to continue this discussion." No one was shut out or shut down.

My rig is what it is by choice, not inablity.

Quote:
Originally Posted by rollerbearing View Post
Ok - we get it. You two have by choice, or inability, decided to keep your rigs more or less stock. Fine. You've also expressed your opinions regarding other's mods. Fine & great.

I agree with Winterbagoal:



The key point is to "move on". Continuing to taunt, one up, beat a dead horse, etc. shuts down the discussion that others may be interested in. So ......time to contribute or move on.
__________________
2013 Itasca Reyo 25R
TJLee089 is offline   Reply With Quote
Old 09-16-2019, 01:20 PM   #38
billbo
 
Join Date: Feb 2010
Location: NW Georgia
Posts: 143
Thanks: 11
Thanked 51 Times in 39 Posts
Default Re: Air Conditioner with Heat Pump

What's really, really funny is the last two posts in our running discussion - Lee and myself. We said almost exactly the same thing yet I am again - 100% wrong. I said heated air holds more moisture per cubic volume which in effect reduces the relative humidity of the same cubic volume and yes, does nothing to reduce absolute humidity. So, we do agree. People and furniture do not benefit from absolute humidity - only relative humidity. The hotter you get the same cubic volume of air the more moisture it takes from that same cubic volume (it holds it). Air movement, air exchange all play a part as well.

Let's say credentials. Electrical Engineer, MS Physics, ya, da, da, Oh yeah, from MIT. One son is certified HVAC for many long years, the other is PhD Math from Auburn. OK, enough credential bashing.

We said the same thing and I'm 100% wrong? Nope, using the heat pump requires moisture to be added back into the air to increase RH for comfort and health.

I'm just as hard headed and anyone and once I even thought I was wrong - I was because I thought it so.
__________________
Bill and Brenda
Traveling with Mobius the Big Dog
2018 View 24D

Last edited by billbo; 09-16-2019 at 01:24 PM.
billbo is offline   Reply With Quote
Old 09-16-2019, 01:30 PM   #39
TJLee089
2013 Itasca Reyo 25R
 
Join Date: May 2012
Location: Lehigh Valley, PA
Posts: 1,385
Thanks: 307
Thanked 679 Times in 466 Posts
Default Re: Air Conditioner with Heat Pump

You stated that heat pumps in heating mode remove moisture. They do not.

My discussion was with you, not your sons.
__________________
2013 Itasca Reyo 25R

Last edited by TJLee089; 09-16-2019 at 01:31 PM. Reason: edit
TJLee089 is offline   Reply With Quote
Old 09-16-2019, 08:30 PM   #40
billbo
 
Join Date: Feb 2010
Location: NW Georgia
Posts: 143
Thanks: 11
Thanked 51 Times in 39 Posts
Default Re: Air Conditioner with Heat Pump

Yes, I stand by that statement and explained exactly how it happens. My discussion is no longer with you until H%$$ freezes. Goodbye, oh, you dumped the "diplomas" etc., I was just playing with you. I suppose you didn't approve of my credentials? Have a good life. But ...I doubt it.
__________________
Bill and Brenda
Traveling with Mobius the Big Dog
2018 View 24D
billbo is offline   Reply With Quote

Tags
air conditioner

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

Forum Jump



All times are GMT. The time now is 07:28 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2019, vBulletin Solutions, Inc.