AC installation (hidden) - Page 5 - Fiberglass RV


Reply
 
Thread Tools Search this Thread Display Modes
 
Old 07-21-2015, 07:07 PM   #57
Member
 
GaryG's Avatar
 
Name: Gary
Trailer: 89 13' Scamp
California
Posts: 47
More pics

This is box, not as nice as yours,but, functional, I hope
Attached Thumbnails
image.jpg  
__________________

__________________
GaryG is offline   Reply With Quote
Old 07-21-2015, 07:09 PM   #58
Member
 
GaryG's Avatar
 
Name: Gary
Trailer: 89 13' Scamp
California
Posts: 47
Cubby hole

Cubby hole
Attached Thumbnails
image.jpg  
__________________

__________________
GaryG is offline   Reply With Quote
Old 07-21-2015, 07:11 PM   #59
Member
 
GaryG's Avatar
 
Name: Gary
Trailer: 89 13' Scamp
California
Posts: 47
Pics

Cubby hole with box
Attached Thumbnails
image.jpg  
__________________
GaryG is offline   Reply With Quote
Old 07-21-2015, 07:16 PM   #60
Member
 
GaryG's Avatar
 
Name: Gary
Trailer: 89 13' Scamp
California
Posts: 47
Darral & Eric hope this helps.
__________________
GaryG is offline   Reply With Quote
Old 07-21-2015, 07:54 PM   #61
Senior Member
 
Name: Eric
Trailer: Scamp 13
Michigan
Posts: 255
Gary, It looks like some nice work.

I am probably pointing out the obvious, but here it goes. The key thing is air flow and it has to go from the outside, through the AC, and then out. First, I assume there is a dryer vent type hose from the fan on the box to the exhaust vent, correct? (I think I see it.) Second, how far does the AC sit in the box (hopefully only an inch or two)? Third, did you seal from the box to the AC (duct tape or...)? We don't want air sneaking around the AC. We want air to go through the AC by the compressor. Fourth, did you seal around the fiberglass cabinet to the front of the AC (so all your cool air in the living space doesn't become exhaust making the AC work harder)?

After seeing the pictures, if all the questions above are "Yes", my best guess is still lack of air flow and the difference in the 3" vs. 4" holes/fans. Consider going with 2 3" holes for exhaust and 2 3" holes for intake (since you have some 3" holes already).

Good luck. Maybe Darral will see something or have more ideas.

Eric

PS What did you use to cover up the holes in the fiberglass where the hinges were? Looks nicer than my "fill it in and try and hide it" job.
__________________
ericw is offline   Reply With Quote
Old 07-21-2015, 09:33 PM   #62
Member
 
GaryG's Avatar
 
Name: Gary
Trailer: 89 13' Scamp
California
Posts: 47
1 more picture

Ac installed, b4 I had to tear it out, and b4 I covered screw holes. Eric, I used stick on screw covers from home depot.
Attached Thumbnails
image.jpg  
__________________
GaryG is offline   Reply With Quote
Old 07-21-2015, 09:37 PM   #63
Member
 
GaryG's Avatar
 
Name: Gary
Trailer: 89 13' Scamp
California
Posts: 47
Eric, The answer is yes to all ?'s. Trying to figure out how to split exhaust to 2 3 inch holes, or how to make a 3 inch hole 4 inches. The intake is no problem, I can just drill another 3 incher.
__________________
GaryG is offline   Reply With Quote
Old 07-22-2015, 07:03 AM   #64
Senior Member
 
Name: Eric
Trailer: Scamp 13
Michigan
Posts: 255
Gary, I am not sure there is a "right" answer to that. I agree on the intake side that it is easiest to just drill another 3" hole.

You could go with a 4" fan to another box that covers the two 3" exhaust holes. Or you could do 2 3" fans to 2 3" exhaust holes. Or you could just do a 4" fan to a 4" exhaust. Depending on how hard it is for you to make the 3" into a 4" hole, I was leaning towards a 4" fan with a 4" hole on the exhaust.

Let us know what you decide.
__________________
ericw is offline   Reply With Quote
Old 07-22-2015, 11:54 AM   #65
Senior Member
 
Name: Darral
Trailer: Scamp Standard 13' 2010
Tennessee
Posts: 1,443
Is the fan blowing in or out?

If it's blowing out, it's backwards, if it's blowing in, then I would suggestion experimenting with an EXHAUST fan that matches your intake fan. I personally do NOT believe that the intake fan is pushing enough air through to clear the entire unit of the hot air. Just a thought.

If you'll notice your setup, the opposite of the a/c where the louvers are is a "dead" area. Remember, those louvers are sucking in air and blowing it out the back. You fan is only pushing from one side of the A/C...another thought.
__________________
Darral T. is offline   Reply With Quote
Old 07-22-2015, 07:55 PM   #66
Senior Member
 
Name: Eric
Trailer: Scamp 13
Michigan
Posts: 255
Quote:
Originally Posted by Darral T. View Post
Is the fan blowing in or out?

If it's blowing out, it's backwards, if it's blowing in, then I would suggestion experimenting with an EXHAUST fan that matches your intake fan. I personally do NOT believe that the intake fan is pushing enough air through to clear the entire unit of the hot air. Just a thought.

If you'll notice your setup, the opposite of the a/c where the louvers are is a "dead" area. Remember, those louvers are sucking in air and blowing it out the back. You fan is only pushing from one side of the A/C...another thought.
Darral, I think I am missing something (or maybe we found the issue???) or I am just confused about which fan you are referring to since he has two.

I think the fan on the left of the cabinet in the 3" hole is the intake fan and should blow outside air into the whole cabinet. I think the fan mounted to the box behind the AC should take the hot air out of the back of the AC and blow it through a short dryer hose to outside the trailer.

I think the fans (3" blower and intake fan) are roughly matched according to the numbers (which I agree with Darral is necessary).

If my statements are wrong or don't correspond to reality in the trailer, speak up because it may be the issue we are having.

Lets keep discussing so we can eventually get to a solution for Gary. The more thoughts we share the better I think.
__________________
ericw is offline   Reply With Quote
Old 07-22-2015, 10:04 PM   #67
Member
 
GaryG's Avatar
 
Name: Gary
Trailer: 89 13' Scamp
California
Posts: 47
Eric, you're right. The exhaust is on the right,looking at the cabinet, and the intake is on the left. As far as the cfm match I can only say this. The intake fan is a Sunon mag lev 90 mm fan, which they say puts out 60-78 cfm. The 3 inch attwood blower is around 120-130 max.. I do do have a motor controller on yhe exhaust fan and have tried various speeds. All with the same results. So I guess I matched them at one time or another. Maybe you and Darral have already mentioned this, but, I had a thought. Could it be that the exhaust blower can't keep up with the ac's internal exhaust fan and the hot air is backing up into the unit. If so, I guess I'm going to have to go with 4 inch.
I also entertained the thought of drilling another intake hole on the exhaust side of the cabinet. But I' concerned the hot air from the exhaust would get sucked back into the trailer. Eric, don't know why yors works witout an intake fan. Maybe 4 inches is the magic number. I really appreciate yours and Darrals help! We'll get it going, I'm sure.
__________________
GaryG is offline   Reply With Quote
Old 07-23-2015, 07:33 AM   #68
Senior Member
 
Name: Eric
Trailer: Scamp 13
Michigan
Posts: 255
Quote:
Originally Posted by GaryG View Post
Eric, you're right. The exhaust is on the right,looking at the cabinet, and the intake is on the left. As far as the cfm match I can only say this. The intake fan is a Sunon mag lev 90 mm fan, which they say puts out 60-78 cfm. The 3 inch attwood blower is around 120-130 max.. I do do have a motor controller on yhe exhaust fan and have tried various speeds. All with the same results. So I guess I matched them at one time or another. Maybe you and Darral have already mentioned this, but, I had a thought. Could it be that the exhaust blower can't keep up with the ac's internal exhaust fan and the hot air is backing up into the unit. If so, I guess I'm going to have to go with 4 inch.
I also entertained the thought of drilling another intake hole on the exhaust side of the cabinet. But I' concerned the hot air from the exhaust would get sucked back into the trailer. Eric, don't know why yors works witout an intake fan. Maybe 4 inches is the magic number. I really appreciate yours and Darrals help! We'll get it going, I'm sure.

Gary, for comparison, the 4" has 75% more area than the 3" and is 235 cfm which is a lot more air.

I agree you don't want the intake and exhaust on the same side. You don't want to recirculate the air. You want cool/normal outside air coming in and not the hot exhaust air. I put them on opposite sides for the same reason you did.

It can work either with just an exhaust fan or with both an intake and exhaust fan. With just an exhaust fan, you shove the air out and count on the air coming from "somewhere" to replace it. Of course I left a 4" hole on the left to be that "somewhere", but since the air also comes from other places such as around the edges of the fiberglass cabinet if I don't seal that off well (which is bad because that is the cool interior of the trailer). The advantage of this system is that all your fan power goes to shoving air out and you get more air flow for the fan power you have (and associated noise). This method is not unlike what we do in our house with an attic fan. The attic fun shoves hot air out of the house and we open a couple of windows on the opposite side of the house to let cool air in. We don't have fans at the windows and attic, just the attic, and it works just fine.

The other option is closer to what you did with fans on intake and exhaust. The advantage to this method is the sealing around the fiberglass cabinet is less critical (but still worthwhile). Theoretically, if you had the fans sized perfectly (which is not the same cfm rated fan), you wouldn't have to seal around the cabinet at all, but of course you never get it perfect. The disadvantage of this method is more fans, power, and noise.

As we have been saying, my best guess is still that you have a fundamental lack of air flow on both intake and exhaust. I think you need dual 3" or a 4" fan/holes. That may be due to the 3" not keeping up with the AC's fan or that in normal window use, most air goes out the back, some air goes up, and some goes sideways. The goal is to get the heat out and presently I don't think we are shoving enough air through to get that heat out.

If I was to do it again I would spend more time on the fan design/choices. I have considered using dual 3" or 4" fans on the intake/exhaust (4 total) where each fan is has to move less air and hence can be quieter than what I have now. But I have never done a detailed design.

Good luck. We will get there. Many people have been helpful to me on this forum and I hope that sometimes I can be helpful to others as well.
__________________
ericw is offline   Reply With Quote
Old 07-23-2015, 08:50 AM   #69
Senior Member
 
Name: Darral
Trailer: Scamp Standard 13' 2010
Tennessee
Posts: 1,443
I've gone back and reread alot of this thread Eric/Gary. IF I'm seeing right, Eric, arent you using CONSIDERABLY more CFM's than Gary???? I understand yall's setup better now....intake fan/exhaust fan for Gary but just an exhaust fan for Eric. But I think I just read where Gary had mentions 60-78 cfms (I thought 35 earlier). Those A/Cs are putting out some MASSIVE hot air. No, you cant feel it as much in a 12" x 14" rear area like you would if it concentrated down to 3"!!

I was kinda curious as to WHY you would need two fans IF the one is strong enough. I would have already upped my CFM's to try and remove the hot air.

I would also be putting a remote thermostat sensor in that bay and see what the temp was BEFORE I made changes. That way, as you experiment, you will (HAVE TO eventually) see the temp start dropping. What would REALLY be interesting, if Eric knew (given the same ambient or outside temps) what his temp was running in the housing or A/C bay; then what Carl's is running. Fellows, the "proof is in the pudding".

Good luck Carl. More air through there is your ONLY salvation at this point.
__________________
Darral T. is offline   Reply With Quote
Old 07-23-2015, 09:05 AM   #70
Senior Member
 
Name: Eric
Trailer: Scamp 13
Michigan
Posts: 255
Quote:
Originally Posted by Darral T. View Post
Eric, arent you using CONSIDERABLY more CFM's than Gary???? [...]

I was kinda curious as to WHY you would need two fans IF the one is strong enough. I would have already upped my CFM's to try and remove the hot air.

I would also be putting a remote thermostat sensor in that bay and see what the temp was BEFORE I made changes. Fellows, the "proof is in the pudding".
Darral, yes, I am using ~100 cfm more than Gary presently. I think Gary is roughly using a 135 cfm on the exhaust so that is more comparable to my 235 cfm. I think that has been clear in our discussions, but Gary is pausing before cutting more/bigger holes.

One "strong enough" fan is what I am using now. The only reason I would change to more fans would be to get similar/more airflow with less noise.

The temperature sensor is a good idea. I have not done it. I should do it. I agree the data is what should guide our decisions. Since I have not had issues I have been lazy (or efficient with my time ). This weekend it is supposed to be kind of hot/humid here so I may try it out then.
__________________

__________________
ericw is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
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


Similar Threads
Thread Thread Starter Forum Replies Last Post
AC installation John Hedden Care and Feeding of Molded Fiberglass Trailers 5 12-13-2014 06:00 AM
Scamp 13, hidden spaces? Ron in BC Problem Solving | Owners Helping Owners 3 02-24-2012 12:39 PM
AC installation Ellen S. Modifications, Alterations and Updates 0 12-31-1969 07:00 PM

» Upcoming Events
No events scheduled in
the next 465 days.
» Virginia Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 05:23 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.