Thinking of adding 3rd AC unit

[BigLar368]

Since me and the wife have bought this RV in 2016 (2004 Camelot 38PBDD) we have always traveled when the weather was nice being all our kids are adults. We live in Southeast TX so we know and appreciate the importance of good AC.

Rewind to last year.....We decided we would take our 1 and only, 7 year old grandchild (the Anti-Christ Diva is what I call her) on a summer trip to Florida. I may have been drinking that day....I can't remember. Anyways summer is about the only time we can travel with her because of school. At the current time we are here now at Mirimar Beach Florida (Camp Gulf). I now remember why we bought an RV that only sleeps two people comfortably. Yee haw for me I guess me

We currently have two 13.5 BTU low profile Dometic Penguins AC/heat pumps that have yet to cause any problems other than being very finicky. In preparation for the summer trip I pulled the covers off the units and found both appear to be the original units. I pulled the evaporator covers off and cleaned the coils along with the condenser coils with coil cleaner. At 85 degrees outside (at home) I was able to get 55 degree air out of the closest vent on both units.

When we arrived to Florida both units were doing ok keeping inside around 72 degrees during the hottest part of the day. We do have outside solar shades on the windshield and side glass up front. We pull all the window shades outside and keep the awning out. Yesterday it got pretty hot and I remembered that I had two rolls of the bubble foil insulation in the closet. I then turned the dinner table into a fab table (while the wife gone doing laundry of course). I was able to find a 2 foot level and some of the Anti-Christ Diva's new scented magic marker set to draw some straight lines. I was only "allowed" to use the blueberry scented marker as that was her least favorite Well within a hour of so I whipped up 5 screens that's came out ok as I am not really a great fabricator. Within a few hours it really helped and dropped the temp about 4 degrees.

So today the heat index is like 106 and once again the front AC is struggling. At the hottest time of the day it's putting out 60 degree air while the rear AC is 53 degrees. Right now it's 5:00ish and the temp outside has dropped to 86 and cloudy so the AC's are now putting out some really nice temps with the inside now at 70 upfront and really cold in the back.

So my grand scheme would be to remove a power vent fan which is in the living room very close to the fridge. I would not even mess with cutting into the existing ducting or even hook it into the original thermostat. I would just use a Dometic unit (AC only no heat) with analog controls so there is no worries of it working with the original thermostat. I have an extra plug behind the fridge that was for the ice maker for the original Nocold that I drop kicked to the curb a couple years ago. Not sure what breaker it's hooked to but with a little work I am sure I can figure it out. The extra AC would only be for the hottest days and most importantly a backup in case of a failure in the future. We had to end a vacation about 10 years ago due to an AC failure.

I once added an extra AC on a fifth wheel but that was years ago. Anyone that has experience or advice please chime in.

Oh and for those people who have a 45' RV with two 8K BTU AC's that cool the inside to 68 degrees in Death Valley during the summer.....please pass this thread by. No disrespect intended. Thanks in advance.

[96 Wideglide]

Don't know if the wires feeding the ice maker outlet would be heavy enough to support an airconditioner, besides it running thru the inverter.

[vito.a]

It may be doable.
First you need to climb on the roof and see if there is enough spacing between the existing AC and the kitchen vent. These AC units use at least 15 amps on startup and come from the factory with a 20 amp breaker. I doubt your ice maker circuit is 20 amps. You should be able to add a soft start capacitor to the new AC to help.

Have you tried pulling electrical cables up into the roof area? This may be very difficult. It's tough getting through the insulation and all the cross members.

An alternative would be a new 15k btu AC on the front. I recently replaced our 13k center AC with a new 15k Penguin. It cools much better than the original 13k. The outlet air temp is several degrees colder than the old one. My wife was impressed and that's saying something.
Once you understand the control board interchangeability, this is an easy swap and you can sell your old unit when you are done.

[nodine]

My suggestion would be to first purchase a new High Output Dometic unit (around 15,000 BTU) and replace the front unit. You can save the old unit and if the new unit does not solve your problem then go to the trouble of installing a third unit using the one removed from the front. We have replaced both AC's on our coach with the new Dometic ones and the difference in performance is remarkable.

Bob

[BigLar368]

Originally Posted by 96 Wideglide

Don't know if the wires feeding the ice maker outlet would be heavy enough to support an airconditioner, besides it running thru the inverter.

That's a negative sir.....I have two outlets in back of the fridge. One runs off the inverter and one runs off the generator/shore power. I keep the fridge plugged in the inverter plug so it stays running while driving. But you may be partially correct. I have no idea what else in on that plug.

[BigLar368]

Originally Posted by vito.a

It may be doable.
First you need to climb on the roof and see if there is enough spacing between the existing AC and the kitchen vent. These AC units use at least 15 amps on startup and come from the factory with a 20 amp breaker. I doubt your ice maker circuit is 20 amps. You should be able to add a soft start capacitor to the new AC to help.

Have you tried pulling electrical cables up into the roof area? This may be very difficult. It's tough getting through the insulation and all the cross members.

An alternative would be a new 15k btu AC on the front. I recently replaced our 13k center AC with a new 15k Penguin. It cools much better than the original 13k. The outlet air temp is several degrees colder than the old one. My wife was impressed and that's saying something.
Once you understand the control board interchangeability, this is an easy swap and you can sell your old unit when you are done.

Vito....I'm really not gonna replace the units just yet as most of the time they cool just fine. It's only in excessive heat that this happens. If they were on their last leg I would pull the trigger and replace both of them at the same time. I really want an extra one mostly as a backup incase one fails. The odds of one failing is fairly good but both failing at the same time would be much less. In the event of losing one unit the extra unit can get me by till I get home. Where I am going to put the unit is about smack dab in the middle of the RV so if either old unit fails then the middle/extra unit air can be directed to the broke unit.

The vent is one foot from the top of the fridge. Going through the ceiling just that foot does not look to difficult. As far as what circuit it's on I will have to check. There are two circuits that I will never even use. The washer and dryer and the block heater. Even if I did use the block heater I doubt I would be using the AC at the same time....

[BigLar368]

Originally Posted by nodine

My suggestion would be to first purchase a new High Output Dometic unit (around 15,000 BTU) and replace the front unit. You can save the old unit and if the new unit does not solve your problem then go to the trouble of installing a third unit using the one removed from the front. We have replaced both AC's on our coach with the new Dometic ones and the difference in performance is remarkable.

Bob

Good idea Bob however I don't wanna play the shell game moving the units around. My plan would be to install the extra unit and using it only when needed on very hot days. Then when one of the unit's dies I will just replace it. Being on the road I would not have to worry about losing a unit. Without it if one dies I am at the mercy of a dealer and their pricing.

We live about 90 miles from PPL in Houston so their carry out units are very reasonably priced. I think I can get a high capacity and the manual analog grill cover for right about 1K.

[sbleiweiss]

A much easier thing (and probably not as good but an improvement) might be to switch the front 13.5 unit for a 15 unit.

[BigLar368]

Originally Posted by sbleiweiss

A much easier thing (and probably not as good but an improvement) might be to switch the front 13.5 unit for a 15 unit.

Yeah....would be easier just to replace them but new unit fail too. The majority of my thinking is two have three units and most of the time use two with the third being a back up.

[RustyTools]

I'm right there with you, Biglar!

We had an '06 Endeavor (and the usual 13.k AC units) with the great big Atrium windows on one side. Talk about a hothouse! But we loved the view - when the sun wasn't coming in. I did just what you're considering, by adding a separate 15k cool-only unit where the center vent was. When done, it was like walking into a meat-freezer, very very much worth it! Worst part was hefting the AC to the roof (As I get older, I find things are being made heavier these days than I remember ).

Not wanting to use an existing and possibly under-sized wire, I ran a new 12-gauge line to the breaker-box. I had to replace an existing breaker with a new double one because there was no more space in the box. I actually ran the new wire thru the ceiling to get from the AC to the nearest cabinet, and then in it to the box. To do that, I snaked a coat-hanger between the white visible ceiling material and the foam/etc right above it. In only one place does the wire make a slight 'bump', but it's not noticeable unless you're looking for it.
At the breaker box, I added a switch and another line to the outside. With that, I was able to run all 3 units off the existing 50amp power cable, or separate the new unit and run it off its own 20/30 amp line.
The 8kw genset was able to run all 3 units, as long as I was careful to not start them at the same time or use a lot of other appliances.
I connected the new AC to the ducting, and it did help a lot for quietness and airflow with all 3 units running.
Wife was very happy with the install, but did mention a few times that she wished we still had the ceiling vent.

I gotta say it was the best mod we ever did to any of our coaches. We now have an '08 Camelot, and I'm getting ready to do the same thing with it. Hey,wanna make it a group project?

BTW, there's been a few threads on here (including mine) about others doing the same thing.



And I'd be happy to share any more details, if you're interested.

[BigLar368]

Originally Posted by RustyTools

I'm right there with you, Biglar!

We had an '06 Endeavor (and the usual 13.k AC units) with the great big Atrium windows on one side. Talk about a hothouse! But we loved the view - when the sun wasn't coming in. I did just what you're considering, by adding a separate 15k cool-only unit where the center vent was. When done, it was like walking into a meat-freezer, very very much worth it! Worst part was hefting the AC to the roof (As I get older, I find things are being made heavier these days than I remember ).

Not wanting to use an existing and possibly under-sized wire, I ran a new 12-gauge line to the breaker-box. I had to replace an existing breaker with a new double one because there was no more space in the box. I actually ran the new wire thru the ceiling to get from the AC to the nearest cabinet, and then in it to the box. To do that, I snaked a coat-hanger between the white visible ceiling material and the foam/etc right above it. In only one place does the wire make a slight 'bump', but it's not noticeable unless you're looking for it.
At the breaker box, I added a switch and another line to the outside. With that, I was able to run all 3 units off the existing 50amp power cable, or separate the new unit and run it off its own 20/30 amp line.
The 8kw genset was able to run all 3 units, as long as I was careful to not start them at the same time or use a lot of other appliances.
I connected the new AC to the ducting, and it did help a lot for quietness and airflow with all 3 units running.
Wife was very happy with the install, but did mention a few times that she wished we still had the ceiling vent.

I gotta say it was the best mod we ever did to any of our coaches. We now have an '08 Camelot, and I'm getting ready to do the same thing with it. Hey,wanna make it a group project?

BTW, there's been a few threads on here (including mine) about others doing the same thing.



And I'd be happy to share any more details, if you're interested.

Man that sounds fantastic. Fishing a wire through the ceiling will prolly be the most difficult. Here is what I am thinking....Whatever the unused outlet is hooked up to in the breaker box can be attached to an unused breaker. I do not have a washing machine or dryer so that breaker is unused. Also unused is the breaker for the block heater which I am sure would never be used at the same time as an AC....right? Once I trace that outlet back and find out what breaker it's tied in with should be as easy as removing the breaker then running it over to the unused breaker. I remember couple months ago when I swapped out the fridge that both outlets had 12-2 wire to them so that will not be a concern.

As far as the swap project I won't start mine until the temps cool off. 95 degrees and 90% humidity where we live is a killer.. I do look forward to your third AC thread

[RustyTools]

Sounds like a plan, for sure. And plenty hot here in the Keys, too. But I do have a lot of room and full hookups for an extra rv Besides, I love working on other people's rv's - that way when I work on mine, I've already learned what to do different.

I like that idea, easier and a shorter run thru the unused 12-2 frig/ice outlet too. Is it a 20 amp breaker? As noted, be sure your new/converted AC line won't be going thru the inverter.

You mentioned the block heater. I got frustrated popping breakers when we'd hook up those little cube floor heaters thru a regular outlet. I added new outlets front and rear and tied them thru the 2 existing AC unit lines, figuring I'd never have on an AC and a heater at the same time - worked great.


Can't wait to hear your progress, keep us posted.

[BigLar368]

Originally Posted by RustyTools

Sounds like a plan, for sure. And plenty hot here in the Keys, too. But I do have a lot of room and full hookups for an extra rv Besides, I love working on other people's rv's - that way when I work on mine, I've already learned what to do different.

I like that idea, easier and a shorter run thru the unused 12-2 frig/ice outlet too. Is it a 20 amp breaker? As noted, be sure your new/converted AC line won't be going thru the inverter.

You mentioned the block heater. I got frustrated popping breakers when we'd hook up those little cube floor heaters thru a regular outlet. I added new outlets front and rear and tied them thru the 2 existing AC unit lines, figuring I'd never have on an AC and a heater at the same time - worked great.

Can't wait to hear your progress, keep us posted.

Yeah....thanks for the invite. I would love to stop by but I gotta get back to work Wednesday. I know that specific circuit does not run through the inverter. I have tested both plugs with no shore power and no generator. I just have to figure out if that circuit is piggy backed with anything else. From what I gather that outlet was for the Nocold ice maker thinking it would go dead when unhooked from shore power therefore it would not make any ice while bumping down the road. Anyways I will trace it back to the breaker box and find out. I'm pretty sure something is piggy backed with it because I doubt they would wire an home run circuit just for an ice maker. Even if it is piggy backed with something I can move that circuit over to another breaker I am not using.

[96 Wideglide]

Just checked mine and the refrigerator does have a dedicated 20A circuit, so if yours is the same, you should be good to go.
I would eliminate the outlet thou, in favor of good crimp on butt connectors.