basement mounted air conditioning

I'm considering purchasing a Winnebago with the basement a/c unit. I would like some feedback as to how these units perform compared to the traditional roof mounted units. Any overheating problems? Is cooling as efficient?

Welcome yippyskippy to the RV Forum.

I had a '99 Chieftain with two roof air units and now I have a '04 Chieftain with basement air.  I really like the basement unit for it's quietness, efficiency (only 23 amps needed), clean roof line & lower center of gravity.  But there are many trade-offs depending on what rig you choose.  Smaller rigs with not so much storage loose one basement compartment and that can be a big deal.  Basement units are more expensive to fix and you don't have full redundancy of 2 independent roof units.  Bigger units with big slideouts and dark paint are hard to keep cool with a 24k btu basement unit.  I now have a 40ft, big slides, and dark paint so in the 100 deg temps plus I put foil reflectors in the windshield & 3 roof vents, and 1" styrofoam in the shower and I have window awnings. I do fine in pretty extreme heat where others struggle to keep cool.

If you get a 08 or newer Winnie, they put in a bigger btu basement unit (26 or 28K btu). 

Over the last 5 years I've read 100's of postings on the roof vs basement air and you'll find many issues & opinions on this subject .....so good luck making up your mind.

Bill

Yes - welcome!

Bill summed it up nicely.  For me, basement air wasn't a deal maker or deal breaker - it's what our Horizon came with.  One of my to-dos is to mount a roof air unit in place of the galley vent for those 95+ degree days and to run while on the road.

I do like having all of the AC weight down low, and the unit is fairly easily serviced.

I like my basement air, but it does use valuable cargo space. I have had problems that were traced to the electrical contacts in the thermostat. I cleaned the contacts and it has worked pretty well ever since. When the temperature is quite low and you are trying to use it for heat, it will sometimes turn on the gas heat also. I don't like that feature. I like to use up the CG's electricity, not my propane. ;D

judway said:

When the temperature is quite low and you are trying to use it for heat, it will sometimes turn on the gas heat also. I don't like that feature. I like to use up the CG's electricity, not my propane. ;D

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Our '03 Brave has heat pumps on top and the same thing happens when the outside temps get low. I was told the heat pumps can only pull so much heat out of the atmosphere - so the system kicks in the gas furnace to help out.  I wonder if the lower mounting of your unit causes this to happen sooner - given the fact that that's where the cooler air is.

That's typical operation for a heat pump.  It only functions down to about 40F, depending somewhat on humidity.  Below the useful temperature the thermostat will automatically switch to the furnace.  On our Duo-Therm Comfort Control it will display Aux Heat when this happens.  In a 2 zone system, this feature usually only works for one zone.

I have found my unit will freeze (and not operate in heat pump mode) up in a range of about 32 to 42 degrees.  My guess this is a function of the humidity - lower humidity means lower temp it will function.  Home heat pumps have a defroster that lets it operate into the 20s (although not very effectively!)

judway said:

...... When the temperature is quite low and you are trying to use it for heat, it will sometimes turn on the gas heat also. I don't like that feature. I like to use up the CG's electricity, not my propane. ;D

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Wayne, one way to avoid having the gas furnace kick in is to adjust the set temp only 3 or 4 deg above the actual temp reading on the thermostat.  You'll have to continue pushing up the set temp over time as the rig warms up.  The Coleman Mach True Air stat is designed to turn on the gas if the set temp is more than 5 deg.

A 2nd way to fix this is to install a 2nd stat just for the gas furnace and disconnect 3-wire connector from the Coleman TrueAir stat.  An inexpensive digital setback stat is easy to connect up.  I like sleeping in cool temps and let the inside temp drop to 50's & 60's and then have the stat turn on the furnace 30 minutes before I get up in the morning.  This works especially well when dry camping to save batteries and not have the heater cycling all night.

John Canfield said:

Yes - welcome!

Bill summed it up nicely.  For me, basement air wasn't a deal maker or deal breaker - it's what our Horizon came with.  One of my to-dos is to mount a roof air unit in place of the galley vent for those 95+ degree days and to run while on the road.

I do like having all of the AC weight down low, and the unit is fairly easily serviced.

Click to expand...

John,

Hope this doesn't go off topic too much but I would be interested in your reasoning on adding the rooftop unit. How is it any better for running down the road over the basement unit? I understand the additional cooling aspect.

Thanks,
Pete

Pete - the big problem with running the basement air while in-motion is all of the dust it can suck up being so close to the ground.  I'm real faithful about spraying Simple Green on the coils and hosing off to keep them clean.

Another problem many are having with their basement air (me included) is when the outside temperature is in the high 60's to low 70's but the inside side temperature has risen to the upper 70's to low 80's due to the sun and you try to cool the inside temperature down the basement air will keep cycling on and off every few minutes but not lowering the inside temperature over a degree or two.

Allen

John Canfield said:

Yes - welcome!

Bill summed it up nicely.  For me, basement air wasn't a deal maker or deal breaker - it's what our Horizon came with.  One of my to-dos is to mount a roof air unit in place of the galley vent for those 95+ degree days and to run while on the road.

I do like having all of the AC weight down low, and the unit is fairly easily serviced.

Click to expand...

I have had both and really like the quieter more efficient basement air. I thought I would miss the cargo space took me 3 weeks to sort through the "stuff" I didn't need. Actually I have more cubic inches of space than our previous Damon Intruder.

We run the air in hot days and it cools the coach just fine. Like John we didn't buy our Winnie because of the basement air but now that we have it we enjoy it a lot.

Duner said:

Wayne, one way to avoid having the gas furnace kick in is to adjust the set temp only 3 or 4 deg above the actual temp reading on the thermostat.  You'll have to continue pushing up the set temp over time as the rig warms up.  The Coleman Mach True Air stat is designed to turn on the gas if the set temp is more than 5 deg.

A 2nd way to fix this is to install a 2nd stat just for the gas furnace and disconnect 3-wire connector from the Coleman TrueAir stat.  An inexpensive digital setback stat is easy to connect up.  I like sleeping in cool temps and let the inside temp drop to 50's & 60's and then have the stat turn on the furnace 30 minutes before I get up in the morning.  This works especially well when dry camping to save batteries and not have the heater cycling all night.

Click to expand...

I am aware of the temperature difference situation and often use your procedure to get the gas heat to stay off. However, the wife doesn't understand the problem and the gas heat usually comes on when she turns it on in the morning.

We also like the cooler temperatures for sleeping and your separate thermostat would solve the problem. I have considered, to just put in a single switch to keep the gas heat off until I want to use it.

The gas heat doesn't seem to heat as well as the electrical heat. I haven't gotten around to looking for why.

Wagonmaster2 said:

Another problem many are having with their basement air (me included) is when the outside temperature is in the high 60's to low 70's but the inside side temperature has risen to the upper 70's to low 80's due to the sun and you try to cool the inside temperature down the basement air will keep cycling on and off every few minutes but not lowering the inside temperature over a degree or two.

Allen

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Allen
I have a 04 Journey 36 and have never experienced the situation that you have described. In fact, we are in Marion,Il now with the conditions you described and had no cycling.
Perhaps you have a problem with your unit (hope not).
Let me know if you have any questions.

TomC

John Canfield said:

Pete - the big problem with running the basement air while in-motion is all of the dust it can suck up being so close to the ground.  I'm real faithful about spraying Simple Green on the coils and hosing off to keep them clean.

Click to expand...

John, can simple green be used on aluminum coils. I was looking for a product (besides acid) to clean my coils at home as well.

yippyskippy said:

I'm considering purchasing a Winnebago with the basement a/c unit. I would like some feedback as to how these units perform compared to the traditional roof mounted units. Any overheating problems? Is cooling as efficient?

Click to expand...

I would have to say, that I've never had roof air, so I have never lost any cargo space to begin with. The only problem I have had with our basement uniit is this. One time the coach was out in the sun all day and it got up to 100 plus inside the coach. Then we decided to use it...that day, it took along time to cool down. other than that, no problems with low temp cycle's .

winnie35 said:

John, can simple green be used on aluminum coils. I was looking for a product (besides acid) to clean my coils at home as well.

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I have used Simple Green ever since we have owned the unit with no problems.  Don't leave it on too long (~60-90 seconds) and rinse thoroughly.

thanks

Wagonmaster2 said:

Another problem many are having with their basement air (me included) is when the outside temperature is in the high 60's to low 70's but the inside side temperature has risen to the upper 70's to low 80's due to the sun and you try to cool the inside temperature down the basement air will keep cycling on and off every few minutes but not lowering the inside temperature over a degree or two.

Allen

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Mine used to cycle on and off like yours, but ours is now fixed and will cool down the inside temp to meat hanging temps even when the outside ambient temps are well below 65 or 70 degrees.  We actually like the inside temps below 65 degrees when sleeping, and the compressors don't short cycle anymore, and will stay on until the set point is reached now. ;D  I have posted about the fix several times.

Also, Duner hit on a point that Winnebago upped the BTU capacity on the 2008 Winnie models with basement air, because of the unsatisfactory cooling of the units over 35 feet in previous models.

The storage/lack of storage is a moot point with us, as we can still get everything we want/need in our current storage areas.