Air Conditioning Question

[BPoland]

About 3 years ago, we had to have our rear AC/Heat Pump replaced under warranty. We had the work done at a local RV repair place an although it does cool to some extent, it’s nothing like the front unit as far as performance. I have heard that Newmar uses a special gasket when installing their AC units, and I’m wondering if the shop used the right gasket. If the front unit is running and the rear one os off, I still have a good amount of air flowing to the vents in the bedroom. If the rear unit is on and the front is off, I still have air flow thru the front vents. Are zone 1 and zone 2 independent, or is it really 1 vent system that both AC units share

We do not get the performance out of the rear unit to keep the bedroom cool in the Florida sun. So before we head that way, I need to figure this out.

Thanks in advance

[Mr_D]

In our '02 DSDP the plenum's were just a straight run so if only one heat pump was on you got air out of the whole system.

[bruceisla]

Originally Posted by BPoland

About 3 years ago, we had to have our rear AC/Heat Pump replaced under warranty. We had the work done at a local RV repair place an although it does cool to some extent, it’s nothing like the front unit as far as performance. I have heard that Newmar uses a special gasket when installing their AC units, and I’m wondering if the shop used the right gasket. If the front unit is running and the rear one os off, I still have a good amount of air flowing to the vents in the bedroom. If the rear unit is on and the front is off, I still have air flow thru the front vents. Are zone 1 and zone 2 independent, or is it really 1 vent system that both AC units share

We do not get the performance out of the rear unit to keep the bedroom cool in the Florida sun. So before we head that way, I need to figure this out.

Thanks in advance

I don't know about a Baystar but all Newmars I've seen use the same type of installation. Techs that are not VERY familiar with a Newmar install may be unaware of the special "dogleg" gasket requirement. It is an additional gasket (available from Newmar ... not Dometic. Not installing the gasket causes an air leak from cool side to warm side. Low performance and frost are the side effects.
Yes... the ductwork is common path for warm and also common for cool.

[BPoland]

Currently both units are Dometic 13K. Can I have them install a 15K heat pump for the rear, or do I have to stay with the original 13K heat pumps?

[We_B_Tripn]

I have a 2018 Bay Star. Our front AC is 15k and the rear is 13.5k. I don’t see why you couldn’t upgrade to the higher unit. I think it’s called “high capacity” now versus 15k. Ours has the common plenum so either unit pushes air throughout the coach.

[FatChance]

The "dogleg" gasket used with a Newmar A/C installation can be easily made from a second inexpensive Dometic 14x14 gasket. In fact, you can do two installations with 3 inexpensive Dometic gaskets. The Newmar gaskets are about $120 each from Newmar, the Dometics are about $30 each...

["007"]

Here is the AC seal set up for your coach and there is more information on AC's in QT's 1 & 2.

[bruceisla]

Originally Posted by FatChance

The "dogleg" gasket used with a Newmar A/C installation can be easily made from a second inexpensive Dometic 14x14 gasket. In fact, you can do two installations with 3 inexpensive Dometic gaskets. The Newmar gaskets are about $120 each from Newmar, the Dometics are about $30 each...

This is true. Make sure you use genuine Dometic gaskets ... many substitutes are a different density.

[imgoin4it]

We have a 13.5 unit in the rear of our kountry Star DP. It is the original unit, never replaced and it will get the bed room cold. Used to tell people I could use it for hanging meat. The original front unit was also a 13.5. I replaced it with replace it a year or so ago with a 15 k unit. Until I replaced the front I put a fan on the floor of the bed room and used to to help cool the front. Putting the 15k unit in the front was the best thing I could have done. Don’t have to use the extra fan any more and can cool both ends of the coach. Suggest you take your coach to a repair facility that understands Nemars and have it checked. Something is wrong

[TXTiger]

Originally Posted by BPoland

Currently both units are Dometic 13K. Can I have them install a 15K heat pump for the rear, or do I have to stay with the original 13K heat pumps?

I would put the 15k in the front and leave the 13k in the rear. The front is the area you use the most and with a large window it is the area that gets the warmest.

[BPoland]

We had the coach out locally over the weekend. I had a partially shaded sight. I had the rear unit set at 71 degrees. It was doing ok, until 11am. At that point the outside temp went to 88, and the rear unit turned on and ran solid until 8:30pm and only managed to keep the temp around 74.

So my plan is:

Go back to the shop that installed the replacement rear unit, and ask them about the dog leg gasket. Since the Dog leg gasket is specific to Newmar, I can't really say it's their fault, I just need it fixed.

Have them remove the rear unit and inspect for the dog leg gasket.
If the dog leg is missing, install it along with a new set of gaskets.

If the dog leg gasket is installed (which I doubt) then install a new unit ….again.

[bruceisla]

Originally Posted by BPoland

We had the coach out locally over the weekend. I had a partially shaded sight. I had the rear unit set at 71 degrees. It was doing ok, until 11am. At that point the outside temp went to 88, and the rear unit turned on and ran solid until 8:30pm and only managed to keep the temp around 74.

So my plan is:

Go back to the shop that installed the replacement rear unit, and ask them about the dog leg gasket. Since the Dog leg gasket is specific to Newmar, I can't really say it's their fault, I just need it fixed.

Have them remove the rear unit and inspect for the dog leg gasket.
If the dog leg is missing, install it along with a new set of gaskets.

If the dog leg gasket is installed (which I doubt) then install a new unit ….again.

You don't need to remove the unit to inspect ... you can stick your hand in from up top with the cover removed and feel it. If I was betting ... it's not there.
If you go here http://www.irv2.com/forums/f103/a-c-...ml#post4466843
and look at #14 you will see an A/C flipped up with the gaskets on it ... note the piece that looks like a hockey stick. That's the dogleg gasket. It keeps the air from bleeding from the small square vent to the bigger oval vent. You can reach into the oval vent and feel the gasket with your fingers.

http://www.irv2.com/forums/f103/a-c-...ml#post4466843

[BPoland]

Originally Posted by bruceisla

You don't need to remove the unit to inspect ... you can stick your hand in from up top with the cover removed and feel it. If I was betting ... it's not there.
If you go here http://www.irv2.com/forums/f103/a-c-...ml#post4466843
and look at #14 you will see an A/C flipped up with the gaskets on it ... note the piece that looks like a hockey stick. That's the dogleg gasket. It keeps the air from bleeding from the small square vent to the bigger oval vent. You can reach into the oval vent and feel the gasket with your fingers.

http://www.irv2.com/forums/f103/a-c-...ml#post4466843

bruceisla,

Forgive the stupid question. When they originally replaced the rear unit, was there any bracketry or base plates that are Newmar specific, that they should have transferred to the new unit, or does the dog leg gasket go straight on the base of the new unit? I ask because if there was a special plate or bracket for Newmars, they probably didn't transfer that over. As I said, I'm not going to be trying to blame them. They are a general RV repair place, and probably wouldn't have known about the dog leg gasket. Even if they were to charge me $150 to yank it, install ALL the right gaskets and reinstall, I would still be money ahead.

[bruceisla]

Originally Posted by BPoland

bruceisla,

Forgive the stupid question. When they originally replaced the rear unit, was there any bracketry or base plates that are Newmar specific, that they should have transferred to the new unit, or does the dog leg gasket go straight on the base of the new unit? I ask because if there was a special plate or bracket for Newmars, they probably didn't transfer that over. As I said, I'm not going to be trying to blame them. They are a general RV repair place, and probably wouldn't have known about the dog leg gasket. Even if they were to charge me $150 to yank it, install ALL the right gaskets and reinstall, I would still be money ahead.

No special hardware is required.
A typical parts list for a Newmar would be:
1) new topside Dometic unit (typically a Penguin low profile).
2) Dometic square foam gasket.
3) Newmar dogleg foam gasket (or make one from a Dometic square gasket).
4) a roll of Reflectix (or similar) metal tape (to repair any loose/damaged ductwork tape).
5) new lag bolts (if necessary).
6) silicone sealer (for lag bolts).


DO NOT OVERTIGHTEN LAG BOLTS. The Dometic torque specs to do not apply to a Newmar install since lag bolts are used instead of Dometic bolts.