in good shape - brunnhilde part 12

This is just a post to capture some dimensions and some of my thoughts of thinking ahead on a few inevitable projects. As always, I want my blog posts to be spontaneous WRT capturing my thoughts.



Brunnhilde's height - about 10 foot 8 inches measure to top of AC err on the safe side
Kerstner air conditioner - H x L x W = 8" x 46" x 32"

I would never thought that I will ever entertain the idea of removing the Kerstner air conditioner and replacing it with one that can be procure here in USA. There were two hang ups that I have. I am reluctant to increase the height of the vehicle and the corresponding assumed worsening in aerodynamic. The main reluctance is the replacement AC unit is likely requires making the evaporator cabinet and cold air vents defunct, and add a big cutout for the replacement AC.

However, it seems quite feasible to install the Dometic Penguin II backwards in order to align the cold air circulation ports of that in Brunnhilde. Given the aspect ratio of the Penguin II it gives the impression that it is much taller than the Kerstner. In actuality it is 10" versus 8". For a vehicle that is already nearly 11 feet tall, an increase in 2 inch is a mere 1.5% increase.

It is next to impossible to find an accurate dimensions of the Penguin II anywhere on the web. I derived the dimensions from the figure in the installation manual. This gives H x L x W of 9.75" x 39.75" x 28.5". I found the 9.75" height in some sales page on the web.

The side by side comparison of the Kerstner and the Penguin, the Penguin is 6 inch shorter and 4 inches narrower, but 2 inches higher.

Kerstner: 8" x 46" x 32"
Penguin II: 9.75" x 39.75" x 28.5"


According to the Dometic's installation manual (for the older Penguin) the installation requires a standard cut out of 14"x14". This rectangles handles the conditioned air as well as the return air. This might be a bit too large length wise WRT the vehicle for Brunnhilde's existing cutout for the Kerstner but I am just guessing. I need to climb up to the roof (moon roof that is) to look closer.

obviously the model would be 60312c (11,000 BTU)

the Penguin would be installed backwards in attempt to align the air ports with that already in Brunnhilde

In this picture below, the bottom figure seems to be viewing the unit from the bottom (based on the square foam seal). I infer the smaller of the two port is the cold air out and the larger one is return air (cold air is denser so requires a smaller opening). This hold good promise one can make it fit.

Checking the dimension of Brunnhilde's cutout for the Kirstner AC shows it is about 23" x 15" with the 15" being slightly less than the depth of the overhead compartment for the AC cold air vents and the return air port. Notwithstanding the order of the cold air duct and the return air duct on the Penguin II, there should be enough space to construct a plenum to accommodate them.

I spent quite a bit of time on the web trying to determine which is the cold air outlet and which is the return air port to no avail. And yes, I did a lot of reading between the lines. While I cannot be quite certain, my research suggests that the larger port is the cold air outlet contrary to my rationale.

Anyway, before deciding to throwing the water with the baby out I wasn't going to just jump in and summarily decommission the Kerstner AC even though it is the worst German product that I ever own. The major prerequisite of a replacement AC is it must be able to be powered by my Honda EU2000i generator, and in Eco mode (the mode in which the engine only runs as hard as the load requires).

You would think that that shouldn't be that hard as both the Dometic Penguin II AC and the Honda EU2000i  have both been out a number of years. I read many forums of small (by US standard) as well as marine, and there is very little evidence that even the lowest BTU model of the Penguin can reliably powered by the EU2000i. To determine if a RV (or Marine) AC can be powered by a specific generator, the only way is to test it. No amount of spec reading will help you because the problem with powering a mobile AC is the initial surge current, which typically are hugely higher than the steady state current. For me any replacement conditioner that cannot be powered by the Honda EU2000i  in Eco mode is no deal. So far my research of the Dometic Penguin II have been disappointing. And this including the addition of Dometic's much touted Smartstart module that costs an additional $500.

For what it is worth, here is one forum thread in which a Dometic manager has posted regarding the design and applicability of their Smartstart module use with their marine AC and the Honda generator in normal and Eco modes.

Here is someone invested in the expensive Dometic Smartstart module for his Penguin 11,000 BTU AC hoping to use with the Honda EU2000i in Eco mode. No go. Only works in normal mode so that alone is a deal breaker for me.

What's wrong with this picture? There is a huge pent up demand for an RV air conditioner that can be started and powered by the efficient generators like those from Honda and Yahama and yet the RV AC manufacturers try to have it both ways. They keep claiming how powerful their AC/heat pumps are and yet none bother to meet the pent up demand of a sensibly sized AC that can be operated by these generators than anyone should buy!

I never ceases to amaze me reading the RV forums on the typical depth of ignorance... Only few understand vaguely the problem of initial current surge. The marine forums are typically better for whatever the reasons. If you want an RV AC that can be powered by a sensible and efficient generator stop buying the big ass BTU models. Demand the manufacturers to sell one that is more sensibly sized - say under 10,000 BTU. And of course that would also mean you stop buying the McMansion of RVs.

Today's forecast is a hot sunny day so I plan to go do more testing of the Kirstner air conditioner in Brunnhilde with my Honda EU2000i. I have done tests before and it has no problem working together. However I didn't test them long enough under more realistic conditions - hot and sunny day where there is appreciable amount of solar gain.