Webasto FCF driving me insane

[SeaMoose]

Hello
The unit is a year or two old. Worked reasonably well when we were up North now that we are in Florida here is the cycle:

It is just a tiny bit cold. I select heat and set the temperature to 70. The unit goes full blast heat mode, temperature inside the boat soars, humidity jumps so high the windows fog. At 77 I can't take it in anymore and I set the unit to dehumidify. The air conditioner kicks on full blast and drops the temperature to 68. Because it's so humid it's now cold and clammy. At 68 it cycles off.

It is now just a tiny bit cold...

I set heat temp to 70 and cold temp to 70. Set the unit to auto. It goes into dehumidity mode and drops the temperature to 68.

I set heat temp to 72 and cold temp to 72. Set the unit to auto. The heat kicks on, humidity soars, at 75 it levels off and cools the boat to 68.

I put it in cool mode, set the temp to 70 and put a blanket on the bed.

The unit is completely incapable of keeping the boat 70 degrees. It has decided that 68 is where it wants to be. The other choice is 85. In essence it has two settings, freeze and fry.

I can't believe I paid $1500 for this P.O.S. does anyone have a line on an aftermarket thermostat that isn't "intelligent"? It clearly has the capacity to turn the boat into a freezer or an oven but the control system is total garbage.

Alan & Darina on Sea Moose
You Tube: The Adventures of Yorksie and Me

 

[rslifkin]

I haven't used the regular FCF, but I do have one of the FCF Platinum units. There are a few quirks in the control setup. The big one is that it has a minimum cycle length limit. So if you only need a tiny bit of heating or a tiny bit of cooling, you'll get hot or cold as it'll overshoot the set temperature. When it needs to heat or cool more significantly, it works fine.

Personally, I've found it best to manually select heat or A/C and lock the unit to high fan speed (the auto fan speed logic doesn't do a great job and occasionally causes a freeze up in A/C mode if it's too humid). And for heating, I end up putting a desk fan in the salon to keep air moving so you don't get a hot layer up top and a cold layer at the bottom due to the vent placement on my boat being optimized for A/C, not heat. Moving air keeps the temperature sensor reading more correctly too.

Where you locate the temperature sensor is a big factor as well. Mine is in the return air grill (where they say not to put it), which works great for A/C mode (as it keeps the fan on low when the compressor is off). The previously mentioned fan helps avoid false readings during the off cycles in heat mode.

 

[Sealife]

I have the FCF, and have no issues. It sounds like your unit may be oversized.

 

[SeaMoose]

Thanks for the info. It seems the minimum duty cycle is the culprit.

It's a 16K unit. Unit it replaced was 16K. I put in a lot of vents so we can selectively heat/cool cabins by closing vents, on a hot day it pretty much runs all the time so if anything it's undersized.

My new problem that started yesterday is constant E1 errors. We blow out the raw water system with a garden hose/dock water and it runs five, six hours before it quits. Going to dive on the intake tomorrow when we are anchored.


Thanks again

Alan & Darina on Sea Moose

 

[Greg QS]

E1 is a water flow problem. Clogged intake, clogged strainer , clogged lines or restrictions in line. You should leave all the vents open or close some slightly to balance the air flow to each space. This will help you with the duty cycling. Also where are you pulling the return air from. If its in the area you are having the problem with, can you move to another area. Also check the calibration of the thermostat. They can go bad.

 

[Pete Meisinger]

Nope, should not be happening. Something is plugged.

pete

 

[tbachelor]

Hello
The unit is a year or two old. Worked reasonably well when we were up North now that we are in Florida here is the cycle:

It is just a tiny bit cold. I select heat and set the temperature to 70. The unit goes full blast heat mode, temperature inside the boat soars, humidity jumps so high the windows fog. At 77 I can't take it in anymore and I set the unit to dehumidify. The air conditioner kicks on full blast and drops the temperature to 68. Because it's so humid it's now cold and clammy. At 68 it cycles off.

It is now just a tiny bit cold...

I set heat temp to 70 and cold temp to 70. Set the unit to auto. It goes into dehumidity mode and drops the temperature to 68.

I set heat temp to 72 and cold temp to 72. Set the unit to auto. The heat kicks on, humidity soars, at 75 it levels off and cools the boat to 68.

I put it in cool mode, set the temp to 70 and put a blanket on the bed.

The unit is completely incapable of keeping the boat 70 degrees. It has decided that 68 is where it wants to be. The other choice is 85. In essence it has two settings, freeze and fry.

I can't believe I paid $1500 for this P.O.S. does anyone have a line on an aftermarket thermostat that isn't "intelligent"? It clearly has the capacity to turn the boat into a freezer or an oven but the control system is total garbage.

Alan & Darina on Sea Moose
You Tube: The Adventures of Yorksie and Me

Did you ever find a solution to this? I have the same issue. Gets too hot or too cold. Thanks.