Mermaid marine air - Heat

[Gpbbard]

Our heat works fine for about two minutes and then the unit itself trips off. The water flow is fine. Excellent heat comes out when it briefly works. Any ideas why it trips off? It works continuously and does not trip off when in cooling mode.

Ok, so after reading a little on the manufacturers website I found the problem. They said it could be caused by an air restriction. So, low and behold when I checked the two cabin air vents, guests had fully closed both of them! I opened the vents and the heat works fine...

 

[Tim R.]

Our heat works fine for about two minutes and then the unit itself trips off. The water flow is fine. Excellent heat comes out when it briefly works. Any ideas why it trips off? It works continuously and does not trip off when in cooling mode.

Call Mermaid. They have good techs that can help you troubleshoot.

Www.mmair.com

 

[Doc_holiday]

This could mean the tubes are scaled which limits the heat exchange. It would then cycle on a pressure switch.

 

[Chris Patterson]

I think Crazy Dave Condon on here has something to do with the Mermaids. And has, or used to have a shop about a hundred miles inland from you.

 

[Snotter]

I bought my AC new in spring. It worked fine all summer. However, when I switched it to heat in the fall, it did the same thing yours does. After reading the troubleshooting table in my manual, I tried re-programming the fan speed. It turned out that the fan speed's lowest setting was set way below the default value. Bumping it up cured my problems.

 

[onecoolair]

All three of my mermaid units have had this same issue since new. I found I like running the gray low profile heaters found at west marine much more reliable. No more messing with raw water strainers in freezing temperatures. If you must use these units for winter heat try using a separate fan blowing continuously on the compressor. I do the same by running a extra fan on the compressor in summer to help with cooling . Big waste of money , to pay extra too have reverse cycle heat with these mermaid units. My opinion. Otherwise I like the mermaid product.

 

[Jackdaw]

As the water temp approaches 40F all RC units have to work very hard to produced heat. Much harder work than summer AC with its much high temp differential. Any shortcoming.. Water flow, fan speed, blocked heat exchanger etc will show up now.

 

[Sanfelice]

Same issue

I have the same issue. Others I know have also told me the same. I think that the water cooling is not sufficient until the water temp gets down to a certain point. Like others I use a little ceramic heater. It is quieter and more reliable.

 

[Tim R.]

All three of my mermaid units have had this same issue since new. I found I like running the gray low profile heaters found at west marine much more reliable. No more messing with raw water strainers in freezing temperatures. If you must use these units for winter heat try using a separate fan blowing continuously on the compressor. I do the same by running a extra fan on the compressor in summer to help with cooling . Big waste of money , to pay extra too have reverse cycle heat with these mermaid units. My opinion. Otherwise I like the mermaid product.

Not our experience at all with our 2 units. We live aboard and use the reverse cycle mode 5-6 months of the year with absolutely zero problems since new in 2007. We did have some issues with the cheap Lux thermostats but I replaced them and no problems since.

We are still using ours in Maine with air temps at night in the twenties. The boat stays a nice 65° with the unit cycling every 10-15 minutes. I have not recently checked the water temp but I bet it is no warmer than anywhere else in the country right now. This weekend I will shut it down and start running our diesel fired hydronic system.

 

[Bob J.]

It turned out that the fan speed's lowest setting was set way below the default value. Bumping it up cured my problems.

That's an interesting observation. Typically a blower fan runs at a higher CFM when in the cooling mode & a lower CFM in the heating mode. The higher CFM in cooling mode is so you don't ice up the coil, the lower CFM in the heating mode is so you don't feel like you're sitting in a draft.

 

[kloudie1]

Jackdaw is exactly right.. Much more work to extract heat from the cold seawater without freezing it .. The good thing is that all that extra work (OK, most of it) goes into heat which helps to warm the boat. I have an old Marine Air that gets a good bit of use as a heater .. but our water rarely falls below 60F. Note that some units have an "auto" fan setting that holds the fan speed low until the air temp and the thermostat set point start getting close.. then the fan is ramped up.. Check out the low speed settings as Snotter noted .. and everything having to do with water flow. ya need more water flow to get heat than to get AC..