View Full Version : Geothermal Heat Pumps

04-23-2013, 09:41 AM
I have been wondering as I've explored our new houseboat and the docks: are there many houseboats with geothermal heat pump systems? It seems to me that it would be a good choice for marine use. Our lake water never got below 48 degrees all winter. A heat pump would work great at that temp. In summer, the water would always be cooler than the air. I know geo units are more expensive for home installation, but a large part of that cost is drilling the wells in the ground. Lastly, it would eliminate the bulky, noisy compressor unit that takes up space either on the roof or rear deck.

I am just curious. Do many of you or your neighbors have geothermal? Is there a big down side that I am missing?

04-23-2013, 10:34 AM
my brother has one on his cloud 9 houseboat. it was installed by a previous owner who was a hvac dealer. it works great on his. i'm not sure of the make. for a water supply for it i know he has a 500 gph pump that is normally used on regular marine air to furninsh the water.its very quiet and very cold air when its on. for some reason the water does'nt flow through it for heat, just the air.

04-23-2013, 12:14 PM
In reality Marine AC units are Geo thermal units using lake water as the heat exchange medium.

The only way to eleminate the compressor is to have water that is at least 20/50 degrees cooler than the air temperature.

04-23-2013, 12:16 PM
My HB utilizes the lake water to heat and cool. I can't remember the pump's GPH rating, but it's really throwing out a good stream! It's a 3 ton set up and it can burn you out or freeze you out if needed. I do enjoy more deck space b/c the HVAC condensor unit is not sitting outside and the entire unit only occupies a couple cabinets in our hallway. As such, ours is a bit loud and is a source of annoyance while watching TV in the salon. Sailabrations built after 2006, all have the HVAC components moved to the inside of the pontoons, which eliminates the noise problem. I wish I could do that to mine!

04-24-2013, 05:14 AM
As OHB said, the compressor is not eliminated. What is eliminated is the fan that draws air over the coils. Instead you get a water pump pumping water over the coils. I have a new R410a 3 ton unit on my boat. It is actually very quiet - except when it reverses to heat the coils. It seems that all of the R410a units are loud when reversing.

04-25-2013, 09:10 AM
I mis-spoke when I said the compressor was eliminated, just the noisy box and fan out back or on the roof. We just love as much silence as we can get with nothing running. We also have a fairly new 3 ton unit and I have observed the same thing. It is pretty quiet when it runs, but sounds like it's going to fly off the deck when it kicks in and out of defrost mode.

Our boat has several spare water inlets through the hull. I wonder if Stardust intended them for geothermal HVAC for some buyers.

04-25-2013, 12:51 PM
These set ups are just simply called "marine air" aren't they? Not geothermal HVACs.

04-26-2013, 07:20 AM
Install a good strainer on your intake, easy to access, as they do require cleaning, and it always seemed to me that mine would get clogged on the hottest days.

As you know, a houseboat will heat up fast, so sweating occurs, hanging upside down, cleaning it, in a hard to reach location.

Not hard to do however.

04-26-2013, 07:48 AM
Yeah - they are called marine air, but they are "geo-thermal" in design. Some of the houseboat manufacturers used the traditional marine air units. Some used units from Florida heat pumps.

05-16-2015, 12:36 PM
Thank you for*good*communication.

09-06-2016, 06:05 AM
One of my friend who is a heating reapir nj (http://www.airdexinc.com/commercial-hvac-services-nyc/heating-services/) technician has installed a geothermal system in a houseboat. I don't have much idea about marine air conditioning units but I have read in an article that they are different from most land Air conditioning because it uses water cooling rather than air cooling. Refrigerant and evaporative are the two types of marine air conditioner.

10-18-2016, 12:52 PM
Issue with the geothermal around here is the lake freezes over in the winter. People with the geothermal found that the water froze in the lines after it past through the heat exchanger. Guess the heat exhanger removed just enough heat to put the water below 32F.

Gotta have some sort of setup to draw water from deeper down in the lake so that when the heat is removed the water isnt below 32F as it tries to make its way back to the lake.

10-18-2016, 08:58 PM
Yes I've seen that happen too. Some setup to bring up deeper water might work, and should improve efficiency in the summer, too.