HVAC frozen up (literally!)

I've not gone up to the boat for a few weeks...longest time ever for us I am usually up there most every weekend but repeated snows, extreme cold, etc. have kept us home. *Came up today to find our main salon HVAC frozen up- literally- covered in ice. *See attached picture. *I melted it and removed the ice but it does not seem to be heating. *It was running when I came on board (we had it set to lowest possible temperature) but sounded funny. *What would cause this? *It's a pretty new unit- really not that old and always in freshwater, never in salt. *Aft stateroom unit was not turned on but I've turned it on now and it runs perfect, is heating, pumping water, etc.





-- Edited by Woodsong on Friday 28th of January 2011 12:33:47 PM

Do you have a way to check?* You my be a little low on coolant.

SD

you mean R22 or whatever refrigerant they use? I'd be surprised but maybe that is it??

Usually one of two issues, although a thorough diagnostic is needed. Either you are low on refrigerant or your thermostat is not working. More likely number one. The reason that the coils form ice is that when the system is short on charge part of the coil runs very cold and ice starts to grow. The bad news is that if it has been operating like this for a period of time, there is a good probability that the compressor is damaged. Chuck

** Does your display have an error code on it?* If so your manual may shed some light as to what happened.* JohnP









-- Edited by JohnP on Friday 28th of January 2011 01:28:36 PM

I had that happen one time and the tech said to run the AC to thaw it out. I thought that since it was not pumping water that it was clogged. The tech said running heat for a long time in cold weather would freeze it up.

To produce heat the unit gets cold. To produce cold the unit gets hot. It is a heat pump after all.

I did it and it worked

-- Edited by Doc on Friday 28th of January 2011 04:18:18 PM

David,* I think you are probably correct.** By this time of the year I have switched to an*oil filled rad and winterized and shut down the hvac unit.*

Doc,* I hope that works for Tony.*** JohnP

-- Edited by JohnP on Friday 28th of January 2011 01:24:18 PM

In the cooling mode, restricted air flow can cause icing. I don't know about the heating mode.

Our Cruisair will not provide heat and shuts down when we try to use it too early in the spring. Error code translates to "water too cold".

no error codes on the digital control. De-iced it and talked to the hvac tech here locally- sounds like water got too cold and froze it up. I've left one of the hvac units on my boats on for the last 8-9 years without this ever happening...guess TN got too cold!
Thawing her out now...hopefully no damage. Will have the hvac tech out (hopefully) this weekend if there is an issue as we plan on enjoying the 60 degree weekend on the boat! It feels like summer to me today @ around 50 after so many weeks of snow and cold!!

60 DEGREES!!* Don't think we will see that in NJ till end of March.* JohnP

Woodsong,
You could try posting your question here:
[/b]http://marine-ac.com/forum/[b]
It's a small free forum run by a professional HVAC guy who seems to enjoy answering novice*a/c questions. He was very patient and helpful with mine.

Thanks guys- that forum looks to be very useful!!

I am glad to report that upon thawing the unit out and letting it warm up for a while, I was able to power it back up and it heated just fine. I was afraid I had fried it but it seems to work just fine after thawing it out.

Needless to say I was very shocked when opened the compartment the unit is in and saw all the ice! I was sure it was gonna translate to a bunch more money I'd have to spend!

Tony,* Any ideas on how you are going to prevent it from happening again?* JohnP

John,
Best way I can figure to prevent it from happening is to move myself and the boat to the bahamas!! Short of that, I actually have to figure out another solution. HVAC guy recommended space heaters. I am very leary of that option due to increased risk of fire. It seems lots of boat dock fire stories revolve around space heaters. So....good question....I am open to ideas! This winter has been exceptionally cold...coldest in many, many years. Hopefully we are past that this season (60 degrees today!) but I do need to find a good solution for winter months here so that it does not happen again.

On my boat I use a single oil filled electric radiator.* What I like about them is they have two switches that control the wattage used.* One switch is 500 watt and one is 1000watt* combined they equal 1500.* They also have a thermostat settings from just above freezing than 1 thru 6.

I also use two small fans to move air around the inside of the boat, these run when we are not there.

I set the radiator on the 500 watt setting* and the temp between freeze and 1.

So far this winter anytime I have visited the boat (weekly at least) the water sitting in bottles in the galley and head is not frozen or containing any ice.

The surfaces in the boat feel slightly warm and dry, due to the fans circulating air.

When entering the boat I switch the wattage to hi and turn up the thermostat. The interior becomes warm and comfortable fairly quickly.* Although the fans go off as soon as I come aboard because the air movement feels drafty.

During the time I keep the heat up I monitor the shore power plug to insure it is not overheating or even getting warm.* This could be just one day or a weekend.

Satisfied that all is well at 1500 watt use, I feel pretty confident things will be okay at 500 when I am not aboard.

The oil radiators only use power heating the oil and the power cycles on and off depending on how cold it is outside.

Of course being a Northren boater anything that could freeze is winterized ( filled with non toxic or drained)

Our boat has transom taps hot and cold for rinsing off, so I cannot keep the water system operating.

Its low tech and the boat is definately in the winter mode ( my insurance has a off season clause anyway). However the boat is dry and warm and very comfortable to visit even on frigid days.

Anyway glad you have not damaged anything.* I am sure the people where you keep your boat can tell you what to expect from the next 6 weeks.

Take care* JohnP

Most everyone seems to keep their HVAC on so I am very shocked ours froze up.
Do you have a link for the exact radiator you use to heat your boat? I really may go that route though I "hope" we are past the worst for this season.

The radiator I have is at least 5 years old but the new ones are very simular.

Mine is a Delonghi-- Homedepot-Lowes-Walmart- they all have them ,check the box for the ones with the 3 output settings(wattage).* These are not expensive.

If you elect to get an engine room heater (Boatsafe)* you can spend a lot more and I think they can be hard wired.

The safest thing to do is winterize everything and only use electric heat while you are there.

In the NorthEast the lowest temps are usually in early February, although the daytime highs usually inch up as the month ends.

If all your neigbors are running their heat pumps with no issues, you might want to do that and have someone on your dock monitor your boat.

I hate Winter but all the Snow Covered Landscape looks nice.* JohnP

I've already got a dedicated bilge heater that I keep in the engine room. I don't want to winterize the systems as we come up here year round so we need everything working. PO literally did nothing to winterize the boat or keep it heated. Then again, he didn't have a working bilge pump either!! Ok- well, he technically had a working pump but the float switch was not anchored so it just floated around in the water.
I think we're ok for rest of this season. 65-70 today, cooling down some at night this week. Friday we take her down the river 125 miles to get her topsides painted so she'll be inside a heated shed for 2-3 weeks or so. That will carry us through to about 1st of March. I think if I get 2 radiator type heaters (one in aft stateroom, one at entrance of forward stateroom in main cabin) and a bilge heater it should be fine.

Sounds like Chattanooga TN has pretty mild Winters and with your boat heading for the paint shop and the bilge heater already in place, you are in good shape.

Shoalwaters wrote:

Woodsong,
You could try posting your question here:
[/b]http://marine-ac.com/forum/[b]
It's a small free forum run by a professional HVAC guy who seems to enjoy answering novice*a/c questions. He was very patient and helpful with mine.

Click to expand...

Hello Everyone...Yes that's me in the link...Thanks to both that posted about me & my site...I do try to help for free in hopes that some might Consider buying from me if you like my advise or help...Nothing more...

As far as reverse cycle heat...You should not run the system with any lower than 40 degree seawater...It will ice up as shown...


The worst part is the ice can rupture that water coil, and that usually ruins the rest of the unit/system due to water getting into the freon circuit, and then shorting out the compressor...


The risks of this are less with digital controls but if your system has been retrofitted to digital you would need to know if a low pressure switch was installed with the retrofit...Most manual knob controlled units did not come with one, and if it did, did the installer wire it to the new digital control...


Here is a link to a icing in heat thread in my forum*http://marine-ac.com/forum/troubleshooting/marine-ac-icing-in-heat/?value=icing%20in%20heat&type=1&include=3&search=2&ret=all


I just did a search & came up with 50 related posts




Steve~*

*

Steve- Great Forum- Lots of interesting Threads and Advice.* Keep up the good work!* JohnP

Steve,
Thanks for hopping over here and hope you stick around here on TF! regarding my particular issue, both the HVAC unit and the digital controls are fairly new...probably 3-4 years at most. We just got home from the weekend on the boat. It ran fine all weekend and heated great so hopefully no damage was done!A question for you if I may though....I talked on the phone with the local marine HVAC guy the other day and he made the comment that we should not leave any of the units on in the winter as he had seen a couple of boats in the recent past that almost sank as a result of the unit icing over and something happening. *I didn't ask enough questions to determine what reportedly caused the near sinkings but, big picture, if I leave one of my cruise air reverse cycle HVAC units on for a week or two and it freezes up, will I be in risk of it resulting in lots of water and possible sinking of the boat? *Will it damage the unit to run iced over?


Thanks!!


-- Edited by Woodsong on Sunday 30th of January 2011 07:06:59 PM

Woodsong wrote:

Steve,
Thanks for hopping over here and hope you stick around here on TF! regarding my particular issue, both the HVAC unit and the digital controls are fairly new...probably 3-4 years at most. We just got home from the weekend on the boat. It ran fine all weekend and heated great so hopefully no damage was done!
A question for you if I may though....I talked on the phone with the local marine HVAC guy the other day and he made the comment that we should not leave any of the units on in the winter as he had seen a couple of boats in the recent past that almost sank as a result of the unit icing over and something happening. *I didn't ask enough questions to determine what reportedly caused the near sinkings but, big picture, if I leave one of my cruise air reverse cycle HVAC units on for a week or two and it freezes up, will I be in risk of it resulting in lots of water and possible sinking of the boat? *Will it damage the unit to run iced over?


Thanks!!


-- Edited by Woodsong on Sunday 30th of January 2011 07:06:59 PM
*

Click to expand...

Here's a repeat & quote...

Cruisair/Marine Air say's ...Under no conditions should you run our systems in heat mode with less than 40 degree F water....


"The worst part is the ice can rupture that water coil, and that usually ruins the rest of the unit/system due to water getting into the freon circuit, and then shorting out the compressor..."


If it can rupture a cupronickel. coil internally, I'm sure it could rupture externally...I just can't say I've seen it being here in central Fl with water temps always above 55 degrees...


Steve~

*

What the deal here folks is...That water coil runs much colder than the water that runs thru it...40 degree & below water may cause that coil to run as low as 22-32 degrees...

It will surely freeze solid...But the less than freezing water before it, will still try to pump....


Steve~



-- Edited by spcoolin on Monday 31st of January 2011 04:33:56 AM

Some marine AC units have optional electrical resistance heating that is controlled by the AC system thermostat. This might be a good option for people in colder climates who keep their boats in the water.

Yep, I agree with David. Your "cooling" water is probably too cold

You might also try Kollman at this:

http://www.kollmann-marine.com/


He too runs a forum and I've run across hime on a couple other sites and he seems to be helpfull.

We have two Ocean Breze Units with resistance heat. They work great in the winter (at least here in north Florida)*without worying about water temperature. Also saves the AC pump running.

I keep a heater in the bilge to keep the Perkins toasty, but why does the rest of the boat need to be kept warm in the winter?* Maybe to keep the FW pipes from freezing?*

Dang, this Winter has been a real pain huh?* This is supposed to be The South!