Heat Malfunction on Winter Cruise

Am I the only one having trouble trying to cruise this Winter? Last week it was a refrigerator that wouldn't come on because if it is already 34 degrees inside the box the thermostat is happy. (See previous post)

Now the new problem. Winter 2016 and 2017 were spent in FL so this year I resolved to do the Albemarle Loop and stay in sunny NC. I left the boat in Edenton, NC which is about 2 hrs north of home. The weather window for this past weekend was excellent so I packed up and headed to the boat. I was going to singlehand this trip to Hertford and Columbia. (Have you ever tried to raise a crew in NC in January?) I arrived to several inches of snow covering the boat and dock, a thin layer of ice covering the waters of the marina and 28 degree temperatures. The forecast promised light winds and mid 40s.

Prior to the bitter cold weather (for Eastern NC anyway) I winterized the systems. I opted to drain the systems since I was planning to use it during the winter and I didn't want to waste antifreeze. Checked all the hoses and clamps opening the seacocks as I went along and found a couple of minor leaks that required tightening.

The boat has three heatpumps. 2 16K BTUs and 1 12K BTU. After a short time the salon and pilothouse began to warm up doing a good job of extracting heat from 40 degree water but I didn't check the cabin. Disconnected shore power, cranked the generator and headed to the fuel dock for water. Took on about 150 gallons then headed out. Once I was in the Albemarle I went down to check the cabin and it was ice cold and the unit was blowing cold. This unit is a Cruisair Turbo less than 3 yrs old and when I opened the cabinet the circulating pipes were completely frozen with no water exiting the discharge.

Normally, when I have a friend or two on board I sleep in the pilothouse and give the cabin to the crew. Reasonably comfortable but I have a new mattress in the cabin and it sleeps soooo good so I was looking forward to having it to myself. I shut down the unit and let it thaw. Once water began to exit the discharge again I turn it back on with the same result, icing and no heat.

Arrived in Hertford and wound up sleeping in the salon. (TV) I'm an early riser, 4-4:30AM and I began to research the heatpump problem on the interweb. Most advice pointed to the reversing valve that switches the heatpump to an air conditioner. They advised that you should regularly switch the unit from AC to heat even during the Summer to exercise the valve to keep it from sticking later. (I'm just finding this out now?). Anyway I took the hair dryer and heated the thermostat sensor on the unit so that the AC would come on and when the unit cranked up if made a significant sound. Maybe I was just expecting a noise of some description but I ran the AC for 2-3 minutes and then switched to heat. I knew the compressor was running and pipes began to frost, not freeze and slowly the output began to heat up. Problem solved, at least for the rest of the trip.

I spoke with Danny at Martin Marine in Wilmington, a good contact for Marine HVAC and he advised that 37-40 degrees water temp is about as low as you can generate heat. He also recommended in low temp situations to set the fan at low to help build up condenser pressure which helps with icing.

The cabin unit was not a show stopper however I sure slept good the next night in the cabin.

Yep, my units randomly freeze up with water temp around 40 and below. Worse if for some reason you have low water flow.

I found that when cold, if I turned them on for like five minutes, then off for five, then on again, that would help prevent freezes. Seems like freeze was most likely in first few minutes when pressures and temps were not yet stable.

I also put a switch on that forces pump to run continuous. That turned out to be a nice feature for a few reasons.

Ski, turning them off and on seems like a good approach. I would have thought that allowing it to thaw completely and getting a positive water discharge might have started the heat cycle but it didn't. Not until I turned the AC on and ran it a few minutes then switched back did the heat come on.

With the continuous flow on the circulating pump does that emlinate the need for triggers?

Don

No, the triggers are still there. Switch just bypasses the trigger. "auto" or "on".

Nice for priming pump or defrosting a unit. Pump runs but compressor is off.

I too run a lot in the winter. Learned to babysit these things in cold water. HATE waking up freezing and defrosting at 3am.

Check that you have plenty of water flow. It takes more flow to make heat than to run ac in summer, as you have the freeze issue.

Danny is an outstanding tech. Also a believer in running them continuously in cold temps. As liveaboards, that's what we did, he pointed out that is why our heat worked and he was doing service calls for all the weekenders. Great refrigeration tech too, by the way. He resuscitated our big Sub Zero and our Scotsman ice maker.

If you need crew some time let me know. Did you anchor out at Hertford, or where did you stay? Did you go to Columbia? Town dock or anchor? Both pretty cool little off the usual cruiser map destinations.

I tied up at both marinas. The bridge tender in Hertford thought my call was a prank. She said they had not opened the bridge in over a month. The docks there are first rate and they even had water. Tried to tie up in Columbia but was too wide for the slip. I had to side tie at the south end of the last slip. A Nimble 20 had laid side to and was there for a while. These towns are probably better during the week but I enjoyed the trip.

Thanks, we ended up anchoring off in both places. The Hertford bridge is scheduled to be replaced with a high rise, but not 65' IIRC. They were probably all surprised to see you this time of year!

Webasto Airtop 3000 does the trick for us in the PNW. What's air conditioning?