Heat tracing on water lines

[Jls]

Has anyone contemplated placing heat tracing on water lines?   I see two reasons...1. eliminate worry while on the road during springtime cold snap after dewinterizing and 2.  possibly eliminating the need to winterize at all.

[Snackchaser]

 

12 volt heat trace is about 3 watts per foot, and I'm not sure how you would calculate the length needed to protect the hot and cold loops.  We picked up our trailer during a terrible ice storm with icicles hanging off the trailer while going down the road.  There was real concern of freezing pipes.  We said: Damn the warnings, we're running the gas furnace while going down the road!

[Mike and Carol]

1 hour ago, Snackchaser said:

We said: Damn the warnings, we're running the gas furnace while going down the road!

We’ve run the furnace while driving too.

[jd1923]

18 hours ago, Mike and Carol said:

We’ve run the furnace while driving too.

We’ve never towed in freezing temps and don’t plan to! 🤣

We use the furnace when it freezes overnight when home and haven’t winterized since we’re often leaving again soon.

[Mike and Carol]

2 hours ago, jd1923 said:

We’ve never towed in freezing temps and don’t plan to! 🤣

Sometimes you get a wild hair and make impulsive travel changes.  We were at Lost Dutchman one January and decided to visit our son/family in Durango.  Once we got past Payson the temps started dropping.  By the time we hit Farmington, NM we were in the 20’s.  The week we were there overnight lows were teens and highs near 30.  No trailer issues.  Another January we were at Dead Horse Ranch and checked temperatures at Zion, highs in the low 60s.  The campground there was empty and we stayed a week in an empty Zion National Park.  On the drive back to AZ we had temps in the 20s, ran the furnace and got back to AZ with no issues.  Travel flexibility!  Mike

[Jls]

We used AC heat trace and just turn on the inverter..we have the premium solar package. Used about 3 percent SOC to run 45 feet of tracing overnite at 20 degrees outside temps. We split the tracing into four runs for max flexibility. Using AC was less expensive and less amps.

[Wayfinder]

@Jls Your question got me thinking.  I do that once a month.  😉 

How do you place your heat trace within the hull? 

I might like your idea over mine, but it was fun to research and geek out about.

My idea was, at first - WARNING: Lots of bla bla from AI research 😞

I might consider using 12v Ceramic heater(s)?  While in my driveway in GA on the coldest of days, I use two of those silver-looking clamp-on utility lamps with 60 watt bulbs in them. On lamp next to the water pump under bunk, and one under dinette facing the front of the camper, or towards the black tank area of bathroom. I've not yet had any issues in the camper.

I might consider, and would be geeky-fun to try, using a Kat's Heaters Ceramic Interior Heater with Fan - 300 Watt - 12V, Part Number: KH37500 from eTrailer.com, or something similar.  These have a 150w and 300w settings.  I asked my uncle AI (Claude) for output estimates since I have four fairly new Lifetime 6v AGMs in my old trailer, 220 AH usable.  How long would one of those heaters last on both a sunny day and with no sun. I have 380 watts of solar.

Down below, I also asked: Compared to a 60watt incandescent bulb plugged into AC, what kind of heat might that put out?

Answer: A 60W incandescent bulb is, in a very real sense, mostly a heat generator that also produces light — about 95% of its energy becomes heat, only ~5% becomes visible light.

BLUF: The Takeaway

• The 150W heater puts out about 2.5× more heat than a 60W bulb
• The 300W heater puts out about 5× more heat than a 60W bulb
• A 60W bulb is roughly equivalent to a very modest hand warmer in terms of room heating ability

This are some non-verified results:

• 4 × 220Ah 6V Lifeline AGMs
• Config: 2S/2P → 12V, 440Ah total
• 50% SOC = 220Ah usable

 

60W Incandescent Bulb as a Heater

• Effective heat output: ~57W of actual heat
• BTU/hr: ~195 BTU/hr
• The glass surface can reach 200–260°C (roughly 400–500°F) — hot enough to burn skin on contact
• The air warming effect in a room is modest, but in a small enclosed space (like a chicken coop or a closet), people have actually used bulbs as supplemental heat

150W Heater

• Heat output: ~512 BTU/hr
• Air temperature near the outlet: roughly 50–65°C (120–150°F)
• Practical use: Takes the chill off a very small enclosed space — great for a car cabin, a small tent, or under a desk. It won't meaningfully heat a room.
• Space it can handle: ~15–25 sq ft (roughly the interior of a car)

300W Heater

• Heat output: ~1,024 BTU/hr
• Air temperature near the outlet: roughly 60–80°C (140–175°F)
• Practical use: Can comfortably warm a car interior or a small enclosed cabin/van space. Still not enough for a full room.
• Space it can handle: ~25–50 sq ft

Important Notes

• 12V power source matters: A 300W heater draws 25 amps at 12V — this is a heavy load. Make sure your battery, wiring, and fuse can handle it.
• Insulation is everything: In a well-insulated camper, a 300W heater can get quite cozy. In a poorly insulated space, even 300W will struggle.
• These heaters are best thought of as comfort heaters, not primary heating solutions for large spaces.

Current Draw

Heater	Watts	Amps @ 12V
150W	150W	12.5A
300W	300W	25A

Runtime to 50% SOC

Heater	Usable Ah	Draw	Raw Math	Real-World Est.
150W	200Ah	12.5A	~16 hrs	~13–14 hrs
300W	200Ah	25A	~8 hrs	~6.5–7 hrs

The real-world figure is lower due to:

• Peukert effect — AGMs lose some effective capacity under sustained load
• Inverter/wiring losses if applicable (~5–10%)
• Cold temps — AGM capacity drops in cold weather, which is exactly when you need heat most 🙃

Solar Reality on a Cold Sunny Day

• 380W rated panels in cold, clear conditions: roughly 75–85% output = ~285–320W realistic
• Flat roof-mounted panels on a highway aren't perfectly angled to the sun, but clear sky and cool temps largely compensate
• Call it a conservative ~285W average while moving

Net Power Balance with Solar

Heater    Solar In    Heater Draw    Other Loads (~20W)    Net
150W    ~285W      150W                  20W                                +115W (charging!)
300W    ~285W      300W                  20W                                ~-35W (tiny draw)

What using Solar Means Practically

150W heater — you're essentially running it completely free, and still slowly charging your bank while driving. Nearly a wash even on a cloudier day.

300W heater — virtually break-even. A slight net drain, but so small it's almost negligible. On a really bright stretch you'll be net positive, on a shadier stretch slightly negative.

For Protecting Water Lines Specifically

This is a low-load task — you don't need to heat the whole camper, just keep the hull above freezing. A 150W heater on low (if it has settings) or even a small 40–60W pipe heating cable would do the job, meaning your solar would be comfortably net positive all day.

Bottom Line

With 380W of solar on a cold sunny travel day, a 150W heater is essentially free to run and your batteries will likely end the drive in better shape than they started. The 300W is break-even. This is exactly the use case solar excels at — offsetting a modest continuous load during daylight hours.

 

Edited 1 hour ago by Wayfinder