(#33) What's the Fun in That?  

It's Cold in the RV!  

We've got a problem.  When we camp in the motorhome and temperatures drop well below freezing, the water lines freeze. Some astute readers are immediately offering solutions: stay home, camp in warmer climes, sell the motorhome.

But what's the fun in that? Those are easy, simple, cost-effective and highly reliable solutions. And no fun.

The manufacturer of our motorhome clearly does not want their product used when temperatures dip below freezing. The waterlines are exposed underneath and essential (nee expensive) parts are also exposed for maximum damage potential.

Foolishly, I've crawled underneath and wrapped 99% of the exposed pipes with pipe insulation. At 14° Fahrenheit, I found out that the one percent missed was significant. We woke up to no water flow.

My fellow northern-hemisphere-equally-foolish-motorhome-owning readers will proffer a reliable, cost-effective solution at this point.  Carry ten bucks of RV antifreeze and spend fifteen minutes doing a quick 'winterize' step before going to bed.  You're right. That would work and be cheap.

But what's the fun in that?

Nope - let's see if we can come up with a way to over-engineer a solution here.  Let's take a cue from the Heated Water (inlet) hoses you can buy and see if we can keep the lines from freezing by keeping them warm.

Heat Tape and Heat Cable

After spending perhaps eight hours, in aggregate, reading blogs posts and manufacturer product sheets, I've learned there are at least a dozen variations on 'heat tape'.  Heat tape is an electrically charged wire that you wrap around the exposed pipe and plug into an electrical source. The heat tape, um, heats. It gets hot. The heat keeps the pipe from freezing.

To cut to the chase, there are a handful of challenges with using heat tape. First is that no manufacturer recommends their product for the use I'm aiming at. Nope. The motorhome pipes are PEX, not copper. The tape gets too hot.  Second is the expense. Third is the power consumption.  Those are just the top three.

There's a similar product that, the best I can tell, is called Roof Heat Cable. It's similar in function but is
apparently aimed at homeowners whose roofs are susceptible to ice dams.  [ At this point, if you're a native Texan, Floridian -- e.g. someone who knows not of ice dams, feel free to Google. ]

I had some heat cable. About 60'. Unused since I added ice-dam prevention sheathing when we re-roofed the house.

300 Watts All of the Time

One cold December day, I grabbed the Heat Cable and my Kill-A-Watt meter and plugged it all in. The Heat Cable I bought consumes 5 watts per foot. My 60 foot cable consumed 300 watts. The Kill-A-Watt meter confirmed it.

Some more expensive products can be thermostatically controlled. Not mine. When plugged in, it's on all of the time.

I filled a bucket with water, coiled up the cable and immersed the coiled cable in the water. After about 10 minutes, the water was 140° F.  That's a bit warmer than I'd like. PEX can handle it, but I'd prefer something cooler under there.

Jumping ahead, my idea was to pulse the electricity to the heat cable.  To come up with a way to turn it on for -- oh say-- 10 minutes, then off for 20 minutes. Then back on, then back off.  Lather-rinse-repeat all night.

I could probably find an inexpensive reliable timer to do this. But, what's the fun in that?
No there has to be a way to make this much more complicated, more expensive and less reliable!

[ January 2024 Update: this winter camping trip, I did use an inexpensive timer. I set it for 30 minutes on, 60 minutes off. Worked great! ]

Another Day Another Pi

Yes, you guessed it. My solution is to take a Raspberry Pi, a relay board, some wire and some sockets and craft a complicated solution.

I chose an 8 relay board, when two would have been sufficient.  I won't cover the specifics of wiring the relay board to the Raspberry Pi as there are dozens of posts that do.

Raspberry Pi and 8 Channel Relay Board

I removed the common tab from each of the four receptacles so I could control all eight sockets independently.

Removing Tab That Ties Two Together

Next is time spent with wire cutters, strippers and a couple of screwdrivers wiring it all up.

The components were secured to a board and then mounted in an inexpensive plastic tool tote from Walmart.  Main line was connected, proper wiring tested.

At this point

I've successfully created an 8 port 120V Glorified Timer. The relays are rated at 10A but because of the wire gauge I used, I will limit the current to each socket to 5A, 500 watts. And the total current will not exceed 1000 watts.

Now, On to part two - real world testing!