Jump to content

Turn on Grey/Black tank heaters?


Recommended Posts

I'm in Wyoming traveling east for the next two or three days. Days are 75-80, nights are 35-40. I'm running the coach heater for the first time at night, but I'm also wondering if I should be turning on the black and grey tank heaters at the same time. Are they just for when it's below freezing consistently? 


2018 Forest River Sunseeker 2290SC
25 feet, Chevy Express 4500
"Angie" (short for Angel)

Link to comment
Share on other sites

Not unless you're making sewer stew. Tank heaters aren't needed until substantially colder temps.

I have been wrong before, I'll probably be wrong again. 

2000 Kenworth T 2000 w/N-14 and 10 speed Gen1 Autoshift, deck built by Star Fabrication
2006 smart fourtwo cdi cabriolet
2007 32.5' Fleetwood Quantum

Please e-mail us here.

Link to comment
Share on other sites

Not until you have sustained freezing temperatures.  Even if it gets to freezing for an hour or two in the middle of the night but warms up in the day you still don't need them.

Here is a rough test for you, put a plastic gallon jug of water outside.  When it gets cold enough to get ice in it and not easily thaw out during the day, it is time for the tank heaters.  Just remember you tanks should be insulated, where the water jug is not so you have a big safety margin. 

2014 Volvo 630. 2016 Fuzion 325T, RZR 900 Trail 
675ah AGM, MSH 3012 inverter, 960w Solar.  (2016 Chevy 3500 DRW, backup)

Link to comment
Share on other sites

Waste tank heat pads are there just to prevent the tank contents from freezing.When sitting still it will take several hours of temperatures well below freezing for that to happen. There is little danger of freezing until outside low temperatures fall below 30° and stay there for most of the night. Most of the heat pads are thermostatically controlled and typically turn on at about 40° and back off somewhere around 65° for the contents of the tank. Since your tanks are mounted up under the floor of the RV with little or no space for air to pass through there, you might be surprised if you could monitor the temperatures inside of them when you are keeping the RV warm. Some manufacturers also recommend that you not operate the heaters with the tanks empty, so check your owners manual for the tank heaters. 

In general, tank heaters will be operating on 12V from your RV system so if you are dry camping without shore power you need to consider the current load. I found the draw of most I am familiar with to be between 5a and 8a for each heater and you most likely have two of them. It could deplete the battery much more quickly if the temperatures are low enough to keep them on very much of the time. 

Good travelin !...............Kirk

Full-time 11+ years...... Now seasonal travelers.
Kirk & Pam's Great RV Adventure



Link to comment
Share on other sites

What Linda and Kirk are saying is absolutely true. I'll just add a little anecdote. Our previous fifth wheel did not have tank heaters on it. It had a thin Coroplast (corrugated plastic) underbelly, but that had no insulation on top of it (the floor was well insulated - though that doesn't help the tanks which are below the floor). There was one small, 2" heat duct going back to the kitchen island and fresh water tank area from the furnace. Anyway, against my better judgement I let my wife talk me into spending the holidays near grandkids at the tip-top of the Chesapeake Bay in Maryland. The week before Christmas an arctic air mass moved in... we had single-digit lows and highs around 21 - 22F with 45 MPH winds for five days. We had a heated water hose and the water standpipe had heat tape and insulation on it, but I filled the fresh tank during the day, disconnected the heated hose, and ran off the tank and pump. I waited until the warmest (if you could call it that) part of the day to drain the gray tanks every two to three days and the black tank once a week. We went through 60lbs. of propane about every four days during this time. Through all this, neither the fresh nor waste tanks froze (the Pex water lines to the kitchen island did, though). The mass of the fluids in the tanks takes a lot longer to drop in temperature and freeze than does water in a hose or Pex line.

This is just for perspective - hope it helps.


2012 F350 CC LB DRW 6.7
2020 Solitude 310GK-R, MORryde IS, disc brakes, solar, DP windows
Full-time since 8/2015



Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

RVers Online University



RV Destinations

Find out more or sign up for Escapees RV'ers Bootcamp.

Advertise your product or service here.

RVTravel.com Logo

  • Create New...