I am thinking about installing a water-heater-powered underbelly tank heating system -- several of our members have already done so. A very big and daunting project, but I think it is within my competence.The advantage of using the water heater to keep the fresh water tank from freezing is that it works even without hookups, while the electric tank heaters don't. (And I can't use my furnace to heat the tanks, both because it uses a lot of power and because there is no way to hook up a duct to the existing furnace.)But here is my concern: if I am traveling in cold weather (let's say about zero degrees Fahrenheit) all day long, the fresh water tank is going to freeze, even if I enclose and insulate the underbelly (which of course I am going to do). So I would want to run the water heater while in transit, to keep the tank minimally warm.At last, my question: is that possible? Will it stay lit? My fridge flame used to blow out on the road, until I installed a metal shroud around it. Would I have to do the same thing to the water heater? Is that safe?Thanks in advance for your advice!

So, your plan is to circulate water out of the potable tank thru thr water heater? I assume your plannjng on some sort of bypass so your not trying to use hot water all the time.Can it be done? Sure, anything is possible. Will the WH keep running and not blow out going down the road? Maybe, maybe not. Likely it will blow out, or burn a lot of propane trying to get all that water hot.

"or burn a lot of propane trying to get all that water hot."That would be my concern. Its not stayin in an insulated tank so isn't it going to be running non-stop?

Fridge flame blew out cause of airflow thru lower access/vent cover....lots of airflowWater heater.....outside door/panel is fairly enclosed so flame should stay lit/relight as neededIssue......Water going to tank will be 130*F/140*F (depending on which brand) and then once all the water is heated it will be HOT water in your fresh water tankYou mentioned 'others have done these'-----what/how did they do it???They do make DC Tank Heater Pads. Easier to run larger DC Charge line from truck to camper battery to maintain camper battery drain

I think its a good idea you could install a adjustable thermostat, no need for 130 deg water. don,t think it,ll blow out you,ll have to test that.

1. The flame on the water heater will blow out.2. If the underbelly is well insulated, have you thought about installing 1 or 2 12 volt 40 watt light bubes to use as heaters. Two light bubes came with my solar system from Harbor Freight so I assume they have replacement bubes. Or even a small 12 volt heater/fan. While driving down the road the 12 volt batteries will stay charged.3. If not well insulated the 50 MPH "wind chill" will take a lot of heat from the underbelly.

Can water heater run while towing? Here's why . . .

48 Replies

Dutch_12078
Explorer III
Mar 20, 2018
TenOC wrote:
1. The flame on the water heater will blow out.

2. If the underbelly is well insulated, have you thought about installing 1 or 2 12 volt 40 watt light bubes to use as heaters. Two light bubes came with my solar system from Harbor Freight so I assume they have replacement bubes. Or even a small 12 volt heater/fan. While driving down the road the 12 volt batteries will stay charged.

3. If not well insulated the 50 MPH "wind chill" will take a lot of heat from the underbelly.

1. Maybe, but ours has never blown out when we've turned the water heater on 30-45 minutes before arriving at our site.

2. I'd think 12-volt tank heater pads made for the purpose would be a better choice that would more evenly distribute the heat.

3. "Wind chill" does not affect inanimate objects, although wind will increase the heat transfer from the warmer object. It will not though, reduce the temperature below ambient as wind chill will on exposed skin.
MDKMDK
Explorer
Mar 20, 2018
I'm going with old biscuit's heater pads, or TenOC's light bulbs and heater fans, but only if you decide that Lantley's "why bother" isn't the answer you like.

I'd try to find some 12V heater pads and a way to power them, instead of running what is effectively a tankless water heater recirculation line from the fresh tank out and back. If I understand what you plan to do?
Lantley
Nomad
Mar 20, 2018
Since hot water can freeze faster than cold I think you maybe going down the wrong road.
While the water in the pipes may freeze as long as the tank remains in motion the chances of it freezing are reduced.
TenOC
Nomad
Mar 20, 2018
1. The flame on the water heater will blow out.

2. If the underbelly is well insulated, have you thought about installing 1 or 2 12 volt 40 watt light bubes to use as heaters. Two light bubes came with my solar system from Harbor Freight so I assume they have replacement bubes. Or even a small 12 volt heater/fan. While driving down the road the 12 volt batteries will stay charged.

3. If not well insulated the 50 MPH "wind chill" will take a lot of heat from the underbelly.
midnightsadie
Explorer II
Mar 20, 2018
I think its a good idea you could install a adjustable thermostat, no need for 130 deg water. don,t think it,ll blow out you,ll have to test that.
Old-Biscuit
Explorer III
Mar 20, 2018
Fridge flame blew out cause of airflow thru lower access/vent cover....lots of airflow

Water heater.....outside door/panel is fairly enclosed so flame should stay lit/relight as needed

Issue......
Water going to tank will be 130*F/140*F (depending on which brand) and then once all the water is heated it will be HOT water in your fresh water tank

You mentioned 'others have done these'-----what/how did they do it???

They do make DC Tank Heater Pads. Easier to run larger DC Charge line from truck to camper battery to maintain camper battery drain
Lwiddis
Explorer II
Mar 20, 2018
"or burn a lot of propane trying to get all that water hot."

That would be my concern. Its not stayin in an insulated tank so isn't it going to be running non-stop?
donn0128
Explorer II
Mar 20, 2018
So, your plan is to circulate water out of the potable tank thru thr water heater? I assume your plannjng on some sort of bypass so your not trying to use hot water all the time.
Can it be done? Sure, anything is possible. Will the WH keep running and not blow out going down the road? Maybe, maybe not. Likely it will blow out, or burn a lot of propane trying to get all that water hot.

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Can water heater run while towing? Here's why . . .

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