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BobJones · 02-10-2019, 03:17 PM

Hi folks!

This is year 2 for me in camping in sub zero during the winter. Each winter my water line feed to the unit freezes on occasion.

As such, I keep the unit's fresh water tank full and run off that until the temperature goes above zero. So, I run off the pump and the tank.

But here's the thing. What I have noticed every single time the fresh water feed to the unit freezes is that I hear a noise from the hot water tank. It's the sound of boiling water.

It only happens when the fresh water line is frozen. This makes me think that the hot water tank is low on water and it is boiling. How can this be? Doesn't the fresh water tank pump also fill the hot water tank?

jacwjames · 02-10-2019, 07:46 PM

The hot water tank has the same supply line so it shouldn't make a difference . Not really sure what the noise you are hearing though.

BobJones · 02-10-2019, 07:51 PM

I was thinking the same thing. I was washing dishes and it occurred to me that because the hot water tank is lower then the sink the water has to be pushed out. The only way that could happen would be if the pump is pressurizing the line and causing the hot water to flow.

I have no idea why the tank makes that noise though. It sounds exactly as if the water in the tank is boiling. You can hear it when you go into the bathroom (it sounds a bit like hissing). When you open the cabinet to the tank then you really hear it. It sounds like the water is boiling.

But it only does that when the main water feed is off. So I have no idea what the relationship is between the two but my concern was that perhaps the tank was running dry and in danger of burning out the heater or something.

I'm not imagining things. When the water feed from the park is working it never does this (which is 99.99% of the time). It only does it when the unit is working on the internal water tank/pump

Old-Biscuit · 02-10-2019, 09:57 PM

Are you using the electric element to heat the water with?

nucleate boiling where small bubbles of vapor form on the surface of the hot element

CG supply water is colder then water in your fresh water tank and most likely at a higher supply pressure then pump
Different press/temp relationship CG supply vs pump supply

BobJones · 02-10-2019, 10:16 PM

Hi Old-Biscuit - many thanks for another great reply!

Yes, I'm currently using the electric heater. It sounds similar to chili simmering in a sauce pan. It could easily be what you say it is. I know for a fact the campground pressure is higher then the pump. Probably by a fair bit.

It definitely only happens when running on the internal tank/pump.

So no danger to the tank then? Just ignore the boiling noise? My fear was that if it was actually boiling it could boil dry.

Old-Biscuit · 02-10-2019, 10:22 PM

Quote:

Originally Posted by BobJones

Hi Old-Biscuit - many thanks for another great reply!

Yes, I'm currently using the electric heater. It sounds similar to chili simmering in a sauce pan. It could easily be what you say it is. I know for a fact the campground pressure is higher then the pump. Probably by a fair bit.

It definitely only happens when running on the internal tank/pump.

So no danger to the tank then? Just ignore the boiling noise? My fear was that if it was actually boiling it could boil dry.

No harm........
Normal occurrence

Besides...can't boil dry as there is no place for vapor to go/so no water loss/pump would replace if water did disappear

BobJones · 02-10-2019, 11:03 PM

Of course. The condensate has no-where to go. Many thanks again - I can rest easy now

PS>You advised me on installing a tune-up kit for the furnace, and I did, and it performed much better. The burner was nearly all gone! A short time later the motor started making noise so I replaced that too. Good thing, it hit -10c the other day and the furnace has gotten a big workout.

So you're two for two with me - if not more!