Low Point Keeps Flowing

[motofabio]

Anyone have an idea as to why when I open my low point drain to empty the lines, the water just keeps flowing and flowing?

It looks like it’s going to drain my entire fresh tank. I’ve done this before and it drained out maybe a gallon. I’m going on 5 gallons here, so clearly it’s tapped into the fresh tank.

The RV isn’t hooked up to city water and the water pump is off. And I’m not mixing up the low point with my fresh dump valve.

2019 Thor ACE 30.2

[BandG]

2 thoughts...

1) I have a bypass valve to physically shut the fresh water tank off located right before the water pump. You could turn the bypass on to keep your water in the fresh tank.

2) When I open my low point drains, it also drains my water heater (or most of it). So, if you had water in the water heater, I would expect it to keep draining until that is emptied. My water heater is 6 gallons, so I have that amount, as well as whatever else is in the lines.

[Trkyte@msn.com]

Sounds like you are siphoning the fresh water tank. Remove the strainer on the pump that should break the flow.

[cavie]

There are 2 low point drains. 1 hot and 1 cold. Both will have caps or valves on them. There will be 1 FW tank drain. It will have a cap or valve on it. There will be a vent/overflow line. This will not have a valve on it. Overflow /vent may be built into the FW fill outlet.

[Pete'sMH]

Try opening a faucet inside. It will allow air in to break the siphon and will allow the lines to drain more quickly and thoroughly.

[Porkchop]

More than likely it's your hot water tank draining also, so no big deal. You could drain it separately, but this way works also, The low point drains and fwt drain may have caps on them but most do not. I was at an rv show yesterday and looked. One out of about 25 had caps. Anyway, sounds like you know which are which. Good luck

Bill

[cavie]

Originally Posted by Porkchop

More than likely it's your hot water tank draining also, so no big deal. You could drain it separately, but this way works also, The low point drains and fwt drain may have caps on them but most do not. I was at an rv show yesterday and looked. One out of about 25 had caps. Anyway, sounds like you know which are which. Good luck

Bill

If the low points don't have caps then there are some valves involved.

[motofabio]

So I just looked over all the lines. It goes from the fresh tank to a shut-off valve, then to the low point drain, then into the pump, then back into the RV. Is that right? The low point drain is between the tank and the pump? That would mean water would have to flow backwards through the pump to drain out. That seems wrong to me.

[Porkchop]

Every manuf plumbs their units differently, but yes, that sounds like it would work, What is your concern? The pump don't care. Gravity is gravity.

Bill

[cavie]

Originally Posted by motofabio

So I just looked over all the lines. It goes from the fresh tank to a shut-off valve, then to the low point drain, then into the pump, then back into the RV. Is that right? The low point drain is between the tank and the pump? That would mean water would have to flow backwards through the pump to drain out. That seems wrong to me.

No. The low point drain has nothing to do with the FW tank. The FW tank has its own drain. There are 2 low point drains. 1 for hot and 1 for cold. It ain't rocket since. There is most likely a 2' Winterizer hose between the FW tank and the pump. It will have a valve. There is also a vent/overflow line on the FW tank.

[Campnjoe]

I agree with bandg that you are draining your water heater as well.

[Jimbo56]

I never caught what year and model coach the OP had. Mine does not have low point drains. The outdoor shower serves that purpose. I do have a fresh water tank drain.

[Porkchop]

The fw and low point may very well share the same exit point. That's probably why he said the fw tank had a shut off in the line ahead of the exit. Yes the hot and cold both do have a drain point on most rigs. Some apparently use the outdoor shower as the drain.
Every manuf has a different way of doing it. God bless America=we have choices.

Bill

[Pete'sMH]

Not to hijack the thread, but what is the actual point of the low point drains? Wouldn’t pumping antifreeze or air through the system force any remaining water out even more effectively than just opening the drains? Draining between trips maybe? But then there is just a lot of air in the lines to deal with on the next trip. Just wondering.

[Campnjoe]

Originally Posted by Pete'sMH

Not to hijack the thread, but what is the actual point of the low point drains? Wouldn’t pumping antifreeze or air through the system force any remaining water out even more effectively than just opening the drains? Draining between trips maybe? But then there is just a lot of air in the lines to deal with on the next trip. Just wondering.

Yes, to drain between trips. Leaving water in the lines can promote mold/algae growth in the lines. This is why they recommend sanitizing the lines periodically.

[motofabio]

Originally Posted by cavie

It ain't rocket since.

Since you said that... haha.

I mentioned that I am not confusing the FW dump and low point drain. I know where the large 2” drain valve is located. This is not that.

Originally Posted by Campnjoe

I agree with bandg that you are draining your water heater as well.

I drained the water heater and this line is still flowing. So it’s not that.

Originally Posted by Jimbo56

I never caught what year and model coach the OP had. Mine does not have low point drains. The outdoor shower serves that purpose. I do have a fresh water tank drain.

2019 Thor ACE 30.2. When I took delivery, this plugged line was said to be the low point drain, but I suppose it makes sense to use the outdoor shower for that. It just seems odd to have a 1/2” line that essentially just slowly drains the fresh tank when there is already a 2” fresh dump.

[Porkchop]

"MOST" rvs have a 3" main black tank drain and a 1 1/2" grey water drain and then it varies from 1/2" up for fresh water drain. "I" have never seen an rv with a 2" drain of any sort, much less a fw tank. YEMV

On our rig it would make absolutely no sense to try and drain the fw tank thru the outdoor shower. I will try that this pm, but can't imagine it will work considering the water manifolds used in ours.

You sure the valve you said was there for the fw tank is turned to "closed"? Can't figure how it would "siphon" any other way.

Bill

Bill

[cavie]

Originally Posted by porkchop

"most" rvs have a 3" main black tank drain and a 1 1/2" grey water drain and then it varies from 1/2" up for fresh water drain. "i" have never seen an rv with a 2" drain of any sort, much less a fw tank. Yemv

on our rig it would make absolutely no sense to try and drain the fw tank thru the outdoor shower. I will try that this pm, but can't imagine it will work considering the water manifolds used in ours.

You sure the valve you said was there for the fw tank is turned to "closed"? Can't figure how it would "siphon" any other way.

Bill

bill