Draining Ariston Hot Water Heater?

[myoung]

There are three openings to the hot water tank: a cold water inlet, a hot water outlet, and a pressure relief valve.

This is all well and good for a hot water heater that is used every day in a home bathroom or kitchen. But, what about periodic use in an RV?

I don't welcome the thought of water sitting stagnant in the tank for days, weeks, or even months between camping trips. So, what to do. Surely there must be some way to drain the tank by adding another opening to the tank itself, rigging some siphon or pump, or repurposing the pressure relief valve to a tube for either siphoning or pumping.

Does anyone have experience with this contraption and the problem of draining the tank? Any and all suggestions would be most welcome.

Thanks in advance.

[Shadow Catcher]

RV water heaters have a bottom drain. You should NOT use the pressure relief for any other purpose period it is there for a reason. I do not know what the construction is but you might be able to install a drain unless it is lined.

[GeoDrop]

I have the same heater and we just completed our first camping trip. I really think we only have two options: 1) remove a connection and siphon out the water, which I did over the winter or 2) run fresh water through it once a month or so.

As to the siphoning.. you could get creative and put some sort of y-fitting with a valve that you can open/close that would allow a small tube to be inserted down into the tank and siphoned out. Just a thought anyway.

[myoung]

RV water heaters have a bottom drain. You should NOT use the pressure relief for any other purpose period it is there for a reason. I do not know what the construction is but you might be able to install a drain unless it is lined.

This is not a standard or typical RV hot water heater. It is designed primarily for a home installation.

The pressure relief valve is designed to work at 150 psi, which is far higher than pressure possible in my installation with a 40 psi regulator on the shore water feed and an electric pump on the fresh water feed.

I'm guessing that the cold water inlet has a pipe that extends to the bottom of the tank and the hot water outlet taps the 2.5 gallon supply toward the top of the tank because hot water rises. Both inlet and outlet feeds attach at the top of the tank.

So, it would seem most feasible to siphon from the cold water inlet and allow air to enter the top of the tank by opening the hot water faucet. I'd have to put a valve in the siphon line and a tee off the inlet to make the installation permanent because it would be inconvenient to detach the inlet piping and attach the siphon each time I wanted to drain the tank.

That's my scheme. I'm looking for some confirmation that it is workable. Thanks.

[myoung]

I have the same heater and we just completed our first camping trip. I really think we only have two options: 1) remove a connection and siphon out the water, which I did over the winter or 2) run fresh water through it once a month or so.

As to the siphoning.. you could get creative and put some sort of y-fitting with a valve that you can open/close that would allow a small tube to be inserted down into the tank and siphoned out. Just a thought anyway.

Matthew & Sandi,

Do you know if the siphoning removed all the water or just some of it?

[bobhenry]

FROM THEIR MANUAL......

Periodic maintenance
Note: For most of these operations, the water will have to be drained from the heater.
For all of these operations the power supply needs to be shut off .

1) If the heater has been installed with flexible hoses, shut off the power supply and
turn the heater upside down over a sink to drain the water out of it, OR
2) If the heater has been installed with rigid piping, siphon the water out through any
(lower) service valve on the (inlet side). Keep a hot water faucet open while
siphoning the water out, OR
3) If the heater has been installed with flexible hoses, it can also be emptied by
siphoning through the inlet side hose. Keep a hot water faucet open while
siphoning.

If stale water is your largest concern what is wrong with simply flushing the system with fresh water by hooking up and opening the hot water side and drain off 10 - 15 gallons of water prior to departure.

http://www.tanklesswaterheatersdirect.com/shop/tanklesswaterheaters/manuals/ariston_manual.pdf

[StandUpGuy]

There are three openings to the hot water tank: a cold water inlet, a hot water outlet, and a pressure relief valve.

This is all well and good for a hot water heater that is used every day in a home bathroom or kitchen. But, what about periodic use in an RV?

I don't welcome the thought of water sitting stagnant in the tank for days, weeks, or even months between camping trips. So, what to do. Surely there must be some way to drain the tank by adding another opening to the tank itself, rigging some siphon or pump, or repurposing the pressure relief valve to a tube for either siphoning or pumping.

Does anyone have experience with this contraption and the problem of draining the tank? Any and all suggestions would be most welcome.

Thanks in advance.

I was looking to add this unit on my trailer. Perhaps the best solution is to have quick disconnects for all connections and remove the unit and drain by turning upside down.

[Larwyn]

For winter storage I always blew out the water lines with compressed air (at about 40 psi). They make fittings just for that purpose which connect to the city water connection. But if you really want all the water out of that little water heater it sounds like removing and inverting it, then allowing it to dry might be the best option. If it removal is not practical, a little air pressure could speed up the siphoning method considerably.

[bobhenry]

If you read far enough in the manual the manufacture suggests an in-line pop off rated lower than the tank pop off to allow trapped pressure in a non vented system to release as the water heats up and expands. This keeps the tank pop off from having to relieve the system. They suggest this be routed to the exterior. Perhaps this could be use as the blow out drain if it were to be installed in the cold water delivery line. This line would be closest to the bottom of the tank as the cold water generally is plumbed to arrive at very near the bottom of the tank.

[starleen2]

This is not a standard or typical RV hot water heater. It is designed primarily for a home installation.

The pressure relief valve is designed to work at 150 psi, which is far higher than pressure possible in my installation with a 40 psi regulator on the shore water feed and an electric pump on the fresh water feed.

Thanks.

That is true - but the assumption of the pressure at 40 psi gives a false impression - if the water temp regulator fails - then the unit could continue to heat up and the hot water gets to the point of making steam and the pressure builds - I had a small 30 gallon unit do this and I caught it in time before it exploded - someone who installed it put a plug in the relief valve. I managed to relieve the pressure by opening every hot water faucet in the home and let the steam escape. I replaced the unit with one with a pressure relief valve on it.

[GeoDrop]

By the volume of water that came out, I would say most of it.... hard to get it all without turning upside down.

I'd be interested is finding/seeing these 'quick disconnects' that someone mentioned.

I have the same heater and we just completed our first camping trip. I really think we only have two options: 1) remove a connection and siphon out the water, which I did over the winter or 2) run fresh water through it once a month or so.

As to the siphoning.. you could get creative and put some sort of y-fitting with a valve that you can open/close that would allow a small tube to be inserted down into the tank and siphoned out. Just a thought anyway.

Matthew & Sandi,

Do you know if the siphoning removed all the water or just some of it?

[StandUpGuy]

By the volume of water that came out, I would say most of it.... hard to get it all without turning upside down.

I'd be interested is finding/seeing these 'quick disconnects' that someone mentioned.

..

I would too as I do not know if they exist. I made it up.

[GuitarPhotog]

I use garden-hose quick disconnects in my home brewery. I use Gardena plastic ones, which have held up to hot water use very well, but Nelson makes them in brass also.

You can find them in the hose section of your local garden supply shop.

Properly applied, they don't leak and last for many connect-disconnect cycles.

If I were to build plumbing into my trailer, I would certainly use quick-disconnects throughout. They just make life easier when it comes to removal/replacement.

My $0.02 worth

<Chas>

[bobhenry]

Since we are not needing a hugh volume of water why wouldn't air hose quick connects work? They hold air pressures up to 150 PSI in garages for air tools and are quick connect. They are somewhat restrictive by design with about a 1/4 inch opening in the nipple but that's a good thing (think water conservation) !

You might want to relieve the pressure before disconnecting to avoid a surprise shower

[48Rob]

Mr. Young,

You can easily add a drain to your water heater by connecting a steel nipple to the tank, then connecting a "Tee" to the nipple.
The horizontal opening on the "Tee" will connect the incoming cold water line.
The vertical opening on the "Tee" will have a nipple and a 1/4 turn valve connected to it.
The nipple will pass through a hole in the floor, and the valve will be either on top of the floor, or under it depending on how much clearance you have.

Once you turn off the water supply, you can open the valve, and a hot water faucet and your tank will drain.

Rob