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Good to hear, sounds like heat plate on first machine was getting too toasty.

dave21 wrote:

princessbelle wrote:I have had my new tub for 5 days, so far no marks in the tub. I did turn down my humidity and have worked my way back up. If the marks reappear I will be sure to post.

That's good news, 13 nights use on my original AirSense 10 and two new tubs every single night I would get the discolouration. ResMed have now swapped the AirSense 10 out and the first night not a single mark has appeared on the tub.

One thing I noticed between the original AirSense 10 and the new replacement is on the original AirSense 10 I would start the machine and within 20 seconds the air would be extremely warm (like at full temperature), where as it takes probably 3-5 mins of slow increases of air warmth for the air to get to the same temperature on the replacement machine.

Here's hoping for more nights mark free

Interesting. Def. sounds like the heating element was bad rather than the tub. Glad your new machine is working better.

Paralel wrote:

dave21 wrote:One thing I noticed between the original AirSense 10 and the new replacement is on the original AirSense 10 I would start the machine and within 20 seconds the air would be extremely warm (like at full temperature), where as it takes probably 3-5 mins of slow increases of air warmth for the air to get to the same temperature on the replacement machine.

Here's hoping for more nights mark free

Interesting. Def. sounds like the heating element was bad rather than the tub. Glad your new machine is working better.

well, I HAD asked if he'd been getting his face steamed off....

dave21 wrote:One thing I noticed between the original AirSense 10 and the new replacement is on the original AirSense 10 I would start the machine and within 20 seconds the air would be extremely warm (like at full temperature), where as it takes probably 3-5 mins of slow increases of air warmth for the air to get to the same temperature on the replacement machine.

The power supply is only 90 watts or so. There's no way the water gets appreciably warmer in 20 seconds with 90 watts of heat.

dave21 wrote:

princessbelle wrote:I have had my new tub for 5 days, so far no marks in the tub. I did turn down my humidity and have worked my way back up. If the marks reappear I will be sure to post.

That's good news, 13 nights use on my original AirSense 10 and two new tubs every single night I would get the discolouration. ResMed have now swapped the AirSense 10 out and the first night not a single mark has appeared on the tub.

Same old tank or new tank? It would be interesting to try the various combinations of old tank (vinegar cleaned)/new machine, and new tank/old machine.

However, I presume you're shipping the old tanks and machines back sometime soon.

It was a new tub and AirSense 10, the two previous tubs had to go back so I couldn't run a test on these with the new replacement AirSense 10, but bearing in mind that two tubs had the problem after 1 night and consistently every night for 13 nights and with the new AirSense 10 and tub replacement I have now run 2 nights without a single blemish on the tub, I really do think it's the machine that's at fault at this stage.

The air on this AIrSense 10 is heating up about the same time it took my S9, I had huge amounts of rainout on the previous AirSense 10 machine where I would wake up 2 or 3 times in the night with water on my face. I had relatively no rainout on my S9 and no rainout on the last two nights on the new replacement AirSense 10. I'm pretty sure there was something wrong with the heater plate/element or something in the machine causing it to get hotter. Maybe the thermostat cutoff wasn't cutting the heat out of the plate when it reached the top temperature so rather than switching the heat on and off when required it stayed on constant for 9 hours? Who knows but hopefully ResMed can run some tests on both the two tubs and the AirSense 10 they have back now and see what is the cause.

I'm just glad the problem hasn't come back on the replacement machine/tub.

Just logged in after a long absence and saw the issue with discoloration. A few observations from a retired chemist (that would be me):

1. While the discoloration resembles that of steel heated to over 550 degrees F (blue-pink), it only occurred on the inside of the tank; the side in contact with water. Tap water contains dissolved minerals and frequently chlorine or residual ozone (don't know how they treat water in the U.K.), which can oxidize metal. Since the discoloration occurred only on the side not in contact with the heating plate it is therefore a surface phenomenon, not the result of excessive heat.

2. The observation that the metal is not magnetic is consistent with the metal being 316 corrosion resistant stainless steel. That is the alloy one would expect to be used in this application.

3. The fact that the discoloration was removed with vinegar, and then returned, but with less intensity after successive uses and cleaning indicates that the 316 stainless steel was not passivated prior to manufacturing. Passivation is a chemical process by which the metal is made passive (hence the name) to chemical attack. With stainless steel, the process involves flooding the surface with citric acid or nitric acid which dissolves free iron and any other contaminants that become embedded in the surface of the metal during processing (cutting, rolling and forming), leaving a pure finish that is resistant to further chemical attack. It is most likely that metallic surface contaminants reacted with an oxidizing agent in the tap water to produce the discoloration.

I suspect that the 316 stainless steel that was used to make the humidifier water reservoirs was, for some reason, not passivated.

I have finally been able to achieve the Power of Invisibility...

Sludge wrote:I have finally been able to achieve the Power of Invisibility...

invisible sludge... that worries me.

palerider wrote:

Sludge wrote:I have finally been able to achieve the Power of Invisibility...

invisible sludge... that worries me.

Just wait to see what happens when he makes 62 more posts.

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Hi Everyone that's affected by this problem. Some good news....ResMed Australia (Manufacturing) have come back saying they can reproduce the problem

it affects a small percentage of HumidAir tubs by a Stainless Steel surface finish problem. ResMed are working to resolve this issue by manufacturing new tubs which will take approximately 2 to 3 months.

If you are experiencing this problem, definitely contact your local ResMed Support, let them know you are experiencing the problem then contact them around mid to late March and hopefully you'll be able to receive a new 'fixed' tub that hopefully doesn't exhibit this problem.

For me, I'm on my 3rd tub now (and 2nd AirSense 10 machine) and although the first 3 nights were perfect on the new tub/machine combo, the tub started to go exactly the same way as the previous two tubs. I have experimented with regular tap water, mineral water and distilled water. The problem isn't with the water, although mineral/distilled water does slow down the process of oxidisation on these affected tubs, but it does NOT resolve the problem or stop it from happening.

My final thought on this is that the heating plate surface area where it touches the tub is a much reduced area than compared to the S9 heater tubs which had a completely flat base, this means much more heat is concentrated on a much smaller area of the base of the tub, which could along with either a reduced or no treatment of the AirSense 10 tubs could be accentuating the problem.

ResMed do say that

the discolouration is completely harmless to patients and does not have any impact on the HumidAir operation

BUT equally say this is not the desired effect they want to happen and are manufacturing new tubs to resolve this issue. I suspect that this won't be a blanket recall and from March 2015 onwards, if any customer contacts ResMed with this problem they'll send out replacement tubs and request original tubs be returned.

Anyway this is good news for those currently affected by the problem and for any future AirSense 10 users that start to experience this problem. The problem isn't to do with the type of water that you are using, it's a manufacturing defect in a small percentage of tubs and will hopefully be resolved in 3 months.

dave21 wrote:ResMed do say that

the discolouration is completely harmless to patients and does not have any impact on the HumidAir operation

the essence of this whole batch of folderol is contained in the above quote.