Does your Bipap auto SV run warm?

[dsm]

I took my machine in to my DME provider's office today and explained my concerns. I told him about feeling that I wasn't getting as much air and I showed him the area of the machine that gets extremely warm after it has been running a while. He seemed genuinely concerned but it was clear he didn't know as much about the innards of the machine as you do, DSM.

I showed him my mask. He thought the cushion was beginning to get floppy. And he suggested that the mask might not be sealing as well as it should, which he said would force the machine to work harder to compensate and thereby cause it to produce more heat. I had been thinking that it was about time to replace my cushion, but I'm not totally convinced that a weak cushion is a plausible explanation for a warmer machine operating temperature.

He's ordering a new cushion for me and we'll see if it changes anything. He did reassure me that if the machine should fail, it would be replaced at no charge. So I was very relieved to hear that!

I should have the new cushion in a few days. I'll let you know if it helps or if anything else changes. In the meantime, thanks to you all for your input!

wearysoul

Good to hear they are co-operative. Re the motor in the blower, while it runs at a constant speed, it is fair to say that the load when the air is mostly directed out the air vent to the sleeper, offers greater resistance to the blower motor than when the air is re channeled back into the blower motor's input (this is what the air valve does as pressure is altered based on what the machine needs to deliver). The difference is very minor.

But, it may turn out that a leaky mask does make a difference. I often get air leak out the junction of where the H/H pushes into the bipap. My wife will pick it up very quickly because she hears a changed noise (I don't always hear it).

Anyaw, keep your fingers crossed.

Cheers

DSM

[OutaSync]

I remembered to check mine this morning! After running all night, it was slightly warm to the right of the screen, behind the air exit area. There was another spot that was barely warm behind the power light. Neither spot was hot, just warm.

[wearysoul]

DSM, I'm hoping that a leaky mask does indeed make a difference. I picked up my new mask cushion today and will use it tonight.

Also, thanks for checking your machine, OutSync. Sounds like yours is normal . . . I think mine is running a little warmer than yours. I don't get burned when touching it, but it's very warm.

I'm more convinced now that I'm not getting the full amount of air. I've awakened with a headache for the last couple of mornings. Also, yesterday and today I've felt so much worse than I was feeling in January that I almost felt I was back in my pre-treatment mode. So I'm really thinking it's the pressure.

I'll update you all tomorrow and let you know what happened with the new cushion.

wearysoul

[dsm]

WearySoul

I'll throw in one other thought but this is just a wild card.

My wife has been asking why my Bipap Auto SV is so noisy (I am deaf sortof).
It has been on a shelf for months while I used a Vpap Adapt SV.

she asked me if I had cleaned the filters - (my wife is a very smart diagnostician ).
I took the filter cover off - it looked fine - no signs of dust. Then I pulled out the foam
filter & saw a hepa filter in there that I had put in a year or more ago (out of
curiosity). It did look a bit clogged. I removed it & reassembled the filter box.

Machine is now so quiet I could not hear it at all !.


So just a though, if you haven't already pulled out the foam filter completely & washed it
give that a try.

But I still think your motor is, for some reason, overloading & struggling & running up
the current through the regulators (they are I think, chips called thyristors).

Again, Good luck

DSM

[wearysoul]

DSM, The suggestion about the filters is a good one, but I have already checked and changed them--both the foam and the hepa. Changing them didn't improve or change anything.

I used the new mask cushion last night and it didn't change anything either. So I spoke with my DME again today. He agreed to check the pressure output of my ASV with a manometer. It showed that the pressure output is accurate--that it matches the IPAP 8 cm H2O/EPAP 8 cm H2O/maximum IPAP of 30 cm H2O.

So at least during the first few minutes of operation, my ASV produces an accurate pressure.

My DME suggested I change the valve in the port through which air exits into the humidifier. He noticed that the flap didn't always stay in place while air was exiting the port and said that this might allow a pressure decrease.

He also suggested I change the "rise" from 3 to 1. He thought a rise of 3 might be causing me to retain CO2 and that this might be causing my recent headaches.

I'm going to try these two things and see what happens. Will let you know.

wearysoul

[timbalionguy]

Thanks to some technical information that DSM posted, I have an idea what might be happening here, especially if your machine is warm all over.

When air is compressed by the blower motor, it is also heated in the process. When the air expands, either in your body, in your mask, or inside the machine, the heat it gained is given up, and radiates into the objects around it. Furthermore, the air circulating inside the machine picks up the heat generated by the blower motor itself, and the electronics.

One effect that most people do not realize is that an unloaded centrifugal blower, like what is used in these machines, actually uses more power than a blower working against a back pressure. This happens with water pumps as well, and I learned about this effect the hard way on a TV transmitter in LaCrosse, Wisconsin.

Now, I noticed your IPAP/EPAP pressure settings are low compared to many users of these SV devices. This means that the rotary 'door' inside the machine is usually open further. This shunts more air from the output to the input of the blower, and less pressure is delivered to the mask. Less pressure also means less flow, because the intential leak rate is less at lower pressures.

This shunted air is actually making the blower work harder, as there is more air to move around in a situation like this. thus, there is more air circulating in the cabinet, being compressed by the blower, heating up, and giving up heat to the machine's cabinet. There is less cooling flow for the motor and electronics. Since the air can only escape through the hose (and it all eventually does), the extra heat in this air has to go somewhere.

Therefore, I am beginning to think your warm machine is due to a higher-than-normal volume of recycling air.

DSM, the motor driver devices in that machine are much more likely transistors (either bipolar or power MOSFET) than they are thyristors. The number of these devices on the PWA around the motor plug suggests an H bridge driver circuit.

[OutaSync]

I believe Kiralynx runs hers at a lower pressure.

Kiralynx, if you are reading this, check to see how warm your unit runs?

[wearysoul]

Just wanted to let you all know that replacing the air valve and reducing the rise to 1 seems to have eliminated my headaches. When you change two variables, it's hard to say which one produced the result, but I'm thinking it was probably the reduction in rise that helped.

Also, I'm no longer feeling that I'm not getting enough air, so maybe one of the above changes helped that issue too.

After it has been running for a while, my machine still feels very warm in the spots identified earlier in this thread.

timballionguy, thanks for your thoughts on what could be causing my machine to get warm. Although my machine gets warm only in certain areas--rather than all over--your theory sounds plausible. Unless my therapy deteriorates again, however, I'm not going to do anything further. My DME is aware of the issue and if the machine fails, he has said he would replace it.

Many thanks to all for your input.

wearysoul

[OutaSync]

I'm glad that it's working better for you with the change in rise time.

Bev

[StormyToo]

Deleted

[raisedfist]

This is a 9 year old thread

[StormyToo]

Thanks for bringing it to my attention. So very sorry.