How should a steam generator be drained?

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uscpsycho

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I am installing a steam shower and want to make sure the steam generator is properly drained.

It's a Thermasol Pro series generator which includes a drain pan that should be drained. My contractor planned to connect the drain from the steam generator with the drain from the nearby tub. This seemed fine at first, but I just read that if there is a power failure a steam generator can release its super heated water. If this happens the water may be too hot (200+ degrees) for the tub's plastic drain. But Thermasol's Pro generators with Auto Powerflush work differently from other steam generators so that might not apply.

I read something on another site about proper trap placement for a steam generator drain. It was rather technical so I didn't fully understand it. What kind of trap consideration do I need to make?

Thermasol's drain instructions don't offer much guidance: Plumb the 3/4" drain connection on pan to an approved drain. Drain Pan must be installed on all generator installations. All plumbing shall be performed by a qualified licensed plumber and in accordance with applicable national and local codes.

Despite these directions and the existence of a drain in the drain pan this Thermasol video oddly suggests that the generator doesn't require a drain at 1:42

I also read somewhere that you can just drain the pan into a bucket. This could make sense depending on how much water is discharged. If I'm understanding the Thermasol video this generator flushes water back through the steam head instead of draining directly out of the generator. So I'm not even sure when water would be discharged into the drain pan.

In a nutshell, given the unique operation of the Thermasol, is it OK to drain the pain into the tub's drain? Are there any considerations necessary with respect to having a trap in the drain? Can I drain into a bucket?

TIA!
 

CountryBumkin

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Where is the steam generator mounted - against outside wall, same level as Shower, etc.)?

On my Steam Generator the pressure release pipe dumps outdoors (like a hot water heater). There is also a "pan drain" line that is outside next to the pressure release pipe (water would only come out of this pipe if the unit is leaking).

My Steam Generator does not have an automatic drain/flush as some do (it's an option for those that want to flush their unit periodically). IIRC, this drain would go the house drain with an air-gap connection similar to a washing machine drain. Mine has a manual drain but it is only needed for maintenance. I have never drained my unit. IMO, using it regularly keeps the sediments from building up inside - but this may depend more on your water quality.
 
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uscpsycho

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The steam generator is installed against a wall in the attic above the second floor and the steam shower is on the first floor.

My Thermasol has an automatic flush feature but the flush happens through the steam head, it doesn't flush from the drain pipe. The video I linked to says that because the power flush feature flushes through the steam head "you're no longer required to plumb to a drain". However the installation instructions clearly state that the drain pan "must be plumbed to outside". The information is contradictory. And what does "plumb to outside" even mean?

Can anyone shed some light on the conflicting info? Do I need to plumb the drain or not? And if it is flushing from the steam head what is the purpose of this drain anyway? In case I need to manually flush it? In case of a leak?
 
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CountryBumkin

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My Steam Generator is mounted in the attic above the Shower like yours (but I have a single story home). Note that the "drain pan line" is different from the flush line.

The drain pan is there in case the unit starts to leak. The drain pan line should be routed to where you can see if any water is ever leaking out.

In my case, the drain pan line, the manual flush/drain line (ball-valve), and the pressure-relief drain line all run parallel to each other from the generator to the outside wall of the attic, then down the exterior wall and end about 12" off the ground. So I have three 1/2" copper lines running to the outside (nothing connected to house plumbing except the in-coming water supply to generator).
 

uscpsycho

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On my steam generator there is no manual flush line. The flushing happens through the steam head so the drain from the pan is only in case of a leak.

So should there be a leak, will it be super heated water or unheated water from the water supply line?
 

CountryBumkin

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On my steam generator there is no manual flush line. The flushing happens through the steam head so the drain from the pan is only in case of a leak.

So should there be a leak, will it be super heated water or unheated water from the water supply line?

I understand that you don't have a flush system like mine (I have a "Mr Steam" system). Your flush setup sounds better.

Regarding the "drain pan's" drain line -
The drain pain is there to catch anything in the event something starts leaking (like a cracked tank or dripping fill valve). It's probably not ever going to be "super heated" water (as that would be steam going into the air), but it could be very hot if the unit has been running or it could just be cold water if something were leaking at the fill valve or the tank just started to fill/heat.

Either way want you need to know if it is leaking long before it falls through the ceiling. :D
 

uscpsycho

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The reason I asked about the water temperature is because I'm wondering is if it is OK to run a copper pipe from the drain pan to an existing PVC drain. I understand that if the water is too hot it could melt/damage PVC.

In my case the water would leak into the drain pan and then travel about seven feet in a copper line before getting to the PVC. So it would have some time to cool before it hit any plastic. Does that sound OK?
 
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uscpsycho

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So after talking to Thermasol they say the water from the generator can be up to 160 degrees.

Assuming worst case and the water hits the PVC at that temperature, is that OK or is 160F too hot for PVC? I have a feeling I just asked a really stupid question but my plumbing knowledge is minimal (obviously).

EDIT: I just answered my own question (thanks Google). According to this article:
"PVC is a thermoplastic, and therefore, at some point it will begin to degrade and break down as it's heated up. It just so happens that Schedule 40 PVC's maximum operating temperature is 140 degrees Fahrenheit, around the same temperature that hot water gets to in most homes. That max operating temperature of 140F means that any temperature above this will cause the schedule 40 PVC pipes to break down, compromising the integrity of the pipe (think leaks and bursting).

For this reason, it is recommended that PVC pipe and fittings be used only for applications where the water temperature does not exceed 140F. Even if your application involves water at temperatures nearing 130F, I would recommend another material, as temperatures have a tendency to fluctuate, and it's always better to err on the safe side."


So I need a Plan B for this drain. FML
 
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CountryBumkin

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Personally I think you would be okay with 7ft of copper to PVC pipe. But I'm not a professional plumber. This pan drain is only used in the event of a failure/leak of the steam generator. It's not like it is going to be draining into the PVC after every use.

The important thing, is that if the generator leaks, are you going to know (see it) if the pan drain lines goes into the PVC pipe somewhere up in the attic.
If you can't tell is the pan is leaking with plan A, then I would say you need a plan B.
 

uscpsycho

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I won't be able to tell if it's leaking unless I see that the drain pan is wet. And that since it's in the attic I'm never going to notice that.

However, if the drain line goes somewhere else I'm going to try to put it somewhere inconspicuous so unlikely I'll notice a leak anyway. At least not in a timely manner.

I don't know how likely this thing is to start leaking, Thermasol makes good stuff, but this might be a good use case for a leak detector.
 

uscpsycho

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Anything is technically possible but it's not a great option in my case. I will have to get a leak detector that can send an alert to my phone/email.
 
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