Thread: Condensate switch

Anybody know if these are supposed to be in the primary drain line?
I see them pretty regularly in the secondary drain as a plug, but I have never seen the flow through design.
Thanks, Jim

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Besides that plastic being close to the draft hood, which requires 6" clearance to combustible material (plastic is a combustible material, as is the insulation on the conductor from the switch), and that there is no trap there ...

*IF* that meets UL 508, it is allowed there, "sort of" (see below).

M1411.3.1 Auxiliary and secondary drain systems.

- 4. A water level detection device conforming to UL 508 shall be provided that will shut off the equipment served in the event that the primary drain is blocked. The device shall be installed in the primary drain line, the overflow drain line or the equipment-supplied drain pan, located at a point higher than the primary drain line connection and below the overflow rim of such pan.

The "sort of" catch - read the underlined section.

While I think these are worthless at preventing overflowing water and resulting damage, and were not allowed until the 2006 code (pressure from the 'industry' caused this to be allowed) ... they are now allowed - but only if installed in accordance with the underlined part.

That one is not, neither have any of the others I've seen.

That one is not, neither have any of the others I've seen

Technically, the switch is installed in the top side (or at least the wires enter through the top) of the primary drain and it would be lower than the rim of the pan (assuming it (the pan) is at the same level as the secondary drain port).

But since I was not able to get a name or model number, I was hoping someone might have a web link or be familiar with this particular switch.

Originally Posted by Jim Luttrall

Technically, the switch is installed in the top side (or at least the wires enter through the top) of the primary drain and it would be lower than the rim of the pan (assuming it (the pan) is at the same level as the secondary drain port).

Yes, but the way the code reads is "A water level detection device conforming to UL 508 shall be provided that will shut off the equipment served in the event that the primary drain is blocked. The device shall be installed ...

That entire 'tee' *is* "the device", at least, that entire 'tee' is the UL listed device, if you take the guts out or modify it in any way, you take away the UL listing.

Thus, to me, "the device" is the "UL listed device", in this case, the 'tee'.

It's an SMD Research SS1Low Voltage Condensate Overflow Shut-off Switch.

Link Photo

Link instructions

Instructions are here:

http://www.smdresearch.com/index.shtml?products/SafeTSwitch/safetswitchss1.shtml~mainFrame

Here's the catch:

Thanks, Michael.
Good Info.

Besides that plastic being close to the draft hood, which requires 6" clearance to combustible material (plastic is a combustible material, as is the insulation on the conductor from the switch), and that there is no trap there ...

Jerry, I am trying to track down that code requirement now-- you wouldn't happen to know it off the top of your head would you?

Also, what program do you use where you can pull up codes so quickly, copy, and paste them? Also, with that program you are using, are you allowed to copy and past those codes and/ or diagrams directly to a report?

Thanks,

Originally Posted by Brandon Whitmore

Jerry, I am trying to track down that code requirement now-- you wouldn't happen to know it off the top of your head would you?

From the IRC.
G2427.7.7 (503.7.7) Clearances.

Minimum clearances
from single-wall metal pipe to combustible material shall be
in accordance with Table G2427.7.7. The clearance from
single-wall metal pipe to combustible material shall be permitted
to be reduced where the combustible material is protected
as specified for vent connectors in Table G2409.2.

Table G2427.7.7

Listed appliances with draft hoods and appliances listed for use with Type B gas vents - MINIMUM DISTANCE FROM COMBUSTIBLE MATERIAL - Single-wall metal pipe - 6 inches

The clearances for the draft hood will be the same as single wall vent, check the installation instructions.

Also, what program do you use where you can pull up codes so quickly, copy, and paste them?

I have the complete set of ICC codes (and others) on my computer.

Also, with that program you are using, are you allowed to copy and past those codes and/ or diagrams directly to a report?

I always have done it.

While it is "copyrighted material", copyrighted material is allowed to be copied in limited context for "training and education" (as explained to be by several attorneys who dealt with copyright issues). 'Limited context' would be such as copying one page of a code, not the entire code, and using that for 'teaching purposes', or, copying one section from the computer program, when used for 'teaching purposes'. After all, isn't the reason we reference code it 'for teaching purposes'?

Besides, for each state which adopts a code, that information is "public domain" information, which is why the Florida codes are on the Florida and ICC web site, and I believe the ICC codes are on the ICC web site, you can only print one page at a time (if I recall correctly) - for the reason I gave ... it is public domain and for teaching.

Now, if you want "convenience", you have to *pay money* for the printed code books and / or CDs. Believe me, it is worth the money for the convenience.

Jerry

"located at a point higher than the primary drain line connection and below the overflow rim of such pan."

Are we talking about the internal pan that drains the water to the primary drain line?

OK, What exactly does that mean.

Higher than the primary drain line (always above the rim of the pan)

But below the overflow rim of such pan (how can you have both unless I am not understanding it right.

The primary drain line is always above the rim of the pan. (Unless it is the internal pan)

Originally Posted by Ted Menelly

Jerry

"located at a point higher than the primary drain line connection and below the overflow rim of such pan."

Are we talking about the internal pan that drains the water to the primary drain line?

Yes.

The primary condensate drain line connects to the primary condensate pan lower than the overflow rim of the pan.

It has to, because the secondary condensate drain line is higher than the primary condensate drain line, and the secondary is intended to allow water filling the pan when the primary condensate line is blocked to overflow into the secondary drain line - without overflowing the rim of the primary condensate pan (otherwise, the secondary condensate drain line would be useless - right?).

Jerry, curious why you think they are worthless at preventing overflowing water and damage. If it works properly, and your argument may be that they don't work properly, then it will shut off the condensing unit preventing the pan from overflowing, yes?

Thanks Jerry

Ok Jerry

When were talking pans, most of the time we a referring the the lower overflow pan. Just got a little lost there for a moment.

And yes I have seen those switches before installed just like that. I guess to find out if they work we have to go beyond the scope of our inspection and block the drain line and see if the float switch shuts the unit off.

Na, ain't doin it.

Originally Posted by Matthew Barnicle

Jerry, curious why you think they are worthless at preventing overflowing water and damage.

Matthew,

You lost me on what is worthless.

If it works properly, and your argument may be that they don't work properly,

Guessing you are referring to cut off switches.

Yeah, they don't always work.

then it will shut off the condensing unit preventing the pan from overflowing, yes?

Maybe.

If you are talking about the large auxiliary pan, yes, that should keep the pan from overflowing as those pans are typically large enough to catch all the water.

If you are talking about the small primary condensate pan, when the ice on the coil melts (from shutting the system down), no, that water will over flow all over.

Many people (HVAC people) tend to *not think about* iced up coils and what happens to all that water when the ice melts. They assume that the coil is not clogged and dirty, only the condensate line is clogged, so shutting the system off does not produce much water - they think. If you have a full primary condensate pan and shut the unit off, the water being held up on the coil by the fan will run down and overflow the pan anyway.

Ted,

Here is an example of a failed shut-off switch. The pan was full of water at this unit and the equipment was still running cranking out the condensation.

As you can tell from the pan, it wouldn't be long till the ceiling below is ruint.

If its electrical you can count on it, it will fail someday.

rick

Rick

I just looked at that picture for about 3 seconds. I hope you went to your truck and brought your shotgun back in and blew that damn thing out of it misery for your client. What a sorry site the rest of the unit must have been.

Yeah, after consulting with the owner and other family members we all decided after a prayer that we'd pull the plug on this thing. It had fought a good battle but it was time to say our goodbyes.

Its gone to little evaporator coil heaven.

rick

Personally (even though allowed by code), I do not trust the float switches as the only means of preventing water overflow in the auxiliary pan. I have tested way too many that did not cut off the unit. As said before "belt and suspenders". When I see a float cut-off switch only and no drain line on the pan I let the client know that it would be better to have a drain line on the pan instead of, or in addition to the float switch.

I told a client as much last week. He had his buddy who is an HVAC guy come out to also inspect the mechanical stuff and he told him the very same thing as soon as he went up in the attic and looked at the unit.

Better safe than sorry IMO. I gotta wonder why the code allows the float switch only approach on the pan. Have the people who wrote this portion of the code never field tested these things?

Eric

Originally Posted by Eric Shuman

I have tested way too many that did not cut off the unit.

What were you checking for?

Many are wired to shut the compressor off and leave the AHU fan running, that is hard to tell when you are in the attic.

Others are wired to shut the entire system down, remember that many have a time delay on shutting the AHU down - to allow for using as much of the already-cooled-coil effect as possible.

Have the people who wrote this portion of the code never field tested these things?

Field test?

How about "ever installed one"?

I found very few installed where they would work.

That includes:

- placing the switch at the high-and-dry end

- placing the switch down in the pan, laying on the bottom

- placing the switch at an angle on the side of the pan, where the float will try to raise at an angle, binding up and not doing anything

- placing the switch so high on the pan that by the time the float rises enough to click the micro-switch, the water is overflowing the top of the pan

- the list is almost endless as to what is done wrong

The list of them being installed correctly is short:

- (okay, not sure I've seen any installed absolutely correctly where they will work as intended)

Then there were the old types which you placed a easily dissolvable (is that a word?) table (many HVAC technicians used aspirin tablets) on the bottom of the pan and the switch arm rested on the tablet, when water got in the pan, the tablet dissolved and the arm dropped, shutting the system off. The problem with them, though, was that the humidity in the attics would soften the tablet over time, allowing the arm to crush the now powdery tablet, shutting the system off needlessly.

Jerry,

Yeah, I have run across both types - shut down the compressor only and shut down everything. Typically, if the air handler fan does not shut down I will wedge the float up and then go check the compressor. However, if there is a time delay on some of these, maybe I am not waiting long enough on some units? When you refer to the time delay type, approximately how long of a delay are you referring to?


Thanks,

Eric

Originally Posted by Eric Shuman

When you refer to the time delay type, approximately how long of a delay are you referring to?

Eric,

Depends on the efficiency of the system. Could be from less than a minute to more than several minutes.

The system we had in South Florida, which we had installed in 1996, 14.7 SEER (near the top in SEER rating at that time), had a variable speed fan and the fan would stay on for several minutes, then slowly 'wind down' before actually stopping.

As I was typing the above, our a/c here shut down, the AHU is in the attic above my office and the condenser unit is outside the exterior wall - I heard the compressor shut down, then the AHU shut down maybe 30 seconds later (it is an older system which was in the house when we bought it, not due for replacement quite yet, but is 'on our list').

The higher the SEER, the more likely the AHU is to run longer, to use all the energy it can from what was produced while the compressor was running - that is one way they get a higher SEER rating (by 'wasting' less). If you allow the coil to 'warm back up' on its own, you have 'wasted' that 'cooling energy' still in the coil.

Got it.

Thanks Jerry,

Eric