Thread: Position of secondary drain

Sometimes I see this (mainly on new houses), where the secondary drain is pointed up (see photo), instead of down as logic would seem to dictate. I don't know why the secondary would be posited this way. Anyone know?

Thanks, Gene

So it is also trapped ... like it is required to be.

The problem I see with it, or it may be an optical illusion from the angle of the photo, is that the top of the outlet is even with or above the bottom of the air handler ... all that does is back the overflow up into the equipment drain pan.

Originally Posted by Jerry Peck

So it is also trapped ... like it is required to be.

The problem I see with it, or it may be an optical illusion from the angle of the photo, is that the top of the outlet is even with or above the bottom of the air handler ... all that does is back the overflow up into the equipment drain pan.

It's not an illusion. You're are right. It is higher that the bottom of the pan. I share your thoughts. I tried to angle it downward but it was cemented with PVC glue.

Gene,

These switches are excellent for the secondary condensate drain outlet fitting - when the primary condensate backs up the equipment pan backs up into these switches, the float raises, and the unit shuts down.

B18-417 | Safe-T-Switch | SS2AP | Johnstone Supply

Being as there is no outlet (no flow-through) there is no need for a trap either. These thread directly into the secondary drain.

I know home inspectors cannot - should not - make recommendations, but being able to describe a potential solution helps the client when they are talking with the a/c contractor and either the contractor brings these switches up or the clients brings these up.

IMO in freezing climates it's better to connect those switches to a 12V alarm sounder - I'd much prefer that a client calls to complain that overflowing AC condensate damaged the ceiling below an attic furnace in the middle of a hot summer than that a condensing furnace shut down the the day they left for a two week vacation - in the middle of winter!

Originally Posted by Michael Thomas

IMO in freezing climates it's better to connect those switches to a 12V alarm sounder - I'd much prefer that a client calls to complain that overflowing AC condensate damaged the ceiling below an attic furnace in the middle of a hot summer than that a condensing furnace shut down the the day they left for a two week vacation - in the middle of winter!

They have audible alarms and switches - I have one or two laying in my garage that I've never installed, was given them at trade shows.

However, if the switch is going to freeze and not shut off, how is it going to sound the audible alarm?

Also, if one places a condensing furnace in an attic open to freezing air ... isn't that kinda dumb, given that they know water freezes and the condensate water is in the freezing air?

The scenario I'm discussing is the one in which no secondary drain is installed, and a float switch at the secondary drain outlet or in a pan underneath an otherwise operable furnace disables the furnace because the primary drain has clogged or has been otherwise disabled.

If that happens in freezing weather and the property is unoccupied, pipes will freeze and burst.

This isn't a theoretical problem. I've actually seen it happen when loose fill insulation gradually obstructed the primary drain from a pan under an attic mounted horizontal furnace. As the pan filled with condensate from the condensing furnace, it tripped the float switch in the pan, disabling the furnace. The owners were out of town on vacation, and water from bursting pipes ran into the house for more than a week prior to their return.

Originally Posted by Michael Thomas

IMO in freezing climates it's better to connect those switches to a 12V alarm sounder - I'd much prefer that a client calls to complain that overflowing AC condensate damaged the ceiling below an attic furnace in the middle of a hot summer than that a condensing furnace shut down the the day they left for a two week vacation - in the middle of winter!

We don't get many condensing furnaces here since we are primarily a cooling climate. The preferred method for me (not code requirement) is to trap and vent the primary drain properly, float switch in the secondary that shuts off the a/c unit only, then also have the drip pan that is drained outdoors. This negates the need for the secondary drain trap which is pretty useless anyway since they are usually dry. I realize this is above code requirements but I'm a belt AND suspenders type of guy and so are my recommendations.

Does anyone have any example of a float switch or even the Safe-T switch failing? I'm a fan of redundancy and like having the secondary overflow. If I see a float switch, I generally think, "One more electric/electronic thing to fail."

Originally Posted by JB Thompson

Does anyone have any example of a float switch or even the Safe-T switch failing? I'm a fan of redundancy and like having the secondary overflow. If I see a float switch, I generally think, "One more electric/electronic thing to fail."

And the secondary condensate overflow drain can get clogged - I have seen that too.

"too" as in, yes, I have seen those safety shut off switches fail, but I have seen more secondary condensate drains clogged, and auxiliary pans rusted out, and float switches in the auxiliary pans fail, and ... yes, everything can fail at any given time.

Originally Posted by JB Thompson

Does anyone have any example of a float switch or even the Safe-T switch failing? I'm a fan of redundancy and like having the secondary overflow. If I see a float switch, I generally think, "One more electric/electronic thing to fail."

During an inspection a while back, I opened the return filter grill below the air handler and when I removed the filter, I saw water dripping down from under the air handler. I removed the float switch and the float chamber was full of water. I turned the float switch upside down ( so the float when to the top as if water lifted it) but it still didn't shut the unit down.

I talked to an HVAC contractor and he said it was pretty common for them to fail.

Originally Posted by Robert Sole

During an inspection a while back, I opened the return filter grill below the air handler and when I removed the filter, I saw water dripping down from under the air handler. I removed the float switch and the float chamber was full of water. I turned the float switch upside down ( so the float when to the top as if water lifted it) but it still didn't shut the unit down.

I talked to an HVAC contractor and he said it was pretty common for them to fail.

It may have shut the unit down, just not shut it down as you expected it too.

The float switches are wired in differently by different contractors: a) some will wire the float switch to shut the air handler off (but not the condenser unit); b) some will wire it to shut the condenser off (but not the air handler); c) some will wire it to shut the entire system down.

Wiring it as in a) is not good as the compressor keeps running and pumping the refrigerate through the system, b) is the way I see it wired most often, but to check it you would need to check the condenser unit to see if it stopped while holding the float switch 'off', while I do not recall having seen any wired as c), some of the ones I thought were wired as b) could actually have been wired as c) and I just did not hear the condenser unit shut off from being at the air handler.

That said, most of the a/c contractors I have talked with in the past prefer b) as it leaves the air handler running with its blower still circulating the air.

Personal preference of the a/c installer/technician I guess.

However, yes, they do fail, probably not as often as some a/c technicians think as they may be wired differently than they would wire it and they did not actually check to see if the condenser unit shut down, they just knew the air handler was still running. If the AHU coil froze up, the melting water could make them think the condenser unit was still operating and creating condensation - just raising a possibility.

Originally Posted by Jerry Peck

It may have shut the unit down, just not shut it down as you expected it too.

The float switches are wired in differently by different contractors: a) some will wire the float switch to shut the air handler off (but not the condenser unit); b) some will wire it to shut the condenser off (but not the air handler); c) some will wire it to shut the entire system down.

Wiring it as in a) is not good as the compressor keeps running and pumping the refrigerate through the system, b) is the way I see it wired most often, but to check it you would need to check the condenser unit to see if it stopped while holding the float switch 'off', while I do not recall having seen any wired as c), some of the ones I thought were wired as b) could actually have been wired as c) and I just did not hear the condenser unit shut off from being at the air handler.

That said, most of the a/c contractors I have talked with in the past prefer b) as it leaves the air handler running with its blower still circulating the air.

Personal preference of the a/c installer/technician I guess.

However, yes, they do fail, probably not as often as some a/c technicians think as they may be wired differently than they would wire it and they did not actually check to see if the condenser unit shut down, they just knew the air handler was still running. If the AHU coil froze up, the melting water could make them think the condenser unit was still operating and creating condensation - just raising a possibility.

No Jerry. It did not shut the unit down. The unit kept on running in cooling mode. It did not shut down until I turned it off at the thermostat. I do know how to check an air conditioner.

Originally Posted by Robert Sole

I do know how to check an air conditioner.

A lot of people know how to check air conditioners but may not be aware that the float switch is not always wired as THEY think the float switch should be wired.

I suppose you are stating that you DID check both units of the system to make sure that both units where not shut off - good, glad to hear that.

I guess next time I will let you keep on truckin' and not offer anything thing which might be of help to you ... some people are like that - they know it all already and do not want any suggestions which might possibly help them --- one way to avoid any of us trying to help you is to put a "Already know it all" in your signature, that way we will know there is no need to offer anything which you might not have known ...

Originally Posted by Jerry Peck

A lot of people know how to check air conditioners but may not be aware that the float switch is not always wired as THEY think the float switch should be wired.

I suppose you are stating that you DID check both units of the system to make sure that both units where not shut off - good, glad to hear that.

I guess next time I will let you keep on truckin' and not offer anything thing which might be of help to you ... some people are like that - they know it all already and do not want any suggestions which might possibly help them --- one way to avoid any of us trying to help you is to put a "Already know it all" in your signature, that way we will know there is no need to offer anything which you might not have known ...

Jerry,

I do not claim to "Know it all". In fact I know that there are many areas in which I have a lot to learn. To be honest, I appreciate your knowledge and especially enjoy your explanations of many of the nuances of the building codes. I am fairly competent in the code but your knowledge of it leaves me far behind. I learn a lot from you posts.

You do, however, tend to respond to many posts (and it seems to me that you do that especially to mine) with an attitude that implies that you do know everything and the person making the post knows nothing. That tends to rub me the wrong way. If that was not your intent, then accept my apology but that it the way it read to me.

As to the post I made, I was answering a question by another poster when he asked for instances where a float switch was found to be defective. Your jumping in and implying that the switch was not defective but that I simply didn't know how it worked was not offering information that would help me. It more seemed to say that you did "know it all" and even though you were not there when I found the problem that you knew that I was wrong in my assessment of the problem.

I don't claim to be an air conditioning tech and have their knowledge but I think it is safe to say that I know more about air conditioners, at least the types common in this area, than most home inspectors I have met. Notice I said most, not all.

I appreciate when you provide information that is helpful and when it is offered in a constructive manner. Please, lets try to keep it that way.

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By the way, I apologize to the others looking for information in this thread. I had no intention of hijacking it. I simply tried to provide an answer to the person who asked a question about the defective switches.

Originally Posted by Jerry Peck

b) is the way I see it wired most often, but to check it you would need to check the condenser unit to see if it stopped while holding the float switch 'off', while I do not recall having seen any wired as c), some of the ones I thought were wired as b) could actually have been wired as c) and I just did not hear the condenser unit shut off from being at the air handler.

There is, to me anyway, an obvious change in the "sound" of the air handler and/or refrigerant lines when the condensing unit cycles Off due to the float being activated.

Dom.

Originally Posted by Dom D'Agostino

There is, to me anyway, an obvious change in the "sound" of the air handler and/or refrigerant lines when the condensing unit cycles Off due to the float being activated.

Dom.

There is a sound difference, however, as I recall, you were an a/c person in a previous life.

Oh, and I was waiting for, looking forward to, a comment from you on the wiring of those switches they shut the AHU off and not the CU.