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XTension Tech Notes

Sandhill Crane


ID: TN.HVACwater
Subject: Water overflow and your Air/Heat system
Date:4/28/98
Applicability:All versions
Contributor:Michael

Your Air Conditioner makes water !

One of the commonest causes of water damage in your home is from the water that is condensed by your air conditioner from the humidity in the air.

Springtime is a good time to call out the 'service person' (you?) who will ream out the pipe in the overflow pan underneath your A/C condenser unit.

If this is not done, you can expect sometime during the next few months that the pan will overflow and you will have water in places that your house doesn't expect.

If your A/C is in the attic, you stand a good chance of having some significant and costly damage...

I have several A/C units, but only one is 'above' the area it cools. The real problem is that it is above the 'Lab' which is chock full of equipment which are always powered on...

I have re-arranged the Lab so that the PS/2 is the only thing directly under the drip, but about once a year for the past few years, the poor thing has been found 'steaming' under a steady pour from above...

XTension to the rescue !

It would be simple to buy and install one of those automatic 'bilge pumps', but that wouldn't be in keeping with our efforts to let the little SE/30 completely take over my life... :-)

Of course, the first response was to put a large bucket under the drip, and just make sure that I checked it ever so often. You know how well that works...

Last week, was the last straw. It's not going to happen again...

Given two X-10 modules, I now can detect the water level and automatically turn on a pump. And, I can have record in my XTension Log. If I get worried about it, I can just search the log files for the last 'HVAC oflow' event.

Of course, I cheated and used a commercial water level sensor which had been lying around for a while, and one of the 'fish pond' type water pumps which are available at just about every hardware store.

I use the common X-10 Powerflash module and connect it to the 'contact' from the water level sensor. Then, when the water level is 'high enough', the Powerflash signals 'ON', and in response, a script causes the 'HVAC pump' to turn on for 5 minutes.

Here's the idea:
The float switch is
really just a 'mercury'
switch in a fancy housing
powerflash/water

And here's my ON script for the water level sensor :
water script

Some things worth considering:

If the HVAC is located above the ground, then once the water pump develops a 'head' and begins pumping, gravity will take over. Even if you don't keep the pump running long enough to empty the reservoir, gravity will do the rest.

Don't mount the float switch so that it triggers before a sufficient level of water has accumulated. Most pumps will just pump 'air' without some water level.

I found that the local feline community has decided that the water overflow pan is a good source of water... And sometimes, they cause the water level sensor to trigger from the 'ripples' in the water as they drink. So, I put a 'guard' in the script to make sure that the sensor doesn't trigger too often.

I've added a 'spoken' message to my system which tells me that the HVAC pump was turned on, and that keeps me a little more aware of the problem, and enhances my pleasure that this system is working for me.

PS: Avoiding just one water overflow event can save you the entire cost of your XTension system....hmmmmmm.....


As with all other tutorials and articles here, please take the time to let us know where things need to be changed or enhanced...

Additional help is available on our website: www.shed.com
Or directly to Michael and Paul Ferguson at: 407-349-5960
Or mail to Sand Hill Engineering Inc. Box 517 Geneva FL 32732
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