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Automatic Water Feeder shuts off at low water? Plumber says it's the thermostat

Automatic Water Feeder shuts off at low water? Plumber says it's the thermostat

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  #1  
Old 04-26-13, 11:31 AM
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Automatic Water Feeder shuts off at low water? Plumber says it's the thermostat

Here's the situation. Hope you can help me. I have a:
-Honeywell YTHX9421R5010 Prestige IAQ Comfort System Kit (Includes Thermostat, EIM, Portable Comfort Control, Outdoor Sensor)
- Burnham SIN5LNC gas steam boiler
- McDonnell low water cut off 24 v.a.c switch PSE-802

We have a manual water feeder before, and everything was working fine. Note that when the boiler ran out of hot water, the water cut off switch would cut off power to the thermostat (not sure if that's normal, but it's part of the problem below).

Our plumber installed a VXT-24 automatic water feeder switch. The problem is that when the boiler runs out of water, the power gets cut off, including to the VXT which is connected to the McDonell, so the boiler doesn't get refilled.

Our plumber is convinced the Honeywell is the root cause of the problems (he hasn't seen this type of thermostat before), but I'm not so sure. Why can't the VXT get it's power from the transformer directly, instead of getting it from the McDonell cut off switch? Does it makes sense the thermostat gets it power cut off when the boiler runs out of water?

Right now we're at a standstill since the plumber doesn't want to deal with it until we install a normal thermostat.

FYI - EIM connectors used: R,C to thermostat, W1, R, C to boiler.

PSE-802 to VXT: N (white), H (Red).

Edit: I have done some more research. Shouldn't there be a 3rd, feed, cable from the PSE-802 to the VXT?

Manuals:
http://ecomfort.com/PDF_files/Hydrol...structions.pdf
http://s3.pexsupply.com/product_file...structions.pdf

Thank you,
Mark
 

Last edited by realexm; 04-26-13 at 01:09 PM.
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  #2  
Old 04-26-13, 06:44 PM
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I am not familiar with your equipment and I did not look at the links. I CAN state with certainty that your equipment is incorrectly wired. It may also be incorrectly plumbed.

As a general rule an automatic water feeder should NOT be relied upon to maintain boiler water level.
 
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Old 04-27-13, 06:35 AM
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Agreed with Furd! It is not the thermostat, the feeder is wired improperly.
 
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Old 04-27-13, 09:58 AM
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Name:  BOILER_WIRING.jpg
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I don't if it this helps... To the best of my knowledge, this is the wiring...
 
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Old 04-27-13, 10:22 AM
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Old 04-27-13, 01:14 PM
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I have no idea what a "splicer", "psi box" or "boiler valve?" may be but I will check the linked manuals and get back to you. It may take a day.
 
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Old 04-27-13, 02:37 PM
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I appreciate all the help. Let me try to describe the items:
- Splicer: a plastic electricity splicer where a bunch of cable come in one side, and go out another
- PSI box: I believe this is called a Honeywell pressuretrol
- Boiler valve: cables that are running down and inside the boiler. I believe this is might lead to the ignition system (I mistakenly called it a valve). Hope this helps.
 
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Old 04-28-13, 01:24 PM
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Do you only have an electronic LWCO? It looks as though that LWCO is a manual reset.
Description
The probe is a manual reset low water cut-off control. The control unit has a red LED light
to alert personnel to a low water condition and a green LED to indicate normal operation.
Lockout delay
When a low water condition occurs, the burner turns off and the red LED begins to blink.
When the water level is not restored to a level above the probe within 60 seconds, the
control locks out. Press the reset button when the water level is restored to a level above
the probe.
You should have a float type LWCO as well but it looks like this LWCO will reset if water level is restored in 60 seconds... it could be that you are not restoring the water level quick enough.

With that many components it is likely that the wiring needs to be gone over in person to verify proper wiring. Find a new contractor.
 
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Old 04-28-13, 07:24 PM
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Okay, I looked over the wiring diagram for the boiler and with the information you have supplied I have come to the conclusion that your "plumber" probably installed the water feeder incorrectly. The feeder should be set up so that it feeds water BEFORE the original low water cut-off actuates. Generally the lwc/o should actuate with a water level between 1/4-inch and one full inch above the bottom gauge glass fitting. The water feeder should maintain the water level at about 1/2 the distance from the bottom to the top gauge glass fitting.

Note that these measurements are approximate. Every installation is unique and needs to be evaluated in regard to the entire system.

Because of the dangers involved I cannot offer any more assistance. HVAC is correct that you need someone else to set up your boiler, preferably a steam heating technician and not a routine plumber.
 
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Old 04-29-13, 04:19 PM
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Thank you

Thank you all for responding. Much appreciated.
 
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