Prevent steam boiler flooding from a leaking VXT-24

Lid431

Hi all,

I recently purchased a rental property that is heated by steam. Currently the system is equipped with an automatic feeder (VXT-24). I'm afraid when it ever gets stuck open, it would lead to a flood. Do you guys think installing a Taco zone valve in series with the feeder could help?. I'm thinking tapping the power from the LWCO feed signal to obtain the 24v necessary to open the zone valve only when LWCO is sending the signal to the VXT. 

Logically I believe this should work out, however I'm afraid CG-400 LWCO isn't designed to power another device. Doing my research online, VXT-24 uses .5A , and adding the taco valve would add another .9(A). Do you think CG400 would have problem powering both at the same time? Not sure if I want to test it and risk blowing the board.  

I have learned a lot from this forum and looking forward to continue to learn from the forum.

Big Ed_4

If the system uses working float type air vents you should not have a flood . A build up of water would also trigger off the burner though the pressure control . In your situation I have seen more flooded boilers caused by tenants then feed valves ....

Lid431

Big Ed_4 said:

If the system uses working float type air vents you should not have a flood . A build up of water would also trigger off the burner though the pressure control . In your situation I have seen more flooded boilers caused by tenants then feed valves ....

Thanks for the reposnse !

My concern is when the feed valves mechanically stucks open.

Long Beach Ed

The VXT tends to fail closed rather than open. Never saw one flood a boiler unless it was incorrectly installed. Remember that it's a safety device and not an operating control. You should be checking the water level at least weekly yourself. If you "set-it-and-forget-it" you are definitely more prone to troubles.

Replace the valve diaphragm and plunger every five years or so and I doubt you'll ever have a problem unless your water's really bad or you are feeding with hot water. I suppose a second solenoid valve would work fine but leaves one more thing to fail.

We're landlords too. We have dozens of these and never had one fail open. But we check our boilers often.

Lid431

Long Beach Ed said:

The VXT tends to fail closed rather than open. Never saw one flood a boiler unless it was incorrectly installed. Remember that it's a safety device and not an operating control. You should be checking the water level at least weekly yourself. If you "set-it-and-forget-it" you are definitely more prone to troubles. Replace the valve diaphragm and plunger every five years or so and I doubt you'll ever have a problem unless your water's really bad or you are feeding with hot water. I suppose a second solenoid valve would work fine but leaves one more thing to fail. We're landlords too. We have dozens of these and never had one fail open. But we check our boilers often.

The feeder was installed back in 2017. So I should definitely get on it with replacing the diaphragm. I do see the kit on supplyhouse.com however it is backorder. I would get it as soon as it is available.  The feeder is piped from the hot water coming off the water heater, should I change it to the cold? 

Do you know if the the LWCO will be able to handle a zone valve in additional to the feeder?

Thanks!

mattmia2

The problem with a zone valve is it takes several seconds to a minute or more to open and the feeder measures water by opening the valve for a period of time. The solenoid valve that is part of the system opens virtually instantly. If half of that time is a zone valve opening then it will underfeed.

Lid431

mattmia2 said:

The problem with a zone valve is it takes several seconds to a minute or more to open and the feeder measures water by opening the valve for a period of time. The solenoid valve that is part of the system opens virtually instantly. If half of that time is a zone valve opening then it will underfeed.

Gonna test it our later. Zone valve from taco opens in 90 seconds and the time delay for the feeder is set to 120 seconds. 

KC_Jones

Honestly, if it's this much of a worry. Valve off the feeder and make arrangements to visit the home once per month during the heating season and use the manual button on the VXT to top off the boiler. That will take you a couple minutes total, should eliminate worry, and give you the opportunity to make sure everything is good with the system.

For me the feeders are dependable and it feels like you have invented a problem that you now want to solve. My last boiler had one that was 32 years old and still working perfect. It was fed from an old galvanized water line and as far as I know, was never serviced in all that time. This was a first generation Safegard feeder (green), so no digital readout, but I believe the actual valve was about the same as the current ones.

109A_5

Hello @Lid431,

mattmia2 said:

The problem with a zone valve is it takes several seconds to a minute or more to open and the feeder measures water by opening the valve for a period of time. The solenoid valve that is part of the system opens virtually instantly. If half of that time is a zone valve opening then it will underfeed.

If you choose to use the Zone Valve as redundant water control. To avoid this situation, you could just put the Zone Valve's End Switch in series with the LWCO circuit that calls for water (the VXT-24 feed wire). So the End Switch has to close before the VXT-24 sees a call for water.

Lid431

Update.

First I want to thanks everyone who commented . Again my concern isn't with feeder malfunctioning and leaving the boiler shut down with no water. I'm more concerned with the feeder sticking open and sends water all the way upstairs. This is a rental property so I'm not always there.


The setup works perfectly. When the LWCO kicks in , the zone valve opens within 90 seconds , and then the feeder opens after a 2 min delay.

Only thing that confused was the orientation of the valve. As you can tell from the arrow in the picture , the zone valve is in backyard. When I installed it with the arrow going with the flow , water pressure overcomes the valve and flows out when it is supposed to be closed, I verified by opening up the union downstream.  Only when I piped it backyard , the valve remains shut when it is not called for water.  

Long Beach Ed

The feeder should be piped with cold water. Hot water will leave more mung on the valve. Whether or not this presents a problem depends on your particular water quality. You'll know when you rebuild that valve. After seven years it should be pretty clean. They usually operate for 20 years with no problems.

I think you are adding one more piece of equipment to give you problems. I've had dozens of automatic feeding steam boilers for 40 years. Only once did one overfeed and it trickled out of a first floor vent. It was an old M&M float controlled valve.

As was suggested by KC_Jones, keep the thing valved off and check on the boiler every few weeks. That's usually what I do. If a boiler needs more water than that, I want to know about it and I want to fix it.

And if you're a landlord, you should have internet controlled thermostats that let you know of a problem before your tenants even feel it.

I even have cameras so I can see my boilers, their water lines and the boiler rooms.

Lid431

Long Beach Ed said:

The feeder should be piped with cold water. Hot water will leave more mung on the valve. Whether or not this presents a problem depends on your particular water quality. You'll know when you rebuild that valve. After seven years it should be pretty clean. They usually operate for 20 years with no problems. I think you are adding one more piece of equipment to give you problems. I've had dozens of automatic feeding steam boilers for 40 years. Only once did one overfeed and it trickled out of a first floor vent. It was an old M&M float controlled valve. As was suggested by KC_Jones, keep the thing valved off and check on the boiler every few weeks. That's usually what I do. If a boiler needs more water than that, I want to know about it and I want to fix it. And if you're a landlord, you should have internet controlled thermostats that let you know of a problem before your tenants even feel it. I even have cameras so I can see my boilers, their water lines and the boiler rooms.

Cameras are a great idea.