Automatic water feeder on steam boiler (C) Daniel FriedmanVXT-24 Steam Boiler Water Feeder Valve FAQs
Diagnostic & maintenance questions about the Hydrolevel VXT-24 water feeder valve

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FAQs about the Hydrolevel VXT-24 water feeder valve on steam heating boilers:

Shown & Discussed here: the Hydrolevel VX-24 24-volt programmable water feeder valve for steam boilers. This automagic water feeder is described by the manufacturer as a universal control that can be used with virtuallyt any type of probe or float type low water cutoff control found on steam heating system boilers.

The VX24 is programmable: the technician can set the make-up water feed volume, timing, and other features. The control includes both an under-feed protection to add more water than programmed if necessary and a lock-out to prevent flooding of the steam boiler.

Reader questions & answers about the VXT programmable water feeder valve & how to contact the valve's manufacturer for installation & maintenance manuals, valves, parts, repair advicve.

These articles provide diagnostic, repair & maintenance questions and answers about the various types of manual and automatic water feeder valves used on steam heating boilers, including questions and answers about when and how to add makeup water to a boiler, questions on keeping the proper amount of water in a steam boiler is a critical function for both safety and to avoid damaging the boiler itself, and questions on leaky or mal-functioning water feed valves.

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VXT-24 Steam Boiler Water Feeder Valve FAQs

Hydrolevel VXT-24 programmable water feeder for steam boilers at

Question: VXT-24 automatic water feeder from Hydrolevel - how to wire up

I just installed a VXT-24 auto water feeder from Hydrolevel company in the make up water line on a Pennco steam boiler. It has a Mcdonnell LWCO and its a gas fired unit. I'm having trouble getting power to auto feeder. It is a millivolt system. Do i need a transformer? I'm not a wiring or controls guy, can you please help - Dan G

[Click to enlarge any image]

Illustrated here, the VXT water feeder as sold by a number of online suppliers as well as at local heating and plumbing supply stores.

Excerpt from the company's product descriptin for the VXT-24 and VXT-120:

Upon a feed signal from low water cut-off, the VXT feeder delays (from 30 seconds to 10 minutes) to allow condensate to return to boiler. If make-upwater is required after the delay period, the VXT will initiate a feed cycle.

TheVXT can be set to feed to the level of the low water cut-off or can be set from 1 to 5 gallons to raise the water level above the cut-off to the normal operating level. The digital feed counter tracks all water fed into the boiler including water added using the Manual Feed Button. - source cited below.

Reply: you need a 24VAC Transformer for the VXT-24V. The commercial VXG-120 uses 120VAC (line voltage).


Yes, the Hydrolevel VXT-24V automatic water feed control for steam boilers is designed to be powered by a 24VA transformer.

That wiring detail should be in the installation instructions that came with your unit - if not, I'd check with Hydrolevel and ask for an installation guide. If you can't find the installation guide you can also send us our email (see our CONTACT link at the "More Reading" links at the bottom of this article ) and I'll send you a copy.

WATCH OUT: The particulars of how your control should be wired up depends on your boiler and the control it is replacing. Hydrolevel shows the wiring connections for quite a few control replacements, McDonnell Miller, Honeywell, etc.

Contact Hydrolevel at P.O. Box 1847, New Haven, CT 06508 Tel: (203) 776-0473, or at hydrolevel [dot] com

Reader follow-up:

thanks, the wiring diagram that came with the feeder matches the mcdonnell LWCO. i guess my problem is that i cant find where the power is coming from. the only wires that come into the unit is from the thermostat upstairs. it goes to the honeywell pressure switch, the gas valve, and LWCO. where do i wire the transformer from? thanks for the quick response. - Dan G.


Yeah Dan, I should have mentioned that sometimes the low voltage transformer that is powering HVAC controls, thermostats, even doorbells can be hidden away in a closet somewhere, or in a ceiling.

Look for an electrical junction box with a small transformer mounted on it. Also look at other controls on your heating systems - some other controls may include a LV transformer that can be used to power more devices.

Start by tracing those physical wires backwards from the LWCO - just keep following them.

Reader follow-up: thank you, you've been a big help. appreciate everything

Question: VXT water feeder digital display reading meanings

(Nov 28, 2014) Kathe said:
My VXT water feeder usually has a reading around 190. It is now 344. What does this mean?



The digital display on a VXT water feeder is a "feed counter" reporting the amount of water fed to the boiler, accurate to +/ 15% at pressures between 20 psi and 90 psi.

The VXT’s built-in feed counter records the number of gallons that enter the boiler during automatic feed cycles or if the FEED button is pressed.

When the number is increasing abnormally that suggests a problem: a leak somewhere or something causing abnormal water usage.

I'm not sure what your numbers mean, because I don't know if someone has been re-setting the counter or not. If the counter is never re-set the number would be cumulative. Hydrolevel suggests that the counter be reset each time the boiler is serviced.

the VXT water feeder is used on steam boilers and is produced by Hydrolevel, in New Haven CT, USA, Tel: 203-776-0743, Web: - the company points out that excessive water usage shortens boiler life - it's time to ask for help from your steam heating tech.

Hydrolevel has some recommendations for the amount of make-up water that should be going into the boiler, but that number needs to be matched to a specific boiler and installation.

VXT-24 Water Feeder Maintenance

Excerpting from Hydrolevel's advice about servicing and maintaining the VXt-24 (contact information & document cited in this article)

Clean Strainer: The Feed Valve Strainer should be removed and cleaned annually.

Check Feeder Operation: Feeder operation should be checked annually during boiler servicing to ensure proper operation and feed amount.

WARNING Water Damage Potential: In hard water installations, the strainer should be inspected during annual cleaning for mineral build up. If significant, the solenoid valve (sold separately) should be replaced to ensure proper operation. Excess mineral build up can impede valve operation with the potential for overfilling the heating system and causing water damage in the living space.

Record and Reset Feed Counter: The feed counter should be checked annually. If the feed amount falls within the recommendations provided in the table above, record this amount on the card provided and press the reset button (DISPLAY RST) on the bottom right corner of the circuit board. Note: If the feed amount significantly exceeds the recommendations above, the system should be checked for leaks by a qualified technician. 

Question: Trouble with & questions about the Hydrolevel VXT-24 programmable water feeder valve

(Dec 3, 2015) Rama said:
My VXT programmable water feeder started making noise. I don't know why, I'm very new to this, any help would be really appreciated

(Jan 7, 2016) Eric said:
Can you use a VXT-24 to feed a millivolt steam system? If so, HOW!

(May 19, 2016) Louise J said:
I had a VXT programmable water feeder installed two years ago to automatically feed water to the boiler for oil fired steam heat furnace. What do the numbers in this feeder's box mean? When the unit (along with a new cut off valve unit) was installed, it read 66 in that box.

It has risen now to 70. The water level in the glass tube has never been as high as the level I used to fill it manually before the system was installed. I would like to know if the rise in those numbers is a sign of something not working right? The flush out valve is opened weekly or no more than every two weeks until water runs clear. It DID have one incident when the water would not turn off from filling boiler and had to hae repair man at that time to clean and reset.

That was one month ago.The little box at that time read 66 and now reads 70, concerned!

2016/09/27 tess said:

I have a vxt automatic water feeder that won't shut off amd keeps humming. The readout sais L90..from what I've read there arethings I can do to troubleshoot before calling a repair man.What do you think it means and how do I do this?

Reply: Basic troubleshooting for the Hydrolevel VXT-Automatic Water Feeder Valve


If it was feeding water that's normal.

Watch out: If the water is not visible in the sight glass shut the boiler off immediately

Call your heating service company


Tess, check the instruction sheet for your water feeder, or if you don't have one, you can pick up a copy from Hydrolevel. 126 Bailey Road • North Haven, CT 06473 • Phone: (203) 776-0473 • FAX: (203) 764-1711 •

Here are some diagnostic excerpts for the VT-24:

Diagnostics / Trouble Shooting for the Hydrolevel VXT-24 Programmable Water Feeder for Steam Boilers

WARNINGTo prevent electrical shock or equipment damage, power must be off during installation or servicing of the control. To prevent serious burns, the boiler should be thoroughly cooled before installing or servicing control. Only qualified personnel may install or service the control in accordance with local codes and ordinances. Read instructions completely before proceeding. 

A small indicating light in the lower right hand corner of the digital feed counter illuminates whenever the low water cut-off is calling for a feed. The light remains on for the duration of the call from the cut-off regardless of the mode the feeder is in (delay, feed or lock-out). The light turns off when the cut-off is satisfied and stops calling for a feed.

If LOC appears in the digital counter, the safety lockout feature is activated. This feature engages only when the feeder completes two consecutive feed cycles and the low water cut-off does not re-energized the burner. The
feeder can be reset by briefly interrupting power to the heating system. Important: The following trouble shooting steps should be taken to determine the cause of the lockout condition before restoring normal operation.

1. If the boiler is overfilled, the low water cut-off is not functioning properly. Using the manufacturer’s instructions, check the low water cut-off operation.

2. If the boiler is in low water:

a. Check boiler and return piping for leaks.

b. If no leaks are detected, check to determine if the flow of the feeder is restricted. Check isolation valves around feeder to ensure they are fully opened. Remove and clean the Feed Valve Strainer.

c. Check the feeder setting to ensure that it is set to feed adequate water in the event of a low water condition.

If ERR appears in the digital counter, more than one or no delay or feed button has been selected. See Step 4 and Step 5 for DELAY and FEED setting instructions.

The feed delay feature is designed to prevent boiler flooding by allowing time for condensate to return to the boiler prior to feeding. If the returns and vents are in good condition, the 2-minute factory setting is usually sufficient. If for any reason condensate takes longer to return to the boiler (such as old return lines or long horizontal runs), a longer delay setting should be selected. 

LWCO Setting: The VXT feeder is shipped in the LWCO feed setting. When operating in this setting, the VXT will feed only until the low water cut-off re-energizes the burner circuit (or a maximum of 5 gallons). This will restore boiler operation, but on some applications may only be enough water to satisfy the minimum requirements. If additional water is needed to reach the boiler’s normal operating level, the 1-Gallon to 5-Gallon settings should be selected using the instructions below. DO NOT USE LWCO SETTING WITH SAFGARD MODEL OEM-24TD. 

1 Gallon to 5 Gallon Settings: When the 1 to 5 Gallon settings are used, the feeder will continue to feed until the cycle is complete, regardless of when the low water cut-off is satisfied. These settings should be used only when the LWCO setting does not provide adequate water to restore the boiler to a normal operating level.

Use the following instructions when choosing these settings:  [See Detailed Instructions that vary depending on the type of cut-off control installed - Ed.]

If the digital counter is flashing, the meter has “rolled over” (exceeded 999) representing an excessive feed amount for most applications.

Check the system thoroughly for leaks. If no leaks are found, check to determine if the make-up waterline is restricted. Check feed valve strainer for blockage or heavy build-up of debris.

Reset Feed Counter (see above) once problem is resolved.

How to contact Hydrolevel for VXT Water Feeder Valve Instructions, Parts, Repairs

Watch out: To prevent electrical shock or equipment damage, power must be off during installation or servicing of the control. To prevent serious burns, the boiler should be thoroughly cooled before installing or servicing control. Only qualified personnel may install or service the control in accordance with local codes and ordinances. Read instructions completely before proceeding.

Retail prices for the VXT-24 vary from about $200. USD to $500. USD depending on the supplier and source.


Continue reading at WATER FEEDER VALVE, STEAM - home, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.





Or see WATER FEEDER VALVE, STEAM FAQs - other diagnostic questions & answers about steam boiler water feeders

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