Model # 400-4

Internet #202312925

Store SKU #748457

null 1/8 in. Hy-Vent

1/8 in. Hy-Vent

$1398 /each
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Product Overview

The Taco Hy-Vent has become the industry standard for dependable long life service. The TACO 1/8 in. Hy-Vent can be easily serviced by unscrewing the vent cap. It is designed to purge unwanted air from the hydronic installation to help improve system efficiency.

  • Automatically purges unwanted air from the hydronic installation to help improve system efficiency
  • Attaches to the boiler, or it can be used throughout the system
  • Nickel-plated, brass-body construction
  • Operating pressure ratings of up to 250 psi
  • Note: product may vary by store

Info & Guides

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Product Depth (in.)
Product Height (in.)
Product Width (in.)


Accessory type
Boiler Replacement Part
Heating Product Type
Heating Technology Type
Product Weight (lb.)

Warranty / Certifications

Manufacturer Warranty

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Customer Questions & Answers

Should the hy-vent be fully closed and opened to bleed air or should the hy-vent be open about 1/4 turn all the time. ty

Asked by: Gus
Sorry for the delay I was on vacation. This is a great question. I actually leave it almost full unscrewed. The cap is there in case the vent gets stuck open and water begins coming out. Normally the vent will just burp periodically when the system is first loaded with water. It the float does get stuck open the vent can be opened and cleaned.
Answered by: chris
Date published: 2017-04-21

can this be used to vent air from a well system that is picking up air

the water system that I'm working on has 500 ft under ground to the house. it does leak down after pressure is achieved. I have a check there to save the pressure and let the pump cut off. it then leaks down and fills with air. when pump comes back on it pushes that air into the house and I need to come up with a way to bleed that air
Asked by: BHE
I don;t think this wold be sufficient to vent that amount of air. However I have heard of well professionals using a product called a spirovent to vent wells. Specially to vent hydrogen sulfide gas that make the water smell. I don;t know if it would work for what your need is but I would suggest you give them a call,.
Answered by: chris
Date published: 2016-02-16

Suitable for use with glycol systems

Asked by: dusty
Yes it can be used with glycol. However keep in mind glycol is bad for your system. The only thing worse is a freeze up. So if you have to use gylcol use it. But remember it turns acid with age. Make sure you check it annually as it will eventually destroy your heating system from the inside out if left unchecked. I put in a generator just so I could avoid using gylcol as it destroyed my last boiler.
Answered by: chris
Date published: 2016-05-14

Why does this fail and need replacing every year?

The original relief lasted 10 years from when system was originally installed. Now I can't go more than a year and this item fails.
Asked by: kvet
This is not a relief valve this is a vent. If you are using a high quality vent on a water system and it is only lasting a year. I would guess you are losing water from your system. The water is being replaced by the automatic feed. Unfortunately the new water has oxygen in it. That oxygen is caution corosion which is destoying the vent. To prove this you can check the preasure. Then shut the automatic feed and check the preasure the next day. If the preaure falls, you know you are losing water. Not all leaks produce wet spots. Often boilers will lose water and and it evaperates at the same rate. Now if you are talking about your relief valve. Please note that it is a fusable link. Once it goes off it will never seat properly again and must be replaced. So if you relief vavle is blowing off or weeping. We need to find out why. It could be that it is doing its job, so we want to find out why you built pressure. This could be caused by an aging preassure reducing valve or expansion tank. Feel free to call if you would like to discuss. Chris 978 651 3301
Answered by: chris
Date published: 2016-12-29
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Customer Reviews

1/8 in. Hy-Vent is rated 3.3 out of 5 by 7.
Rated 1 out of 5 by from Leaks less than a year I went through two of these in less than a year. They leak around the air vent plastic that the cap screws on. Replaced with a Honeywell FV180 this time, hopefully this will hold up better.
Date published: 2013-01-11
Rated 1 out of 5 by from Nor durable Did not last, starts leaking at the cap within a year
Date published: 2014-02-15
Rated 5 out of 5 by from needed for well water We live in the mountains where natural gas is abundant . Noticed the hot water would spurt and spit when turned on, sometimes extreme. Holding lighter at faucet when this occured produced flames from the water. Decided to try this as a cheap way to stop this. On hot water outlet side of the water heater added a T fitting. Out of the side port added a small length of pipe to a 90 degree fitting and then up to our hot water pipe. Straight out the top of the T added pipe to just below ceiling and used a 90 degree fitting with a 1/8 inch female port to fit the hydro vent and plugged the other side. Put plastic tubing on the air vent and ran it to the outside of wall. We can now turn on the hot water and no more spitting and sputtering and explosive venting from the faucet. Have to think outside the box.
Date published: 2016-08-16
Rated 1 out of 5 by from Avoid if can Buy it as a temporary fix but my original one lasted 23 years, and this Taco one just rotted apart after only one year. Taco not so great anymore.
Date published: 2016-06-25
Rated 5 out of 5 by from Excellent vent for baseboard convectors Very easy to install. Just put a small amount of plumbers teflon pipe seal paste on the threads and hand tighten the tools needed! I purchased these to replace my old maid-o-mist air vents. After you put your system back in service, just loosen the top thumb nut to release the trapped air- you hear the air rush out and then the unit stops the flow. Then, you just hand tighten the thumb nut again. This prevents any leakage or spitting from the unit. The other reviewers wrote bad reviews because they did not know how to use these devices properly. You just loosen the top nut, let out any air (you can hear it release and internally snap shut), then tighten the nut again. The other reviewers could solve their problem by simply following these directions. Do not follow the manufacturer's loosen the top nut one turn and leave it that way to automatically release the air - you should tighten the top nut and only loosen it when you want to manually release any air, then tighten it so you won't get any water leakage if some dirt or scale gets inside the mechanism and allows water to get out. Always tighten the nut on top after releasing air!
Date published: 2015-09-12
Rated 5 out of 5 by from excellent! It's equal if not better in quality compared to o.g. mudbone.
Date published: 2011-11-01
Rated 5 out of 5 by from Perfect ! Easy to install East install. glad I bought from Home Depot great staff to help
Date published: 2014-09-02
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