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#1, 3/4" x 1/2" Main Vent Valve
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$25.13 each
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Product Highlights
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3/4" x 1/2"
Steam
240°F Max Temp
140°F - 240°F
140°F Min Temp
Straight
Description
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Jacobus (Maid O' Mist) J1 Model #1 3/4" x 1/2" Main Vent Valve (3563000)
A straight, non-adjustable steam main vent used to release air from steam main lines so steam can fill the piping more quickly and evenly.
Key Features:
Compatibility & Applications:
Installation & Operation Notes:
Maintenance & Troubleshooting:
User Reviews & Q&A Summary:
A straight, non-adjustable steam main vent used to release air from steam main lines so steam can fill the piping more quickly and evenly.
Key Features:
- Steam main vent (Application: Main Vent; System Type: Steam)
- Straight body pattern / mount
- Non-adjustable vent
- Connection size listed as 3/4" x 1/2", with male and female threads
- Vent size: 0.1850"
- Steel construction
- Temperature range listed as 140°F to 240°F
- Manufacturer description: designed to vent air from main lines and longer runs depending on building size; suggested placement includes using one or more at the end of a short/warm-side main, and two or three at the end of a long/cold-side main
Compatibility & Applications:
- Intended for steam heating main venting applications (as listed/stated)
- Manufacturer describes use on steam main lines and longer runs, with quantity guidance based on main length and building "warm side" vs. "cold side"
- Must only be used where the manufacturer specifies this exact part number/model: J1 (Model #1 / 3563000)
Installation & Operation Notes:
- Installation should be performed by a qualified steam/heating technician.
- Reference the steam system/boiler installation and service documentation for correct vent location, safe shutdown/cool-down steps, and correct sealing practices for threaded steam fittings.
- Verify the vent is installed in an orientation consistent with the system's service guidance for proper operation (the provided sources do not include detailed installation drawings or step-by-step procedures).
Maintenance & Troubleshooting:
- Main vents are commonly serviced or replaced when a steam system vents air poorly (slow heat), heats unevenly, or when an existing vent leaks or does not seal properly.
- If performance issues persist after replacement, consult the steam system documentation to confirm vent placement, main pitch/drainage conditions, and that the installed vent capacity matches the main's venting needs.
User Reviews & Q&A Summary:
- Fit/use themes: reviewers commonly describe it as a good-value main vent with useful venting performance, often comparing its function to other "#1"-sized main vents.
- Installation themes: many describe it as a quick, straightforward replacement when matching existing connections.
- Performance themes: several reviews mention replacing vents that leaked steam and reporting improved system behavior afterward; a smaller set of feedback notes variation versus older units and occasional sealing/leak concerns in some installations.
Specs
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| Application: | Main Vent |
|---|---|
| Model: | #1 |
| System Type: | Steam |
| Size: | 3/4" x 1/2" |
| Adjustability: | Non-Adjustable |
| Temperature Range (F): | 140°F - 240°F |
| Min Temp (F): | 140°F |
| Max Temp (F): | 240°F |
| Vent Size: | .1850" |
| Mount: | Straight |
| Material: | Steel |
| Body Pattern: | Straight |
| Thread Type: | Female Male |
| Thread Size: | 1/2" 3/4" |
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Product Reviews
4.67 out of 18 reviews
94% would recommend this product
5 star
78%
4 star
17%
3 star
0%
2 star
6%
1 star
0%
Most Liked Positive Review
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Good main steam vent
Good quality main vent with decent venting capacity. Versatile threading (male 3/4" or female 1/2"), and removable orifice for cleaning. Got two of these to augment smaller steam vents on my residential mains that needed more venting. Roughly equivalent to a Gorton #1. Fairly compact vent so good if you don't have a lot of clearance.
VS
Most Liked Negative Review
Not what I ordered previously
I ordered six of these in 2012, and those are rock solid. However, the three I just received are now different than those previous six, and after installing them, two are not sealing well.
I wish I could find a main vent that doesn't leak as Gorton also changed and these are replacing several of those which have leaked since day one, even replacements of those Gorton leakers.
Showing 1-10 of 18 reviews
All good
Came quickly! Installed easily and is venting as expected.
Jeff
PA
4 months ago
Verified Buyer
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Prompt Service!
I was looking for an original Maid-o-Mist air valve for my steam boiler. Supplyhouse.com had just the part I needed. I would recommend their products.
Adrian
New York
2 years ago
Verified Buyer
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Main vent valve
Part arrived in a very good timely manner. Was identical to existing part. Took about 10 minutes to install....supply House rocks....
Joe
Ohio
3 years ago
Verified Buyer
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Plumbing needs
This is my go to place for my plumbing needs. Great service and quick delivery.
Buddy
New York
3 years ago
Verified Buyer
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Work great
Not only did I get the one above , I replaced some leakers with #4,5,and 6, will see how it goes this winter
Butch
Mi
3 years ago
Verified Buyer
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I would buy this product again.
This vent works very well.
Tom
Mohawk, NY
3 years ago
Verified Buyer
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Works fine- Quick Delivery
Replaced an almost new Gorton air valve that leaked steam with this one. It's woking fine. The delivery was ver fast.
Jack
Bronx, NY
4 years ago
Verified Buyer
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You get what you pay for!
I purchased main vent valves on 2 occasions from 2 places. Both were the same type : China made in a plastic bag. They leaked steam every time turning my basement into a sauna. I saw this advertised (American made but more expensive) and figured, "why not try'? Well they worked. My boiler has not needed water in 2 months. (Used to top off every other day) I am so pleased I purchased these brand for every vent in the house. The heating system has never worked better! Life lesson learned.
Mike
NYC
4 years ago
Verified Buyer
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yes
Good service - good price !! Whats not to like !
Alfie !
Blue Island IL>
5 years ago
Verified Buyer
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I would buy from Supply House again.
Products arrived on time and performed as intended
Mcgyver
Queens NY
6 years ago
Verified Buyer
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