MoM Vents - Alternative Orifice Source

AdmiralYoda · February 3

I recently replaced all of my Maid O' Mist vents as they only tend to last 2-4 years on my system before clogging up and rusting shut or open.

I like the interchangeability of the orifices to fine tune the system but I don't have many #4's. Rather than buy new vents just to get some #4 orifices I put my thinking cap on.

The Maid O Mist orifice thread size is 5/16-32. My first thought was to buy some short aluminum or brass bolts of that thread size and drill a hole the same diameter as a #4 but this thread size is an odd ball. I can order some bolts from McMaster but the cost of a single bolt is higher than a new vent.

My next thought was to buy some brass rod and a die and cut my own…but again still more than I wanted to spend.

The Solution

Gas/propane orifice's for gas stoves come in 5/16-32! And they are cheap as heck too, only $2.97ea. Here is a link for an orifice with a #70 hole size which equates to 0.028". The MoM #4 hole size is 0.040 so you can drill it out to any size you want. Amazon also carries some for $6.64ea with free shipping.

ethicalpaul · February 3

I was able to get the 5/16-32 tap from Amazon and I made my own devices out of brass to attach to them with my small lathe. It was a fun exercise, I was trying to make a very low-pressure check valve but I wasn't successful.

But creating the threads was successful and very easy.

But given how inexpensive a #4 vent is I would just buy a couple of them to get your orifices. Good solution on those gas orifices. I guess that must be why Jacobus chose that thread for theirs.

mattmia2 · February 3

is that a pipe thread size?

looking, it looks like 5/16 27 is 1/16 npt/nps

ethicalpaul · February 3

It's a straight thread, I'm not sure if that's what you're asking.

mattmia2 · February 3

https://forum.heatinghelp.com/discussion/comment/1839930#Comment_1839930

diameter and pitch

ethicalpaul · February 3

It's 5/16-32 as stated above

https://www.amazon.com/gp/product/B07SR6YFPK/

Jells · February 3

https://forum.heatinghelp.com/discussion/comment/1839927#Comment_1839927

I've measured what you say, but for the 2 or 3 threads that are engaged I don't think it makes a difference. Like you can use a 5mm nut on a 10-32 bolt, but not a deep tapped hole.

I've been considering an even cheaper option, these 12 for $13 range burner orifices with a 10-32 thread: https://www.amazon.com/dp/B0B5XWP548. Just tap your MoM orifice for that thread, then use it as a bushing for one of these drilled to whatever you want!

SteamingatMohawk · February 4

Search on "Maid O Mist orifices for sale. Choose Supply House for a set of 5.

In my earlier days with HH, I called MoM and a very nice lady offered to mail me a set for free. I have no idea if they are still doing that.

Your time is money, too.

Good luck.

Jells · February 4

https://forum.heatinghelp.com/discussion/comment/1840243#Comment_1840243

>Your time is money, too.

Exactly. and chasing around trying to find the correct size when I have 14 rads to deal with is a far bigger waste of time, at least IMO. But tapping and drilling is an everyday thing for me, so it's not a time sink.

Jells · February 6

So I got a 6mm x 0.75 tap (off Amazon for $4.44 with a 5.25mm drill) and tapped a MoM orifice to accept a Frigidaire range orifice and act as a bushing. The only trick was I had to flat the drill bit so it didn't catch and spin the orifice in the lathe collet. I used a 5.5mm drill since a deep thread is not an asset in this case and made it easier to tap. When I do it again I think I'll just clamp a bad valve in the drill press vise and drill the orifice installed on it, as I don't have a 5/16-27 (or 32) tap to make a jig to hold it.

The max hole diameter for the range orifice is .138" a little bigger than a 0.1285" C, if you don't install one it's hole is 5.5mm, or 0.2165, a bit bigger than a 0.185 D. Again, these orifices are $13/doz on Amazon, so you can endlessly screw around customizing the port size for very cheap.

Just one more way to skin the cat!

SteamingatMohawk · February 8

The "tinkerer" factor always wins. When I bought my rental, I had to figure out how to satisfy 4 tenants in different parts of the building, with different arrangements and orientations to the sun and wind and probably more important/annoying, different personal preferences with one thermostat. Renters turn over "occasionally" with differing "needs/wants" which I try to satisfy.

I spent lots of time swapping and adjusting an assortment of vent valve designs, but didn't get to the solution until….

I realized my two mains came together above the water line, which apparently resulted in the rear main, which is shorter, venting through its main vent and then because the front main was significantly longer, the rear main vented through the front main's vent. The guys on HH validated the need to meet below the water line and I finally reached success with the competition between the rear and front of the house. Then it was back to tweaking the specific radiator vents.

This is before.

Aside, does anyone want a pile of leftover vents, Varivalves, MoM, VentRite and maybe a couple of Gortons?

Be safe in the coming snow storms.

Jells · February 8

https://forum.heatinghelp.com/discussion/comment/1841379#Comment_1841379

Sure, PM me your address, email and the weight/box size and I'll send a UPS shipping label.

ethicalpaul · February 9

I realized my two mains came together above the water line

All too common! Nice job fixing it

MoM Vents - Alternative Orifice Source

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