Maid-O-Mist Failure Rate ?

Harry_6

Is it just me, or perhaps a bad batch, but I have recently been finding that after about a year the failure rate of Maid-O-Mist radiator vents has been around 15%. I installed 15-20 in a house and a year later 3 have failed shut. Has anyone else had this experience?

EdTheHeaterMan

Water or Steam?
Never mind, I just saw you posted in Strictly Steam!

BobC

Is the boiler water reasonably clean?

Many years ago i had a few (2 out of 6) with the wrong thread on them - straight threads, not tapered. I ran those through my 1/8 NPT die and installed them. That has to be 8-9 years back and they have all worked fine since.

i did contact Maid O Mist and they went through the stock on hand and said all the threads were fine. They did offer to replace them but I had already reworked them. You may have gotten a bad batch, i would contact them and see what they say.

Bob

ChrisJ

BobC said:

Is the boiler water reasonably clean? Many years ago i had a few (2 out of 6) with the wrong thread on them - straight threads, not tapered. I ran those through my 1/8 NPT die and installed them. That has to be 8-9 years back and they have all worked fine since. i did contact Maid O Mist and they went through the stock on hand and said all the threads were fine. They did offer to replace them but I had already reworked them. You may have gotten a bad batch, i would contact them and see what they say. Bob

They went through all of their stock and all the threads were fine.


Sure they did...... 

I'm selling a bridge if you're interested.

BobC

I worked as a tech and then an engineer at a military quality power supply house for 25 years. The reason military hardware costs so much is the mind numbing number of tests something has to be subject to to pass a military quality test. We had to follow the DOD quality practices and went through an audit every year to make sure those standards were meant. Part of the requirements were to use the AQL method to make sure a given part was up to snuff. A number of units would be randomly selected and subjected to a battery of tests. A table in the MIL spec was used to determine how many of a batch were subject to the tests.

When I contacted MOM I told them the date, vendor and failure rate I encountered. I talked to someone down there a couple of days later and they said existing units from that batch had been looked at and records examined, they could find no evidence of bad units. This was not something that took detailed examination, you could tell something was off so I was willing to believe it was a random event. The gent I spoke to gave me his extension number and asked me to call him if I found any more bad threads.

I worked in QA long enough to smell a rat and this didn't smell like one to me.

Bob

ChrisJ

BobC said:

I worked as a tech and then an engineer at a military quality power supply hose for 25 years. The reason military hardware costs so much is the mind numbing number of tests something has to be subject to to pass a military quality test. We had to follow the DOD quality practices and went through an audit every year to make sure those standards were meant. Part of the requirements were to use the AQL method to make sure a given part was up to snuff. A number of units would be randomly selected and subjected to a battery of tests. A table in the MIL spec was used to determine how many of a batch were subject to the tests. When I contacted MOM I told them the date, vendor and failure rate I encountered. I talked to someone down there a couple of days later and they said existing units from that batch had been looked at and records examined, they could find no evidence of bad units. This was not something that took detailed examination, you could tell something was off so I was willing to believe it was a random event. The gent I spoke to gave me his extension number and asked me to call him if I found any more bad threads. I worked in QA long enough to smell a rat and this didn't smell like one to me. Bob

I'm curious why a military generator using a 4A032 is so massive and heavy but only 3kw.

We have several of these engines at work and they just seem..... anemic.

BobC

Military gear is very conservatively rated but should be very robust. This assumes all the specs were met and it wasn't affected my chicanery in the procurement process. Commercial gear is usually lightly built and only lasts a few years, When I was overseas (many decades ago) we had generators 20+ years old that were used 24/7 and they just ran and ran as long as the PM was done.

Bob

Harry_6

Boiler water is fairly clean. Years ago I had a Gorton vent, out of the box, perfect and beautifully plated except with no vent hole machined in it. It was as good a vent as a pipe plug is.

PaulKolb

Check for rust inside vent . My MoM vents internal bimetal strips rusted after one year and the vents stopped working.
Shake/tap the vents to see if any rust particles come out.

RTW

As an aside, once a vent is installed and confirmed working, is there any consensus as to how often one should boil/clean them in white vinegar? Its been suggested to boil them approximately 5 minutes on this site but never read anything about frequency. Regards, Bob

ethicalpaul

I don't touch mine until/unless they show a failure

SteamingatMohawk

To what extent does boiling have any positive effect? Agitation, increased rate of chemical reaction, magic?

Neild5

Our building has approximately 100 radiators, I switched over to MoM as the old ones failed, in the last 5 years I had 2 of the new ones fail to the point that a vinegar bath didn't work. 

dko

How many years would you say a specific vent should last to get your money's worth?

BobC

A MOM #5 costs 36% as much as a Gorton #5 on Supplyhouse.com - that tells me a Gorton would have to last almost 3x as lonh assuming your replacing them yourself.
I've used them for about 8-10 years now and had no failures. I replaced all my Hoffman 1a's with MOM because the Hoffmans did not work on my system. I think ChrisJ was having the same problem, both our systems hace long horizontal radiator runouts.
The Gorton's seem better built but are they 3x better? i settled on them because of the interchangeable orifice. I have noted some complaints about them here but don't know how widespread it might be.

Bob