Some gas regulator pressure readings..

Just to characterize these MM units more, I decided to take some actual readings of the units gas pressure while it was operating, via the Schrader valve. I was going to make a valve adapter, but in the end I was able to buy a nice set of adapters for about $5. Here are the readings I got from my digital manometer:



The left unit is one of my Independence and shows a reading of 10.73" WC, while the right unit is my Liberty, showing a reading of 8.09" WC. Both my Independences measured the same and had the silver Type 689 regulator. The Liberty had the old blue Type 803 regulator.

I've been running the Independence for quite a few years and feel they are running correctly. I believe 11" WC has been the regulator pressure floating around for a while, so it's well in the ballpark. I just got the Liberty last year and don't really have anything to compare it to. It is definitely running at lower temperatures than the Independence, but I don't know if it's by design or if my unit is off kilter. I have cleaned the nozzle and the catalytic converter on the Liberty so I think its running per spec, especially since it IS catching pests. However, a low pressure regulator could be causing the lower temperatures, so if anyone out there can make an equivalent measurement on a working Liberty or Defender, I'd sure like to know the results.

So there you have it, a snap shot of 3 of my units. I'm not sure how a clogged nozzle will manifest itself in terms of pressure, but I would expect a slight increase. Perhaps I should have tested it with the nozzle closed up, but I was too lazy to open them up. At least now I will know if my regulators are acting up....

However, a low pressure regulator could be causing the lower temperatures, so if anyone out there can make an equivalent measurement on a working Liberty or Defender, I'd sure like to know the results.

This was explored in September, 2019 on the blog. Briefly, the regulators put out the standard 11 inWC. I think my problem with my old and damaged regulators was that they provided a fluctuating irregular pressure that led to an "abnormal combustion" mode that was unstable and ineffective. Since replacing the regulators, that problem has not re-appeared, I hope.

Dev wrote:

This was explored in September, 2019 on the blog. Briefly, the regulators put out the standard 11 inWC

Interesting investigation... so it would seem that my old Liberty regulator is definitely on the low side. I have purchased an IGT regulator and will see what difference it makes to the operating range.

As an update, I did get an IGT regulator and it is showing the same readings as my old unit. As an aside, I DID find a slight leak on the connection to the Schrader valve that resulted in the slightly lower initial readings. With the fittings tightened up, I now get an operating reading of 9.42" WC with either regulator. Still lower than my Independences, but it seems to be operating normally and catching pests, so I guess I'm leaving it alone...