Natural Gas Regulators in Series

[edwardkm68]

I have a project where there is a 5"-14" w.c. regulator installed on the natural gas header line that leads to two separate condensing boilers. The natural gas lines on the boilers themselves also have regulators installed on them that are 5-15" w.c. This seems to be causing the boilers to fail on a low gas pressure alarm when put into high fire. Having two of essentially the same regulators in series like that doesn't seem like something that should be done, but I don't really know the exact effect it has and was hoping someone more well versed in this topic would be able to provide some insight as to what is happening. Regulators are a fairly new topic for me and searching online hasn't really come up with much so far.

 

[Jadnashua]

It could be that the size of your gas line is not sufficient for the volume of gas needed when they are on high fire.

What are their BTU's, and what size line is feeding them? What is the volume rating on the regulators involved? I'd expect the ones at the appliances would be adequate for the burner, since they manufacturer should know what's required, but the one upstream may not be able to handle the volume needed, or the supply pipe may be too small or long.