steam pressuretrol experiment

[Deleted User]

factory indicated settings/scale on pressuretrols.
i made a test rig and utilizing a column of water, found that on a new honeywell pa404a control, i had to set the cut in at almost 2psi and the differential at 1 1/2 in order to get the switch to close at 1/2 psi and open at 1 1/2 psi. utilizing the water tube column. i feel safer trusting the water column over the dials. was just looking for other opinions on this. im now going to think twice before adjusting a pressuretrol based solely on its dial.

frank_2

I'm wondering if the lack of a pigtail has anything to do with the differance in the settings.
HONEYWELL------what do you think?

Unknown

Works for me...

I put a hose adapter on a piece of clear hose and set the control right in place on the boiler, measured from the water line. It measures vacuum, too. Just connect to the boiler drain valve.

canuckDale

Notoriously Inaccurate

I have never trusted those dials nor the modulating ones with the wiper blade rheostats.

Nice rig!

For higher settings we use a pneumatic sequencer. Bulb charger (like a Dr.'s bp device) and an 'accurate' gauge.

And a pigtail shouldn't matter because the valve/control train is a closed system.

Boilerpro

I think you got lucky..Most of the time

they seem to operate much higher than the scale indicates at least on the newer ones I've seen. They don't appear to be properly adjusted from the factory. Oh course, they are only supposed to be accurate midscale 5 to 7 pounds... which makes them useless for most applications. I would like to see the boiler manufacturer's either start using a control and pressure guage with a more appropriate range or just leave the components out and let the contractor install what is appropriate.

Boilerpro

Unknown

Pretty much is that way.

> they seem to operate much higher than the scale

> indicates at least on the newer ones I've seen.

> They don't appear to be properly adjusted from

> the factory. Oh course, they are only supposed

> to be accurate midscale 5 to 7 pounds... which

> makes them useless for most applications. I

> would like to see the boiler manufacturer's

> either start using a control and pressure guage

> with a more appropriate range or just leave the

> components out and let the contractor install

> what is appropriate.

>

> Boilerpro

Unknown

Pretty much is that way.

> they seem to operate much higher than the scale

> indicates at least on the newer ones I've seen.

> They don't appear to be properly adjusted from

> the factory. Oh course, they are only supposed

> to be accurate midscale 5 to 7 pounds... which

> makes them useless for most applications. I

> would like to see the boiler manufacturer's

> either start using a control and pressure guage

> with a more appropriate range or just leave the

> components out and let the contractor install

> what is appropriate.

>

> Boilerpro

Unknown

Pretty much is that way.

Code requires a gauge that reads twice the relief valve setting and a limit. If you desire an operating control, such as a vaporstat or a thermostat, you already can put one in. If you want a second gauge, that's ok too. Codes are slightly different in places, but the minimum is there, like you suggested. The other things are optional.

Boilerpro

Noel, I suppose..

if you guys didn't put a limit on, there would be alot of contractors out there installing steam boilers with no pressure control. Anyway of getting a pressuretrol that uses a more reasonable scale? I suppose we are facing the company accountants in this type of issue ( the p404 is cheap). The next time I get some time, I want to begin to check out your company's products... unfortunately some of the distributors that carry you products my way aren't the best. They are doing things like insisting that how water boilers be sized based on radiation and not structure heat loss. But hey, we've got you right at our fingertips, couln't ask for much more!

Boilerpro

Unknown

I would

I'd be in favor of a control that wasn't adjustable to over 12 PSI and was fine tunable with a single adjustment down to 0. 12 is the max allowable pressure on a 15 PSI relief valve; at 80%. We use controls made by major manufacturers rather than making our own. Customers want that. Most customers, by far, want the control that is on there. A lot of systems are lifting condensate with steam pressure. This is where a limit that is full range and inexpensive is required. We use Honeywell as a supplier, and they do work well. Some jobs get special attention by the installer. He can call for a vaporstat, or a Heat-Timer control, or a tekmar control. These job specefic controls will never be included on everybody's boiler. The designer chooses these, job-by-job, like a condensate tank or a backflow preventer or a zone valve.
Since the second pressure control has to be manual reset in some places, the limit we provide becomes the operating control. Some people only use ONE pressuretrol as both operating control and limit, Some people don't put a LWCO in the piping above HOT WATER boilers (yet), either.

If you order the vaporstat at the same time as the rest of the boiler trim, it becomes second nature. If control manufacturers make a better suited control, I'd love to hear of it.

Noel