Pressuretroll Question

cubicacres

We just had a new single-pipe steam boiler install, and were thinking of the .5psi cut-in & 1.5psi cut-out. We saw our 2 pressuretroll meters per the photos below. Any thoughts on what they're reading? Our 0-30psi gauge doesn't register at all, so maybe we should get a 0-5psi gauge or something that's more sensitive? We thought they said it was set for .5psi cut-in & 2.0 cut-out, but both read "cut-in" at the top.

ChrisJ

The reading on the pressuretrol is meaningless.

Get a good low pressure gauge and use that to set things up.
You may also find you have trouble getting those units to work well at low pressure, I don't like them at all which is why I kept my old mercury type.

ChrisJ

If I needed something to control pressure, I'd want this.

http://www.supplyhouse.com/Honeywell-L408J1017-Vaporstat-Controllers-0-psi-to-4-psi

Jamie Hall

Well now. The reading on a pressuretrol -- like yours -- isn't meaningless, just incomplete. It appears that yours are set for a 1 psi cutin pressure, which is a bit high for most systems -- but is about as low as a pressuretrol can go, reliably. What you also need is the cutout pressure, which is set by taking the cutin pressure -- which you can see -- and adding the differential, which you can't see. If you take the cover off, though, you would find a white dial labelled, as I recall, differential -- and it should be set to 1.

Chris is right, in a sense -- it would be better to use a device called a vaporstat in place of either of the two pressuretrols, but this may be an unnecessary frill for many steam systems. There are some which require it, however -- two pipe vapour systems, which operate at lower pressures. Without knowing what your system is, I can't comment on that.

ChrisJ

Jamie Hall said:

Well now. The reading on a pressuretrol -- like yours -- isn't meaningless, just incomplete. It appears that yours are set for a 1 psi cutin pressure, which is a bit high for most systems -- but is about as low as a pressuretrol can go, reliably. What you also need is the cutout pressure, which is set by taking the cutin pressure -- which you can see -- and adding the differential, which you can't see. If you take the cover off, though, you would find a white dial labelled, as I recall, differential -- and it should be set to 1.

Chris is right, in a sense -- it would be better to use a device called a vaporstat in place of either of the two pressuretrols, but this may be an unnecessary frill for many steam systems. There are some which require it, however -- two pipe vapour systems, which operate at lower pressures. Without knowing what your system is, I can't comment on that.

Jamie,
Every Pressuretrol I've checked the scale did not agree with a pressure gauge, not even close. That's meaningless in my book.

The Vaporstat I posted is 0 to 4 PSI. This is the proper operating range for any steam heating system and will be easier to adjust and more reliable at normal pressures. That Vaporstat is what all boiler manufacturers should be shipping with new boilers, but I guess they don't like the extra cost.

cubicacres

That 0-4psi Vaporstat would seem like a closer match for our operating pressures, along with a 0-3 or 0-5 psi gauge. Would that just be a single Vaportat to replace both pressuretrolls that we have now? Any harm in swapping them out in the future? Kind of makes us wish they did that Vaporstat setup instead of the 2 pressuretrolls on a shared pigtail recently.

ChrisJ

cubicacres said:

That 0-4psi Vaporstat would seem like a closer match for our operating pressures, along with a 0-3 or 0-5 psi gauge. Would that just be a single Vaportat to replace both pressuretrolls that we have now? Any harm in swapping them out in the future? Kind of makes us wish they did that Vaporstat setup instead of the 2 pressuretrolls on a shared pigtail recently.

I would assume you have two pressuretrols because it's required by code? If so, I'd just swap out the main one with a 0-4 vaporstat. The other one is just a safety limit so it's fine.

Jamie Hall

I guess I've just had better luck than you, Chris -- both of mine are within a few ounces of what they're set for. They're older...

ChrisJ

Jamie Hall said:

I guess I've just had better luck than you, Chris -- both of mine are within a few ounces of what they're set for. They're older...

The newer style ones are really really bad.
I've heard even the Vaporstats aren't anything great when it comes to the scale on it.

SteamedInWharton

When I finally got a low pressure gauge and then cleaned the pigtail, I found my nominal 1.5 cut out/ 0.5 cut in was in fact 2.2 and 1.2 . I got out the .050 hex key per directions here and started tweaking the adjustment. I ended up at about 1.35/0.35 and called it good enough.

Fred

These Pressuretrols can be calabrated to be virtually dead on. I've done it and have posted the procedure on this site several times and others have recalibrated theirs with great success (or so they have told me). Obviously, they are not meaningless, probably 90% of the steam systems in use depend on them for some level of control and/or safety.
Many of us prefer the vstats but they are not a requirement, especially for a single pipe/most two pipe, single stage residential boilers.
@cubicacres , put a 0-3 pSI gauge on the boiler and see how far off your Pressuretrols are before spending more money on a Vstat. The fact of the matter is, if the boiler is reasonably sized to the EDR, neither the Pressuretrol or the Vstat will trip because the pressure will never get to the Cut-out pressure. The boiler will shut down because the thermostat is satisfied. In reality, the Pressuretrol and Vstats are a safety device to shut the boiler down, should pressures get too high, for some reason.

KC_Jones

I have 2 new vaporstats on mine and I can tell you they were WILDLY off out of the box. First they didn't agree with each other by 5-6 ounces. Second one of them was so bad I set it at 8 ounces and buried the 15 ounce gauge and it still didn't trip. I was able to get them close, but they still aren't right. The fine tuning only has so much adjustment before it gets "screwy". I even went so far as to adjust the front read out to the limit to get it closer. Btw these are 0-16 ounce vaporstats so being off by over 8 ounces to me is quite unacceptable. I thought about sending them back, but since they didn't even agree with each other that seemed like a complete waste of effort. Oh and when I was calibrating I actually borrowed a second gauge to verify it wasn't my gauge, I duplicated the result with the second gauge. It became very clear why Gerry Gill created his own setup.

cubicacres

I think that 2nd pressuretroll is per code-I'll verify that when I call the city inspector back.

Can I simply switch the 0-30 psi gauge with a 0-3 psi gauge? Is there any reason to want a gauge that reads above 3 psi if it almost never gets that high? Is it as simple as turning off the boiler & replacing the gauge? If so, would there be a reccomended brand or type of gauge to look at?

KC_Jones

Generally the 0-30 is a code requirement.

vaporvac

NO. You need the 0-30 by code.

Fred

The 0-30 has to stay, per code but you can put a brass Tee on one of the Pressuretrol pigtails and add the 0-3 PSI gauge. Yes, turn the power to the boiler off, take the 0-30 PSI gauge off, add a short nipple and a Tee, another short nipple and an elbow install the 0-3 PSI Gauge and re-install the 0-30 PSI gauge. It is a simple task. Here is the site for the 0-3 PSI gauge most of us use:
http://www.valworx.com/product/low-pressure-gauge-25-0-3-psi

SWEI

IIRC, the code requires a pressure gauge capable of reading twice the rating of the relief valve. Residential translation: 30 PSI gauges on steam boilers, 60 PSI gauges on water boilers.

ChrisJ

Fred said:

These Pressuretrols can be calabrated to be virtually dead on. I've done it and have posted the procedure on this site several times and others have recalibrated theirs with great success (or so they have told me). Obviously, they are not meaningless, probably 90% of the steam systems in use depend on them for some level of control and/or safety.
Many of us prefer the vstats but they are not a requirement, especially for a single pipe/most two pipe, single stage residential boilers.
@cubicacres , put a 0-3 pSI gauge on the boiler and see how far off your Pressuretrols are before spending more money on a Vstat. The fact of the matter is, if the boiler is reasonably sized to the EDR, neither the Pressuretrol or the Vstat will trip because the pressure will never get to the Cut-out pressure. The boiler will shut down because the thermostat is satisfied. In reality, the Pressuretrol and Vstats are a safety device to shut the boiler down, should pressures get too high, for some reason.

I need to make something clear.
I didn't say Pressuretrols are meaningless, I said the scales on them are meaningless and a low pressure gauge should be used to set them.

As far as 90% of steam systems depending on them for control and safety, sure, the unit will do that but some steam systems are also running more pressure than Titanic's low pressure turbine did (9 PSI).

Using a 2 - 15 PSI Pressuretrol at the extreme low end of it's range just seems like a bad idea in my opinion.

Then again, maybe the entire reason for this is because it's intended to be nothing more than a high pressure limit for safety reasons rather than a device to modulate steam pressure. The system it self should be handling that. For a high pressure limit for safety, 5 to 10 PSI is perfectly acceptable.

ChrisJ

cubicacres said:

I think that 2nd pressuretroll is per code-I'll verify that when I call the city inspector back.

Can I simply switch the 0-30 psi gauge with a 0-3 psi gauge? Is there any reason to want a gauge that reads above 3 psi if it almost never gets that high? Is it as simple as turning off the boiler & replacing the gauge? If so, would there be a reccomended brand or type of gauge to look at?

With all of the changes I've done, you'll notice my stock 30 PSI gauge and Pressuretrol are still mounted on the supplied pigtail from WM. My actual pressure limiting device for normal operation (1 ounce) is mounted without a pigtail next to the large low pressure gauge on a straight piece of pipe on top of the boiler. It's gold colored with a large sideways mounted diaphragm.

But, should something go horribly wrong, I still have the OEM equipment for protection.

cubicacres

Thanks for the info. That explains the 0-30 psi gauge that we never see move off 0 psi, to satisfy our code requirements.

When our installer's tech returned to fix a few things yesterday, we had a leak in the 4 inch riser at a union just off the header (all new piping). He didn't have a 4+ inch wrench for the large union, so just whapped it with a hammer on one side several times to tighten it up and prevent it from dripping again. Any thoughts on if this might lead to future problems we should watch out for before insulating all that near-boiler piping up again? Another thought was was this a sign our steam was wet a foot up from our 4 inch header where we saw the leaking union? He thought it just turned back to water once it hit the 80 degree boiler room air, and we shouldn't worry about it being a sign of wet steam after the header.

ChrisJ

Yeah.......
I'd tighten the union properly.

It has nothing to do with wet steam, but it does mean the union is probably loose. Still.

cubicacres

With a 4 inch pipe & union around it, would we need a 5-6 inch pipe or so pipe wrench to fit around that union?

Fred

cubicacres said:

With a 4 inch pipe & union around it, would we need a 5-6 inch pipe or so pipe wrench to fit around that union?

Yes you will need at least a 5" probably a 6" to grasp it well. Hammering is not a good idea.

cubicacres

Then we might want to ask them to return with a 6 inch wrench. Does hammering have the potential to work other joints lose?

Maybe tighten the other side to get a little slope towards the eqaulizer while their there, since tightening the union might make it slope the wrong way, back to the first riser. Ideally should it slope a little toward the equalizer for water to flow back to the boiler? They thought with a 4 inch header, enough water would flow back even it if didn't have a good slope or was close to level.

KC_Jones

There should always be a little slope towards the equalizer especially with a drop header. Even with slope there is always a little water laying in the fitting because the pipe itself creates a dam in there. No need to add to that with poor or no slope. If it's level I don't think I would raise a huge stink about it, if it is sloped the wrong way that I wouldn't want.

ChrisJ

A 4 or 5 foot wrench should fit a 4" union.
The wrenches go by handle length and he'll need two of them.

cubicacres

ok-thanks.