Reply to Thread

Originally Posted by valdelocc

Would like to know where you got the 136mph data?

It's from a unit change calculation for unrestricted steam velocity at 1.5 PSI in a engineering text used to estimate the damage caused by water hammer and a slight exageration for a system at some reasonably normal operation. At 131 Ft/sec (the highest recommended velocity for low pressure steam in a system to avoid unnecessary errosion), the steam is traveling in a restricted system about 90 MPH (131 ft/sec*60 sec/min*60min/hour divided by 5280 ft/mile= 89.318 miles/hour). Directly below the paragraph was a test cylinder used to determine the actual force generated on an end cap by water hammer in a LP steam system and they have an insert photo showing the end cap blown off (that was what really got my attention!). Wish I still had the book; I'd be glad to give you the title...

Attachment 353851

Originally Posted by valdelocc

Weird that anyone would pipe cold make up water direct to the boiler, it doesn't make sense and seems kind of dangerous. I work on 50 to 500hp steam boilers and I dont recall ever seeing one piped that way, I have also never seeing a boiler flying through the roof at 250mph and like to keep it that way.

This is a photo of a Hoffman Series 47 water feeder and low water safety device, often found on smaller boilers and sometimes piped with a bypass "fast flood" valve around the fill valve. For gravity return systems, it's outlet is near piped at the condensate return conection or into the boiler jacket. it doesn't feed a lot of water at a time but I agree with you that tempering the water by mixing with the condensate is a much better idea where it works. If a 50 HP is as small as you work on, I doubt you see many gravity returns.

And Yes, I agree that the first boiler I see leave it's pad is one too many. My underwear will look like I hit a deer!

Originally Posted by bearfromobx

If you correct the problems, the extra pressure is a detrement, not an advantage and 1.5 PSI steam already moves about 136 miles per hour.

Would like to know where you got the 136mph data?

Originally Posted by bearfromobx

Some systems use float style mechanical water makeup directly into the boiler jacket rather than injecting into the condensate return tank and being pumped into the boiler with the returning condensate.

Weird that anyone would pipe cold make up water direct to the boiler, it doesn't make sense and seems kind of dangerous. I work on 50 to 500hp steam boilers and I dont recall ever seeing one piped that way, I have also never seeing a boiler flying through the roof at 250mph and like to keep it that way.

Originally Posted by Tecman1

One other point and something I am dealing with now at a location. The air vents at some time were capped off and in order to heat the building the pressure was increased from 1.5 lbs to now nearly 5 lbs. We are in the process of uncapping these vents which should allow for a lower pressure in the system etc. Old steam systems are very tricky.

If you correct the problems, the extra pressure is a detrement, not an advantage and 1.5 PSI steam already moves about 136 miles per hour. The higher pressure tends to create flash gas problems in the condensate system, causes water hammer and noisy operation. Back it down and find the problems rather than covering them up with extra pressure and the problems it can cause please!

No matter what you find PLEASE TAKE THE HANDLE OFF THAT VALVE!

Originally Posted by qwerty hvac

But that would not cause it to flood would it? If the air is trapped then water will not get past it.


Sent from my iPad using Tapatalk HD

Garbage in the air vents restricting the air removal or the air vent jamming up from the water pushing up on the mechanism could cause air locking of the radiators. Pull the automatic air vent out of one of the offending radiators and temporairly install a manual valve you can operate without getting in front of the outlet (remember you will have live steam coming out after the air is relieved), reactivate the system and manually bleed the radiator until you get steam at the valve, then close the valve and allow the system to run. If the air vent is the only problem, the radiator should heat normally until the system shuts down and refills with air. If the radiator heats initially and loses capacity, it is probably filling with condensate due to a problem with the steam trap not releasing the condensate back to the return and letting in fresh steam (hot on top and cooler toward the botom of the radiator after a period of operation and you might even have enough water build up to see water escape from your temporary valve).
BTW, thanks Dan Holohan and the Dead Men's Steam Society for all your help with steam heating (heatinghelp.com). When I ordered my first books, I had two sorrority houses with 80+ year old systems (a one pipe and a two pipe system) which taught me more than I would ever have expected.

Originally Posted by qwerty hvac

Attachment 340711Attachment 340721

Here is one that I was talking about. PRV on the makeup water.


Sent from my iPhone 4s
using Tapatalk

Float style valves generally don't like closing fully with more than 50 PSI on their incoming water line and can flood out the tank. Same is true of cooling tower float valves...

Originally Posted by valdelocc

thats is very weird! cause the boiler water level is controlled by a float that turns on/off the feed water pump, opening the bypass valve would overflow the condensated receiver not the boiler.

Some systems use float style mechanical water makeup directly into the boiler jacket rather than injecting into the condensate return tank and being pumped into the boiler with the returning condensate.

Checkout and drain all the water and crud in the traps on the drops first.
If that doesnt help try opening the steam traps on the rads and once again clean out any sediment which probably clogged them.
While you're at it checkout the bellows on the opened traps.

I usually go straight down to the basement directly under the return lines and work my way backwards from the cold return pipe till I check everything back to where we have heat.

Sounds like a trap issue to me. My guess would be possibly a damaged or stuck riser trap somewhere, but we would need more information about your system layout to diagnose it.

Yikes. Oh no my boiler low on water and over heating. Here I'll jus open this BOOM!!!!!

Just a note the system I am referring to has a dry return. It is important to know if you have a dry return or liquid.

One other point and something I am dealing with now at a location. The air vents at some time were capped off and in order to heat the building the pressure was increased from 1.5 lbs to now nearly 5 lbs. We are in the process of uncapping these vents which should allow for a lower pressure in the system etc. Old steam systems are very tricky.

The supply lines may have low points where condensate collected many steam systems are not the same as the original design and changes cause low points that are only noticeable when the system floods. You could try to increase the pressure to blow by these points. This is one of many logical possibilities that could cause this type of problem.

Your right but the problem wasn't the flood was it? It was after the flood when they drained the system and refilled it. Or did they even put any water back in the system. Maybe not a air problem maybe not enough water. Could be a number of things maybe need more info about what all they have checked and done.

Originally Posted by oshieldsa14

yea its called steam locking or air binding

But that would not cause it to flood would it? If the air is trapped then water will not get past it.


Sent from my iPad using Tapatalk HD

yea its called steam locking or air binding

Originally Posted by qwerty hvac

You realize we are talking about steam system?


Sent from my iPad using Tapatalk HD

Lol

Originally Posted by oshieldsa14

I think you may have air in system.

You realize we are talking about steam system?


Sent from my iPad using Tapatalk HD