High Temp hot Water

Bob_19

wouldn't a leak in a HTHW system flash to steam and become extremmly dangerous due to the high pressures needed to keep the liquid... liquid?
I have no experience on these systems, but the picture is not good, I see this being more dangerous than a steam leak at the same pressure.

Jim_47

HTW=High Temperature Water or HTHW

Guys & Gals, I need information on High Temperature Hot water. A reference book with a lot of information would make me very happy. I currently am servicing 5 Steam generators and 6 Secondary hot water heat exchangers all "fueled" by High temperature Hot Water sold to my company from another company. As always your assistance would be greatly appreciated.
thanks
MRHEAT
(previously residential only, til now)

Gary Fereday

First ! it is dangerous

Just like high pressuer steam. It is water above the boiling point and under pressure. You should be able to get those prearmeters from the supploying co. Second Most of the pipe fitting will be welded only, by certified welders! Just have a lot of respect for it and be sure of your ideas before proceeding !
bigugh

Bill N.

Neat stuff, not new technology, be careful

Another poster already admonished you to be careful, he's right. There are some safety advantages actually, since if you have small leak, there isn't that jet of high pressure steam shooting out that can cut you (think of the legend/myth that utility steam plant guys talk about, using broom handles to check for leaks, they know they found one when the steam leak cuts the handle off). With HTHW your leak isn't quite so high velocity.

The air force was one of the first people to use it on their bases. There are some advantages (fewer leaks, smaller pipe sizes, slightly easier control of your systems, water chemistry isn't so important, no water level concerns in boiler drums) that they bought into big time. Also, here in NY a lot of the state colleges (SUNY for locals) have HTHW systems. Some are not that high (250 deg. F/250 psig) some are scary high (at least for a dumb engineer like me) 400/400.

There are some negatives of course. Your pumps need to be extra special, you need expensive control valves (one site I know likes Masonelian valves, 600 lb class, flanged in EVERY size, even 1/2"). Your expansion system needs some fancy controls and maintaining the pressure bubble (either nitrogen or steam) can make operators nervous.

I think it is pretty neat stuff. I don't think anybody is building campuses or bases with it anymore though.

Back to your original question, you're looking for a good book or manual. I think you are just about out of luck, since nobody really makes these systems anymore, I don't think many people are publishing. I remember coming across a operator guide printed in the early 1970's from International Boiler. IB made a lot of these HTHW systems that I've seen (they used to call them generators, not boilers). I don't know how many different IB names there have been (I know at one time they were Universal Boiler).

There was an article in one of the journals recently (HPAC or Engineered Systems or maybe PM Engineer) that gave you a primer.

Good luck maintaing that stuff. Your control valves will probably be the most challenging thing to maintain.

-Bill

Jim_47

HTHW

Just FYI, Our high temp hot water is 370'F @ 275PSI.
Depending on where in the system the leak occurs is how it will react. We have a differential of about 170'F at times making the return loop around 200'f. My concerns are mostly about thermal effects when I bring a system back online, how long should I take to ramp the system temperature up to 370'f after being idle for a couple of days for maintenance.

Two Mechanical rooms to feed my building. I calculated that a maximum BTU load (flowing the max HTHW that can be delivered to that end of the building) to be in the vicinity of 32M BTU/hr. Thats for 1/2 the building!

If I can get some pics of the Mech room I'll post 'em.
Jim

Firedragon_4

Try this link,

> Guys & Gals, I need information on High

> Temperature Hot water. A reference book with a

> lot of information would make me very happy. I

> currently am servicing 5 Steam generators and 6

> Secondary hot water heat exchangers all "fueled"

> by High temperature Hot Water sold to my company

> from another company. As always your assistance

> would be greatly appreciated. thanks MRHEAT

> (previously residential only, til now)

Firedragon_4

Try this link,

http://www.army.mil/usapa/eng/DR_pubs/dr_a/pdf/tm5_810_17.pdf

The military is an excellent source of material and they know their stuff, FACT! This is a pdf file so you'll need adobe Acrobat to read it. Go here first and download it FREE if you don't.
www.adobe.com

Tony Conner

The High Temp...

...water feeds heat exchangers, and a lower temp loop actually heats your building, right? (This is the typical installation.) Think of the heat exchangers as hot water boilers, because they're doing the same job. There should have properly sized and set relief valves on the low temp side heat exchangers, just like on boilers. If this is the case, the low temp-pressure side of the building will be just that, and it's business as usual for compression tanks, pumps, etc. With heat exchangers, there's no combustion, so you don't need to worry about flue gases condensing.

Whoever is supplying the high temp hot water should be able to help you. Very often in these arrangements, they'll look after the high pressure/temperature equipment anyway. The piping on the high temp side of things will likely fall under the ASME B31.1 Power Piping Code. The HXs themselves will likely fall under the ASME Boilers & Pressure Vessels Code. The big thing is to not assume that just because a fitting or component WILL fit, that it must be OK.

It sounds like your building is a big load. The operators of the high temp system will likely appreciate it if you call them before your system goes into service, so they can make sure they've got their end cranked up to meet the demand. They should also have somebody experienced who can come over and walk you through your start-up.

Jim_47

HTHW

Tony, you hit the nail on the head. Both secondary hot water as well as steam generators (to provide humidity). Yes If I am offline for awhile I do have to notify the power plant to "be aware" that they will be getting a cool slug of HTHW. If I bring it online slow enough it will mix with the rest of the HTHW return and will only be a little cooler than they are expecting. As time comes I will try to share more info and Pics with the WALL.
As far as getting the provider to "assist", Little assistance with out a service charge. The two companies act like children. Not like my friends here.
"Can't we all just get a long?"

Tony Conner

Sounds Like...

... the old "We want the absolute LOWEST price!" meets the typical "We'll beat ANYBODY'S price!" This "thinking" is alive and well in every industry/business.

The district energy business is a strange, strange animal. I learned a LOT working in it, but I sure don't miss it.