Steam boiler, multi boiler apt site ????

Guy_6

I will give you my gut feeling on this: I think that adding chemicals to an 80 year old system may open up the proverbial can of worms. I agree that the returns should be flushed out, however after 80 years, the crud might be what is holding the return water in. Sort of an organic lining. If they have been maintained all along, it would be one thing, but it sounds as if this effort is fairly recent.
I would find out what is left of the chemicals in the system, and either wean them out, or just get them out completely. I would also suggest one of the new water feeders that monitors the volume of water into the system, so you can troubleshoot the problem areas.

tim smith

Steam boiler, mult boiler apt bldg questions

Multiple questions that I am discussing w/ owners rep on 230 unit site w/ 5 weil mclain steamer, 1.5 to 2 million btus appx.
1: they have added chemical treatment to this 80 yr old system covering 11 acres with underground mains that run from boiler rooms to 22 separate buildings. He is finding quite a bit of mud and scale etc in boiler legs, he is wondering if the chemicals were a good idea as to if they are breaking down the old crud in piping and it is coming back to boiler. I would suspect that may be partly true but once the system is pretty much clean it will protect what good piping there is left. Btw 1000s of feet of piping. But after most is de scaled etc this should be a good thing. One problem is they had chems added but have not tested since for the last couple years, not so good. What do ya think. What do you think about doing a flush on the old condensate and steam lines now that chems have been running through for awhile???
2: the boilers are appx 20 years old and this year they have lost appx 5 sections near front sections with cracks above water line. I am in question of why above water line.. Any thoughts. If I remember right these are 7 and 8 series boilers w/ Webster gas/oil burners.
3: The last thing is hard to answer, the old undergrounds get replaced as needed by their maint. staff but most if not all should be replaced as I would suspect many leaks in the old undergrounds after seeing some of the pipe they replaced. Problem is the owner keeps planning on demo of entire site for development so they won't do a major overhaul yet he wants reliability. Hard answer.
PS: We have not been doing all the service, another co. has been doing most. We are not always available when they need a section replaced or such, time not always available.

tim smith

Thanks for the reply.

Christian Egli_2

Long ranging ideas that won't leave you stuck in the mud

Chemical feed is the best thing one can do for pampering a boiler, but often the risk is, like that of an over-indulgent mother, excessive cuddling eventually spoils the brat.

It's only a very short leap to believe that chemical feed treatment takes the place of the ordinary blow down... while in truth, the more chemicals you add, the more you urgently need to blow down.

I've seen a bunch of boilers and feed tanks that ended up packed full of dried up mud. The mud is composed of 1) the dissolved solids from fresh water (which fall out as expected with the chemical), and 2) the chemicals themselves, they bind themselves to the dissolved rocks in order to make them fall out, and all those five gallon pails that go into the system have to end up somewhere... unless you are dutifully performing the blow downs.

One place I remember had records of water testing that showed the whole story. There was an automatic blown down and an automatic chemical feeder. At first pH numbers and such showed everything going just fine, but not long after things started creeping out of control. The first reflex of the operator was to increase the blow down time - that was ok. Then, still frustrated with growing symptoms of illness in the water quality, the second reflex the operator had was to steadily increase the dose of medicine.

By the end, the boiler was receiving massive intravenous injections of pail after pail of chemical treatment and an equal dose of fresh water. No one really worried about the boiler's addiction because this was a process boiler and such boilers are supposed ??? to go through lots of water...

In about less than a few months, the boiler water quality charts went from seemingly normal to showing huge water intakes, huge chemical ratios, and out of whack pH and dissolved solids. The patient itself did not look so healthy, it was jam packed full of mud up to the normal water line, with the fire now more than ever burning full blast, and all the metal parts exposed to heat, particularly those above the water/mud line all cracked and distorted. Oh dear.

The very simple and healthful cure to all these illnesses might have been to remove the automatic blow down from the skim port it was on and move it to drain the bottom of the boiler. My diagnosis was an aha moment.

Tim, this may be a plausible scenario for your situation. Mud in the returns prevents them from drying out nicely. In time, year-round permanently moist mud makes for permanently ongoing steel rust. Stainless steel returns are a nice extravagance.

Playing in the mud might be cool, but here are ideas that may provide even more fun.

Depending on what exactly the owners want to do with the property, I see nothing but great opportunities to do something smart. There certainly is the scale to your project to be able to consider anything.

There is more to steam than just heat, opportunities for combined heat and power schemes abound. Either free heat or free electricity for the price of just one of the items. I say free rather loosely, you have to invest some money up front, but such schemes also provide economical cooling. Lots of opportunities to consider before they disappear when only tiny individual roof top natural gas dependant furnaces are used, to the great disappointment of everyone.

Your 11 acre site with its 22 buildings is a tough project to handle in one manageable chunk. I imagine there have been plans to replace each building, eventually ending up with stand alone systems. However, you can't get to that point without the difficulty of weaning yourself off a centralized system. Once you shut down the main boiler house, you're immediately stuck with buildings that have lost all commercial value. This makes the redevelopment of the whole site in one chunk very daunting.

Breaking down projects into manageable chunks

Regardless of how exactly the site might be rebuilt, why not stick with the mini district system already in place? This has many advantages in economies of scale for optimum full energy usage, but it is also a very attractive system for tenants who do not want to be burdened by home heating plant operation. It is very nice in a residential or light commercial affectation to have an environment where heating and cooling comes just as simply as electricity does, most people are not enamored with the idea of dealing with such system maintenance, they have other things to do.

With this campus heat/cooling concept, the next idea to maintain the distribution pipes is easy to embrace. It maintains the value of the old buildings and is a sales argument for the new development.

Next comes the maintenance and upgrade of the boiler house. This all remains easier because the large scale of the project is maintained (while smaller changes in size can be dealt with easily). Your future boiler house might not even look like it does today; you may very well have a combination of interconnected plants in several of the larger buildings that might be built there, the interconnected network serving to feed the other buildings, thus insuring that the remaining older ones never become obsolete overnight... Banks don't favor lending money on obsolete properties.

It seems to me such a commitment to at least maintain the distribution network in perpetuity is sound. Then, short to medium term upgrades to the current boiler house make sense too, particularly in view of energy costs. And ultimately, long term comprehensive energy considerations for the whole site will crystallize.

There is an immediate pay off to this commitment, it's the immediate decrease in fuel costs you get from moving away from the current absolute zero maintenance. Another pay off is the maintained value in the older buildings that won't become obsolete. A third pay off comes from the simplifications in the future construction of individual buildings with no need for each a heat plant. All this for no additional cost (probably much less cost) compared to simply and expensively retrofitting the whole site with small heating units everywhere. All this without even factoring scale efficiencies and cogeneration possibilities.

Regardless of the buildings, whether they are kept or replaced, you'll still need heat.

Or

Have the steam shovels come in and push everything over. Either way, we're still taken care of by steam... and we're still playing in the mud.

Best regards

tim smith

replies

Christian & Guy, thanks for the insight and reply. You have stated exactly regarding the chemical build up as I have to their head of maintenance. This site is a tough one regarding long term capital improvements. As stated in my intitial post, this site is due for development and will definately not be steam boilers when it does happen as this is right across the street from a large shopping mall complex. It will be a retail and maybe mix use site. Soooo any work done now will not be reused and in the mind of the owner, a waste except for he wants to maintain reliability and efficiency? Cant have it both ways but maybe we can find a happy medium point. Thanks, Tim.

ttekushan_3

and one last thing:

Ya can't do continuous automatic chemical injection without feedback. If no one tests the boiler water, you can reach a point where caustic attack sets in. pH ≥ 12.

When I descale and clean CI boilers that have never been cleaned, I dose the system one last time with a Rhomaresque water treatment before I leave. I know that the concentration will be virtually nil by the time I come back for seasonal check-up, but the worst case of chemical addition w/o proper blowdown is completely avoided.

Oh. and what Christian said!

-Terry

Christian Egli_2

The steam shovel it is, then

This sounds like it's going to be developed into all roof top units and the developer won't care one bit because it's the tenants paying the utility and maintenance bill each on their own.

There go the leaks and roof damage from walking all over the roof in the coldest of the winter $$$ emergency service call. There go the conked out AC compressors $$$ in the middle of the hottest summer day. There go the copper $$$ innards stolen off the roof top units by the homeless bums. There go any fuel $$$ savings in efficiency gain. Are there enough $$$ in retail business for no one of the future tenants to care? I'd be concerned about such things if I were to consider leasing such space.

A large flea market around here (with probably a dozen halls) switched its system to a centralized cooling plant with a chilled water loop and air handlers. One owner organizing the whole show who decided roof top AC units were not the easiest and cheapest way to go. Smart. Heat is provided by hanging gas furnaces.

A distributed heating / cooling system is an asset worth quite a lot all on its own. Abandoning it just for the sake of demolishing it is a big shame. But no doubt, the steam shovel will have no trouble taking away from the owner and the tenants all of those $$$, by the scoop full.

For the current system and its current operation, need it be mentioned that phenomenally efficient and resilient steam systems can be run equally well with or without the return of condensate. You could resort to that in your buildings or on some portions of the non-functioning returns - the only thing is the additional cost of the feed water and the feed water deaerating equipment.

This would allow you to save the repair of the returns for a later date. Steam is great in so many ways.

Perhaps they'll even have a future bakery selling mud pies on your site.

Best regards.