Treasurer-Condo Assoc

JimCh

05-01-12





 I am the

Board member responsible for managing a common heating system for an 18-unit

condo in Boston - 3 units across for six floors and about 36,000 squ ft of

interior space .   We currently have a

steam-system using a forced-draft boiler sized for 1,987 MBH gross output and

6,427 sqft  steam.





 We have

had noise, performance and efficiency concerns regarding this present boiler --

and have received a proposal from a reputable heating contractor to replace the

system with a condensing hot-water system. 

There are significant costs to tearing up everyone's to re-pipe for hot

water and a rationale we have been given for taking these costs is a

significant annual savings in fuel.





 This hydronic-system proposal sizes for (3) boilers ganged

to provide a combined 1,140 MBH gross output -- about 60% of that of our

current system.   I realize that a

condensing boiler operates at a higher efficiency than our forced-draft boiler

-- but the uptick in thermal efficiency from 83% to 96% is only a +15% jump.





 We have

been told that the remaining efficiency gain (40% - 15% = 25%) is due to the

operating characteristics of delivering hot-water versus steam heat.  I don't find anyone on the Web promoting

such an operational difference between the two types of heat.





 Am I

seeing a proposal to convert from a grossly over-sized existing boiler -- or

have I missed something in the literature about the special efficiencies of

hot-water over steam heat?





 Thanks for

your help on this -- Jim Charnley 

Paul48

?

The contractor did a heat loss for the building?

nicholas bonham-carter

steam problems

i suggest that you get a competent steam specialist in for a second opinion, as i would say that the cost of re-piping/new hot-water radiators/boiler, etc will be much more than simply fixing what you have.

there is less difference between the operating costs of well-functioning steam, and hot water than you might think, especially when the cost of pumping is taken into account.

if you have noise and discomfort with your present system, then it is not functioning correctly!  the original owner of the building would not have accepted anything less than quiet, comfortable efficiency! your job is to return the system to its original state of operation, and we are here to help! have a look at the "find a contractor" section here, and do not use the zip code feature, but search by state.

a real pro will measure the radiators in the building to see if the boiler is sized properly for the radiation of the building, and then see what burner adjustments might be more suitable, including modulation of the burner.. he will verify that the main venting is able to allow the air to escape at a mere 2 ounces of back-pressure, and will make sure your system operates on only ounces of pressure.

he will check your control system/thermostat for correct operation, and location.

this will be much cheaper than the cost of going to hot water. in the meantime, post some pictures of the boiler piping, and of the radiators and valves.--nbc

Paul48

You're

not taking into consideration the fact that the 3 ganged boilers, need not all run at the same time to satisfy demand. That will make a huge difference in your efficiency. The boilers must be sized, and controlled correctly. A proper heat loss is critical to sizing.

Henry

Conversions

We have done several in commercial situations in downtown Montreal. The savings were unbelievable! The comfort for the user went up as radiator temperature varies with the outdoor temperature due to the out door temperature reset. Actual electricity costs went down, by a little. Another saving was the maintenance costs associated with steam heating: trap replacements etc..

When one sizes for an existing steam system, all the radiators must be measured and a safety factor added. For a hot water system, the building energy loss at an outdoor design temperature is used. Just off the cuff, your plumber has calculated a realistic load.

Boiler efficiencies do not show system efficiency. It is all in the boiler selection, control strategy, piping and proper pump selection, that make the difference. The greatest savings are in micro-managing the heat load by having the highest turn-down available, something that is not possible with most steam installations.

jumper

don't do it

you didn't say what terminal units you have. radiators,convectors, forced air ?

Is the noise from the boiler or the heating system?

I was involved in steam to hot water conversions and each one ended up more costly & expensive than planned.

There are other options. First is a modern control setup. Or better steam water separation.

Rod

Upgarding Your Heating System

Hi- Some of the figures you mention don't sound quite right though it is hard to interpret them without a lot more information. A complete (all new components) modern mod/ con hot water system is generally more efficient than a steam system but in reality the efficiencies aren't as much as the brochures would lead you to believe. Mod /con boilers are also have shorter life spans before replacement and require more maintenance. (Mod/cons aren't very forgiving and doing frequent regular maintenance is directly related to the life span)  Depending on the situation it may be more prudent to go with a regular hot water boiler rather than a mod /con boiler, which then brings the efficiency difference much closer to a modern steam system.  If you are trying to work out your payback time period of switching over to hot water, I would use the efficiency figures of a regular hot water boiler in the calculations as that way you won't get any nasty surprises.



You didn't mention whether your present steam system is one or two pipe or whether they plan to use the present steam radiators for hot water.  If they are planning to use the present radiators there several things you need to consider. With steam, the radiators run at less than 2 PSI pressure, with hot water it will be ten times more pressure so considering the age of the radiators there is a potential leak problem. Using the same radiator for hot water the heat output will be less. A square foot of steam radiation is equal to 240 BTU Net per hour. A square foot of hot water radiation @ 190 degrees F is equal to 185 degrees F Net per hour.  Since mod/cons run at a much lower temp than 195 degrees, the heat out of the radiator is much less.

In a modernized steam system, boilers can also be ganged together. I've attached below a system done by Boiler Professionals, a Chicago heating company. This results in a big savings as you use only one boiler in the fall and spring when the heating requirements are minimal and then add more boiler(s)  on line as it gets colder. Having multiple boilers also gives you backup redundancy, if one of the boilers shuts down and needs repair, you still have some heat.

It would seem you have two choices: one being to replace your present system with hot water or the second replace your steam boilers with a modernized steam system. The big factor in replacing your steam system is to find a pro that really understands steam and unfortunately this isn't all that easy. You might want to check in the Find a Contractor section at the top of this page. Scroll down past the zip codes section to the "States" as this works better. I would also monitor this board for a few days as being the off season for heating, a lot of the pros don't come on as often. If you have more questions let us know and we'll do our best to help you out. 

- Rod

Steamhead

Every time I hear of miraculous savings

from converting steam to hot-water, the condition of the steam system is glossed over and the writer asserts that all steam systems are inefficient. When we start questioning this, we eventually learn that the steam systems were in very poor condition, which explains why they used so much fuel.



This is not a fair comparison and never was.



The reality is that fixing the steam system can produce much of the efficiency of hot-water. And, it's much less risky since you're not increasing the system pressure on the pipes and radiators over ten times which hot-water requires, which WILL make them leak.



Best way for you to go is to fix the steam.

Paul48

The

way I read his post, it would be a complete system change. I would fix what you have now, and wait until the existing boiler is at the end of its life.

Charlie from wmass

Converting is the option used by those who can not

fix a steam system. Yes they save money, sometimes, sometimes not, over steam. There is no reason why steam should not by quiet, even, and efficient.If your system is not it may not be the system but the repair techs that need changed. I consult and work all over this great state so if you want me to diagnose what is wrong with what you have then email me or call me.

Henry

Efficiency experts?

Not to get into a pissing match, but we redo more boiler rooms than anybody on the East coast: 200 plus, one year 400! These are not single family 1000 sq ft homes. Yes, you can improve steam efficiency. We have done that, but it cannot come close to a hydronic system. We have done two major commercial buildings who have steam in downtown Montreal. One had 10 million BTU the other 9 million BTU. Our modernisation project with new watertube boilers and digital controls reduced the energy consumption by 35%.

We converted the first Montreal skyscraper from steam to hydronic heating/cooling. The savings were over 50% plus now there is air conditioning! We converted Notre Dame Cathedral off of steam to hot water. I have a copy of the gas bill: 65% saving! We are presently working on a multimillion dollar modernisation of a one pipe hydronic system whose boiler room provides 29 million BTU.

We have repaired and maintained many steam heating systems including several apartment towers that have a one pipe vacuum system. We are of of the handful in the East that can handle all variations of steam heating besides industrial applications. Many other contractors refer to us for both steam heating/process problems and boiler installations. We are referred also by boiler and equipment manufacturers.

Do an energy analysis and you will easily find that steam should be used to work with and not heat with, specifically compared to hydronic heating! I am willing to part with one of my 2005 Brunello Riserva, if you can prove otherwise!

Charlie from wmass

Henry that's interesting

If I can save them 30% and they have a simple system without a raise in their electric meter I am quite sure they would be happy. The reason to tear out steam is there are so few who can actually work on it and those that do know their worth.

I have replaced same make and models of boilers in 7,000 sqare foot buildings and dropped the fuel usage by 15% with proper installation and tuning.

Viva Le Steam!

Steamhead

What condition were the steam systems in

before they were converted?



I think I already know the answer.....................



JimCh, if you can get Charlie to work on your system, you'll be working with one of the best.

gerry gill

my co worker

converted his steam system to hot water and his gas bill actually went up..we converted it back to steam..gas bill went back down.

nicholas bonham-carter

.....That is the question

It must be hard to be on the condominium board to begin with, and then to be delegated a job which may require study and consideration outside of one's normal thoughts.

Especially difficult is getting advice from those in the profession associated with the problem area, and hearing different advice about various routes to follow.

I am sure that you may follow this advice, and therefore be in a better position to advise your board how to proceed:

Get a quote from a qualified steam professional for restoring the present system you now have to it's former stat of operation-silent, economical, and comfortable. Then you can compare that cost to that of ripping everything out and replacing all the pipes, and radiators, and boilers, therefore starting afresh.

Certainly each form of heating has its pluses, and minuses, but as you already have an existing system in place, which only needs to be brought up to scratch as far as basic maintenance; I think the board would vote in favor of keeping what you have when restored, --nbc

SWEI

Brunello

Can't take you up on the bet, but I do have a few fantastic 1990's left that I'd be happy to share with the right 'company' if you know what I mean.



I think a lot of the efficiency numbers are related to radiation differences.  Convectors versus radiators y'know...

jumper

won't happen

We're not supposed to mention prices but I figure owners don't want to spend what it costs to change to hydronic. Repurposing pipes doesn't work. You need different tees for one thing.

gennady

steam to FHW conversions

i had done steam to FHW conversions, and savings were considerable, ( up to 80% fuel cost reductions) but of cause those steam systems were shot. Then again, restore steam system ( I done that too) also not a cheap thing. I got excellent results with TXV control  and proper sizing of steam  boiler and savings were unbelievable as well. The trick is in the contractor, not a system. Real professional can fix and set up any system and make it efficient, knucklehead can screw up any system

Henry

Major savings!

YUP! Your are in the same region of our projects. While it is a substantial investment, the payback is so short and the new comfort levels of having LOW temperature heat to counteract the outdoor temperatures, is a plus plus. Use steam to produce use water to heat!  One needs to train people to get steam as efficient as possible but it will NEVER be as efficient as water. We need people to undestand the shortcomings and problems of steam to maintain the existing systems at the best efficiency and comfort level possible using steam. But as professionalls, we must all understand that mod/con is the way to go!

Steamhead

Never say never, Henry

Look at Gennady's post again. He tells us he has done both things, and achieved "considerable" savings from converting and "unbelievable" savings and increased comfort from fixing the steam. Coupled with the risk of leaks from trying to re-use old steam pipes and rads for hot-water, I think it's a fair question as to why one would want to convert.



His quote says it all: "The trick is in the contractor, not a system. Real professional can fix and set up any system and make it efficient, knucklehead can screw up any system."



I think when you look at total system efficiency, including how many BTUs (or calories, depending on where you live) you can move with a given quantity of steam vs. the same quantity of hot water, steam looks pretty good. For example, a pound of steam packs 970 BTUs, whereas a pound of hot-water can only carry 20-40 BTUs depending on the ∆T being used.



And it seems to me that we'd be seeing plenty of 90%+ steam boilers if American boiler makers weren't so busy trying to beat Viessmann/Buderus at their own game. Yes, it is possible to make a 90%+ steam boiler- it's been done elsewhere, but as usual the Americans are lagging behind.



Also, steam has some advantages of its own. For example, all the pipes above the boiler's waterline drain dry when the system shuts off. So if you have an extended power or fuel failure, a steam system will not suffer near-total destruction from freezing like a hot-water system can. Sure, you can use glycol, but that opens up a whole 'nother can of worms.



If I thought steam was that bad, would I have been able to build (with my partner Gordo) a successful business de-knuckleheading these grand old systems?

Hap_Hazzard

Change of State

"I think when you look at total system efficiency, including how many BTUs (or calories, depending on where you live) you can move with a given quantity of steam vs. the same quantity of hot water, steam looks pretty good. For example, a pound of steam packs 970 BTUs, whereas a pound of hot-water can only carry 20-40 BTUs depending on the ∆T being used."



Interesting how many HVAC professionals out there overlook the significance of phase transition in this context, considering it's the principle that makes AC, refrigeration and heat pumps possible.

Jean-David Beyer

that opens up a whole 'nother can of worms.

Do not forget one of Murphy's Laws: When you open a can of worms, to recan them takes a larger sized can.

Henry

Fuel efficiency

We make a whole lot of $$$ fixing steam systems in both heating aplications and process. I have reduced energy costs on steam heating systems by over 35%. But, steam cannot ever compete with hydronic mod/con. Boiler combustion efficiencies are rated at 0 PSI. Every little bit you go up in pressure, it uses more fuel to get there. The old vacum systems originaly on one pipe were to quickly fill the raidators with steam. The later systems like Trane, were to lower the temperature of steam to make it more comfortable. Both systems utilise MORE fuel for the same comfort level compared to hydronic systems of comparable vintage. How can steam be as efficient as a mod/con? On cast iron systems we get between 35 and 55% reduced energy usage when we switch over to a mod/con. Doing the same with a one pipe or two pipe system, will save more.



We do re-use the old radiators. We don't re-use any of the old piping. Therefore there are no leaks. There are no steam traps to replace nor air vents. We use nearly exclusivly Grundfos pumps therefore there is no maintenance issue as with condensate or vacuum pumps. Also, on the larger systems, there is no need for stationnary engineers. We have one project of $4 million that replaces 4 steam boilers and 4 heat exchangers at four different levels to condensing hot water. 6 statinnary engineers are gone and just that is a $770K saving! Just this past Friday, I was with a hotel chain property manager. We are getting a major hotel off of a central steam system like NY City, to mod/con boilers. The estimate savings are $4 to 5 million annualy! In both cases, why use steam to heat a hydronic network?

Steamhead

No need to shout, Henry

(MORE)



we can hear you just fine.



I've said many times that 90%+ boiler efficiency is possible on steam. It has been done, but not in the States. This is something we need to address with boiler manufacturers. But that still does not negate steam's inherent advantages:



Lower operating pressures;

Smaller radiation units for the same heat loss;

Drastically reduced danger of freezing damage;

Lack of parasitic pumping power consumption if gravity return is used, etc.



Trane wasn't the only company who did vacuum. The most famous vacuum system  is the Dunham Vari-Vac, which could adjust steam temperature by varying the vacuum in the radiators. Somewhere I have some of that company's fuel-savings figures on systems converted to Vari-Vac, and I'm sure a de-knuckleheaded Vari-Vac would produce significant savings.  The original Vari-Vac used a floating-point zone valve to adjust the amount of steam entering the vacuumized portion of the system. Nowadays we could do that with a modulating burner.



You say "Both systems utilise MORE fuel for the same comfort level compared to hydronic systems of comparable vintage". So how much is the "MORE" you talk about? Do you have any numbers to back this up?



Oh, and your assertion that one can do away with stationary engineers might not fly in all jurisdictions. There are some places where any boiler (or group of boilers) over a certain size or pressure rating requires the attention of a stationary engineer. It would be well to check local Codes before pitching this to a client.

jumper

NYC messed up ?

If folks in NYC switch from ConEd steam to gas, doesn't that mean ConEd steam costs too much ?

gennady

NY steam

Their minimum charge $1500 per month.

gennady

NYC

It really does not matter what system better. Here in NYC, all what matters is initial cost of the job. Whoever gives lowest bid gets the job. Savings? Who cares, just give me new boiler. Cheap.

The Steam Whisperer (Formerly Boilerpro)

It's funny....

when I hear about all the money that can be saved by converting steam to hot water.  35% savings, 80% savings.   It is interesting to note that I have consistantly achieved similiar savings by converting a HOT WATER system to a hot water system with staged, noncondensing boilers and modern controls.  The big savings does not appear to be in the steam to hot water conversion, but simply better management of the system and better management of the heating plant.   Condensing technology only improves boiler efficiency at most 7% (if operating at low temps all the time).   Staging or modulation improves heating plant efficiency about 15%.  Outdoor reset (which can be readily implemented on two pipe steam systems....many are already equipped to be operated this way) saves about 12 % more, according to most studies.   It can also be added to at least some one pipe systems. Improved temperature control (TRV's for both hot water and steam) can also provide big savings, depending on the degree of overheating that occurs. 

On the simple one pipe systems I see all over Chicago, it is easy to save 15 to 20% just by tuning the system to heat more evenly.   Another 20% can be saved by installing a more efficient heating plant configuration (there is test data is from the 1980's even).  Add TRV's and we're probably talking a 40 to 50% reduction in fuel usage....using simple atmospheric boilers with no condenstate pumps.....almost no parasitic losses. 

Before making claims of big savings from conversions, why not spell out the fact that the steam systems are using 60 year old technology, while  the hot water conversion is using present day technology.   Apply present day technology...Modulating, condensing steam boilers, Outdoor reset of steam pressure/ temperature, room by room control....  to the steam system and see what happens.  

When you get down to it, the only real gain to conversion is the condensing aspect and this comes at the cost of increased electrical usage to run draft fans, pumps etc. when compared to staged atmospheric boilers.   And even this advantage is diappearing as large condensing steam boilers are already in use in the US and more are coming out soon. 

jumper

I'm curious how Henry does it ?

Use old steam radiators with new piping. Steel or copper ?

Do you use thermostatic valves on each radiator ? On return or supply ?

Do you need balancing valves ?

If it was one pipe, do you use those concentric adapters ?

Henry

Steam to hydronic

When we do towers that have a steam heat exchanger for the make-up air, we use the steam supply riser as a supply and run a new return. We then install a plate heat exchanger and the old steam heat exchanger is converted to use glycol. It gets cold here: -30F very often. BTW, all piping is steel no copper is used. On a two pipe system, we replace all the piping and install a TRV on each rad. The rare one pipe system, everything gets replaced: rads, pipes etc..

Henry

A steam job

In this large tower in Montreal, we removed one 5,000,000 BTU boiler and installed two 5,000,000 in its location. The boilers were completely assembled by us in place. We lowered the maximum steam pressure to 2 PSI. We installed a digital management system that you can see on the column between the new boilers. There is an outdoor sensor, steam pressure sensor, return temperature sensor and a room sensor on the second floor. The panel controls the full modulating Gordon-Piat burners. The actual fuel savings were over 35% in volume. The building no longer met the minimum annual gas purchases that the utility and building owner had signed for.