Percent of water lost in steam boiler?

RayWohlfarth

Is there a normal percentage of water lost from a two pipe steam system? I was asked at a class about how much water loss is "Normal" for a space heating steam boiler. My internet research and discussion with two water treatment techs suggests that 90% returned is what we should strive for. I believe that is for large industrial facilities and not someone's home. If the boiler cycled ten times in a day, all the water would be gone. I think the only loss on a properly operating system is through blowdown. I would love your opinion. Thank you so much.

Jamie Hall

I really don't have an opinion, Ray, but I can tell you that the system in the main place I care for uses about 2 gallons a month, over and above blowdowns for the LWCO. Which I regard as borderline excessive -- but I haven't worried enough about it to find out where it's going!

RayWohlfarth

Jamie
Thanks for the info
Ray

DanHolohan

I think that a system in a house, if the system isn't leaking, should lose water through normal evaporation, and some more from one-pipe air vents if they're not new.

All in all, not much.

Abracadabra

RayWohlfarth said:

Is there a normal percentage of water lost from a two pipe steam system? I was asked at a class about how much water loss is "Normal" for a space heating steam boiler. My internet research and discussion with two water treatment techs suggests that 90% returned is what we should strive for. I believe that is for large industrial facilities and not someone's home. If the boiler cycled ten times in a day, all the water would be gone. I think the only loss on a properly operating system is through blowdown. I would love your opinion. Thank you so much.

On larger apartment buildings (5000+ EDR (one-pipe)) i see water use of about 1-2 gallons a day.

One specific location I just checked out last week, dry returns, entire system has been checked for leaks. WM LGB-16. Water content is 146 gallons plus a few (5 or so) for the return header. Call it 150 gallons.

That's about 1.5% loss over 24 hours (9-10 cycles/day)
That's about .16% loss per cycle
99.84% water returned.

My guess is that some water is lost as humidity when system starts up the air that is vented has a higher humidity than the winter air. After the cycle is completed, dyr winter air is sucked back into the radiators/piping sucking out some of the humidity with it. Next cycle the humid air comes out.

DanHolohan

My guess is that some water is lost as humidity when system starts up the air that is vented has a higher humidity than the winter air. After the cycle is completed, dyr winter air is sucked back into the radiators/piping sucking out some of the humidity with it. Next cycle the humid air comes out.

That's what I meant by evaporation. You said it better. Thanks.

ChrisJ

My small 392sqft EDR 1 pipe system loses around 4 cups a month in mild weather and upwards of a gallon per month during very cold weather I.E. January and February .

Probably around 2.5 to 3 gallons total per season.

To my knowledge, this is 100% from the system breathing through vents. I do not have any leaks that I am aware of and steam rarely reaches at radiator vents, only the main vents.


I realize you asked about 2 pipe, but I figured I'd throw this in there as well. I've always assumed 2 pipe would lose less but really don't know.

jumper

Depends on system. It's said that modern pump seals lose water (and let air in?). Some plumbers believe that water evaporates right through steel and iron. There was an ASHRAE survey some years ago that concluded that steam systems in multi-residential buildings use much more water than renovated heating hot water systems in similar buildings. Some engineers,including me, strenuously disagreed.

Hermetic freon systems don't leak. Why should steam?

DanHolohan

Steam systems are open to the atmosphere. I had this conversation with a dead guy a while back and he had some strong opinions:

https://heatinghelp.com/systems-help-center/what-do-to-with-boilers-during-the-summer/

RomanGK_26986764589

I have a 1 pipe steam too. My EDR is 260 sq feet. I loose about a gallon a month during cold months. However, I have small leak under the bathroom radiator. But it's not easily accessible since it is under the tiled floor and I would have to break up those tiles to get to it....

ChrisJ

jumper said:

Depends on system. It's said that modern pump seals lose water (and let air in?). Some plumbers believe that water evaporates right through steel and iron. There was an ASHRAE survey some years ago that concluded that steam systems in multi-residential buildings use much more water than renovated heating hot water systems in similar buildings. Some engineers,including me, strenuously disagreed.

Hermetic freon systems don't leak. Why should steam?

I want to build a hermetic steam system.

That said, as Dan stated, steam systems are not hermetic, they are wide open to the atmosphere.

I dream of building a hermetically sealed copper steam system with no valves and no threaded connections, no vents, all soldered or brazed connections. After which a deep vacuum will be pulled to remove the air. It would be "charged" with water and could easily run at low enough temperatures for a condensing boiler. Basically, imagine a multi-legged heat pipe.

No moving parts, no maintenance items, no leaks, no noise.

All I need is an extra house, money to buy everything and time to build it.


Heat pipe video : https://youtu.be/Az_gXrealkI

RayWohlfarth

Thank you everyone I appreciate your input

Paul3

I had a similar question and found some (hopefully) good info in my VXT-24 feeder documentation (attached see the last page). My 160k BTU, 22 gallon EG-75 boiler, single family, two-pipe air-vent, 3000 square foot, two story house in northern MA uses about 1 gallon/week during heating season... if thats any help.

Fizz

In my previous house, I had a 2 pipe system(Richardson), with 478 sf edr, SGO=-6, converted to ng in 2011and added water every 7-10 days til I put system in vacuum and changed thermostat setting to hot water(3cph), the last 2 yrs: water was clear as a bell and added water twice!
Now have small, 218 sf edr, SGO-3, having to add water every week or so about 1/2 gal; changed thermostat and average 2-3 cph, resulting in less water consumption, about 50%.

clammy

I have a trane 2 pipe no traps convector job that I did a replacement of the original ideal coal / oil steam boiler and it had taken no water aside from when the ho would blow down the 67 lwco . I replaced and HO hasn’t added any water what so ever being there’s a electronic lwco so no blow down . I ve asked if he has added any water and he says everytime I go down and take a look it’s at the same level . This was a vacuum system and still is it holds about 15 hg when off and when I service it ,it’s usually still in a vacuum when I get there . But his water lose is nil . Looked at one the other day 1 pipe bad nbp w a auto feed vxt after 3 years he s used 2 gallons ,he does need new mains and rad vents and his distribution is terrible and uneven but still 2 gallons in 3 years with no insulation on any piping , I would condenser excellent .i think it all depends on the system ,the system piping and venting aside from leaks on buried returns the only water you should be losing should be minimum And I would hope only from raditor air vents and possibly main vents .i would think anything more on a standard home of 2000 sq ft then 3 to 5 gallons a season is excessive and at that point or any point the water should be tested as to not void warranty . I have a few single piped systems that also take just about nothing per season maybe HO adds water once or twice a season which I consider reasonable . But most of these systems have all piping insulated and returns flushed whistle clean and boiler skimmed flushed wanded and clean with in a inch of there lives water lines while steam steady theses systems see barely any water lose possible again 3 to 5 gallons a season max . For my self if your adding water once a week due to water lose then there’s a leak some where maybe not a big one but there s one and adding water once a week by the end of the season can you say excess ,this is the main reason I’m not a fan of any auto feeds they mask a issue that should be repaired . As a former old friend used to say if you got a auto feeder and a steam boiler and you don’t want to go check it once in a while cause the auto feeder takes care of it for you ,don’t be surprised when your boiler calls you to tell you your fired ,I always thought that was very funny at least to me maybe not the home owner who has the auto feeder and needs a new boiler from excessive make up. If your adding water once a week u got issues some where Peace and good luck clammy

dopey27177

Many years ago when the New York City Housing Authority was the pride of public housing we budgeted 1 gallon a month per apartment.

This was for new buildings. As some of the well maintained buildings got older 4 gallons a month became the norm.

These numbers are actual and for all the two pipe steam buildings. This includes blow downs and pump gland leakage.

As the Licensed Master Plumber for NYCHA my staff of plumbers made all the piping repairs and mechanical failure replacements.

We had one project on Staten Island with (BERRY HOUSES) that had well trained and proud heating plant technicians taking care of five high rise buildings with Dunham Vari Vac Systems and 3 Pacific Steel HRT boilers that in my time were 30 years old (all original equipment) The water loss in this project was 2.1 gallons per month.

When I lived in a house (my House) with a Richardson Pancake Boiler with one pipe steam I used only 3 gallons per month and that included LWCF blow downs. I had 11 radiators ( 450 square feet of steam) with Hoffman #1 A air vents.

Jake

ScottSecor

I am aware that you asked about two pipe steam systems, however I thought some might learn from my example of an exceptionally tight one pipe system.
A relative purchased his house in 1970 and decided to replace the aging oil fired steam boiler (circa 1920). While he was at it he decided to re-pipe both of the steam mains and the wet returns. He added two new radiators to the relatively small house. He also replaced all of the original radiator angle stops and the vents. The new load was approximately 300 EDR so he opted for a Weil McLain 3 section with tank-less coil for dhw needs.

This system is still in place and consumes less than two gallons a year. Note, the tankless coil has been disconnected since approximately 1990.

Jamie Hall

A bit of an update. Having found a tiny pinhole drip at an elbow on a dry return (by accident. Couldn't see it -- but I happened to be under it when it went drip...) back in December, Cedric has used exactly no water for a month and a half. Amazing what a tiny drip will do...

ChrisJ

ScottSecor said:

I am aware that you asked about two pipe steam systems, however I thought some might learn from my example of an exceptionally tight one pipe system.
A relative purchased his house in 1970 and decided to replace the aging oil fired steam boiler (circa 1920). While he was at it he decided to re-pipe both of the steam mains and the wet returns. He added two new radiators to the relatively small house. He also replaced all of the original radiator angle stops and the vents. The new load was approximately 300 EDR so he opted for a Weil McLain 3 section with tank-less coil for dhw needs.

This system is still in place and consumes less than two gallons a year. Note, the tankless coil has been disconnected since approximately 1990.

Sounds very similar to what my system uses.

retiredguy

I can not comment about the normal amount of water lost in a residential system since the company I worked for only did a few houses. 99% of our work was in hospitals, schools, large buildings and industrial systems, So the term "normal" usually meant at least 90% returned. On the newer low pressure systems (below 15 psig) that I serviced anything more than the water lost for blow down was considered excessive. For industrial high pressure steam boilers the allowable loss always depended on the quality of the feed and make-up water. Systems that treated, deareated, and softened that water could run on near 100% fresh water. So for me the allowable loss is that it depends on the quality of water supplied to the boiler. On some systems the water that could have been returned was so contaminated that returning it to the boiler was not feasible so it would be cooled and dumped down a drain . So for me the amount of water lost is "it depends".

jumper

Some years ago ASHRAE published a survey of apartment building with new steam boilers in NY State revealing atrocious water consumption. I suspect pumps. A two pipe pumpless system can operate with negligible water consumption.

mikeg2015

A 2 pipe system in good condition should use virtually no water. It’s a completely sealed system other than main vents. However if a vapor vacuum system, it should use none, as it’s sealed. It will however in reality have some valve stem leaks and slowly loose vacuum.

In theory, you could design a steam system with copper tubing and making it completely sealed like a refrigeration system, or hot water boiler system.

Steam heating after all operates the same as a refrigeration system except there is no compressor to do work to move the energy, instead heat is applied in one location and transferred to another. Radiators are condensers and the boiler is an evaporator.

After replacing my boiler, my water use is around 0.1 gallon a week. I figure it will use about 2 gallons a year. It’s a 700EDR system, though can only heat about 450 with pickup factored in.