Is this a crazy idea?

Sal Vigilante

<span style="font-size:12pt">I have an elderly customer that bought a boiler about two years ago and she has been having trouble.  Whoever installed it did a pretty good job, nice header and piping.  The problem she is having is one half of the build is getting much hotter than the other. The boiler is located almost in the center of the building and we have spent a ton of time trying to balance the system.  There were time I could take an air valve off with the boiler running and nothing would come out.  So, I did a connected load take off and found out that the connected load is 995 EDR and the boiler is only 900 EDR.  So, the boiler is too small.  The problem is the customer does not have the money to re-replace the boiler.  I guess she could chase down the guy who put it in but it sound like she can’t find this him (a friend of a friend kind of thing). So, I was thinking the back of the building is overheating and the front (where the thermostat is) is under heating. What if I install a motorized zone steam valve on the steam main back of the building connected to a thermostat. When the back is satisfied it will leave enough steam for the front of the house.  I know it’s a bit of a Rube Goldberg but the customer does not have that much money and I would like to help her out.  </span>

<span style="font-size:12pt">Is this a crazy idea?</span>

Dave in QCA

Not Crazy, but lots to consider

It might resolve the problem, but it would create a whole other set is problems and issues that would have to be dealt with, and those big steam valve are very expensive, and if it were mine, it would be a very last resort.

You have not told us what you have done so far to attempt to balance the system.  What kind of vents are on the radiators?  I am assuming that this is a one pipe system.  How about the main vents?

The approach of "Vent your mains fast and your radiators VERY slow" might be able to solve a lot of the problems here.



I recently help a freind who had purchased a new boiler.  The company that installed it put in a bunch of new Hoffman 1A vents without even attempting to balance the system.  She had one radiator, located in the same room as the thermostat that would not heat at all.  It would get just a bit of warmth in the the first section or 2 after the boiler had been steaming for an hour and the rest of the house was like a sauna.  Resetting the Hoffman 1A vents down to the area where they matched the flow of the original Hoffman 40 vents that were removed finally got the system balanced and working great.   Fast venting radiator vents can cause a lot of problems!  It is even worse when main venting is inadequate.  Steam should be getting to the main vents within 3 minutes of the time that the boiler starts to steam.

BobC

Insulation?

Sal,



i agree with Dave that adjusting the radiator venting down might help this system a lot. Also his comment about venting the steam main fast should be followed.



Another item is insulating all the piping in the basement, any heat your losing in the basement is not available for use upstairs and that might just be enough to make it all work.



If you could post some pictures of the boiler and basement piping it might help us visualize what your dealing with.



Bob

Sal Vigilante

still crazy

I know, I’m really concerned about the valve.  The ends of the basement mains have Gordon #2 valves on them and they vent very nicely. The rest of the radiators are vented with #D, #C and 40s.  My first thought was vent the vertical mains and the radiators slow but the fact that the boiler is a bit too small is gnawing at me.  Do you think we can overcome the undersized boiler by doing this?   

Sal Vigilante

Insulation yes - pics no

Someone insulated it already and next time I’m up there I take some photos (I guess I should have thought of  taking pics sooner)

Dave in QCA

Firing Rate?

It has also occured to me that the actual firing rate might be less than what the boiler is rated at.  It would be a very idea to clock the meter and see what the boiler is actually doing.  As for the steam EDR rating of the boiler, there is an extra 34% capacity for piping losses and pickup.  Anything you can do to reduce the piping losses will bring the boiler in closer line of matching the system.  You indicate that the piping is insulate, I hope it is with actual pipe inslation, and not a makeshift application of someone trying to wrap loose fiberglass around the piping.



The main vents sound great.  Are you getting steam to the main vents in 3 minutes or less?  If not, I would consider putting 2 Gorton #2 vents at each location.  It depends on how long those mains are and what size pipe is there.  There is a chart in one of Dan's publications that shows the volume of the pipe at various sizes per lineal foot.  Assuming that there is about 1 oz of pressure when the boiler starts to produce steam, it is easy to calculate what vents are needed to get the job done.



As for the radiator vents, a mixture of Gorton vents, each based on the volume of the radiator it is installed on is the accepted method of balancing one pipe steam systems.  However, the original piping practices when these systems were installed put different size laterals and supplies to the different size of radiators.  With this in mind, a small radiator will get less steam than a large radiator, even though they may have identical vents because the head loss created by the smaller piping will somewhat restrict the flow of steam.

With the above thoughts in mind, I would be very tempted to experiment with Hoffman #40 vents.  They are about as reliable as they come, and are quiet.  They also have a slow venting rate, about the same as position #2 on a Hoffman 1A.  However, I have noticed that the actual venting rate of the Hoffman 1A is unpredictable and erratic at the lower end of the scale because of sloppy tolerances between the retaining screw and the rotating adjuster.  At any rate, the #40 vents are often available on ebay at very low prices. Pex supply has good prices too. It would be probably the most inexpensive option you have, after verifying that the boiler is firing correctly and that piping is insulated.



Using orifaces as a means of balancing 2-pipe steam systems is a proven method, and the oriface approach can be used to balance 2-pipe systems where the boiler is undersized for the EDR load.   Using very slow radiator vents on a 1-pipe system will work somewhat the same way in that if the radiator vents are slow enough, all radiators will get some steam, and with good fast main vents, they will all begin to get steam at the same time.



This may not work, but it is about the cheapest option that you have.  I think it would be worth a try.

The Steam Whisperer (Formerly Boilerpro)

Sal, take a look....

at my article in the Hot Tech tips    "Taking another look at steam boiler sizing methods".   I have purposely installed boilers that are "undersized" by conventional sizing methods and used this design process to make them heat evenly.  The only reason I see for sizing boilers to radiation is to help them heat the system evenly (which we all know rarely happens anyway), but this can be done by other means.  Sizing boilers to radiation typically results in a boiler that is at least 60% bigger than the heat load and all that does is run up the fuel bills.

Big-Al_2

TRVs

I'm a non-pro tightwad, so I'd try some cheap ideas first.



1) Install Maid-O-Mist #4s on the hottest radiators to slow them way down.  If you start with #4s and they are too slow, you can drill out the orifices without having to buy new vents.  Unlike adjustable valves, once you have them set right, nobody can mess things up without the use of power tools.



2) Move the air vents up to the top "hot water system" position on the hottest radiators, making them close earlier and effectively reducing the radiator size.



3) Install TRVs on the hottest radiators.



4) Put air flow constricting radiator covers on the hottest radiators.

Sal Vigilante

Wow thanks a lot

What an amazing amount of great information.  Some of it I have done already and the rest gives me some more options to think about before I build a Frankenstein.

Thanks so much for taking the time for me today.

Sal Vigilante

Great article

Dave really good article it was clear and easy to read. It also described my situation perfectly. I went ahead and did a heat lose calculation on the building. Boy, was that an eye opener. The building needs 215,064 BTUs the current boiler is burning 349,000 BTUs. That’s almost 40% more than the building needs. So, I am going to vent my mains to the top floor and slowly fill my radiators.

I’ll keep you posted.