thermostatic traps and simple elbows

SteamedInDC

The 100 yr old building in DC that I bought into has a two-pipe steam heating system with a one year old Weil-McLain 80 Series (780) boiler. The water feed has been adding about 20 - 40 gallons of water a day to the boiler according to the reading on the VXT-120.

The system has a gravity condensate return system, no condensate tank or pump. We've been looking all over the building for major water leaks and have not found any. All of the returns are exposed or in crawlspace and have been look at, we did not see any leaks.

This system has been poorly maintained up to this point, none of the shareholders/residents knew anything about steam heating before I moved into the building a year ago. We've started to eliminate air vents that have been installed on the two-piped radiators and have seen some improvements. We have been able to eliminate about 50% of those so far, a few of them are stuck and others are stripped - we'll leave these for the professionals to address. The next step that we are going to do is have the thermostatic traps replaced by the pros. The quandary is that only 25% of the radiators have thermostatic traps and the remaining 75% have simple elbows - there are 50 radiators in the building. One direction would be to install thermostatic traps on all of the radiators, give the building consistent control of the system - that is what our pro recommends. The concern with this approach is that since this building is 100 years old, we may end up cracking a pipe, breaking a pipe etc. during the process of having the thermostatic traps installed. The other direction would be to only replace the traps that are already on the radiators and to check the others to see if they have orifice plates and install those where they are missing. Would this be an option? Will the trap replacement and valve work have a significant impact on the water feed problem? Any other thoughts on what is going on with the water feed? My concern is that we are significantly damaging the boiler with this amount of chloraminated water (DC water) feeding into the boiler, basically refilling the boiler every 36 hours.

Mark N

I would get Steamhead there ASAP he is in Baltimore. His company is All Steamed UP.

Mark N

Does this system have buried returns? They are most likely leaking. They need to be replaced.

SteamedInDC

Thanks Mark N for your reply, I've edited my description to address your question.

Mark N

Are you losing steam out of the main vents? You're losing the water somewhere. The boiler is new otherwise I would suspect it was leaking. Does the water level drop low enough to trip the feeder on while the boiler is firing? Do you then have to drain excess water after the condensate returns?

SWEI

SteamedInDC said:

only 25% of the radiators have thermostatic traps and the remaining 75% have simple elbows - there are 50 radiators in the building.

Can you post some photos of the "simple elbows" and the inlet piping for those radiators?

I'll second the recommendation that you reach out to Frank. You're lucky to have such a resource in the area.

SteamedInDC

Below are photos of the typical elbow and valve.

SteamedInDC

here they are.

SteamedInDC

The main vents are new and are operating properly from what I can tell. They seem to vent, but there is not a lot of steam profusely coming out of them. The water level does get low enough to trigger low water cut-offs while the boiler is firing. I have adjusted the feed delay trigger on the VXT-120 to 4 minutes, the feed amount has been set at 2 gallons. We have two float-type cut-offs. We do not have to drain excess condensate.

Mark N

There should be no steam coming out of the vents once they close. Do you have any idea as to what the pressure is when the boiler is running.

Mark N

You state you are adding 20 to 40 gallons a day. If you were losing that all as steam it would be noticeable, 1 gallon of water is 1700 gallons of steam. I would give the returns that are in the crawl space another look.

Fred

I know this is a 1 year old boiler but is it always cloudy over DC with the cloud starting at your chimney? That much water has to go somewhere and it should be noticable in a big way!

Mark N

Is the pro that is working on your system the same one who installed the boiler? Was the boiler assembled on site? Was the block pressure tested for leaks after is was assembled?

RobG

I think DC is outside of Steamhead's area. You should contact Dan Foley (Foley Mechanical) and get him out there to troubleshoot the system. He is one of the best in the business.

nicholas bonham-carter

Those elbows may be more than simple 90's, as they have unions incorporated in them. They may contain some special feature which keeps the steam (at very low pressure) from getting out.
Can you see the waterline drop as the boiler fires?
See if there are any horizontals in the reurns whose height is just above the height of the boiler waterline. These could be hiding a lot of water, as pressure rises, forcing water up into the returns.
However, the fact that you are not having to drain excess water from the system, would indicate a loss of water, rather than hiding water, which always comes back to overfill the boiler.
Getting a real steam expert like Mr Foley is recommended. We can help with diagnosis, but we are not there.--NBC

SteamedInDC

The boiler, when running, runs at around 1 psi. No noticeable humidity in the crawlspace.
The initial installer of the boiler was let go after two faulty header installations. The pro that we have working on it was recommended to us by Dan Foley, Dan was too busy for the project. The pro installed a new header and it has all of the manufacturer recommendations accommodated and should be providing dry steam. Dan Foley is familiar with the problem though and thought that much of it was due to the initial faulty header design and installation. That's been taken out of the equation hopefully and we're moving down the list. There are two places that have been identified where the water is being delayed in getting back to the boiler. Some water is probably being held in radiators with failed traps in the closed position, some water is being held in a low spot along the horizontal return in crawl space - that probably accounts for why the water is not getting back to the boiler. The big question is where is that 20 - 40 gallons going.

Fred

If you see no water anywhere and we know 50 radiators (I assume most heat) won't hold 20 to 40 gallons of water for long before they are causing a lot of water hammer and/or cold radiators, are you sure the meter on that VXT is working properly? Are there any drain spigots on any of the return lines that are piped to a floor drain where the spigot may be partially open? Are you 100% sure there are no buried returns? We're not talking about slow return here, we're talking NO return.

nicholas bonham-carter

if you are there most of the time, why not valve off the auto-feeder, and just keep checking the boiler often. this will confirm the loss of water.
if so, then do the overfill test. after the boiler has cooled a bit, then fill until the header gets cold from the fresh water, and let stand for a few hours.
look n the firebox and on the floor for any signs of leaking.
it is possible that the assembly of the boiler sections was imperfect, and that there is a leak above the waterline into the flue, where you would not see it.
I think that maintaining very low pressures will improve this situation, when you find out where the water is going. checking for orifices between the valves, and the union face of the spud --NBC

SteamedInDC

Thank you NBC - I'll give that a try. Could you tell me if the overfill test is something that a non-expert should attempt to do? I am mechanically inclined and have a fairly good understanding of our boiler.

SteamedInDC

Fred, that's a very good question, I have sat down there and watched the autofeed add water back to the boiler after a 15 minute cycle. Maybe its calibrated in ounces rather than gallons

nicholas bonham-carter

yes, the overfill test is very simple, and will catch any leak inside the boiler, and wet return pipes. patience is all you need!--NBC