Loop seal on condensate tank??

jlt83

I’m new to steam heat and to my home. I have Weil-McLain egh-95 boiler and about 1,750 of radiator EDR (so I think the boiler maybe under sized - but that is not the main subject of this post). The piping is complex (not the original boiler). The only vent for the system is at the condensate tank. The returns coming to the tank meet together on the floor and then raise up 18 inches to the top on the tank (creating a loop seal). As best as I can tell the boiler runs until is producing 10 oz of pressure, at which point it can force the condensate into the tank and vent itself. This continues in cycles until all the steam traps close (I assume) and the pressure reaches 11 or 12 oz and the vaporstat shuts down the boiler. On a related note, after the thermometer stops calling for heat and the boiler cools, a vacuum is created in the boiler. I added a vacuum breaker to the boiler to stop it from sucking water from the condensate tank into the boiler (flooding the boiler) - which is how the system previously was relieving the vacuum (this also indicated to me that there were no other (working?) vents other then the loop sealed condensate tank.

My question is: Is piping like this good / standard / OK / safe? What ought I be looking for? What ought I consider changing? (Note: after the F&T trap on the main supply line there in not a vent - just a drop into the wet return on the floor).

clammy

Post some pictures of your condensate pump and its inlet and discharge piping . Usually there is a check valve on the discharge of your condensate pump to prevent your boiler from sucking the water out of the receiver .Is your system a single pipe or a 2 pipe system . Your system probably never had a condensate pump at some point and one was added . Either for a basement to be finished or the buried returns rotted away . Again post some pics and possible of your boiler and it’s near boiler piping peace and good luck clammy

jlt83

There is a check valve, but its purpose is to stop boiler water from flowing back into the condensate tank. The system is two pipe - originally installed in 1930 (oil fired - now gas). Two photos attached show returns (vertical pipes and horizontal pipes near floor) and connection to tank. Second picture show pipe from tank (and its pump) to boiler.


Finally, last photo shows F&T trap at end of supply line and shows it directly flowing into wet returns (below level of condensate tank input)

clammy

From the looks of it it is a mess . What you have is a A boiler feed pump w a reservoir , the piping looks to be a mess I m just kind of wondering what the contractor was thinking . It looks like what you have is a 2 pipe vapor system which original had no condensate pump and worked by gravity . There may have been some other issue which all this was done to band aide it and mostly like hide some other issue ,I mainly say this because unless there’s another remote condensate pump some where else it looks like all the piping is already there for it to be a gravity return .
The unseen issue may have been lose of water seal due to lower water line of new boiler ,or possibly they may have ran into issues w not enough water volume in the boiler and attempted to do that to resolve . There’s much easier ways to solve those issues with the use of false water lines and reservoir tanks which will be less in maintenance and future replacement
The near boiler piping looks smaller then the main its connected to thats is a no go . A quick look at the piping layout w a swing joint is fine but I would educated guess from your picture that the header size that you have is not even the manufactures mim . It most likely should have been a 4 inch header w a 2 equilizer . A lot of guys forget a big thing about 2 pipe vapor systems especially w no traps and this in general they where original piped to a boiler that produced extremely dry steam not like today’s boilers it’s the headers job to do that and if you want a system to perform as it should it all starts back at the boilers near boiler piping and there is absolutely zero short cuts when it comes to that . Everything aside from that is just chasing dreams of a ghost that’s long gone . Possibly if piped correctly half of the issues may have never happened bad near boiler piping is a disease w tons of symptoms .
If you can’t find a real steam pro who has some answers and real cures not Band aides unless that’s what you want ? Or get some of Dans books and read and educate yourself so that you will know the cause and effect of what’s happening and even if you are unable to perform the work yourself you will at least be able to pick and kick the bums out instead of paying them form accomplishing nothing
Peace and good luck clammy

EBEBRATT-Ed

Any traps that drop into the wet return upstream of the loop seal should be vented....a vent installed after the traps. Weather you need multiple vents or one vent depends how it is piped.

They make boiler feed tanks wher you dig out the floor and they sit flush wit the top of the floor. That is probably what should have been used unless the condensate pipe can be raised to that the air removal can be done by the tank vent which is usually the case.

EBEBRATT-Ed

Here is an underground tank

jlt83

Thanks for the input. I’m still most surprised by the lack of vents on the returns. Assuming the original system was a gravity system, there should be vents on each of the return lines (which are still the original piping right up until the loop seal for the condensate tank.)

For me my main question still remains unanswered. Does using a 18 inch water loop seal between the wet returns and the condensate tank cause any fundamental problems (other that requiring the boiler to build 18 inches of water (about 10.5 oz of steam pressure ) before the system can vent? If I add vents to all the return lines (between the last steam trap and the waterline) what benefits will I get (in addition to faster venting)?

Thanks all

clammy

Sorry i did not answer your first question . The answer is no you should not have a loop seal on inlet piping to your condensate receiver . The loop is not allowing your system to vent through the reciever and it’s open tank vent . I see a old dry return trap hanging up high there usually on the main dry return and usually there is a system air vent on them when the system is a vapor system as yours was at one time . They did the loop seal to prevent steam from blowing through the receivers vent mainly because they are missing a water seal or f and t else where in the system or those existing f and t are passing steam .
You should again take a look at the manufactures installation and operation manual and check there suggested boiler piping diagram of your size boiler w what was installed. There was some knuckle heading done w the piping and i would guess aside from it flooding your boiler I feel that’s if the pressures troll and the Low water cut off are working them I guess you’re safe . I will state that constant draining of a flooded boiler may seem a short cure all that’s fresh water being added will do not good for your boiler and will surely shorten it lifespan w daily draining . You would be wise to see if a pro listed on this site is locate in your area if so contact one of them and have them take a look at it . It may be well worth your time and money to get it operating correctly or you just deal w it till the boiler rots away . Peace and good luck clammy

EBEBRATT-Ed

I agree that Ideally you should not have the loop seal. That is a given.

So what options do you have:

Get rid of the condensate tank if the system will work without it

Vent the returns before the condensate tank to improve heating.

Put in an underground condensate return tank . Big $$

Raise the condensate line to eliminate the loop seal

Collect the condensate into another condensate pump and let the air vent there then pump the condensate to the boiler feed pump ...overly complicated.


Your decision should be based on

1. how is the system heating now.....any problems?
2. How much can you spend and what will it cost to fix?

jumper

I like Clammy's question about what contractor was thinking.