False waterline, or reservoir tank?

Mike_Sheppard

One pipe system. Five story apartment building. Boiler was replaced and feedwater tank was installed due to low water content of boiler. The installer did not trap any of the mains or use a false waterline.

I was planning on giving the customer a quote for installing a false waterline tank as described in TLAOSH. But today I ran across something I have never seen - reservoir tank next to the boiler for extra water capacity. The feedwater tank for this boiler is tiny. It holds, I’m guessing, maybe 20 gallons.

I’m thinking that taking the feedwater tank out and installing a reservoir tank (changing back to a gravity return) instead would be a simpler, cheaper option. Although maybe the boiler even holds enough water already.

Like this one:
https://www.gwgillplumbingandheating.com/webapp/p/644/field-fabricated-reservoir-tank

Thoughts?

Mike_Sheppard

Picture of boiler and feedwater tank.

JUGHNE

This one might be overkill.

JUGHNE

The equalizer is connected to the top. There are 2 bottom connections going into both of the boiler inlets.
The Hartford loop connection from the dry/wet return on the floor goes into the end of the tank. This takes 90 gallons to fill the entire system. Was built by a gas company welder.
Never runs out of water and makes no noise even with the 6' horizontal connection of the "HL".

The water fill is connected into this tank and also the boiler return inlet.

nicholas bonham-carter

How was it determined that the boiler had not enough water to make steam for the whole system?
There may have been other reasons for the boiler running low on water, such as high pressure pushing water up into the wet returns, or too small of a boiler, (unheard of!!).
I’m sure the engineers at the factory made the active water content large enough to fill the system with steam.
A reservoir tank is easy enough to make, using an old hot water system expansion tank on legs, but I wonder if it really needed in this case.—NBC

clammy

mike Would u be able to use the tank that s there as your resiviuor you would just have to get hung mid way and install a sight glass and a top and bottom connection . If u traced ur boilers water leaves and see that u have non sealed drips then by all means do a false water line if u don’t have much distance then u may be stick w putting a valporstat on it for insurance if you don’t have enough height .if u look at tha manafactures lit it should give u a steam to water rate on about how many gallons are steam per I think it’s 15 minutes if I remember right . It should be a easy sale considering it’s cheap then traps and all the rest that goes with it and all that maintaince false water lines and water seals and a resiourve tank is the best way to get away from pumped to gravity . The tanks are usually the only way to help a low water content steam boiler on a single pipe system function correctly with out flooding on the off cycle .looking at your pics it looks like it’s already piped in as a resiuorve tank .i think I would shut that feed valve and run her for a few days or put in a meter and chk water use and see what happens when she runs . In the past I ve run into system with seals and tha off cycle flooding what a pia . I think u have a good plan going forward peace and good luck clammy

Mike_Sheppard

@clammy there is a pump on the far side of the tank that pumps into the equalizer.

I need to time the system first to see if the even needs a reservoir tank at all. The boiler might already hold enough water, it is oversized.

It’s already running at 10 ounces with a vaporstat.

They have more than enough A dimension if I were to convert back to a gravity system and use a reservoir tank or not. All the drips come down into a wet return.

clammy

I think that’s a smart idea to isolate make up and cycle it from a idle and see if it shuts off on low water . It would be nice if you could isolate the tank also so it’s completly outta the picture just to see if boiler water volume is enough .Do u have a equalizer line to the tank from your header or from your equalizer which ideally would be higher up like right before u drop to tie into the boilers return to the top of the tank . In re reading the nbp ing equilizer pipe goes directly into the tank ? I would myself rather see the nbp equilizer go directly into the boiler as standard practice and then pipe a 1 1/2 to 2 supply equilizer to the top of the tank and the same off the boiler return as per wiels diagrams even though there may be no issue the way it is . I would do it as I said then the tank sits idle on the side not acting as a equilizer go between and would be far easier to isolate and flush also . Sounds like a interesting project make sure to pay attention to all the details never want to be in between a rock and hard place .most I deal w would keep the way it is until boiler and or pump went but in rare cases the only way to make them function correctly is to go back to gravity and add the resiouve tank and possible false water line which in some some cases is far less then the alternative . Peace and good luck clammy

EBEBRATT-Ed

@Mike_Sheppard

When I am in that situation I usually look at the building and see how compact it is. That is it spread out or is it more of a vertical building?

Guessing that it's more vertical being 5 stories. With that set up I would think the condensate would return fast.

When I do a feed tank I usually allow a tank sized for a 20min runtime before getting condensate back.

I would suggest running on a cold start and seeing how long it takes for condensate to come back

That tank is tiny and the capacity is determined by the level the overflow pipe and the level of the make up water.

Are you getting steam out of the tank vent or overflow??

A simpler solution if water capacity is not an issue is to leave the tank. Pipe a drop into the return to the tank to keep steam out of the tank. Install large vents on all the returns