Hoffman Boiler Feed, persistent trickle feed and overflow

04090

Update 7/15/14:   Found a considerable amount of muck in the line leading to the feed valve, coal like material that could be dug out.  Photo posted below.  Disassembled and flushed valve to no avail; it wouldn't seat properly so I replaced the whole thing. 



This thread morphs into asking how I can prevent another failure.



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On a Burnham V 905 series steam boiler (small commerical, 4GPH) there is a Hoffman Boiler Feed Series VBF Model 30-VBFS-B condensate tank.  Feeding it from a 1/2" domestic water supply, there is a Watts 9D-M3 backflow device and then a Bell and Gosset FB-38TU pressure reducing valve.



The condensate tank slowly feeds water all the time, and as a result the boiler floods. 



Here's what I've done:

1)  The screen leading to the backflow device on the supply side is clean and clear.

2)  The strainer on the side of the PRV was totally crudded.  I removed it, flushed fresh water through the valve into a pail and installed a new strainer.  I activated the valve's feed lever several times in hopes of clearing anything that might be lodged in the seat.  Sidenote, the tank says not to allow more than 30 PSI feeding it, the PRV is set to factory default of 12. 



The tank continues to trickle water and will overflow.  What else do I need to do so the trickle will stop?

Jamie Hall

Somewhere...

there is a shutoff valve in the mechanism -- not the pressure reducing valve, nor the backflow preventer.  It's that valve which is leaking and needs repair.  Find it and you'll be good to go.

04090

Yes

But where and how?



The valve inside the tank is a Hoffman DL-1634.  Is it a serviceable part and could it be a malfunction of a valve outside the tank (ie one described in first post) that could be the culprit?

Jamie Hall

Most likely

that valve inside the tank.  The others just prevent backflow and reduce pressure, but don't turn the feed on and off.

04090

Likely, but

Is it possible that when a PRV leaks, fails or otherwise malfunctions that it will supply street pressure? 



I think the PRV was replaced years ago when the system had the same flooding problem, and that fixed it.  I just don't remember if they did anything else, but for sure the valve inside the tank is original.



If the PRV does supply street pressure, then the valve inside the tank is under too much pressure and would possibly flow as a result.



What should I do next?

Pumpguy

Typically........

boiler feed units will have a float operated make-up water arrangement.  This could be an internal  mechanical float valve like a toilet water closet, an external float valve arrangement like a McDonnel Miller, or a float switch and solenoid valve. 



The mechanical types don't like high water supply pressure, so a PRV is used to reduce the pressure to 45 psi or so. 



I would check the make-up supply valve first to see if its leaking.  IMO this is most likely the problem.  The PRV may need to be adjusted to a lower outlet pressure. 



Hope this helps.  Good luck.

RobG

Replace

While your at it replace the PRV. I have never repaired one. They are not expensive.



Rob 

04090

I replaced

I replaced both the backflow (only because it was getting old) and the PRV with an identical model and the slow feeding to flooding stage problem persists.



I drained the tank and tried removing the float/valve assembly from the condensate tank.  Used a 24" pipe wrench and couldn't budge it,even after rapping it via sledge hammering (with a 2x scrap as intermediary) and then gently bouncing on it with my foot.  I guess using the torch is next.



Anything else I should be looking at?

Steamhead

I'd be looking at

changing back to gravity return. 90% of the condensate tanks I've seen are unnecessary. This would not only get rid of the pumps, but also any F&T traps that were added.

04090

Next step

I've tried all I can to loosen the 2" or so fitting that's holding the tank's float valve in place.  My 24" Ridgid pipe wrench is pretty hardy; I've tried tapping it with a hand held sledge, pouncing in it but not enough to displace or endanger any connections, sprays, patience, adding 18" or so in handle length with what I think they call a cheater bar and more.



Tempted to drain it again and play a propane torch on it, but hesitate.  What can I do to get this thing out, short of calling in a pipefitter?



As suggested, I'd really like to get rid of this condensate tank.  It's been the only unreliable part of the system but for now just need to get it going.

ChrisJ

Pictures

Can you post some pictures?

It will likely help greatly.  In my experience as little as it is, a 24" wrench isn't very big when dealing with 2" pipe.

04090

Photos

One photo shows the replaced PRV and backflow device along with the part I've been trying to loosen from the tank.  The other shows what the part looks like that I'm trying to remove.



It's very simple to remove the PRV to facilitate removing the float valve from the tank, except I can't budge the float assembly!

Pumpguy

If you're going to try heat........

you will need something hotter than a propane torch unless the burner head is real big.



Propane is a rather cool flame.  Mapp is hotter, but best choice is oxy-acetylene.  The problem is all that mass of iron just sucks up the heat. 



A longer wrench is probably needed along with shock and heat.  Problem is there often isn't enough room for the big wrench to fit. 



As a last choice, you may need to break up the fitting and pick out the pieces.  I wouldn't try this unless ALL ELSE FAILS.  To do this, chain drill a series of holes just inside the threaded portion of the fitting's OD.  Then use a larger drill to decrease the space between the holes, but not going into the threads.  Then you should be able to break up the fitting with a hammer and punch.  To get what's left out of the threads, take a close quarter hack saw and saw a series of slots into the fitting.  Now with a hammer and punch, you should be able to knock out the pieces of the fitting, leaving the female threads in the tank undamaged. 



Another solution is to plug and abandon this leaking fitting and fit an external McDonnell Miller #25 make up float valve assembly.  This is a common recommendation to deal with leaking obsolete internal make-up float valves.  You will need to make top and bottom pipe connections to your boiler feed tank, but you'll end up with a much more reliable make up float valve. 

RobG

Tank

I am no expert on condensate receivers but there is no way that valve in the picture is the one in the tank unless there is an access hole elsewhere. There is no way for it to thread in with the float attached.





Rob

Charlie from wmass

it goes in through the tapping

that is the float valve used in many tanks. They can also use the McDonnel Miller they use as boiler feeders. The model numbers 47 or 51.

RobG

Does it

Does it swivel at the plunger when you install it? How do you set the water level or tighten the wing nut



Rob

04090

There's a mark

There's an alignment mark on the outside face than indicates bottom.  The level is adjustable based on the hinge setting, but I believe it comes preset for standard use.



Once I do get it out, and I will, can these valves be cleaned or serviced... decruded or perhaps just the float replaced if it leaks, or is it just best to have another on hand?  At this point it's preferable to get what's there going rather than replumb the area.  There's a glass gauge on the other side of the tank with standard fittings, but the area it's in is almost a crawl space.



I'm going to let it bask in PB Blaster for a week while away. 



Thanks for the help.

RobG

I guess

I just don't see how it could be installed without access. If it was able to swivel when installed it could turn instead of going up to shut of the water? It has to be stationary, but to be stationary it would have to spin in a circle to get screwed in and would hit the side of the tank. Am I dense? 

04090

clearly

The device is shown folded over itself in the stock picture. 



It hangs straight out, much like a toilet valve.



When unscrewed from the tank (someday for me) it'll all pull out - one long straight assembly with a few hinges.

04090

Got it off!

Got it off with some help.



Found a superduper mucked up feed line...  this coal like muck is packed straight through the 2" nipple and ends at the valve assembly within the Hoffman mechanism.  How can I stop this from happening again? 



System design:  a copper water line comes from the street, goes through a ball valve, a backflow preventer and a pressure reducing valve, then into this float valve.  Faucets don't get clogged.... why is this different?