New boiler installed! Some remaining questions...esp LWCO/Feeder and condensate return

samglo

Thank you all for prior input regarding my boiler replacement! The install ended up being a Burnham PIN6SNI-ME2 175K BTU natural gas boiler, with 2" risers and 3" header to the 2.5" steam main.

The system is currently running at about 0.5 to 0.7 psi pressure without the vaporstat kicking in, so the boiler output seems pretty well matched to the radiator condensation.

However, the boiler level is currently dropping below the LWCO after running for longer periods of time. The boiler came with a M-M PSE-800 probe LWCO, and a 101-A mechanical auto feeder was also added for the install. Therefore, the feeder is kicking in when the LWCO calls for water, but then the boiler is overfilled when the condensate eventually makes its way back. It's been overfilling by about 2 gallons.

The other thing I don't like with the probe/feeder combo is that the LWCO runs through the test cycle when power is turned on to the boiler, which causes the feeder to also add water if the power were to go out and come back on. Why is there no delay??

So, some questions:
1. Is it possible to add a time delay switch between the LWCO and feeder to delay the overfilling, particularly during power off/on? I think that would also give time for condensate to return during normal cycles, although that means the boiler would be cutting out due to LWCO.

2. The water is still dirty and oily, so is it reasonable to expect that the operation will improve as the water becomes cleaner? I've skimmed a couple of times, but there is still a lot of oil and sediment.

3. Should I be doing something to improve the flow of condensate back to the boiler? Or adding more condensate storage in the wet return piping (i.e. section of 3" or 4" pipe)?

4. Should I add a 2-stage gas valve to reduce the firing rate and give the condensate time to return to the boiler?

Install pictures are attached. A Dwyer WM2 meter will also be added to the water supply. The gas supply was also changed from 1/2" to 3/4" after the picture was taken; the 1/2" was causing about 3.5" of pressure drop, way more than it should have based on head loss calcs.

Thank you,
Sam

KC_Jones

I'd be willing to bet you are still surging from all the oils. How many hours have you skimmed for?

Calm down until you are absolutely sure everything is clean.

All boilers are different, but on my install I used a wand to wash things out AND did roughly 12 hours of skimming. The more new piping the worse it will probably be.

AnthraciteEnergetics

I assume it was wired right from the factory. There is normally an output terminal for the feeder inside the LWCO that should only feed on a true low water condition.

I hate that "test" feature of those CycleGards and I got mine to stop doing it by pulsing the "Burner" terminal with 120 V 9 min on, 9 min off using a duty cycle timer module and a relay. There is nothing worse than shutting down a steam system (esp 1 pipe) over and over again in the middle of a heat call.

EBEBRATT-Ed

@KC_Jones is correct.

If the boiler water is dirty, surging water level bouncing etc you can't expect the lwco to work properly. Fix that problem first. Your not going to know if you have other issues until you do that first

New England SteamWorks

Agree. You need to skim a whole lot more. And you should have gone with a VXT feeder!

Steamhead

New England SteamWorks said:

Agree. You need to skim a whole lot more. And you should have gone with a VXT feeder!

This.

The Hydrolevel VXT not only has a digital counter that shows how much water it has fed to the boiler, but it also has a built-in delay so it won't activate during the low-water cutoff's self-test.

Once this change is made, that problem will go away. But you still need to flush and skim.

Fred

I have a Burnham also, an older one but one thing I can tell you is that they are very sensitive to any oils introduced into the system, pipe repairs, whatever. Keep skimming it very slowly and you will see the water level stabilize and the problem will go away. I assume the installer flushed the wet returns with the installation? Looks like he did a very nice job.
I do think that MM LWCO does have a 10 second delay before it shuts the burner down and a 15 second delay before it refires. not adjustable but I have the MM #67 float type with no delays and it never shuts the boiler down. You won't have a problem once you get the oils/dirt out. I also assume there is a skim port on the back side of the boiler?

Lance

I noticed in your pic the old pipe behind the boiler. If the reason for the filling is a delay returning water due to a partially clogged pipe.....? A system that old will probably need the wet return completely replaced or you will forever be returning dirt. You could even flush it and it may still plague you again. I have successfully flushed some with 60 psi pressure and others had to be replaced. Squick is a great cleaner. Nice job, but you should never ever trap a gas pipe or flex. Wishing you success.

samglo

Thank you all for the input!

I'll continue skimming. I've been skimming through a skim port on the other side where the relief valve is, I had the contractor put a tee there instead of the elbow. I think I'd also like to drain and use a wand.

The water I drain from the wet return is quite clean, especially compared to the boiler. But I have no idea if there is some unknown blockage somewhere along that pipe. The pipe seems pretty clean where the boiler return trap check valves are located, but I completely understand the point of replacing the 90 year old steel pipe. I think my spring time project will be to repipe the wet return.

Funny about the VXT. That was my original plan, but the local supply house originally supplied the 110V version rather than the 24V. They had the MM 101-A on the shelf, so the contractor went with that one. So overall it was about twice as much money for the feeder and meter, without control over the delay. But it sounds like the MM may be more reliable? Should I really replace with a VXT at this point?

@Lance , could you clarify about not trapping a gas pipe or flex? The Burnham I&O manual shows a 3" minimum length grit trap at the boiler. I think I'm misinterpreting. Do you mean the dip in the flex line before the grit trap?

samglo

And I'm overjoyed having a 3 psi gauge so I can now geek out on the boiler operation. Definitely should have had that on the old boiler!

Fred

I skim through a Tee off of my PRV as well, on my Burnham. Just a little tip, if you have a fairly warm day and a floor drain, turn the power off to the boiler, open that skim port and open the manual water feed just enough to get a trickle out of the skim port. Run a garden hose over to the floor drain and let it go for 8 to 12 hours. I usually do it over night. That slow skim does the job every time and doesn't require you to stay with the boiler.

BobC

Why have a water feeder, it's just another thing that can fail and cause untold problems.

I've lived in steam heated houses for 70 years now (except when serving in the army) and never had an auto water feeder on the steam boiler. The last 8 years of my working life had me going out to Oklahoma for 2-3 weeks a couple of times a year and i never had a boiler problem. I did have some one check the house and the boiler a couple of times a week when i was away in winter months.

I do test my LWCO operation every month or two and I keep a boiler log and note any water I add by sight glass column inches, I added 1/2" of water last Friday and that is the first water I've added this heating season. Boilers should be visited at least a couple of times a week, ignoring them leads to trouble. Unless you expect to be away for extended periods in winter weather I would not have one in the house, not worth the expense or the trouble they can cause. If the house occupants can't handle the basement stairs that would be justification for an autofeeder.

Bob

Lance

About the trap on gas. The grit trap is not a trap. We call it a drip leg. It collects what falls to prevent the branch pipe from getting blocked or from particles, sand, getting into the gas controls. Usually if this is present, anything after the tee branch is safe. But lets assume water, or oil in pipe. Where will it go? and if there is a U trap like shape in the flex off the tee it can fill up or get restricted. A drip leg has a cap to remove to maintain should it fill up. To handle a gas flex after the tee to the unit if it is too long it can be bent in an arch or made horizontal, but never like a sink a u bend. Also gas flex are not unions and are not designed to be used like unions. A union in the pipe is still required and unions cannot be in the appliance and gas flex connectors cannot pass through walls, floors or appliance housings or be in the appliance. At least in the code I follow. A gas flex connector is not the same as gas flex pipe.

Lance

Let me add one more thing since I checked the pic. No trap in a gas pipe can exist between the meter and the drip leg. Its a gas code requirement. There must be fall to or away from the meter to the drip leg at the appliance. In your pic the flex connector is looped making a trap. If it is arched it must be after the drip leg. If it is arched before it sees the drip leg it would form a trap. It must be properly sloped without trapping. The problem with flex pipe is when piped horizontal it requires more support to keep it from trapping. Sloppy work makes failed inspections. The problem with flex connectors is unlicensed or untrained people can easily get it wrong. Might it work? Yes. Will it work later? ?
Will it pass inspection? No!
When accidents and disasters occur, code installed communities are more quickly repaired, protected and brought back on line.

Jamie Hall

As you can tell, there are differing opinions on automatic water feeders. @BobC feels one way about them. I, on the other hand, find it very nice to have. The one on the main place I care for is a VXT with a nice long time delay and a meter, operated by a McDonnell-Miller float type LWCO. Maintain everything properly, and it is great peace of mind.

EBEBRATT-Ed

@Jamie Hall & @BobC

I think a good compromise would be to have a feeder but under normal conditions keep it valved off. That way you can get a feel for how much water the boiler needs and how often.

Then if your traveling or away on vacation you can turn it on for piece of mind.

Suppose a water meter on the feader would do the same thing

Jamie Hall

I wouldn't have one without a water meter. If you don't have a meter, you have no way of knowing if you have a minor problem -- until you have a major one. Not the way I like to fly...

EBEBRATT-Ed

@Jamie Hall true but if you keep it valved off and only use it when away theres little risk of a problem.

Feeders are fine only if paid attention to

Jamie Hall

EBEBRATT-Ed said:

...Feeders are fine only if paid attention to

So true. But that applies to a lot of machinery besides feeders!

acl10

I also had a problem and installed a VXT feeder and set it at 8 minutes and no more problems with overfilling