Weil McLain 88 boiler surging and looking for a boiler feed pump design

plumbfava

I’m replacing two condensate pumps on a large 6 story building system, also adding a sediment trap and throttle valve with pressure gauge for the pumps to help extend the life of the pumps. The boiler model is 888 Weil McLain very large commercial boiler lots of hands Been on it. Surging started happening when a company put a chemical feeder to correct PH. Boiler is blown down daily very old building lots of old pipes and leaks causing fresh water to be put into system. I recommended a boiler feed pump to communicate with the boiler but they do have a LWCO with pump combo controller I’ll attach photo, does this pump controller actually tell it when to pump or only tells it not to pump? I’m fixing multiple leaks to try and keep freshwater down but my first priority is replacing the broken pumps because they’ll have no heat come winter. I really would like to design a boiler feed system, but it’s a little over my head I do more hydronic vs steam but I’m willing to try with proper understanding and confidence in my design. FYI boiler level stayed great when first installed, after injection system things started to surge.

Thanks

Jamie Hall

Let's start with cutting down the operating pressure. Try a cutin of 1 psig and a cutout of 2 psig (you'll have to go into the pressuretrol and adjust the differential.

I think that that LWCO has two sets of contacts — on to cutout the boiler, and a slightly higher one which signals the feed. That one could be used to signal your boiler feed pumps — but I'd put a relay or contactor in between, as I wouldn't like putting the starting current of the pumps through the controller. Not hard to do. Then there should be a float control on the boiler feed tank, to feed makeup water when it gets low — and an overflow to a drain.

I'm not at all surprised that the boiler surges. Too much additive is a good deal worse than too little. Dial the feed back until it is just barely enough to keep the pH slightly basic (I'd shoot for around 8, but at least more than 7).

ethicalpaul

At risk of disagreeing with Jamie, and of giving you too much information, I have proven that the PH level doesn't cause surging (and I would aim for more like 11, personally, to greatly reduce corrosion, as several boiler manufacturers recommend).

But the typical boiler additives can trigger surging when the water quality is poor from too many dissolved solids and/or other issues.

What additive are you using?

I see the water softener…are you feeding softened water into the boiler?

mattmia2

It seems pretty obvious that whatever treatment is being applied to the feed water is causing it to prime. Exactly what that is probably has to be figure out by a competent treatment company.

Is this 1 pipe or 2 pipe? I'm betting the insane pressure is a result of many failed vents or traps and a desperate attempt to compress the air that can't get out and get some steam in to the emitters.

EBEBRATT-Ed

Looks to me like you already have a boiler feed system. Condensate tanks do not have automatic make up feed water system which you have.

Maybe it is not set up or wired properly. Looks like it may be a Shipco. If you have the Model # contact them for wiring instructions.

clammy

is the boiler is equipped w only one pump controller lwco combi which is set for the boiler min water level then aside from possible ph priming issues you will need to install a pump controller set to the correct height as to maintain the proper water level in the boiler. Trying to use one lwco for both never works properly and leads to one or the other cycling on low water then feeding ,steam and cycling again vicious cycle . . If you really think that it ph water primer i would drain boiler of all chemicals and re fill w clean fresh ,take some ph and tds reading and cycle the boiler and see if is foaming and priming causing carry over which is usually the case. . As for lowering the pressure i would measure the mains length and work backwards but if the system is working and heating properly i would leave it for now .check to make sure there are no lift fittings and or heat exchanger being they will not operate correctly or as designed at below 1.5 psi usually in my experience. After a quick re read of your post if the water line and issues only seemed to worsen over time i would suggest that the boiler possibly needs to be cleaned . draw some water off the skim line and check by boiling and see if its foaming ,in some cases just rubbing or running the water on your hands can give u a feel of soaps or oils in the water and a film forming in a clean bucket . If the boiler operated properly before i would say its the chemicals and ph .

peace and good luck clammy .

plumbfava

@Jamie Hall thanks for that info. I failed to mention the boiler pump controller is on the right side of the boiler and opposite is a separate LWCO with reset switch. I believe you are correct, the sole function of the pump controller is to not allow pumps to turn on if boiler is too high it does seem the pump controller piping is centerish with the sight glass. I will definitely turn down chemicals! Maintenance mentioned it got better when he turned it off for a few days. I’ll check to see if the pump control is separate by a contact switch for separate circuits I know this all too well dealing with some valves transformers and new thermostats in hydronics (best to keep loads and switches separate.) I’ll take @clammys advice and drain down boiler from its chemicals and start fresh and test existing ph and verify foaming.

plumbfava

@mattmia2 2 pipe

plumbfava

@Jamie Hall the first pressuretrol is controlling the standard cut on cut off, correct me if I’m wrong the second to the right is just a high pressure safety that’s why it’s at 7psi?