Click here to Find a Contractor in your area.
In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
Need to contact us? Visit

Rydlyme Descaler?

MilanDMilanD Posts: 1,105Member
Hello to all good and brave people of the Wall!

Has any of you used Rydlyme for descaling steam heat boilers? How did it go? Did you like it?

Why I ask:

As some of you may recall, I oversee an LGB steamer that last winter had a section failure, in its 7th winter. Long story short: we had quite a water use for 6 years of new boiler (and also for the old LGB that lasted 20+ years) due to inoperable traps (unbeknownst to me at a time). This lead to a lot of make up water. Coincidently our city water is also 200+ in TDS, chlorides, the works - good for people, bad for boilers. When it became obvious to me that steam coming out of the condensate return tank's vent is not normal operation, I serviced all the traps with MEPCO replacements (Hman ft cover assembly, and Warren Webster 784 cages, one of each piped in parallel at the end of 3 mains, as well as 3 Hman 17c to catch any carryover condensate at the beginning of the main, after the zone valves - quite clever in fact - there are other post on this here on the Wall so I won't elaborate further). After I was done, there was no more steam from the condensate tank vent. Yay me!

The winter flowing fixing of traps (winter #7 of the new boiler, end of January), the end section of the boiler failed and sprung a leak above the water line (I installed a water meter and kept a log, which alerted me to a lot of makeup water, which lead to me flooding the boiler and finding a leak). This section was replaced and the system is now tight and the boiler worked fine the rest of the winter. Plan is to use distilled water plus steamaster tablets for ph balance and o2 scavanging to keep the water as free of solids as possible yet having the benefit of chemicals found in steamaster and maybe sodium sulfite for additional o2 control if needed. Not sure if I'll go with Rhomar fluid just to be on the safe side...

Anyhow, while one section was getting swapped, I took a good video of the inside of the remaining boiler sections and discovered one other large blister scale buildup mound below waterline. The failed section had a pinhole leak opposite the alike mound, but a much larger one - 8-10" diameter, 4" tall! (Again, pics are in an earlier post.) Luckily, the replaced section was the end section, so swap did not take more than a day. The remaining section with the smaller blister is the opposite end section, this one below the waterline. Should it fail it will not be necessary to dismantle the entire boiler. I suppose that's a good thing. The other good thing, my video shows that the rest of the sections look pretty good with some light sporadic scaling that looks like a 3 pm beard shadow: stubby small growths, but no blisters. The only bad thing, the mound being below the waterline. Should it start to leak we won't be able to heat at all...

At any rate, I would like to remove this blister and the rest of the scaling the best I can. WM does not recommend descaling. I have read some accounts of Rydlyme descaler being a miracle. Also, talking to their engineer, he is 100% sure it will not damage the o seals, which is what I am mainly worried about. The other worry is that descaler could be removing some buildup that may have pitted into the castings and could thus exacerbate premature failing of another section(s). I am aware this is a possibility, but my inspection of the inside does not indicate scaling like that, so I am cautiously optimistic this won't be an issue. On the other hand, if I don't deal with the "mound", it will fail for sure at some point - excessive heating, graphitic corrosion, etc. Thus, a catch 22 if you will: damned if you don't and maybe also damned if you do.

So, my thought is to run Rydlyme descaler per manufacturer recommendations, but for only 75% of the daturation, therefore trying not to remove all scale, but only 60-75% of it (the manufacturer suggested concentration/time and I'll do 3/4 time and 3/4 of concentration to keep on the safe side). Then, rinse well and use either distilled water and steamaster or Rhomar. This should help keep things in check going forward. I do have testing kit for tds, chloride and o2 as well as ph strips and meter, so this will help with dialing in the acceptable water quality for distilled h2o.

Does anyone have any thoughts on what you'd do, and has anyone used Rydlyme? I am fully aware that if anything is to go wrong I'll have to eat the cost of new boiler sections. I think that it will happen for sure at some point if I do nothing, but I'd rather find out before the heating season starts and have the time to deal with it at a slow pace.

On the other hand, can a tds-free water act as a descaler and reduce the current scaling over time? This I don't know. Anyone here knows?

Thanks all!


  • The Steam WhispererThe Steam Whisperer Posts: 206Member
    It sounds like you may have a much bigger problem if this is a standard two pipe steam or vapor or vacuum system. If those traps at the ends of the return mains they are typically installed to address steam getting into the condensate pump due to bad traps throughout the building. If this is the case, the traps at all the radiators and any others draining steam mains, equipment, zone valves, etc. need to be tested and repaired and those big traps removed. They will not allow the system to function properly.
    Distilled water typically becomes acidic in a steam system, but if you add treatment you probably are good. I'd definitely be careful with the new fluid.
    As to the descaling, I haven't used that product yet. I have found that once the excessive water use was addressed about 5 seasons ago on one boiler I service and I started using 8-way boiler treatment, that I was flushing out large amounts of flakes of deposits ever since. The amount of deposits being flushed out has steadily declined in volume and size. The first 2 years flakes were big enough to plug a 1 1/2 line. Also, nearly all of the flakes came from sections 2 to 4 ( the end section wasn't as bad) next to the water feed line on a 19 section LGB boiler. At last, we now have a small above water line leak in probably the 2nd or 3rd section.
    Just as an FYI, the time scale for this boiler is quite altered due to its application...heating a church.... since it only runs about 2/3 the amount of a standard heating boiler.
  • MilanDMilanD Posts: 1,105Member
    Thanks Whisperer.

    Our is a 1 pipe but instead of wet returns, end of mains have an ft + Warren Webster going to a condensate receiver that's pumped on the float in the boiler. Thus no 2 pipes, rad traps, A or B dimension to worry about. I could repipe ft out and do a p trap setup, but instead repaired the traps. Saves on headroom in the boiler room.

    System is used all day 6 days a week, and it's not a church. So, water in the boiler stays hot for the most part of the winter.

    At any rate, most of the sections are clear aside from that one blister that I want to reduce. I attached the shot of it. I'm pretty sure it's a matter of time for this section to fail. That blistering changes heating surface area, increases temperature of the casting and creates graphitic corrosion. Mr. Holohan talked about this here on the wall. So, I am leaning towards descaling as I think section fail is inevitable without it.

    Thanks for your caution on water - that's why I was thinking of adding steamaster and sodium sulfite. 8-way is also an option. Ph is low on distilled water, and I am aware that untreated it has a tendency to be corrosive quite more than regular tap water.

    Thanks again!
  • The Steam WhispererThe Steam Whisperer Posts: 206Member
    Makes me wonder if the condensate pump and traps are needed at all. I often find that the system is just fine when returned to gravity return, as long as you have the pressure low enough and adaquete A dimension.g
  • MilanDMilanD Posts: 1,105Member
    1975 edr, when full steaming on a cold day, the 50 gal tank is almost empty. I don't have enough wet return capacity as mains are arranged as loops and have classrooms in the basement. I had a new extra thick steel tank made last year in a metal shop. This should last another 60 years for sure - I doubt I'll be around for that one failing. It replaced the off the shelf 30 gal which was fine with LGB 11, but ended up too small when LGB 7 replaced it. I'm now running on 8 oz limit on a vaporstat, 2 stage kicks in at 8oz (have one zone that's mostly off so low fire helps a lot), and usually op pressure is at 2-4 oz of pressure when all zones calling and the same on low fire when one zone is closed off. A thing of beauty. 3 mains are 200ft each, start as 4" and step down to 2.5" - about 650 edr per loop.

    I'd suggest for your steamer to check tds and chlorides. And you do know that the few holes you have will eat water and water use will kill what's left of that boiler. I was surprised we have tds at 200+ out of the faucet. Makes my post-blowdown boiler water 350+ tds. Btw, condensate pump is float operated, and weakly blowdown is suggested. Water is usually quite black and sludgy at the bottom after a week of operation. I did test the sludge too, off the charts tds on that, of course.

    I feel water quality for steamers will be very important in the future as water quality seems to be getting worse and worse with chlorides, although with all this global warming, we may stop using all the road salt, so who knows....

    Thanks again for your thoughts!!
  • The Steam WhispererThe Steam Whisperer Posts: 206Member
    One thing I check is the main vent capacity. If the steam can get further out into the system faster, then it will begin returning faster, and you don't run short of returning condensate as quickly or at all. Steam moves way faster than the trickle of water at the bottom of the pipe. This way, you start returning condensate often in only a couple minutes rather than 10 to 15 minutes when the steam takes forever to get to the end of the mains. When of the biggest secrets, it seems, about F&T traps is that they have very little venting capacity. I almost always install additional large one pipe steam vents sized to get the main free of air in about 2 minutes or less.
  • MilanDMilanD Posts: 1,105Member
    Thanks for that tip. Makes total sense. After getting here on the wall and dealing with unbalanced system and high pressures, I replaced all the old vents. All traps have new main vents in front of them. Hoffman 75 on the 2 separate auditoriums' loops with 4" mains. I know that 75 vent is not that fast and rads on these 2 mains (arranged as a loop - that pic above shows the end of those 2 mains) do get warm one at a time, but I have one long 2.5" main that I wanted to nudge steam into first, so that one has BJ Big Mouth, plus another Big Mouth on a long riser on that same main, and another m-o-m D on another long riser. With this arrangement, the system is balanced, last rad is getting warm as quickly as the 1st one on that 2.5" main, and the boiler operates on about 2-4 oz of pressure, as mentioned above. This is in line with friction loss for 3x200ft of main, if I'm not mistaken... some condensate starts coming back quickly, just not enough volume when all 1975 EDRs are getting warm. I do wish we could get rid of the tank and all that electrical stuff. For now, it'll have to be what it is.

    Thanks again!
Sign In or Register to comment.


It looks like you're new here. If you want to get involved, click one of these buttons!