Proper water chemistry for SS modcon boiler

S Ebels

Do what the manufacturer says to do. They have the spec's that they want to see in their particular boiler. I could throw numbers around for PH and hardness all day but in the end, I'm not the one offering the warranty on your boiler. Check with Lochinvar for spec's on your Knight.

Personally, I think that the care and maintenance of boiler water quality will be THE main issue for long life from these little condensers. The rate of heat transfer across the HX is incredible on all of them. A great share of them use pretty light gauge metal and have small water passageways in the HX. One chunk of buildup on the water side of the HX and you have a hot spot which leads to total failure rather quickly.

This is not meant to scare anyone away from a condensing boiler. They are the way of the future. The point is however that high efficiency = good maintenance. If it's not done regularly and correctly, you can plan on problems down the road and a short life cycle for your boiler.

Bill Spencer

Proper water chemistry for SS modcon boiler

Would the life of my Lochinvar Knight stainless steel heat exchanger be shortened if I were to use my well water with a PH of 6.37? The installation manual states water hardness must be 7 grains (120 ppm) or lower. I'm getting this tested to be safe too. What would be the ideal PH and hardness to maximize my boiler's life? How can I attain this assuming PH is low and hardness is high? Thanks

-Bill

hr

A hydronic water treatment

is designed to handle conditions like that. They handle hardness, O2, ph, and provide protective film coatings. www.rhomarwater sells a brand of cleaner and conditioner that I have used.

Chlorides is another thing to watch in stainless steel components, but more of an issue with an open system like indirect tanks.

It's not that hard to get the fluid into the spec required by the boiler manufacture. Failure to do so not only voids warranty but also cuts down on the efficiency of the high efficiency boiler you purchased

Test it, treat it if needed, and also check the fluid on a yearly basis.

hot rod

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Rodney Summers

The Knight installation manual doesn't specify PH range

Unfortunately there seems to be no mention of a PH range requirement in the Knight installation manual and I did not get a definitive answer from the Lochinvar tech I spoke with. I spoke to RhomarWater and believe their conditioner would leave the PH normally in the range of 8-8.5 but perhaps less with my water. I would like to pursue using their cleaner and conditioner but I want it to be easy to add additional conditioner as needed and perform cleanings over the years to keep efficiency up. I've heard mention on The Wall about glycol fill systems. Can one be used instead for the cleaner and conditioner as needed? Is this the recommended long term approach? Thanks.

-Bill

hr

The ph

will vary depending on what you fill the system with. Plain tap water would want to be in the neutral ph range, low to mid 7's like pool water

If you start adding conditioners this will change, as Rhomar indicated.

If you chose hydronic glycols you want to see the ph in the 8- 10 ph. glycol below 7 ph should be changed, according to some manufactures.

It's the chemicals in the conditioners that will change the ph.

Once the system is cleaned, filled, and tested it should be fine for many years if it is not opened to air again.

It never hurts to take a sample and test it or send it off for testing. These small, thin walled HXers are not going to be a forgiving as the thick cast iron we are use to.

You could build or add a simple pot feeder. Basically a place to add chemicals with a ball valve to allow it to flush into the system. I doubt you need to go to this much trouble for a residential system.

Flush it well, use good clean filtered fill water, and a dash of conditioner for piece of mind.

It's easy to see what happens to the outside of those HXers, with the required yearly inspection.

Not so easy to see whats happening within that HX. That's why I error on the safe side.

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Unknown

water chemistry on the Knight

Actually, Lochinvar isn't too worried about moderate low PH. The S/S Heat exchanger will handle some variations as long as it isn't extreme.

I'd be more worried about the copper piping. copper will pretty much disappear with acid water in a short time.

Suggest you invest in one of thw water teatment systems that are available for the whole house or at least treat the water you are using for the Heating system

Good luck!!!

Bill Spencer

Hotrod, thanks for your help

I've spoken to Rhomar and believe their Pro-Tek 922 conditioner is close to being officially approved for modcon boilers from two manufacturers. Based on this and your recommendation I feel more confident using it. Wouldn't cleaning with Rhomar Hydro-Solv 9100 and flushing remove the bulk of the gunk that could affect the HX? Do you feel strongly that I still need to filter after this cleaning? How would I go about it while keeping costs down if possible? Thanks.

Bill Spencer

Copper piping in jeopardy?

I had my well water retested today and the results are more encouraging. PH is 6.97 and hardness is 64 ppm (3.74 grains). Apparently acceptable values as long as I don't have a problem where I have continual fresh makeup water entering the system.

My copper pipes have been in use for 25 years so I'm hoping the 6.37 reading was an error or a temporary dip and my pipes are still OK. My main cold water pipe will be cut for some other improvements in the near future so I'll make sure we check for internal corrosion then. Now that you've got me worried about this, one thing I just noticed is the cold water pipe recently uncovered in the boiler room ceiling seems to be pretty brown and somewhat corroded looking compared to the baseboard hot water piping. I've attached a picture with the cold water pipe going vertically and the baseboard heating pipe going horizontally. Should I be concerned? Both were installed 25 years ago. Thanks.

-Bill

Plumb Bob

> Plain tap water would want to be in the

> neutral ph range, low to mid 7's like pool water


Plain tap water has a pH of just under 6. It is slightly acid because of carbon dioxide absorbed from the air, which makes "carbonic acid".

Pure water (distilled and then kept away from contact with CO2 and anything else that could dissolve) will have a pH of 7.0.

hr

If it were either or

I would use the cleaner, flush, and install the water you have at the jobsite. It doesn't sound like your water would harm anything.

As far as the copper plumbing lines... I've found when you cut into just about any, been in use, copper system you will find a thin film inside the pipe. It's this film that protects the pipe from internal corrosion.

The only time I have seen ph attack copper is from the outside in. A few subdivisions were built in Utah over old mine tailing dump sites. Type K copper would pin hole in less than a years time. Road salt or excessive fertilizers over shallow copper in California has also been an issue with buried copper. It's the ChemLawn guys fault !

I've found sloppy workmanship ie unreamed pipe, excessive flux, high velocities from oversized recirc pumps cause more copper damage than anything else.

Go to www.copper.org for some excellent reading on copper. order the technical report "Service Experience with Copper Plumbing Tube" for some good reading.

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Plumb Bob

As I said before, plain water left in contact with air (which has CO2 in it) will reach a pH of under 6. There is no problem with this. It will not hurt your copper pipes!

Your vertical pipe isn't "corroded looking", for heaven's sake. It just has surface oxidation. Don't obsess over it, it looks fine.

Ike Gatlin

funny...

Lochinvar agrees with all that has been stated here. You know it is funny... almost all of the statements made in the manual to protect the heatexchanger are driven by the fact that 90% of the installers we deal with dont visit the wall.

Hot Rod... got your voice mail, software on the way.

Ike Gatlin
Knight Dude

Bill Spencer

Must be caused by condensation

The corrosion is caused by condensation on the cold water pipes forming carbonic acid as you said and I won't worry about it. Thanks for your analysis and knowledge of chemistry.