Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Filtered Feedwater & Testing Strips

Hello all,

Seeing how all many issues with steam systems seem to arise from, and are commonly blamed on, water quality, I attempted to get ahead of this issue on my personal install.

Perhaps my method has already been disavowed and I missed the memo, but I feel comfortable with it, and all quality tests I've done have come back favorable. Simply put, I added a 0.5 micron carbon block filter on the water line upstream of the backflow preventor.

The filter itself is intended for whole house installs, and rated for 20,000 gallons - which far exceeds the life of my boiler. I used the W-5CB for the filter and W34-PR for the housing. At a total cost of materials of under 40 dollars, it is worth its cost (to me) for insurance against current as well as unknown future changes in water quality. I'll note that I am in an area of a generally high-quality water system, but I added it as a precaution.

Secondarily, I picked up a packet of 'pool water testing strips' that will typically go on sale at the beginning of each heating season. They have a dip stick to measure free chlorine, pH , alkalinity, hardness, and cyanuric acid. I've included a picture of the the dipstick and color chart for a sample of water I pulled out of the boiler.

So - has anyone else done something similar? From a contractor's point of view, the extra cost of a filter cartridge and a few feet of pipe might seem 1) like an unnecessary cost to the owner or 2) bringing up the potential for issues about the quality/longevity of the unit.

From the owner/operator's perspective, there could be a variety of economic strategies in play. For me, rather than calculating payback periods or time value of money, I just assumed that filtered water would be better than unfiltered water - and installed accordingly.


  • hot_rod
    hot_rod Member Posts: 19,924
    You are wise to look into the water quality.

    Have you tested your water, and compared it to the boiler manufacturers spec?

    The filter you mentioned is mainly taste and oder, I doubt it will remove scaling minerals or change hardness or ph much?

    I think steam boilers like a bit higher alkalinity compared to hydronics.

    In hydronics the TDS and chlorides are the ones to watch, a TDS meter reads conductivity of the water to come up with a measurement of the solids in the water, that type of TDS meter is not all that expensive, and it gives you important data about the scaling potential of water.

    Knowing the hardness will help also.

    SlantFin recently published a water quality spec, good for them to approach the topic. I'm pleased they talk about using boiler cleaners and good air removal devices.
    Possibly their boiler manuals contain actual ranges that are suggested for ph, TDS, hardness?

    A few of their suggestions I don't totally agree with like the use of D.I. water and prohibiting EG?

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • FriendlyFred
    FriendlyFred Member Posts: 27
    I've tested with with pool-quality dip sticks, and with water testing kit intended for educational sector.

    Yes - this is for steam, and as far as I've found - Burnham hasn't published any docs on water specs. However, some older posts refer to a recommendation of

    The Chlorides at source are @ 20ppm (~same as mg/L), which is under the 30 limit suggested by Burnham. pH is on the alkaline side. The 'free chlorine' is at ~2.2 ppm. My test kit showed a solid zero on free chlorine, which may be due in part to the filter.

    The Langelier Index is a measure of how saturated the Calcium Carbonate is for a sample of water, and indicates how it will corrode/deposit on water transmission equipment. A negative value is not saturated, and will have ion-seeking behavior in the system, a positive value is saturated, and will tend to deposit scale. A range from -1:1 is typical - We're on the hard water deposit side.

    Hot rod - correct, that filter does not have mechanisms for replacing the water hardness through ion exchange or otherwise. My concern with those filters was the potential that it would rob the hardness, but add extra sodium or chlorides.
  • hot_rod
    hot_rod Member Posts: 19,924
    That is a pretty detailed analysis, does the water provider have that available, or is this from an independent lab?

    Looks like 191 Mg/l = 11 GPG on total hardness? that seems high?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream