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Hydronic Heating - protection against corrosion

stevenknaubstevenknaub Member Posts: 15
my son has an 8 year old hot water heating boiler (I think called Hydronics) in his home. When new, I don't believe any type of additive was put in the boiler/piping/radiators. 2 weeks back, I drained a small amount of water out of the boiler drain, and the water looked very clear. A couple of questions:
1. Should I PH test the water?
2. Is the fact that the water from the boiler drain was very clear an indication that there is no need for a conditioner to be present in the water to protect from future corrosion of the boiler / piping / radiators?
3. If it is advisable to add an additive, would Rectorseal 8-way be suitable?
I've only added water to the system perhaps 2 times in 8 years, and it was due to a radiator valve dripping, and that has now been repaired. (by repacking the stem)
thanks, and feel free to add other information if you wish, I enjoy reading folks answers that have more experience than I, which is not much.


  • hot_rodhot_rod Member Posts: 13,182
    Clear water in a cast iron radiator and steel pipe system? Usually after a short period of time the water will at least discolor form the ferrous metals in the system. Make sure there is no leak and fresh water being added.

    Ph, hardness and TDS are good numbers to know. It's best to check that on the fill water before it enters the system.

    Most boiler manufacturers have fluid guidelines, here is one example.

    I am a proponent of :
    1) run a cleaner in the systems, flush.

    2) Fill with water within the manufacturers spec, this may involve filtering your water.

    3) Add a hydronic condition to protect cleaned metals, buffer Ph, and add a filter provider. Many brands to chose from Rhomar Water, Fernox, Sentinel, etc.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • fenkelfenkel Member Posts: 80
    go on-line and down a copy of the manual for the boiler you have.. it should have recommendations on approved chemicals for boiler care..
    As "hot Rod" states they are many to use... We prefer to use Rhomar, Rhomar has a testing facility , where they can get your water tested and aid you with suggestions on make up water.. it is somewhat expensive, but it takes the guess work out of it..
    one thing that is very, very important for boiler longevity, is to make sure the water quality is within the boiler manufactures recommendations.. we prefer to use demineralized make up water..
    for this reason,we use a axiom 2.5 gallon system feeder to house our make up water.. this is also helpful if the system springs a leak... ( some communities will not allow an auto feed filler on boiler systems without the use of an RBZ). you'll get a few gallons of water in your house verses be attached to an auto fill system...
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