Oil fire'd H.W. Boiler Knocks a little

Old 12-19-12, 01:06 PM
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Join Date: Jun 2012
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Oil fire'd H.W. Boiler Knocks a little

I have a 20 year old Ultimate Boiler with a Beckett burner. I'm the second owner, been in the house about 5 years now. The system was operating with Anti-Freeze in it for years. I've done some research and have successfully saved a lot of oil by firing it correctly, installing a HW+ controller and removing the glycol. Last year it started knocking slightly towards the end of the heating cycle. It's been serviced and cleaned yearly and seems to be in excellent shape. The combustion chamber was replaced last year and the eff. is up there at 85%, burning nice and clean. HW coil is in place as well.

I believe the slight knocking might be some sediment inside the boiler so I purchased some Hydro Solve 9100 and pumped it in the other day. I've sampled the water and it looks pretty clean still. I see maybe one or two very small particles in a tin pan. Overall looks clean.

Rohmar says leave the Hydro Solve in for a few days or even weeks. I'm not comfortable with that, but do want to let the product do it's thing before I flush and put in Rohmar's 922 conditioner.

We do have well water, whole house filtration system is in place. No leaks at all in the system, Extrol tank is pressurized correctly. System runs at 150 - 180 about 15 - 20 psi.

Opinions wanted - Leave the Hydro Solve in for a while? Should I be concerned with the slight knock? You only hear it upstairs, yet I can feel it on the pipes at the boiler. It's not loud at all, but at night when it's quiet I hear it. This didn't happen the first or 2nd year in the house, it's only started 2 years ago. When I flushed the glycol out, it got much quieter.

Comments appreciated.


BTW: Went from 900 gal/year down to 650 gal/year with the changes I've done, so the system is indeed running quite well now. It's amazing what a good controller and the correct firing rate does for a system.
Old 12-20-12, 05:32 AM
Join Date: Sep 2006
Location: NJ
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Go by Rhomar's recommendation about leaving the Hydrosolv in for a few weeks. It won't hurt the boiler. The knock is probably from scale that's built up on the boiler surface just above the combustion chamber. The HydroSolv should dissolve it in time, the conditioner should prevent it from happening again.

This is not really uncommon is systems with antifreeze if the system was not thoroughly cleaned before adding, then properly maintained. Even then .....

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