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Oil-to-Gas Conversion Service Pressure Question

mmanske Member Posts: 6
edited December 2022 in Strictly Steam
Looking into doing a gas conversion on my oil-fired steam boiler. The boiler conversion doesn't seem controversial (Peerless ECT05 - seems like there are several burner options) but I'm getting conflicting opinions on my gas service.

We have gas service run to the house already & our utility has told us they guarantee 4" WC on our UP system. I've been told by contractors that it's both sufficient & insufficient pressure to reliably run our boiler and I'm not sure what to believe.

Looking at the specs for two possible conversion burners, they state 3.5" WC manifold pressure but 4.5" WC (Beckett CG4) or 5" WC (Carlin EZGAS) supply pressure.

Am I asking for trouble trying to run this boiler on utilization pressure service?
(no other gas appliances would be tied in)


  • ethicalpaul
    ethicalpaul Member Posts: 5,704
    You can hook up a manometer to your gas line to see what it really is. I bet it's more like 7 and they just say guaranteed 4" to make the lawyers happy.
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
    Long Beach Ed
  • Long Beach Ed
    Long Beach Ed Member Posts: 1,210
    I'd say Paul is correct that you will have higher service than what is guaranteed. But why take a chance? Specify a burner that requires less than the guaranteed pressure.
  • mmanske
    mmanske Member Posts: 6
    makes sense - thanks @ethicalpaul. I'll hook up something and see what I can find.

    @Long Beach Ed those burners seem to be pushing it in terms of BTUs for my boiler (280,000) - are there other available burners you know of that would meet that capacity but at lower pressure?
    EBEBRATT-Ed Member Posts: 15,544
    There are two different pressures to be concerned with. The burner manifold pressure (usually 3.5"wc) is downstream of the burner gas valve. The burner inlet pressure is at the inlet to the gas valve and it the pressure supplied by the gas company minus piping losses. That's the one you need to be concerned with.

    You need to pick the burner you want to use and find the minimum inlet pressure that it requires by reading the manual.

    Then you need the gas company to commit to providing that pressure.

    With the gas valve pressure drop and piping losses I would probably want at least 2" more than the burner requires to be reliable. 4" is not going to work.

    In Massachusetts where I am the gas coder requires a "letter of availability" from the gas company in order to get a permit for a new install.

    Not all states require this but should
    Long Beach Ed