I just moved into a house with a gas-boiler steam system that provides heat (in-floor) and also runs the hot water tank. It works well enough but the floor heat seems a little weak.

In a previous boiler-heated apartment the system worked poorly until we noticed that the water gauge on the boiler was near zero. We hooked up the supply, ran it til the needle went from red to green, and just like that it ran great again.

I'm wondering if something similar could be at play here. The new system has a pressure gauge and supply inlet but the dial is just 0-10 bar, no "target" shown. How do I know if it's low? If it is, how do I know what to fill it to?

  • In case it matters, the system is running now and reads 2 bar exactly.
    – James B
    Nov 11, 2016 at 9:18
  • 1
    Is this system not equipped with an automatic fill system, or a low water cutoff for that matter? Nov 11, 2016 at 12:43
  • The fill is manual - there's actually a short length of garden hose that hooks to a fixture. (I'm in Germany if that makes a difference)
    – James B
    Nov 11, 2016 at 16:13

1 Answer 1


Questions Is the floor a radiant system with the piping in the floor like concrete or under the floor (tubing running under the floor between the joists). It makes a difference. You said the system was steam but if is that would be odd. I am going to say that you mean hot water. One note; a radiant floor heating system has a large lag time, the house does not respond quickly to a thermostat change of a quick weather change. Also if it is a radiant slab system in concrete the slab water temp is rarely above 140 degrees F. I think you need to call a heating expert.( D. George)

  • Yes, it is hot water, the previous owner was translating from German so it was probably a miscommunication. It's a marble floor with piping underneath. I'll try to get someone to look at it.
    – James B
    Dec 4, 2016 at 21:04

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