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Hot water problems

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Wingwang
Wingwang Member Posts: 9
edited November 2023 in Domestic Hot Water
Hi We have an NTI Boiler unit. Hot water in-floor heating is great however the domestic water is hit and miss at best. We have flushed entire system with new glycolic, added a separate clycol feeding unit. Removed excess ( small) piping. 
  The plumber is now suggesting to switch out the floe sensor and if that doesn’t work change out the heat exchanger. 
We would appreciate any advice you could share with us.
Thank you very much
Penny

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  • Jamie Hall
    Jamie Hall Member Posts: 23,433
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    Is this a combi or a boiler with a coil or a boiler with an indirect? Makes a big difference.

    If it is a combi, when you open a hot water tap and the water flows, what happens? The boiler is supposed to fire to heat the water. If it doesn't, there's a problem, and it could very well be the flow switch. On the other hand, if the boiler does fire, then the flow switch is doing its job, but if the water stays cold or cool, the heat exchanger isn't. Before replacing it, though, how about just descaling and cleaning it?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Wingwang
    Wingwang Member Posts: 9
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    Thanks Jamie, yes the boiler fires up. The lines to the floors are really hot but the lines to the sinks, showers and tub are only warm. Would the heat exchanger be cleaned out when we flushed the system? If not, how would you recommend descaling it? Thanks again for your help
  • Jamie Hall
    Jamie Hall Member Posts: 23,433
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    Flushing the heating system will not flush -- or clean -- the domestic hot water side of a combi. They are completely separate. Your plumber should be able to help you with flushing and descaling the heat exchanger for the domestic hot water -- it's not hard, but does use some nasty chemicals -- if he isn't too intent on selling you a new one...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Wingwang
    Wingwang Member Posts: 9
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    Thank you very much Jamie, appreciate your help. 
    Take care
  • Wingwang
    Wingwang Member Posts: 9
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    Hi again Jaimie. Today the taps do reach temperature (eventually) then falls directly back down. After your input we believe we’ll go the direction of the heat exchanger 
  • Intplm.
    Intplm. Member Posts: 2,000
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    @Wingwang

    Is the hot water failing at - All - of your fixtures or just one or two?