No hot water Remeha boiler


I've been using tado conntected with my Remeha boiler about 3-4 months and very happy with it. I've installed Tado myself.

Then the problem starts..

Occasionally there's no hot water when I want to take a shower. The boiler shows an error message. On the app, the hot water is on. I have to turn the boiler off and on in order to get hot water....

Has anyone experienced a similar issue? My boiler maintenance guy said that it's a frequent issue for tado & Remeha boiler user. and they suggested me to install "by-pass", which costs 250 euro..!

I wish there's a cheaper solution!!

Look forward to hearing your wisdom...




  • A bypass valve allows hot water to circulate through the boiler when there is too much resistance in the pipework. The resistance increases when TRVs close, causing the flow of water to slow or even stop. This causes the heat exchanger to overheat and the boiler locks out until it is reset.

    If fitted you may have too many TRVs, or your motorised valves are closing prematurely. Your heating engineer is right to suggest a bypass is fitted, and a lot of boiler manufacturers now mandate the fitting to protect their boilers from damage.

  • gary333
    gary333 ✭✭

    Do you have the model of boiler, and the error code by any chance?

    It's a good idea to have a bypass valve fitted however most modern combis have these already. I would say the cheapest option is to ensure you have one (or maybe a couple) of smaller radiators that do not have TRV's fitted. This will allow the water to pump around.

    If it's built in to the boiler, did the heating person check it hasn't been wound right down (i.e. not setup correctly?)

  • ohyoonk
    edited March 19

    Thanks both! What's TRV? Does it refers to Tado thermostat attached to each radiator? My house 80m2 and we have one floor heating (has one tado valve) and 2 radiators. And all have Tado products.

    If I understand correctly, The problem may occur there's too much hot water available but there's no way to go out because all radiators are closed.

    My boiler model is installed in 2019, Remeha Tzerra Ace.

    The error codes are H.01.05 and H.01.14

    In my Tado app the hot water temperature sets as 55 degree, perhaps lower the temperature can help?

  • TRV = Thermostatic Radiator Valve.

    The problem occurs because the heat exchanger needs a constant flow of water. When the water stops flowing the heat exchanger becomes a kettle and the water boils, leading to increased pressure. Lowering the temperature will not help. The only solution is to keep the water circulating. This means removing one of the radiator valves are fitting a bypass valve.

    This is what the two error codes mean:

    H.01 - .05

    Temporary Fault - Maximum difference between the flow and return temperature exceeded. Non-existent or insufficient circulation. Sensor error.

    H.01 - .14

    Temporary Fault - Maximum flow temperature value exceeded. Non-existent or insufficient circulation. Non-existent or insufficient circulation.

  • Thanks! I understand. The error codes indeed indicate the issue. Then what happens in summertime, when all radiators are closed....

    I assume that Tado triggers this problem. Is it true?

  • In the summertime you should not have a problem when hot water is only required for shower/taps. This type of problem normally only affects heating circuits. The heating engineer who visited your home will give the best advice.

    Any brand of smart valve is likely to trigger this issue. Not a specific problem with Tado.

  • GrilledCheese2
    GrilledCheese2 ✭✭✭

    In the summertime when you are only using hot water for shower/taps there should not be a problem. This type of error normally only affects the heating circuit.

    Tado is triggering the problem, but the source of the error is the absence of the bypass valve. Changing the brand of smart thermostat is not going to the problem.

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