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Tempering valve water not hot enough

I just installed a new boiler and on demand instant hot water heater that uses the boiler water to make hot water. The  manufacture recommended a tempering valve so the water isn't scalding hot. So I installed a Taco  5003-C2. When first using the hot water it wasn't hot enough. So I adjusted it to the hottest setting and the water was still not hot enough for me. The water heater is making the water plenty hot ,  but the tempering valve is cooling it off too much. The valve seems pretty simple as for installation and set up.  Is there something I'm missing or anything  special I need to do to set this tempering valve up? 


  • AHerra
    AHerra Member Posts: 15

    The first thing I would check is the rating on the valve. Is it even approved for domestic hot water. What is the flow rate. Is it thermostatic. I have been using a similar product made by watts that is a thermostatic valve. Meaning, as the water temp from the supply goes down it will not mix as much giving you a constant temp going to your domestic mixed water supply. If you valve is thermostatic and approved for domestic water and has a temp range of 100 to 160 my guess is there is debris caught in the valve and needs to be cleaned. I have not seen any defective valves right from the factory so the best bet is there is something caught in the valve.

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