mixing valve low output temp

[grumpy chief]

Hello all, been using the heat the last few weeks and probably the rest of the winter here in VA. I have a basement with pex in poured slab for one circuit. Main floor is pex stapled to bottom of subfloor with lots of insulation under pex. System has been in place 4-5 years now. Last week I woke up to 64deg main floor temp with thermostat calling for heat. (set at 68). Storage temp was 159 out and 149 in. Had not recharged storage since previous midday. Outside temp was 33 deg. Started fire and recharged storage but house took 4 hours to reach 68. Went down to mech room and used IR temp gun to shoot lines. Had 150 reading on supply line and 135 on return. Water temp supplying manifold was only 100 with temp leaving manifold around 82. I remember that I had set the mixing valve at 130 when installed. I have a Cash Acme 110-hx valve installed. Ran the adjustment knob through range and set it at max and could not get over 105 reading to supply manifold. Had a spare new valve and replaced original, could only get up to 115 on max setting. The spec sheet states the valve is set to 120 outlet with 150 in temp. Any suggestion on why I can not get outlet temp higher.

 

[BoiledOver]

The IR guns require a flat black surface to read from. Learned this through a process of trouble shooting low temps myself. Flat black spray paint works very well on any piping to get more accuracy from the guns readout. Friction tape will also work better than bare copper and such.

Why you are not getting heat to your floors, I probably have nothing but will share what my basic mixing valve does. It is manual and only controls proportions. Therefore the outflow is wholly dependent on the temperature of the hot supply mixed with return, meaning the hotter the supply and return will result in hotter outflow.

Best of luck and stay warm.