Water gets cold when running the tub

jc0267

I just moved into my house a couple months ago it was summer time now as the temperature gets colder it doesn't seem to be holding the hot water as long I have hydrostat 3200

mattmia2

Some pictures would help. What is the boiler? What does it use to make hot water, is it an indirect tank or a tankless coil or what? As the outdoor temp gets colder, most municipal water supplies get colder so the amount of hot water a system can make decreases. Ideally the system would be designed so that this is still enough for your needs.

STEVEusaPA

All of that ^^^ and do you have a mixing valve at the boiler/water heater?
Keep in mind if it's not storing hot water with an indirect, it will never keep up for a tub.
These calls usually come in when it gets very cold for a sustained time as now the incoming water temp could be in the high 30's low 40's and the tankless coil can't produce/maintain enough hot water.

Jamie Hall

And furthermore... if there is a hot water tank, how big is it? What is it fired or heated by? For reference, you need at least 3 gpm from a tankless or 30 gallons from a tank -- at 140, with a mixing valve -- for a standard size tub.

EBEBRATT-Ed

And your HW should be120 at the fixtures you should get a thermometer and measure it.