Indirect HW Thermostat Question

David_16

Hi,

I just had a Weil McLain WG0-4 and the WM Gold Plus 40 Indirect HW heater installed yesterday.

I think something might not be working right with the termostat on the HW heater.

Previously, I had a tankless coil and the water is still coming out just as hot as it was with the coil. I had the HW heater set to the default/factory suggested setting (matching up the white tick marks - see attached picture).

Here's why I think something is wrong though. I lowered the termostat a few notches and ran the hot water from the tub until it wasn't hot (I know that you can't lower the temp of the stored HW, so that's why I did that). After the water re-heated, it still was super hot. Also, when I turn the termostat, I hear the HW heater call for more hot water once the tick marks match up again, not at slightly above the lower value I had changed it to. That would mean that the temperature is hotter than the termostat is set for, no?

Either way, I don't see how the default setting would be scalding hot water (which is what is coming out)

Does anyone know what the default temp is on a this heater? I don't know why they just don't put degrees on the dial.

I wanted to let things settle until tonight before I call them back, but I wanted to post here in case I'm missing anything.

Any ideas? Any other reasons for this maybe?

Thanks!

Ron Schroeder_2

There is a trend now (and probably code in some places) to set the DHW to at least 140 degrees to prevent Legionella and to use a thermostatic/anti-scald mixing valve on the output of the tank. That is why the wight marks are so hot.

Do you have a mixing valve on your output?

Ron

David_16

So...

Should they have added the thermostatic/anti-scald mixing valve or is that something that wouldn't normally be done? Does that have a temp setting or if that's on, I might not get water that's hot enough after it's mixed?

Even so, it appears as if adjusting the termostat doesn't have any effect on the temperature of the hot water. As I said, if I lower the setting, drain the water, and wait, the new batch is just as hot. Plus, it doesn't appear to be calling for hot water until I turn the knob back to the default setting, then it kicks in. It should kick in at just above where it's set.

It's like it's hardcoded to the default setting.

Ron Schroeder_2

The mixing valve will not come with the tank. It will also be adjustable. It will have to be set for a safe output temperature, preferably at least 10 or 20 degrees below the tank temperature.

As far as your thermostat problem, you may not be waiting long enough. Measure your water temperature where it is now and then move it down about 1/4" from the white marks. Use the water but wait at least a day before you make a new temperature measurement or move the knob. Due to stratification etc. it takes a while for things to stabilize.

Ron

David_16

Mixing Valve

Ok, I'll wait for everything to settle a bit.

What kind of job is it time and expense wise to add the mixing valve now after everything's been put together? Is that a big deal?

Is that something that most contractors would do by default or would I have had to request that?

Thanks.

David_16

Weil McLain Response

I asked WM the temp ratings on the dial and here's what I got
--
The white triangle on the Gold plus is approximately 120 degrees. The thermostat low end in the blue is 90 degrees and the high end in the red is 160 degrees. you can extrapolate from there.
--
It's definitely hotter than 120 degree water that's coming out.

I think there's some sort of problem somewhere, unless it's really going to take some more time to settle down.

Ron Schroeder_2

You would have to request the mix valve. It would go inline with the DHW tank output but would also have to have cold water run to it too.

Ron

David_16

Oil Co Came

Well, I had the oil company come out. At least I can admit when I'm clueless.

Guy measures the hot water and says it's about 107, which is about where it should have been for the dial.

At that temp I was able to keep my hand under, but it was really hot. I bumped it back to 120 and I couldn't keep my hand in it. I guess the thermometer doesn't lie.

I probably shouldn't leave it at much under 120 or I could have some bacteria problems?

I guess I was just way off on this one, but thanks all.