Brass Thermowell for boiler tap?

JaymeHart · January 17

Is brass the right material for a 1/2" thermowell in the boiler cast iron block?

hot_rod · January 17

Brass, copper and stainless are options.

JaymeHart · January 17

https://forum.heatinghelp.com/discussion/comment/1882710#Comment_1882710

Is there anything I need to consider with brass?

My plan was to use both Teflon tape and pipe joint compound to seal it.

I definitely dont want to deal with galvanic corrosion and have to replace the boiler in 10 years.

hot_rod · January 17

Pretty much all the trim and safety valves screwed into a cast block are brass or a brass alloy. Same with stainless, copper, steel and aluminum block boilers. Occasionally you see stainless wells in some high efficiency boilers.

Yes teflon tape with a smear of teflon thread dope is a common method, for threading into the boiler.

Do you have a failed well? If so what material is it?

Some wells are a brass connection with a thin copper tube as the well. Those have been known to pin hole from aggressive water often.

pecmsg · January 17

a little Teflon and never-seize

JaymeHart · January 17

No, not a failed well. Just adding a new well to add a aquastat for my hot water loop, so I can control the boiler firing better when just that hot water loop is calling for heat.

Currently, there is an unused 1/2" tap below the LWCO line, which right now is sealed with a black iron plug.

pecmsg · January 17

concentrate on getting that plug out first.
easier said than done

EBEBRATT-Ed · 12:34AM

Or use a strap on aquastat.

hot_rod · 12:53AM

Good point @EBEBRATT-Ed

consider an electronic setpoint control with a thermistor probe

Take a hose clamp and fasten it to the pipe coming off the boiler, a piece of insulation around the probe

It is probably less$$, has more adjustability , and digital display
.
Skip the well and drain down😉

JaymeHart · 3:01AM

https://forum.heatinghelp.com/discussion/comment/1882729#Comment_1882729

just installed a month ago, and I see some teflon tape around the plug.

Therenis an existing aquastat for the hot water loop, but it was installed on the pipe out of the boiler. Which would have been fine, but the plumbers had no idea I needed a bypass loop/mixing vale to keep it from flash boiling. When I called them, they insisted it was plumbed properly. It wasnt. I was getting loud flash steam in the hot water loop when the boiler was calling for steam for my main line.

So I had to remove that drain, and plumb in that bypass loop myself.

Now, that exisiting aquastat is right between the water flows, and the water temp at that junction is of course quite variable.

I ordered a new digital thermometer/aquastat to plug into the boiler and measure the water temp there. unfortunately, I dont have anywhere else to put it without having to break into the copper lines. And I have no interest i doing that right now.

JaymeHart · 1:14PM

Last question: How do I wire the White Rogers 16E09-101 to the boiler TT wires?

I have the old aquastat wired inline with the Boiler TT wires (managed by a Taco panel), so it only fires when the Taco is asking for heat AND the boiler temp is low. (If the boiler temp is OK, the Taco just runs the pump, no call for boiler fire).

Do I wire the boiler TT as the Load? And use a separate 24V transformer for power (or run additional wires from the boiler 24V transformer)?

Brass Thermowell for boiler tap?

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