Residential boiler fire/heat won't turn off

gondon

Hello,

We have water boiler that heats the whole house and separate hot water boiler for water (this one is okay).
We have AQUASTAT RELAY Type L8148E and resideo S8610U (Previously had Honeywell S86F).
We don't have vent damper.

We had problem about boiler not firing or it fires then turns off right away or sometimes works and sometimes doesn't work.
But later on it just keep trying to fire up but never did.

First we replace the burner pilot and it did nothing.
Then we replaced Honeywell S86F to resideo S8610U and it worked.
But after about two hours it was keep heating the house and we heard huge noise and found out water and air and steam was coming out of Relief Valve.

We tried the lower the thermostat to all the way down but it still heating up.
We disconnected two wires (TV & T) from AQUASTAT RELAY Type L8148E and it still heating up the house.
So for now we turned it off to figure out what's wrong.

Right now we are thinking it's either Aquastat Relay Type L8148E needs replacing or we have done something wrong when wiring to resideo S8610U.

Originally it had 7 wirings to old Honeywell S86F but when we installed resideo S8610U with 7 wires, it didn't work.
Then we follow the manual and didn't put one wire to 24V.
And it worked. But now we are thinking what about the one wiring that's just hang in the air?
Maybe it's the cause?
It's one of that black wires. It's either B1 or B2.
Any idea how to properly connect these wires to resideo S8610U?

Or maybe Aquastat Relay Type L8148E somehow got bad whiling calling for heat for few days?

Or any other problems that we are missing?

HVACNUT

Remove the White wire from TH-W and put it on 24V (GROUND).

Take the Black wire that was on 24V (GROUND) and put it on 24V.

Take the Black wire that's "just hang in the air", and put it on TH-W.Turn off the power first of course. Hope nothing shorted the way it is.

No jumper needed for the vent damper molex?

realliveplumber

Respectfully,

You should probably get someone that knows what they're doing.

If that relief valve failed and stuck closed, you could have had a real big problem.

gondon

Thank you so much HVACNUT!!!

We tried your way but didn't work and tried other way and it's working now.
And we also found out that zone vale and one room thermostat is not working properly.
We will replace those when new parts come.

Lastly, Vaillant Boiler Temperature Pressure Gauge is leaking.
Any idea what model this is or replacement model?
I might have to open a new post about that.

Again, thank you so much!

Dave Carpentier

This puzzle increased in complexity in no time at all.