Aquastat ???

briski58

I'm trying to control the temp of the water in the boiler. The aquastat installed on the boiler now is a Honeywell L8148A. The only zone in use on the boiler right now is my indirect hot water tank. The only time that the burner starts is when the indirect tank calls for heat. The aquastat on the tank is set at 130* F with a factory default differential of 20*F. This temp drop takes a long time due to the quality of the tank In the meantime the boiler temp has dropped to 90*F. So when the burner does fire the circulator is sending 90*F water thru the tank coil until the boiler reaches its high temp limit. It will continue to circulate until the tank is satisfied, the burner will restart to raise the boiler temp again and the tank circulator will continue to pump after the burner has shut down. after this second cycle the pump doesn't run much longer before the tank has reached it's high limit.
I don't shower at the same time everyday so if I get in the shower at the wrong time I don't get that "good hot water" that I like. And I'm never in there long enough for the boiler to cycle up to temp twice.
I've been thinking of changing the aquastat to one that will maintain the boiler water temp. Looking at a Honeywell L8124E. I have a gas fired boiler with a 24v gas valve. The only difference I've noticed in pictures is that there are only two burner terminals B1 B2. I have a third wire a red that comes from the burner control and goes to L3 on the L8148A control. The controller on the gas valve says this wire needs constant 120v power. There is probably a terminal for this wire on the L8124E control I'm not sure what one it is. Or if I would source power from some where else?
I tried unsucesfully to attach some images. The gas valve controller is a Carlin 60200-02FR.

EBEBRATT-Ed

20 deg. diff on the indirect is too much. Should be more like 10 deg. I would fix that first. Then check the boiler temp when the indirect calls on a normal run. Check it a few times. If the boiler runs at less than 125 (some would recommend 130 or higher) you may have to set the boiler up to maintain temp. I would check the indirect (boiler water side) in and out temp on a normal run Your looking for a 20 degree drop in temp. May need to put a balancing valve on it

briski58

Thanks for that advice. I will make diff on indirect 10 deg then watch boiler temp as you suggest. If I ever do need a balancing valve where would that need to be located?

HVACNUT

I wouldn't go with a triple acting aquastat (L8124E) on a gas boiler. It defeats the purpose of saving fuel.
Was this always a problem?
Do all zones go to a switching relay, and XX dry contacts to TT on the aquastat?
Sounds like a faulty aquastat on the indirect and 20 degrees is a wide diff. The L4006A can go as low as 5 degrees.
I think what @EBEBRATT-Ed meant was a thermostatic mixing valve on the domestic side. You can set the indirect temp to 160 and temper it down to 120 going out to the house.
This way you're not depleting the tank because you're mixing cold with the hot going out.

newagedawn

do you get 24 volt on the burner circuit when the aquastat goes bellow low limit set point? if so the aquastat is bad

Paul48

The 8148A is a line voltage aquastat.

HVACNUT

> @Paul48 said:
> The 8148A is a line voltage aquastat.

>>yeah, must have a transformer powered by B1,B2

newagedawn

you wanna bash me or help the guy, THANKS, your right about the aquastat and like you guys never made a mistake, ya sure !!!!!

HVACNUT

> @newagedawn said:
> you wanna bash me or help the guy, THANKS, your right about the aquastat and like you guys never made a mistake, ya sure !!!!!

>> I don't know if your being serious or not. I missed that too from his first comment. When he mentioned the E aquastat, I assumed the burner circuit was 24v.

Zman

What kind of indirect do you have? What are on/off temps on the boiler.
It seems strange to me that the boiler/ indirect cannot maintain temp with just one shower running. The boiler cycling is also unusual.

Paul48

I mentioned that the aquastat was a line voltage one, to point out that there was more going on than meets the eye. It was not to "BASH" anyone, or point out something someone might have missed. Sometimes the solution to a poster's problem lies in what they have neglected to say. It's no ones fault, it just happens sometimes.

briski58

I believe that the TPI immersion control on my Burnham indirect tank is bad. I have a Taco ZVC406 control W/ priority. I bring power from zone six R W on the top row to the 24v contacts on the bottom right of the TPI this control also has contacts on the bottom left that say pump. When the Taco control is connected to the TPI as mentioned I do have power to the TPI I have a green flashing light that tells me it is calling for heat. shouldn't I have power at the pump contacts at this time? Because I don't. also I never see the red light that TPI tells me means error. Taco tells me that if I use a pump on my priority zone that I need to use a jumper from terminal 3 to terminal 4 on the bottom row. Would the wires from the pump contacts on the TPI go to terminal 1 and terminal 2 on the bottom row of my Taco controller?

Zman

HVACNUT said:

> @newagedawn said:

> you wanna bash me or help the guy, THANKS, your right about the aquastat and like you guys never made a mistake, ya sure !!!!!



>> I don't know if your being serious or not. I missed that too from his first comment. When he mentioned the E aquastat, I assumed the burner circuit was 24v.

I can't tell if he is serious or not, as well.
One of the things I like about this forum is that people back check my work and assumptions.
I don't see any bashing going on.

Zman

To the OP,
I am having trouble following your description on this one.
A wiring sketch would sure help.

briski58

Thanks very much to all of you. After reading all of the comments, and doing some further checking. I saw that HVACNUT mentioned it sounded like a faulty aquastat on the indirect hot water tank so I sent a message to him directly. He informed me that the TPI aquastat on the tank was not wired correctly. He instructed me on how to properly wire it to my Taco ZVC406 controller and I did and it works as it should.
Thanks again I appreciate all of you. And your knowledge.