Hi Guys,

I had my aquastat replaced yesterday on my Wells McLain boiler (i have a steam system). Before i would only get hot water if the boiler ran to heat the house. After the change however, the boiler cycled on and off continuously which concerns me because when the old aquastat was working it didnt run as much. It didnt matter what temperature i set the water at, 180, 140 or 100, the boiler behaved the same for each.

I have a Taco 006-BT4 circulator
and a honeywell R8184 G 4009 controller and a new honeywell aquastat with a single dial to control temperature.

I have a 40gal insulated water tank which the hot water from the house is drawn from. the circulatory pump seems to be circulating a closed system between my boiler and the water tank. If im following this correctly the pump should've been circulating the hot water to exchange heat with the tank, but the line that the pump was on was still cool after a couple hours running. I'm thinking my circulator pump will go soon, it makes a clicking noise. It also seems like it was setup to run continuously, it's only controlled by a light switch on or off and ive never ever heard it stop regardless to if the boiler was running or not.

Here are some pictures:

Aquastat, circulator and tank

aquastat and circulator

circulator

Both the aquastat and the thermostat are wired to the T T on the boiler controller and there are dead wires which are connected to what i think is a transformer next to the two power switches for the circulator and the boiler.

Since the boiler seemed to be stuck in a loop and the house was burning up, the house temp was higher than the thermostat temp, and i didnt want to take any chances so i shut off the boiler over night, which i've done before with no problem. But now it wont turn back on. The red light indicator turns on when i manually lockout the system, but it wont turn on when i push the reset button. I thought it was a weak circulator but now im not sure. Any thoughts?

 

You need to call back whoever you paid to do that job for you and make it right...

 

From what I can tell from your pics someone hooked up the domestic hot water coil in the steam boiler to act as a pre-heater for the 40 gallon electric water heater which is used as a hot water storage tank. I have seen this done on a closed hot water system but never on steam. It is referred to as an aqua-booster which is basically a big ol' thermos.

If your setup is wired, piped, and valved correctly, (It doesnt appear that way though!!) it should work during the cold seasons when the temp. of the boiler water is hot from making steam. During the warmer months you can turn off the switch that powers the circ and aquastat, close the supply valve to the coil and use the 40 gallon tank as a stand alone water heater, this way you don't have to maintain temp. on a steam boiler all summer. From what I can see in your pics it appears that your circulator may be hot wired to that switch without a relay which will make it run constantly, not good!!

If that bronze Taco circulator failed it is costly to replace and if that domestic coil is plugged it too can be a bit pricey to change. I would highly recommend that you have a plumbing/heating professional come to your residence evaluate your current set up.

 

The whole system was put in about 18 years ago and my dad never understood how it worked. All the technician did yesterday was swap out the old aquastat (which was smaller and why the new one is a little off).

I took a closer look at the tank and it doesnt appear to have anything to control its temperature. I think it's just a insulated tank as we have always needed the boiler functional even in the summer. So the circulator should run off of a aquastat controlled relay and only circulate when the aquastat calls for hotter water? Would this include a delay for a call to the boiler?


We've taken a "If it ain't broke" mentality so far but the more i learn about heating systems the more i dislike the way mine is set up. I really appreciate all the input, i want to learn as much as possible before i call in a professional.

 

If that isn't an electric water heater then that tank is indeed a hot water aqua booster which is basically a storage tank for your domestic hot water. Looking over your pics again, it appears that the BX electrical cable that feeds into the top of the tank is probably wired to an aquastat device mounted inside the 40 gallon tank. When this aquastat calls, it sends power to the bronze Taco circulator which then circulates water through the coil inside the boiler. When this water is heated to the temperature that the aquastat is set for, it cuts off power to the circulator.

I believe that the aquastat mounted on the coil plate of the boiler is used as an operator to keep the water temperature in the boiler hot when there isn't a call for heat. It should probably be set somewhere in the 170-180 degree range.

 

My current system has the aquastat and the thermostat both wired in parallel to the T T connections on the boiler controller. The thermostat breaks the 24 volt circuit and the boiler fires when it is suppose to (it seems to get stuck if its on for a while), however the aquastat does not.

I think i've found the diagram that is close to my desired setup if i were to rewire.



My system however only has a low-limit aquastat controller. So do i omit the high and circulator aquastat controllers from my design? if thats the case whats the use of 1 and 2 on the diagram? i'm also not sure how the circulator would fit into the equation

Thanks for all the help so far!