Replies

1. 
   Tim | Oct 14, 2006 12:57am | #1

   The Honeywell L8148 aquastat has about 7 variatons, but they all basically work the same. If you have a voltage teaster or a multimeter, there are some simple checks to make. Sometimes a short on these will burn out the transformer. For an L8148A:

   Check both T or Tv terminals, with power to the controller an the Thermostat turned off or way down. One should have 24 vac, the othe other should have 0 vac. If both are at 0, and line voltage is connected, you need a new transformer.

   Next step, turn the t-stat to call for heat. Both TT's should have 24 vac. If not, t-stat or the control wiring to the stat is bad. If its good, check the voltage at the B1, B2, C1 & C2 terminals. If you are getting voltage (120 vac) out of these terminals, the pump and gas valve/burner should operate.

   At leats this can help to narrow the problem. There should be a wiring diagram inside the cover. Look at it and see how its supposed to work, if my terminal designations do not apply to your version.

    

1. 
   redtoolbox | Oct 14, 2006 01:53am | #3

   thanks tim, I am running out to lowes right now to get the volt meter.
   dave brown

2. 
   redtoolbox | Oct 14, 2006 03:31am | #5

   I bought the volt meter. Here's what I have done: I made the t-stat call for heat while I checked the voltage of all the terminals in the aquastat. The L1 and L3 indicated power and the rest were dead. Do you think it is the transformer ?
   thanks, dave

1. 
   Tim | Oct 16, 2006 03:57pm | #6

   Yes, I believe that you blew the transformer.

   There are some variations, but this is how your aquastat works. It takes 120 volt (L1, L3) power supply, drops that to 24 vac for control power, and uses relays to start and stop line voltage loads, which includes in most cases, the boiler circ pump and the gas valve/burner. If the trans former is blown, there is no low volage avialble to close the relays for th other loads. For the boiler to fire, the water temperature has to be below the high limit set point and the thermostat has to call for heat. This completes all the control side of the circuit, which would cause 24 vac across the low voltage terminals on the relay(s). IF you have 24 v across the TT terminals and still nothing, then one or more of the relays may be bad. Look for any signs of charring or arcing.

   Look here http://customer.honeywell.com/Techlit/pdf/95-0000s/95-6940.pdf and find your specific model. Check the wiring diagram for yours.

   A transformer can be found at your local HVAC supply house (Berkheimer, First Supply, Ferguson, etc.,). Honeywell is very prevalent and should be easy to find. Should cost around $40. A new aquastat, available at the same place aroud $80. You can probably find both online.

2. 
   BillHartmann | Oct 14, 2006 01:06am | #2

   "It worked fine before I double clicked the wires together. "

   What does that mean?

   "Installed a power vent etc. "

   I would expect that has some kind of sequencing and interlocking with the boiler buner. What is the state of those?

   "Hello, I have been working on my hot water boiler for days and finally got it going."

   What do you mean "got it going" if the boiler won't fire.

   Do you have a voltmeter or test light?

   Have you verified that there is power from the transformer?

   I don't know what double clicking is, but if you shorted the output of the transformer then you might have blown a fuse or or near the transformer.

1. 
   redtoolbox | Oct 14, 2006 01:56am | #4

   thanks for your reply. But I have found help elsewhere.