Peerless Boilers 

Click on the picture for a larger view  The old peerless gas fired boiler notice the black carbon around the gauge. This is common with this type of boiler make sure you have a carbon monoxide detector in the house.

Does This Look Like your boiler?  All the controls are behind the front cover. So remove the cover Turn the switch to the boiler off. Warning the switch may not turn all the power off. turn off breaker too and test line to make sure power is off.

This is the old defective Aquastate relay. The relay sticks and causes the boiler not to run.
 to get this off you have to loosen the screw/nut on the top see the next picture. I had to pull the top or the boiler Jacket over to get to the screw  

once the screw is loosened push the screw down to remove the aquastate from the well. when loose enough it will pull straight out

now that it is out you have to remove all the wires. This is where I get nervous about giving further  instructions, because if you misunderstand, you can burn your house down and possible be killed.
So the only way I will give Instructions with regards to wiring an aquastate and gas valve is through my open dialog service Click here for details

  this is the well If the Aquastate relay you are replacing is a White Rogers you may have to replace the well because the old wells are to small for the new probes on the new aquastate this one was a Honeywell so I did not have to replace the well. 

This is a picture of the new aquastate the copper looking thing coming out of the back is the probe It has to go all the way into the well. this one is secured with two screws from inside the aquastate.

Taco 007 Circulator Pump

As luck would have It After I replaced the Aquastate, I found that the pump was bad too. So Now I will show you how to replace a Taco 007 circulator Pump. Again make sure the power is off. You can't trust the switch at the boiler and breakers and fuses are almost always marked wrong. test the wire it's self to be sure the power is really off.

This is the old one, See all the rust along the back of it. now The boiler needs to be drained first. so turn off the valve that supplies water to the boiler. Then hook up a hose to the drain at the bottom of the boiler. On this boiler it is on the right side but some of them are in the back where you can't reach them. What a pain this can be.

Now that the water is drained. you will need two wrenches 1 5/8" ant the other 11/16" most pump bolts are this size. Sometimes the bolts will not come loose and you have to cut them off. And in this very tight working area that can be a real Bi__h  Once again, If you don't fully understand what I am saying, Stop And call Plumbing And Heating professional.
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    with the two wrenches loosen and remove all 4 nuts and bolts. then lift up on the pipe a little and pull the pump out.

    Remove the screw remove the wire cover. Again Make sure the power is off. there are only two wires one black and one white or yellow. remove the 2 wire nuts. they should just un screw.
 

remove the wire guide And through the old pump away.

Taco 007 Pumps Have a direction of flow. Indicated by the arrow stamped on the back of the pump As a rule of thumb the pipe that goes into the boiler at the lower point is the return line and you want to pump the water from the house to the lower part of the boiler. In this case you want the arrow facing down Because the pump in on the return pipe of the boiler.
 

  Another problem, The old pump had the power supply box on the right (with the arrow pointing down But the new one has it on the left I can not install it this way because there will be no way to get to the power box with out removing the pump. So I have to spin the motor.                          

There are 4 little bolts on the front of the pump remove all 4 then turn the head 180 % and pump the screws back make sure to tighten them down evenly  

   Now it is facing the right way

Now put the wire guide on the new pump and tie the black wire to the yellow wire in the pump and the white or yellow wire to the white wire in the pump put the wire nuts back on Make sure they are tight and no wire strands are showing. put the cover back on and put the screw in.

Now put the rubber washers between the pump flanges make sure they do not get pinched and put the 4 nuts and bolts back and snug them up good but don't make them too tight and don't tighten one side more then the other. Now you have to fill the system with water and make sure you don't have any leaks. Then you will need to get the air out of the system

This is for gas fired boilers only I will be adding oil fired soon.

How Do I Know, If it is my pump that is bad? This is not a simple question. because allot of things could be the cause of a pump not running. and there can be many other reasons that you don't have heat. This may be mush more then you should try to do on your own. Maybe you should call a Pro.
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I'm just going to list some of the things that could be the problem. Every problem is unique and there is never a one reason answer for not having heat.

First the thermostat, Although they do fail, Most of the time it is not the thermostat. Many people think it's the thermostat and replace it. I look at the Thermostat last.

The First thing I do Is see what the temperature of the boiler is. If it is hot between 160 and 190 % f I know the boiler is working. If it is cold, I check to see if it is set up as a hot boiler (one that is always hot) Or a cold boiler (only gets hot if there is a call for heat) if it is set up as a hot boiler but is cold. I check pilot light 
if pilot is lit I check to see if there is power. coming to boiler If no power I check breaker.

ok so we have power and pilot is lit Boiler is set up to be hot, but boiler is cold Why? most boilers have 24v gas valves, some have 120v but most have 24v this power is supplies by a transformer the power goes through the transformer through the aquastat then through all the safety switches, rollout switches and spill switches any one of these can be tripped and or burned out. not all boilers have these safety devices the older one we worked on above does not have any. just the Aquastat I have to stop now, I have other things to do and this is going to take a long time to complete, I have a ton of free questions to answer and I have to go out a do some plumbing jobs So, To be Continued.