Summer is almost over. The lazy days of doing the annual tune-ups and the occasional service call are over. Now is time to wake up those sleeping heating systems.
Imagine, if you will, you are one of those systems. You have been sleeping for the past few months and now someone comes and wakes you up.
You would be not unlike the bear as he awakens from his long winter nap. Now someone has the idea to turn on a switch and you get kicked in the behind with a jolt of electricity and they expect you to react like you have been raring to go all summer.
You start to pump your life’s blood, the oil, out to get burned; all is well. You start to heat up the water in your body and move it around, but you get the feeling that you are stuffed and bulging at the seams. What a relief when you get to relieve yourself via the relief valve. You say to yourself, “Someone should have emptied my bladder before they asked me to do this job.” OK, come on back to reality now, but do you get the point?
There is more to getting the system ready for the winter than simply telling the customer to turn the system on. On a lot of systems, there is still a ceiling mounted expansion tank that may be nearly full. That tank must be emptied so the system pressure can maintain itself without leaking. In order to do this it must be emptied completely! Simply taking a bucket of water out does not do the job.
Newer systems may have a diaphragm type expansion tank. Now as you may have experienced, these tanks have a mind of their own! The air on one side of the bladder trades places with the water on the other side, without ruining the bladder!
The easiest way to check this type of expansion tank, without removing it from the system, is to drop the system pressure to zero and test the amount of air pressure still in the tank. This should be equal to the required system pressure for this particular application. For example, if the building requirement is 15 psi. then the reading on the tank WITH THE SYSTEM PRESSURE AT ZERO SHOULD BE 15 psi, if the system pressure needs to be at 20 psi and the tank psi is at 15, the tank pressure is low and will probably cause you a problem.
In the past, instead of changing the tank I have added some pressure to the tank by using a bicycle pump to add pressure back to the tank. The pressure, by the way, should be checked and adjusted (as necessary) every time you install or replace a diaphragm style tank.
Now that we have the pressure checked and the expansion tank empty, comes the other half of the procedure. Remember, the system has been sitting idle for a long time. When the boiler feed valve activates to put pressure back into the system, what do you think the chances are that it will stop feeding at the correct pressure? In my experience, 50/50 at best. Well, I don’t like those odds, so I would check the pressure cut off of the boiler feed valve before I put it back into service. This is also fairly easy to do while the system is at zero.
I always had a 30 psi gauge in my tool box as well as a ½” pipe cap. I would remove the boiler feed valve while the system is at zero psi and install the pipe cap on the boiler side where the feed valve was to keep the system from losing any water. Now I will simply thread my 30 psi gauge into the boiler side of the feed valve and open the shut off valve to it. Watch the gauge. Within a few moments the gauge will read the pressure. If it stops at around 12 psi, the feed valve is good. BUT if it continues to climb to near 30 psi, you need to shut the valve to the feed valve before it ruins your gauge.
In this case, the feed valve will over feed the system and you will be back again. I, for one, would rather spend an extra 10 minutes in my customers home to solve the problem than have to return to face them since the repair I did last time did not fix it. How about you? If you do this, I can guarantee your odds of a repeat service call on an overfeeding hydronic system will be cut down to near zero. The next question is will the Flow Valve re-seat (if you have them)? You will find out rather soon, if the customer calls with a “too much heat” complaint. I have a solution for that too, while the system is at zero psi. If you want it, drop me a line at my e-mail address below.
Hey, why not send me some of your “tricks of the trade” that you have learned. Till next time, see ya.