When it gets cold out, we want it to be nice and warm and toasty inside our customers’ homes, right? Well, the systems in use today do just that, they deliver heat to the areas we want to heat, and that’s a good thing. The kids are happy, the wife is happy—if the wife is happy, the husband is happy, and if all is well, you have a happy customer. So, is it possible to have too much of a good thing?
Even your happiest customer can get heated up if things go astray, when the heat will not stop. Can you guess who gets the call? Yep, it’s you. If you get a call about too much heat, the first thing to do when you walk in the building, after talking to the customer for a few minutes, is turn off the boiler switch and be sure it is operating.
We will be talking about a hydronic system here. Now you know that the system circulator(s) will not turn on before you can check the system out. Now look at the tridicator. This will give you a good idea what you will be looking for. High pressure, check diaphragm tank or expansion tank to be sure it is not waterlogged, or possibly the boiler feed valve. High temperature, check the aquastat for proper operation. If all looks good then you may have a flow valve bypassing. It is important to make sure the thermostat is not overriding, but more often than not the customer will tell you this when you get there.
O.K., you think you have a flow valve issue. You need to shut off the feed valve and close all air vents to insure the system will "pull a vacuum" when you drop the pressure. Now connect your jumper hose to the boiler drain and put the other end in a bucket where you can see the discharge. Open the drain valve and watch the pressure gauge on the tridicator. When it hits zero, the boiler should stop draining. CAUTION, THE BOILER IS NOT EMPTY, it is pulling a vacuum. If air can’t get in, water will not come out. Now close the boiler drain valve, but keep the discharge end of the jumper hose submerged in the water.
Now you unscrew the top of the flow valve and remove it to clean it. If you notice water coming out the open flow valve, you can slightly open the boiler drain to drain it. It is good to have a spare flow valve top so you can install it as a temporary stop while you clean the flow valve seat. (You can get one of these out of the junk pile of a boiler replacement.) Steel wool works very well on the brass seat.
Once it has been cleaned (bright and shiny) you are almost ready to reinstall it. Open the boiler drain valve again to make sure you still have a vacuum. Once you are sure, close the drain valve and remove the temporary flow valve top. Using a rag, insert your rag wrapped finger into the flow valve and clean any debris on the seat. CAUTION, the water in the valve will be hot! Now run your finger around the valve seat to clean any dirt on the seat. Feel the seat. It should be round and smooth. If it has any chips in the seat, the valve needs to be replaced, but this is a rare occurrence.
At this point, some technicians will pour some boiler cleaner into the flow valve, but that is a personal preference, I never felt the need for it. When done, replace the flow valve top, open valve to the expansion tank and open any air vents and then the boiler feed valve. Most of the air will either go into the expansion tank or out the air vents. Now turn the boiler switch back "on" and run the circulator to be sure all air is vented.
If this is done correctly, there is little chance of air getting to the radiators, but there is a chance. My normal procedure is to finish my cleanup and after ten minutes or so, I would ask the customer to check each radiator and feel if it is getting hot. If I needed to vent a radiator, I would rather do it while I am there now and not get the next call where there is no heat in a radiator. You will be happy, your boss will be happy AND you will again have a happy customer.
I want to take a few words here to wish all happy holidays and remember make 2012 your best year yet. Keep sending me those war stories, some of them really make my day.