How to Install an Overflow Water Tank Valve

When it comes to a do-it-yourself project, the level of complexity of the project and confidence in your ability to take on said project could determine success. For instance, take having to install a drain valve in the overflow water tank of a hot water boiler system.

I recently purchased an old row house in need of much renovation. It is livable. But, that is only because I choose to live in it. Winter was approaching and I needed to verify that the boiler was working. So, naturally I called the local utility company to come out and service it. The repairman came out, took a look at the boiler and said he could not activate it until I replaced the drain plug in the overflow tank with a drain valve, and that he would happily charge me $239.00 to replace it. I immediately accepted his estimate, thanked him for coming out and helped him to the door. I said to myself, "$239.00, I'm going to have to think about that one."

A couple of days later I went to the home improvement store. While shopping in the plumbing section, I found the drain valve the repairman required for activating my boiler system. It cost less than $6.00! He was going to charge me $239.00 to install a valve that cost less than $6.00. There is no way, "I thought", that I'm paying that kind of money to install a $6.00 valve! So, I went home to face my next do-it-yourself project.

I am not a novice do-it-yourselfer. However, I have never worked on a boiler style furnace. In fact, I have never attempted more than a simple filter replacement on any furnace. But, I was not going to pay such a high price for a simple valve installation. So, here are the steps I took to install the valve.

First, you must understand that a hot water home heating system is a closed and pressurized system. The purpose of the overflow water tank is to relieve pressure on the system. Consequently, it fills with water, and is under pressure. I began by putting a large bucket under the tank and slowly opened the drain plug, letting water drip from the tank.