Category Archives: diy

Hot Water Boiler Relief Valve Leaking Problem – Fixed

This weekend I came into the house and it smelled like rusty steam. The air was humid. Also the temperature in the house dropped.

I went to the boiler and saw that the aquastat had been tripped. The aquastate was set to trip at about 220F. As its a hot water boiler and no a steam boiler the warer should really not exceed 212F.

After resetting the aquastat the boiler fired up.  About 3 minutes into the boiler running I heard a hiss from the Pressure Relief Valve(PRV) drop pipe. Water began to drip on the floor. It was only then I noticed that there was water on the floor the whole time. So I went to home depot and purchased the last PRV they had in stock for about $40. After a lot of struggling and the use of a butane torch and some banging I was able to replace the PRV. Turned on the the boiler feeling proud that the problem was solved.

Later that night around 2AM I started to feel a draft. I went to the radiator and it was cold. So back to the basement I went. I again reset the aquastat but stood there watching the boiler for some time. Again the PRV was letting out water. I wondered whether I had damaged the temperature sensitive spring inside with the butane torch. So I decided to turn down the internal temperature limit of the boiler in hopes that the pressure would not increase to the point where the PRV would release.

So I stayed there watching the boiler. Still the PRV released water.

So I looked at the built-in pressure and temperature gauge. I was able to see that the pressure in the boiler was increasing constantly as the temperature increased. Also the PRV was doing its job correctly as it released the pressure at 30psi exactly.

God inspired me to suspect the expansion tank. So I googled what are the sypmtoms of a bad expansion tank. There I found that the expansion tank is supposed to absorb approximately up to 50psi of pressure(may be different for different boilers). So I went to Lowes the next day and purchased their biggest(same size as mine) 4.4 gallon expansion tank.

Using my butane tank and a vice grip(not the best tool) as my two plumber’s wrenches were too big to grip the hex area of the tank I was able to eventually replace the existing unit.

I skipped descrition of some steps in the story: I had to drain the boiler a few times and then bleed the radiators. I also reset and reprogrammed my thermostat. I was able to get the heat to function for about 18 hours with the bad expansion tank connected but a lot of water was wasted during that time possibly up to 10 gallons. The expansion tank dropped as soon as I screwed it off as it was filled with water and heavy. I used the butane torch to dismantle the copper PRV drain pipe and to soften up the iron threads to assist removal.

So in conclusion if your PRV is leaking but the pressure gauge on the boiler says the PRV is working correctly then the PRV is fine. Its something else probably the expansion tank.

This applies to “hot water boilers” but does not apply to “hot water heaters” as they have combination Tempereture and Pressure Relief valves. You can tell the difference between the valves as the T&P valve(for heaters) has a rod sticking out of it while the PRV(for boilers) does not. 

Unrelated to fanance kinda.. Volvo S80 2.9 Alternator change

Just got my first European car Swiss to be exact. I have had Japanese and Korean so I am familiar with metric bolts. Never had a car over 4 cylinders until now though. I find I prefer the expendable nature of small 4 cylinder economy cars as I am so delicate with this one. Its a used Volvo S80 2.9 non-turbo. Recently the car would not stay running unless it was connected to another running vehicle. I took the battery to Autozone for a free test and it passed. Going through the forums and asking for help eventually got the alternator out for a free test and it failed. So that was the problem. The dealership wanted over $600 for the alternator and I got one from Ebay for $50 plus fees. Popped it back in and got back on the road. This is unrelated but I found the instructions on the forums to be somewhat inaccurate.

1. Disconnect the battery terminals(10mm and 12mm bolt)
2. Remove the cover from the computer box and the outer cover
3. Use a flat-head screwdriver to remove the plastic cap from the tensioner pulley.
4. Rotate the pulley nut now visible clockwise(14mm bolt)
5. Pull the belt off while releasing the tension from the belt.
6. Remove the plastic cap from the positive terminal on the alternator(13mm)
7. Remove the three bolts from the power steering pump(12mm)
8. Remove the 2 bolts that are at the top of the AC compressor(12mm)
9. Loosen the 2 bolts at the bottom of the AC compressor(12mm)
10. Remove the bolt holding the top of the alternator(12mm)
11. Remove the water hose at the end to the Radiator(7mm)
12. Remove the bolt from the dipstick hanger(10mm)
13. Pull the alternator out(hard) Be careful not to break anything while forcing it out.

Autozone will sell you a cheap alternator about $190+ without a pulley. You have to remove the pulley by spinning the bolt clockwise(i really mean clockwise)(24mm)with an impact wrench. Or a 10mm star tool with a special open ended 24mm wrench. There are 2 different amps available. 120A and 140A so have it handy when you visit the parts store.

Or just buy a used alternator on Ebay as the dealership will charge 500 for the alternator unit only. I got one from Ebay for $50, and it came with the pulley.

Also you could simply order a regulator(Bosh or Chinese generic) which comes with the brushes inside for $20 to $50. Swap out the old regulator and the alternator will act like new.

Photos pending.

Now for something more related. Buy shares in Pep Boys(PBY) hold and sell at the end of spring. The summer compels long distance trips, dates, racing, car shows, car sales. Its also income tax return time.